CN113726208B - Hybrid four-level converter and low-frequency fluctuation suppression method thereof - Google Patents

Abstract

The invention discloses a hybrid four-level converter and a low-frequency fluctuation suppression method thereof, wherein the converter topology comprises three circuit structures of a hybrid active neutral point clamped four-level converter and two hybrid cascaded four-level converters, and the method comprises the following steps: 1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr The method comprises the steps of carrying out a first treatment on the surface of the 2) Capacitor C with PI regulator₂ Voltage of (2)Adjusted to 1/3U_dc The method comprises the steps of carrying out a first treatment on the surface of the 3) Calculating three-phase zero sequence voltage components; 4) Acquiring a modulation signal of a A, B, C three-phase circuit; 5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter. The invention moves the switch tube with large voltage stress to the inner side, reduces the current stress, reduces the total switching loss and is beneficial to improving the conversion efficiency of the system. In addition, the low-frequency fluctuation suppression method is not only suitable for the four-level converter topology in the patent of the invention, but also suitable for other four-level converter topologies.

Description

Hybrid four-level converter and low-frequency fluctuation suppression method thereof

Technical Field

The invention relates to the field of converters, in particular to a hybrid four-level converter and a low-frequency fluctuation suppression method thereof.

Background

The four-level converter requires a greater number of switching devices than the three-level converter, but its operating performance is significantly better than that of the three-level converter. At medium-high pressure>1.5 kV) application fields, such as photovoltaic power stations, wind power systems, large motor drive systems and the like, compared with a three-level converter, the four-level converter has smaller device voltage stress, lower output harmonic component, smaller switching loss and smaller volume of a required passive filter device. In recent years, along with the popularization of wide forbidden band devices, high-frequency high-power converters are operated at low voltage<1.5 kV) becomes a research hotspot, and the multilevel converter technology is a feasible technical scheme, so that the multilevel converter technology is hopeful to become a break of the research hotspot. The prior art has an active neutral point clamped four-level converter (4L-ANPC), as shown in fig. 1, a switching tube (S_a2 、S_a2 '、S_b2 、S_b2 '、S_c2 、S_c2 ') is 2/3 of the DC bus voltage and is subject to a large output current, thus resulting in a large voltage stressSwitching loss is unfavorable for improving the conversion efficiency of the system, and it can be seen that although the converter is compared with the traditional three-level uninterruptible power supply technical scheme, the conversion efficiency and the power density are improved. However, the balance control of the three capacitor voltages at the dc bus of the converter is realized based on an additional capacitor voltage balancing circuit, which not only increases the cost and volume of the system, but also reduces the conversion efficiency and reliability of the whole system. In addition, the capacitors C1 and C3 have larger low-frequency voltage pulsation, and the low-frequency voltage pulsation is more serious under the working condition of smaller fundamental wave frequency.

With the increasing popularity of continuous pursuit and wide bandgap devices (SiC, gaN) for high frequency high power density specifications, high power converter systems will be expected to operate at switching frequencies above 100 kHz. Under such high frequency conditions, the switching losses of the switching tube will be much larger than the conduction losses. How to reduce the switching losses of the switching tube becomes a key to improve the conversion efficiency.

Disclosure of Invention

The invention aims to provide a hybrid active neutral point clamped four-level converter, which has the following circuit structure:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_a3 Is formed on the drain electrode of the transistor. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor.

Switch tube S_a3 The grid electrode of the air conditioner is suspended. Switch tube S_a3 The source of (2) is at the A-phase output. Switch tube S_a3 Source series switching tube S_a1” Is formed on the drain electrode of the transistor. Switch tube S_a1” The grid electrode of the air conditioner is suspended. Switch tube S_a1” Source series switching tube S_a3' Is formed on the drain electrode of the transistor. Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source series switching tube S_a2 Is a source of (c). Switch tube S_a1' Source series switching tube S_a3” Is formed on the drain electrode of the transistor. Switch tube S_a3” The grid electrode of the air conditioner is suspended. Switch tube S_a3” Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_b3 Is formed on the drain electrode of the transistor. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor.

Switch tube S_b3 The grid electrode of the air conditioner is suspended. Switch tube S_b3 The source electrode of the transistor is the B phase output end. Switch tube S_b3 Source series switching tube S_b1” Is formed on the drain electrode of the transistor. Switch tube S_b1” The grid electrode of the air conditioner is suspended. Switch tube S_b1” Source series switching tube S_b3' Is formed on the drain electrode of the transistor. Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source series switching tube S_b2 Is a source of (c). Switch tube S_b1' Source series switching tube S_b3” Is formed on the drain electrode of the transistor. Switch tube S_b3” The grid electrode of the air conditioner is suspended. Switch tube S_b3” Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_c3 Is formed on the drain electrode of the transistor. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor.

Switch tube S_c3 The grid electrode of the air conditioner is suspended. Switch tube S_c3 The end of the source electrode is the C-phase output end. Switch tube S_c3 Source series switching tube S_c1” Is formed on the drain electrode of the transistor. Switch tube S_c1” The grid electrode of the air conditioner is suspended. Switch tube S_c1” Source series switching tube S_c3' Is formed on the drain electrode of the transistor. Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source series switching tube S_c2 Is a source of (c). Switch tube S_c1' Source series switching tube S_c3” Is formed on the drain electrode of the transistor. Switch tube S_c3” The grid electrode of the air conditioner is suspended. Switch tube S_c3” Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

The circuit structure of the hybrid active neutral point clamped four-level converter is as follows: recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_ap Is provided. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor.

Switch tube S_ap The grid electrode of the air conditioner is suspended. Switch tube S_ap The emitter of (2) is at the A phase output end. Switch tube S_ap Emitter series switching tube S of (C)_a1” Is formed on the drain electrode of the transistor. Switch tube S_a1” The grid electrode of the air conditioner is suspended. Switch tube S_a1” Source series switching tube S_a3' Is formed on the drain electrode of the transistor. Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source series switching tube S_a2 Is a source of (c). Switch tube S_a1' Source series switching tube S_a3” Is formed on the drain electrode of the transistor. Switch tube S_a3” The grid electrode of the air conditioner is suspended. Switch tube S_a3” Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_bp Is provided. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor.

Switch tube S_bp The grid electrode of the air conditioner is suspended. Switch tube S_bp The emitter of which is positioned at the end of the B phase output end. Switch tube S_bp Emitter series switching tube S of (C)_b1” Is formed on the drain electrode of the transistor. Switch tube S_b1” The grid electrode of the air conditioner is suspended. Switch tube S_b1” Source series switching tube S_b3' Is formed on the drain electrode of the transistor. Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source series switching tube S_b2 Is a source of (c). Switch tube S_b1' Source series switching tube S_b3” Is formed on the drain electrode of the transistor. Switch tube S_b3” The grid electrode of the air conditioner is suspended. Switch tube S_b3” Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_cp Is provided. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor.

Switch tube S_cp The grid electrode of the air conditioner is suspended. Switch tube S_cp The emitter of which is positioned at one end of the C-phase output end. Switch tube S_cp Emitter series switching tube S of (C)_c1” Is formed on the drain electrode of the transistor. Switch tube S_c1” The grid electrode of the air conditioner is suspended. Switch tube S_c1” Source series switching tube S_c3' Is formed on the drain electrode of the transistor. Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source series switching tube S_c2 Is a source of (c). Switch tube S_c1' Source series switching tube S_c3” Is formed on the drain electrode of the transistor. Switch tube S_c3” The grid electrode of the air conditioner is suspended. Switch tube S_c3” Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

The circuit structure of the hybrid active neutral point clamped four-level converter is as follows: recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_ap1 Is provided. Switch tube S_ap1 The grid electrode of the air conditioner is suspended. Switch tube S_ap1 Emitter series switching tube S of (C)_aH Is formed on the drain electrode of the transistor. Switch tube S_ap1 Emitter series switching tube S of (C)_aN1 Is provided.

Switch tube S_aH The grid electrode of the air conditioner is suspended. Switch tube S_aH The source of (2) is at the A-phase output. Switch tube S_aH Source series switching tube S_aL Is formed on the drain electrode of the transistor. Switch tube S_aL The grid electrode of the air conditioner is suspended. Switch tube S_aL Source series switching tube S_aN2 Is formed on the drain electrode of the transistor. Switch tube S_aN2 The grid electrode of the air conditioner is suspended. Switch tube S_aN2 Emitter series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_aN1 The grid electrode of the air conditioner is suspended. Switch tube S_aN1 Emitter series switching tube S of (C)_a2 Is a source of (c). Switch tube S_aN1 Emitter series switching tube S of (C)_ap2 Is formed on the drain electrode of the transistor. Switch tube S_ap2 The grid electrode of the air conditioner is suspended. Switch tube S_ap2 Emitter series switching tube S of (C)_aN2 Is provided.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_bp1 Is provided. Switch tube S_bp1 The grid electrode of the air conditioner is suspended. Switch tube S_bp1 Emitter series switching tube S of (C)_bH Is formed on the drain electrode of the transistor. Switch tube S_bp1 Emitter series switching tube S of (C)_bN1 Is provided.

Switch tube S_bH The grid electrode of the air conditioner is suspended. Switch tube S_bH The source electrode of the transistor is the B phase output end. Switch tube S_bH Source series switching tube S_bL Is formed on the drain electrode of the transistor. Switch tube S_bL The grid electrode of the air conditioner is suspended. Switch tube S_bL Source series switching tube S_bN2 Is provided. Switch tube S_bN2 The grid electrode of the air conditioner is suspended. Switch tube S_bN2 Emitter series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_bN1 The grid electrode of the air conditioner is suspended. Switch tube S_bN1 Emitter series switching tube S of (C)_b2 Is a source of (c). Switch tube S_bN1 Emitter series switching tube S of (C)_bp2 Is provided. Switch tube S_bp2 The grid electrode of the air conditioner is suspended. Switch tube S_bp2 Emitter series switching tube S of (C)_bN2 Is provided.

N₁ End series capacitor C₁ Rear connection switch tube S_cp1 Is provided. Switch tube S_cp1 The grid electrode of the air conditioner is suspended. Switch tube S_cp1 Emitter series switching tube S of (C)_cH Is formed on the drain electrode of the transistor. Switch tube S_cp1 Emitter series switching tube S of (C)_cN1 Is provided.

Switch tube S_cp The grid electrode of the air conditioner is suspended. Switch tube S_cH The end of the source electrode is the C-phase output end. Switch tube S_cH Source series switching tube S_cL Is formed on the drain electrode of the transistor. Switch tube S_cL The grid electrode of the air conditioner is suspended. Switch tube S_cL Source series switching tube S_cN2 Is provided. Switch tube S_cN2 The grid electrode of the air conditioner is suspended. Switch tube S_cN2 Emitter series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_cN1 The grid electrode of the air conditioner is suspended. Switch tube S_cN1 Emitter series switching tube S of (C)_c2 Is a source of (c). Switch tube S_cN1 Emitter series switching tube S of (C)_cp2 Is provided. Switch tube S_cp2 The grid electrode of the air conditioner is suspended. Switch tube S_cp2 Emitter series switching tube S of (C)_cN2 Is provided.

The circuit structure of the hybrid cascade four-level converter is as follows:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor. Switch tube S_a1 The source of (2) is at the A-phase output.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source series switching tube S_a2' Is formed on the drain electrode of the transistor.

Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor. Switch tube S_b1 The source electrode of the transistor is the B phase output end.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source series switching tube S_b2' Is formed on the drain electrode of the transistor.

Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor. Switch tube S_c1 The end of the source electrode is the C-phase output end.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source series switching tube S_c2' Is formed on the drain electrode of the transistor.

Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor.

N₂ End series switching tube S_a3 Is formed on the drain electrode of the transistor. Switch tube S_a3 The grid electrode of the air conditioner is suspended. Switch tube S_a3 Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

N₂ End series switching tube S_b3 Is formed on the drain electrode of the transistor. Switch tube S_b3 The grid electrode of the air conditioner is suspended. Switch tube S_b3 Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

N₂ End series switching tube S_c3 Is formed on the drain electrode of the transistor. Switch tube S_c3 Is a gate of (2)The pole is suspended. Switch tube S_c3 Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

The circuit structure of the hybrid cascade four-level converter is as follows:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor. Switch tube S_a1 Source series switching tube S_a2 Is formed on the drain electrode of the transistor.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source connection N of (2)₁ And (3) an end.

Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source electrode of (C) is connected with switch tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2 Source electrode of (C) is connected with switch tube S_a3 Is formed on the drain electrode of the transistor.

Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

Switch tube S_a3 The grid electrode of the air conditioner is suspended. Switch tube S_a3 Source electrode of (C) is connected with switch tube S_a3' Is formed on the drain electrode of the transistor. Switch tube S_a3 The source of (2) is at the A-phase output.

Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor. Switch tube S_b1 Source series switching tube S_b2 Is formed on the drain electrode of the transistor.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source connection N of (2)₁ And (3) an end.

Switch tube S_b2 Is suspended in the air of the grid electrode. Switch tube S_b2 Source electrode of (C) is connected with switch tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2 Source electrode of (C) is connected with switch tube S_b3 Is formed on the drain electrode of the transistor.

Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

Switch tube S_b3 The grid electrode of the air conditioner is suspended. Switch tube S_b3 Source electrode of (C) is connected with switch tube S_b3' Is formed on the drain electrode of the transistor. Switch tube S_b3 The source electrode of the transistor is the B phase output end.

Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor. Switch tube S_c1 Source series switching tube S_c2 Is formed on the drain electrode of the transistor.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source connection N of (2)₁ And (3) an end.

Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source electrode of (C) is connected with switch tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2 Source electrode of (C) is connected with switch tube S_c3 Is formed on the drain electrode of the transistor.

Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

Switch tube S_c3 The grid electrode of the air conditioner is suspended. Switch tube S_c3 Source electrode of (C) is connected with switch tube S_c3' Is formed on the drain electrode of the transistor. Switch tube S_c3 The end of the source electrode is the C-phase output end.

Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

The low-frequency fluctuation suppression method of the four-level converter comprises the following steps:

1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr 。

The three-phase reference voltage signal is as follows:

u_refa ＝mV_m sin(2πf_m t) (1)

u_refb ＝mV_m sin(2πf_m t-2π/3) (2)

u_refc ＝mV_m sin(2πf_m t+2π/3) (3)

where m is a modulation factor. V (V)_m Is the voltage amplitude. f (f)_m Is the fundamental frequency. u (u)_refa 、u_refb 、u_refc Is A, B, C phase reference voltage signal.

2) Capacitor C with PI regulator₂ Voltage of (2)Adjusted to 1/3U_dc 。U_dc Is the bus voltage. The input of the PI regulator is DeltaU_C2 The output is k.

Input DeltaU of PI regulator_C2 The following is shown:

3) Calculating three-phase zero sequence voltage components, namely:

wherein u is_za 、u_zb 、u_zc Is A, B, C phase zero sequence voltage component. Voltage (V)i_a 、i_b 、i_c A, B, C phase current. k (k)_z Is the scaling factor of the proportioner for calculating the zero sequence voltage.

Three-phase zero sequence voltage component for capacitance C reduction₁ And capacitor C₃ Low frequency fluctuations of (a).

4) Based on step 3), a modulation signal of the A, B, C three-phase circuit is obtained.

The modulation signal of the a-phase circuit is as follows:

u_refa1 ＝0.5u_refa –0.5min(u_refa ,u_refb ,u_refc ) (8)

u_refa2 ＝(u_refa +V_m )/k (9)

u_refa3 ＝0.5u_refa –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_za (10)

wherein u is_refa1 、u_refa2 、u_refa3 Is the modulated signal of the a-phase circuit.

The modulated signal of the B-phase circuit is as follows:

u_refb1 ＝0.5u_refb –0.5min(u_refa ,u_refb ,u_refc ) (11)

u_refb2 ＝(u_refb +V_m )/k (12)

u_refb3 ＝0.5u_refb –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zb (13)

wherein u is_refb1 、u_refb2 、u_refb3 Is a modulated signal of a B-phase circuit.

The modulation signal of the C-phase circuit is as follows:

u_refc1 ＝0.5u_refc –0.5min(u_refa ,u_refb ,u_refc ) (14)

u_refc2 ＝(u_refc +V_m )/k (15)

u_refc3 ＝0.5u_refc –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zc (16)

wherein u is_refc1 、u_refc2 、u_refc3 Is a modulated signal of a C-phase circuit.

5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter.

The invention has the technical effects that the switching tube with large voltage stress is moved to the inner side without doubt, the current stress is reduced, the total switching loss is reduced, and the conversion efficiency of the system is improved. In addition, the low-frequency voltage fluctuation suppression method is not only suitable for the four-level converter topology in the patent of the invention, but also suitable for other four-level converter topologies.

Drawings

FIG. 1 is a prior art active neutral point clamped four level converter (4L-ANPC);

FIG. 2 is a hybrid active neutral point clamped four level converter (4L-HANPC-I);

FIG. 3 is a hybrid active neutral point clamped four level converter (4L-HANPC-II);

FIG. 4 is a hybrid active neutral point clamped four level converter 4L-HANPC-III);

FIG. 5 is a hybrid cascaded four-level converter (4L-HC-I);

FIG. 6 is a hybrid cascaded four-level converter (4L-HC-II);

FIG. 7 is a low frequency ripple suppression method;

FIG. 8 is a modulation scheme for 4L-HANPC-I, 4L-HC-I and 4L-HC-II;

FIG. 9 is a modulation method of 4L-HANPC-II;

FIG. 10 shows a method of modulating 4L-HANPC-III.

Detailed Description

The present invention is further described below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples. Various substitutions and alterations are made according to the ordinary skill and familiar means of the art without departing from the technical spirit of the invention, and all such substitutions and alterations are intended to be included in the scope of the invention.

Example 1:

referring to fig. 2 and 8, the hybrid active neutral point clamped four-level converter (4L-HANPC-I) has the following circuit configuration:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_a3 Is formed on the drain electrode of the transistor. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor.

Switch tube S_a3 The grid electrode of the air conditioner is suspended. Switch tube S_a3 The source of (2) is at the A-phase output. Switch tube S_a3 Source series switching tube S_a1” Is formed on the drain electrode of the transistor. Switch tube S_a1” The grid electrode of the air conditioner is suspended. Switch tube S_a1” Source series switching tube S_a3' Is formed on the drain electrode of the transistor. Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source series switching tube S_a2 Is a source of (c). Switch tube S_a1' Source series switching tube S_a3” Is formed on the drain electrode of the transistor. Switch tube S_a3” The grid electrode of the air conditioner is suspended. Switch tube S_a3” Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_b3 Is formed on the drain electrode of the transistor. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor.

Switch tube S_b3 The grid electrode of the air conditioner is suspended. Switch tube S_b3 The source electrode of the transistor is the B phase output end. Switch tube S_b3 Source series switching tube S_b1” Is formed on the drain electrode of the transistor. Switch tube S_b1” The grid electrode of the air conditioner is suspended. Switch tube S_b1” Source series switching tube S_b3' Is formed on the drain electrode of the transistor. Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source series switching tube S_b2 Is a source of (c). Switch tube S_b1' Source series switching tube S_b3” Is formed on the drain electrode of the transistor. Switch tube S_b3” The grid electrode of the air conditioner is suspended. Switch tube S_b3” Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_c3 Is formed on the drain electrode of the transistor. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor.

Switch tube S_c3 The grid electrode of the air conditioner is suspended. Switch tube S_c3 The end of the source electrode is the C-phase output end. Switch tube S_c3 Source series switching tube S_c1” Is formed on the drain electrode of the transistor. Switch tube S_c1” The grid electrode of the air conditioner is suspended. Switch tube S_c1” Source series switching tube S_c3' Is formed on the drain electrode of the transistor. Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source series switching tube S_c2 Is a source of (c). Switch tube S_c1' Source series switching tube S_c3” Is formed on the drain electrode of the transistor. Switch tube S_c3” The grid electrode of the air conditioner is suspended. Switch tube S_c3” Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

All switching tubes are SiC switching tubes.

Each phase of 4L-HANPC-I circuit consists of 8 switching tubes, and the switching tubes work at a higher switching frequency, compared with a 4L-ANPC converter, the 4L-HANPC-I circuit moves the switching tubes with large voltage stress to the inner side, and the current stress is reduced, so that the total switching loss is reduced, and the conversion efficiency of the system is improved.

Example 2:

referring to fig. 3, a hybrid active neutral point clamped four-level converter (4L-HANPC-II) has the circuit configuration shown below: recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_ap Is provided. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor.

Switch tube S_ap The grid electrode of the air conditioner is suspended. Switch tube S_ap The emitter of (2) is at the A phase output end. Switch tube S_ap Emitter series switching tube S of (C)_a1” Is formed on the drain electrode of the transistor. Switch tube S_a1” The grid electrode of the air conditioner is suspended. Switch tube S_a1” Source series switching tube S_a3' Is formed on the drain electrode of the transistor. Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source series switching tube S_a2 Is a source of (c). Switch tube S_a1' Source series switching tube S_a3” Is formed on the drain electrode of the transistor. Switch tube S_a3” The grid electrode of the air conditioner is suspended. Switch tube S_a3” Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_bp Is provided. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor.

Switch tube S_bp The grid electrode of the air conditioner is suspended. Switch tube S_bp The emitter of which is positioned at the end of the B phase output end. Switch tube S_bp Emitter series switching tube S of (C)_b1” Is formed on the drain electrode of the transistor. Switch tube S_b1” The grid electrode of the air conditioner is suspended. Switch tube S_b1” Source series switching tube S_b3' Is formed on the drain electrode of the transistor. Switch tube S_b3' Is a gate of (2)And (5) suspending. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source series switching tube S_b2 Is a source of (c). Switch tube S_b1' Source series switching tube S_b3” Is formed on the drain electrode of the transistor. Switch tube S_b3” The grid electrode of the air conditioner is suspended. Switch tube S_b3” Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_cp Is provided. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor.

Switch tube S_cp The grid electrode of the air conditioner is suspended. Switch tube S_cp The emitter of which is positioned at one end of the C-phase output end. Switch tube S_cp Emitter series switching tube S of (C)_c1” Is formed on the drain electrode of the transistor. Switch tube S_c1” The grid electrode of the air conditioner is suspended. Switch tube S_c1” Source series switching tube S_c3' Is formed on the drain electrode of the transistor. Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source series switching tube S_c2 Is a source of (c). Switch tube S_c1' Source series switching tube S_c3” Is formed on the drain electrode of the transistor. Switch tube S_c3” The grid electrode of the air conditioner is suspended. Switch tube S_c3” Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

Except for the IGBT tube, the two transistors are all SiC switch tubes. Wherein IGBT switch tube S_aP 、S_aN 、S_bP 、S_bN 、S_cP 、S_cN All operate at the fundamental frequency. Other switching tubes operate at higher switching frequencies. Each phase of circuit consists of two IGBT switching tubes and six SiC switching tubes. Under high frequency conditions, all switching tubes of the 4L-HANPC-I topology require the use of SiC switching tube devices, the 4L-HANPC-II topology being due to the use of IGBT devicesThe cost of the device is saved.

Example 3:

referring to FIG. 4, a hybrid active neutral point clamped four-level converter (4L-HANPC-III) is shown in the circuit configuration: recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_ap1 Is provided. Switch tube S_ap1 The grid electrode of the air conditioner is suspended. Switch tube S_ap1 Emitter series switching tube S of (C)_aH Is formed on the drain electrode of the transistor. Switch tube S_ap1 Emitter series switching tube S of (C)_aN1 Is provided.

Switch tube S_aH The grid electrode of the air conditioner is suspended. Switch tube S_aH The source of (2) is at the A-phase output. Switch tube S_aH Source series switching tube S_aL Is formed on the drain electrode of the transistor. Switch tube S_aL The grid electrode of the air conditioner is suspended. Switch tube S_aL Source series switching tube S_aN2 Is formed on the drain electrode of the transistor. Switch tube S_aN2 The grid electrode of the air conditioner is suspended. Switch tube S_aN2 Emitter series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_aN1 The grid electrode of the air conditioner is suspended. Switch tube S_aN1 Emitter series switching tube S of (C)_a2 Is a source of (c). Switch tube S_aN1 Emitter series switching tube S of (C)_ap2 Is formed on the drain electrode of the transistor. Switch tube S_ap2 The grid electrode of the air conditioner is suspended. Switch tube S_ap2 Emitter series switching tube S of (C)_aN2 Is provided.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor. Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source connection N of (2)₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_bp1 Is provided. Switch tube S_bp1 The grid electrode of the air conditioner is suspended. Switch tube S_bp1 Emitter series switching tube S of (C)_bH Is formed on the drain electrode of the transistor. Switch tube S_bp1 Emitter series switching tube S of (C)_bN1 Is provided.

Switch tube S_bH The grid electrode of the air conditioner is suspended. Switch tube S_bH The source electrode of the transistor is the B phase output end. Switch tube S_bH Source series switching tube S_bL Is formed on the drain electrode of the transistor. Switch tube S_bL The grid electrode of the air conditioner is suspended. Switch tube S_bL Source series switching tube S_bN2 Is provided. Switch tube S_bN2 The grid electrode of the air conditioner is suspended. Switch tube S_bN2 Emitter series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_bN1 The grid electrode of the air conditioner is suspended. Switch tube S_bN1 Emitter series switching tube S of (C)_b2 Is a source of (c). Switch tube S_bN1 Emitter series switching tube S of (C)_bp2 Is provided. Switch tube S_bp2 The grid electrode of the air conditioner is suspended. Switch tube S_bp2 Emitter series switching tube S of (C)_bN2 Is provided.

N₁ End series capacitor C₁ Rear connection switch tube S_cp1 Is provided. Switch tube S_cp1 The grid electrode of the air conditioner is suspended. Switch tube S_cp1 Emitter series switching tube S of (C)_cH Is formed on the drain electrode of the transistor. Switch tube S_cp1 Emitter series switching tube S of (C)_cN1 Is provided.

Switch tube S_cp The grid electrode of the air conditioner is suspended. Switch tube S_cH The end of the source electrode is the C-phase output end. Switch tube S_cH Source series switching tube S_cL Is formed on the drain electrode of the transistor. Switch tubeS_cL The grid electrode of the air conditioner is suspended. Switch tube S_cL Source series switching tube S_cN2 Is provided. Switch tube S_cN2 The grid electrode of the air conditioner is suspended. Switch tube S_cN2 Emitter series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

Switch tube S_cN1 The grid electrode of the air conditioner is suspended. Switch tube S_cN1 Emitter series switching tube S of (C)_c2 Is a source of (c). Switch tube S_cN1 Emitter series switching tube S of (C)_cp2 Is provided. Switch tube S_cp2 The grid electrode of the air conditioner is suspended. Switch tube S_cp2 Emitter series switching tube S of (C)_cN2 Is provided.

Except for the IGBT tube, the two transistors are all SiC switch tubes. IGBT switch tube S_aP1 、S_aN1 、S_aP2 、S_aN2 、S_bP1 、S_bN1 、S_bP2 、S_bN2 、S_cP1 、S_cN1 、S_cP2 、S_cN2 Operating at the fundamental frequency, the other switching tubes all operate at a higher switching frequency. Each phase circuit consists of four IGBT switching tubes and four SiC switching tubes. The modulation method of the 4L-HANPC-III topology is shown in figure 7. Under high frequency conditions, the topology cost of the 4L-HANPC-III topology is lower than the device cost of both the 4L-HANPC-I and 4L-HANPC-II topologies.

Of the three four-level converter topologies 4L-HANPC-I, 4L-HANPC-II, 4L-HANPC-III, the loss of 4L-HANPC-I is minimal, the cost of 4L-HANPC-III is minimal, and 4L-HANPC-II is compromised. Therefore, in practical application, a proper circuit topology can be selected according to the technical index requirement.

Example 4:

referring to fig. 5, the hybrid cascode four-level converter (4L-HC-I) has the circuit structure shown below:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_a1' Drain of (2). Switch tube S_a1 The source of (2) is at the A-phase output.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source series switching tube S_a2' Is formed on the drain electrode of the transistor.

Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor. Switch tube S_b1 The source electrode of the transistor is the B phase output end.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source series switching tube S_b2' Is formed on the drain electrode of the transistor.

Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor. Switch tube S_c1 The end of the source electrode is the C-phase output end.

Switch tube S_c1' The grid electrode of the air conditioner is suspended. Switch tube S_c1' Source series switching tube S_c2' Is formed on the drain electrode of the transistor.

Switch tube S_c2' The grid electrode of the air conditioner is suspended. Switch tube S_c2' Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

Switch tube S_c3' The grid electrode of the air conditioner is suspended. Switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series switching tube S_a2 Is formed on the drain electrode of the transistor. Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source series switching tube S_a2' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_b2 Is formed on the drain electrode of the transistor. Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source series switching tube S_b2' Is formed on the drain electrode of the transistor.

N₁ End series switching tube S_c2 Is formed on the drain electrode of the transistor. Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source series switching tube S_c2' Is formed on the drain electrode of the transistor.

N₂ End series switching tube S_a3 Is formed on the drain electrode of the transistor. Switch tube S_a3 The grid electrode of the air conditioner is suspended. Switch tube S_a3 Source series switching tube S_a3' Is formed on the drain electrode of the transistor.

N₂ End series switching tube S_b3 Is formed on the drain electrode of the transistor. Switch tube S_b3 The grid electrode of the air conditioner is suspended. Switch tube S_b3 Source series switching tube S_b3' Is formed on the drain electrode of the transistor.

N₂ End series switching tube S_c3 Is formed on the drain electrode of the transistor. Switch tube S_c3 The grid electrode of the air conditioner is suspended. Switch tube S_c3 Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

All switching tubes are SiC switching tubes.

Example 5:

referring to fig. 6, the hybrid cascode four-level converter (4L-HC-II) has the circuit structure shown below:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ 。

N₁ End series capacitor C₁ Rear connection switch tube S_a1 Is formed on the drain electrode of the transistor. Switch tube S_a1 The grid electrode of the air conditioner is suspended. Switch tube S_a1 Source series switching tube S_a1' Is formed on the drain electrode of the transistor. Switch tube S_a1 Source series switching tube S_a2 Is formed on the drain electrode of the transistor.

Switch tube S_a1' The grid electrode of the air conditioner is suspended. Switch tube S_a1' Source connection N of (2)₁ And (3) an end.

Switch tube S_a2 The grid electrode of the air conditioner is suspended. Switch tube S_a2 Source electrode of (C) is connected with switch tube S_a2' Is formed on the drain electrode of the transistor. Switch tube S_a2 Source electrode of (C) is connected with switch tube S_a3 Is formed on the drain electrode of the transistor.

Switch tube S_a2' The grid electrode of the air conditioner is suspended. Switch tube S_a2' Source connection N of (2)₂ And (3) an end.

Switch tube S_a3 The grid electrode of the air conditioner is suspended. Switch tube S_a3 Source electrode of (C) is connected with switch tube S_a3' Is formed on the drain electrode of the transistor. Switch tube S_a3 The source of (2) is at the A-phase output.

Switch tube S_a3' The grid electrode of the air conditioner is suspended. Switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End series capacitor C₁ Rear connection switch tube S_b1 Is formed on the drain electrode of the transistor. Switch tube S_b1 The grid electrode of the air conditioner is suspended. Switch tube S_b1 Source series switching tube S_b1' Is formed on the drain electrode of the transistor. Switch tube S_b1 Source series switching tube S_b2 Is formed on the drain electrode of the transistor.

Switch tube S_b1' The grid electrode of the air conditioner is suspended. Switch tube S_b1' Source connection N of (2)₁ And (3) an end.

Switch tube S_b2 The grid electrode of the air conditioner is suspended. Switch tube S_b2 Source electrode of (C) is connected with switch tube S_b2' Is formed on the drain electrode of the transistor. Switch tube S_b2 Source electrode of (C) is connected with switch tube S_b3 Is formed on the drain electrode of the transistor.

Switch tube S_b2' The grid electrode of the air conditioner is suspended. Switch tube S_b2' Source connection N of (2)₂ And (3) an end.

Switch tube S_b3 The grid electrode of the air conditioner is suspended. Switch tube S_b3 Source electrode of (C) is connected with switch tube S_b3' Is formed on the drain electrode of the transistor. Switch tube S_b3 The source electrode of the transistor is the B phase output end.

Switch tube S_b3' The grid electrode of the air conditioner is suspended. Switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

N₁ End stringCoupling capacitor C₁ Rear connection switch tube S_c1 Is formed on the drain electrode of the transistor. Switch tube S_c1 The grid electrode of the air conditioner is suspended. Switch tube S_c1 Source series switching tube S_c1' Is formed on the drain electrode of the transistor. Switch tube S_c1 Source series switching tube S_c2 Is formed on the drain electrode of the transistor.

Switch tube S_c1′ The grid electrode of the air conditioner is suspended. Switch tube S_c1′ Source connection N of (2)₁ And (3) an end.

Switch tube S_c2 The grid electrode of the air conditioner is suspended. Switch tube S_c2 Source electrode of (C) is connected with switch tube S_c2′ Is formed on the drain electrode of the transistor. Switch tube S_c2 Source electrode of (C) is connected with switch tube S_c3 Is formed on the drain electrode of the transistor.

Switch tube S_c2′ The grid electrode of the air conditioner is suspended. Switch tube S_c2′ Source connection N of (2)₂ And (3) an end.

Switch tube S_c3 The grid electrode of the air conditioner is suspended. Switch tube S_c3 Source electrode of (C) is connected with switch tube S_c3′ Is formed on the drain electrode of the transistor. Switch tube S_c3 The end of the source electrode is the C-phase output end.

Switch tube S_c3′ The grid electrode of the air conditioner is suspended. Switch tube S_c3′ Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

All switching tubes are SiC switching tubes.

In 4L-HC-I and 4L-HC-II, each phase circuit is composed of three half-bridge circuit cascades.

Example 6:

referring to fig. 7, the low frequency ripple suppression method of the four-level converter includes the steps of:

1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr 。

The three-phase reference voltage signal is as follows:

u_refa ＝mV_m sin(2πf_m t) (1)

u_refb ＝mV_m sin(2πf_m t-2π/3) (2)

u_refc ＝mV_m sin(2πf_m t+2π/3) (3)

where m is the modulation factor. V (V)_m Is the voltage amplitude. f (f)_m Is the fundamental frequency. u (u)_refa 、u_refb 、u_refc Is A, B, C phase reference voltage signal.

2) Capacitor C with PI regulator₂ Voltage of (2)Adjusted to 1/3U_dc 。U_dc Is the bus voltage. The input of the PI regulator is DeltaU_C2 The output is denoted k.

Input DeltaU of PI regulator_C2 The following is shown:

3) Calculating three-phase zero sequence voltage components, namely:

wherein u is_za 、u_zb 、u_zc Is A, B, C phase zero sequence voltage component. Voltage (V)i_a 、i_b 、i_c A, B, C phase current. In the process of calculating zero sequence voltage, a proportional regulator is used, and the proportional coefficient is k_z ；

Three-phase zero sequence voltage component for capacitance C reduction₁ And capacitor C₃ Low frequency voltage fluctuations of (a).

4) Based on step 3), a modulation signal of the A, B, C three-phase circuit is obtained.

The modulation signal of the a-phase circuit is as follows:

u_refa1 ＝0.5u_refa –0.5min(u_refa ,u_refb ,u_refc ) (8)

u_refa2 ＝(u_refa +V_m )/k (9)

u_refa3 ＝0.5u_refa –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_za (10)

wherein u is_refa1 、u_refa2 、u_refa3 Is the modulated signal of the a-phase circuit.

The modulated signal of the B-phase circuit is as follows:

u_refb1 ＝0.5u_refb –0.5min(u_refa ,u_refb ,u_refc ) (11)

u_refb2 ＝(u_refb +V_m )/k (12)

u_refb3 ＝0.5u_refb –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zb (13)

wherein u is_refb1 、u_refb2 、u_refb3 Is a modulated signal of a B-phase circuit.

The modulation signal of the C-phase circuit is as follows:

u_refc1 ＝0.5u_refc –0.5min(u_refa ,u_refb ,u_refc ) (14)

u_refc2 ＝(u_refc +V_m )/k (15)

u_refc3 ＝0.5u_refc –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zc (16)

wherein u is_refc1 、u_refc2 、u_refc3 Is a modulated signal of a C-phase circuit.

5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter.

The embodiment provides a zero sequence voltage injection method for reducing the capacitance C₁ And C₃ At the same time, a Proportional Integral (PI) regulator is introduced to control the intermediate capacitor C₂ The purpose of balancing three capacitor voltages and having small low-frequency voltage fluctuation is achieved, and a control block diagram is shown in fig. 7.

Example 7:

referring to FIGS. 8,4L-HANPC-I, 4L-HC-II, the low frequency fluctuation suppression method includes the steps of:

1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr 。

The three-phase reference voltage signal is as follows:

u_refa ＝mV_m sin(2πf_m t) (1)

u_refb ＝mV_m sin(2πf_m t-2π/3) (2)

u_refc ＝mV_m sin(2πf_m t+2π/3) (3)

where m is a modulation factor. V (V)_m Is the voltage amplitude. f (f)_m Is the fundamental frequency. u (u)_refa 、u_refb 、u_refc Is A, B, C phase reference voltage signal.

2) Capacitor C with PI regulator₂ Voltage of (2)Adjusted to 1/3U_dc 。U_dc Is the bus voltage. The input of the PI regulator is DeltaU_C2 The output is k.

Input DeltaU of PI regulator_C2 The following is shown:

3) Calculating three-phase zero sequence voltage components, namely:

wherein u is_za 、u_zb 、u_zc Is A, B, C phase zero sequence voltage component. Voltage deltai_a 、i_b 、i_c A, B, C phase current. In the process of calculating zero sequence voltage, a proportional regulator is used, and the proportional coefficient is k_z ；

Three-phase zero sequence voltage component for capacitance C reduction₁ And capacitor C₃ Low frequency voltage fluctuations of (a).

4) Based on step 3), a modulation signal of the A, B, C three-phase circuit is obtained.

The modulation signal of the a-phase circuit is as follows:

u_refa1 ＝0.5u_refa -0.5min(u_refa ，u_refb ，u_refc ) (8)

u_refa2 ＝(u_refa +V_m )/k (9)

u_refa3 ＝0.5u_refa -0.5max(u_refa ，u_refb ，u_refc )+V_m +u_za (10)

wherein u is_refa1 、u_refa2 、u_refa3 Is the modulated signal of the a-phase circuit.

The modulated signal of the B-phase circuit is as follows:

u_refb1 ＝0.5u_refb -0.5min(u_refa ，u_refb ，u_retc ) (11)

u_refb2 ＝(u_refb +V_m )/k (12)

u_refb3 ＝0.5u_refb -0.5max(u_refa ，u_refb ，u_refc )+V_m +u_zb (13)

wherein u is_refb1 、u_refb2 、u_refb3 Is a modulated signal of a B-phase circuit.

The modulation signal of the C-phase circuit is as follows:

u_refc1 ＝0.5u_refc -0.5min(u_refa ，u_refb ，u_refc ) (14)

u_refc2 ＝(u_refc +V_m )/k (15)

u_refc3 ＝0.5u_refc -0.5max(u_refa ，u_refb ，u_refc )+V_m +u_zc (16)

wherein u is_refc1 、u_refc2 、u_refc3 Is a modulated signal of a C-phase circuit.

5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter. In particular, if u is present_refa1 ≥V_carr Then the switch tube S is turned on_a1 Otherwise, turn on the switching tube S_a1′ Switch tube S_a1″ 。

If u is present_refa2 ≥V_carr Then the switch tube S is turned on_a2 Otherwise, turn on the switching tube S_a2′ 。

If u is present_refa3 ≥V_carr Then the switch tube S is turned on_a3 Switch tube S_a3″ Otherwise, turn on the switching tube S_a3′ 。

If u is present_refb1 ≥V_carr Then the switch tube S is turned on_b1 Otherwise, turn on the switching tube S_b1′ Switch tube S_b1″ 。

If u is present_refb2 ≥V_carr Then the switch tube S is turned on_b2 Otherwise, turn on the switching tube S_b2′ 。

If u is present_refb3 ≥V_carr Then the switch tube S is turned on_b3 Switch tube S_b3″ Otherwise, turn on the switching tube S_b3′ 。

If u is present_refc1 ≥V_carr Then the switch tube S is turned on_c1 Otherwise, turn on the switching tube S_c1′ Switch tube S_c1″ 。

If u is present_refc2 ≥V_carr Then the switch tube S is turned on_c2 Otherwise, turn on the switching tube S_c2′ 。

If u is present_refc3 ≥V_carr Then the switch tube S is turned on_c3 Switch tube S_c3″ Otherwise, turn on the switching tube S_c3′ 。

Example 8:

referring to fig. 9, the low frequency ripple suppression method of the hybrid active neutral point clamped four-level converter (4L-HANPC-II) includes the steps of:

1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr 。

The three-phase reference voltage signal is as follows:

u_refa ＝mV_m sin(2πf_m t) (1)

u_refb ＝mV_m sin(2πf_m t-2π/3) (2)

u_refc ＝mV_m sin(2πf_m t+2π/3) (3)

where m is a modulation factor. V (V)_m Is the voltage amplitude. f (f)_m Is the fundamental frequency. u (u)_refa 、u_refb 、u_refc Is A, B, C phase reference voltage signal.

2) Capacitor C with PI regulator₂ Voltage of (2)Adjusted to 1/3U_dc 。U_dc Is the bus voltage. The input of the PI regulator is DeltaU_C2 The output is k.

Input DeltaU of PI regulator_C2 The following is shown:

3) Calculating three-phase zero sequence voltage components, namely:

wherein u is_za 、u_zb 、u_zc Is A, B, C phase zero sequence voltage component. Voltage (V)i_a 、i_b 、i_c A, B, C phase current. In the process of calculating zero sequence voltage, a proportional regulator is used, and the proportional coefficient is k_z ；/>

Three-phase zero sequence voltage component for capacitance C reduction₁ And capacitor C₃ Low frequency voltage fluctuations of (a).

4) Based on step 3), a modulation signal of the A, B, C three-phase circuit is obtained.

The modulation signal of the a-phase circuit is as follows:

u_refa1 ＝0.5u_refa -0.5min(u_refa ，u_refb ，u_refc ) (8)

u_refa2 ＝(u_refa +V_m )/k (9)

u_refa3 ＝0.5u_refa -0.5max(u_refa ，u_refb ，u_refc )+V_m +u_za (10)

wherein u is_refa1 、u_refa2 、u_refa3 Is the modulated signal of the a-phase circuit.

The modulated signal of the B-phase circuit is as follows:

u_refb1 ＝0.5u_refb -0.5min(u_refa ，u_refb ，u_refc ) (11)

u_refb2 ＝(u_refb +V_m )/k (12)

u_refb3 ＝0.5u_refb -0.5max(u_refa ，u_refb ，u_refc )+V_m +u_zb (13)

wherein u is_refb1 、u_refb2 、u_refb3 Is a modulated signal of a B-phase circuit.

The modulation signal of the C-phase circuit is as follows:

u_refc1 ＝0.5u_refc -0.5min(u_refa ，u_refb ，u_refc ) (14)

u_refc2 ＝(u_refc +V_m )/k (15)

u_refc3 ＝0.5u_refc -0.5max(u_refa ，u_refb ，u_refc )+V_m +u_zc (16)

Wherein u is_refc1 、u_refc2 、u_refc3 Is a modulated signal of a C-phase circuit.

5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter. In particular, the method comprises the steps of,

if u is present_refa More than or equal to 0, the switch tube S is turned on_ap Otherwise, turn on the switching tube S_aN 。

If u is present_refa1 ≥V_carr Then the switch tube S is turned on_a1 Otherwise, turn on the switching tube S_al′ 。

If u is present_refa2 ≥V_carr Then the switch tube S is turned on_a2 Otherwise, turn on the switching tube S_a2′ 。

If u is present_refa3 ≥V_carr Then the switch tube S is turned on_a3 Otherwise, turn on the switching tube S_a3′ 。

If u is present_refb More than or equal to 0, the switch tube S is turned on_bp Otherwise, turn on the switching tube S_bN 。

If u is present_refb1 ≥V_carr Then the switch tube S is turned on_b1 Otherwise, turn on the switching tube S_b1′ 。

If u is present_refb2 ≥V_carr Then the switch tube S is turned on_b2 Otherwise, turn on the switching tube S_b2′ 。

If u is present_refb3 ≥V_carr Then the switch tube S is turned on_b3 Otherwise, turn on the switching tube S_b3′ 。

If u is present_refc More than or equal to 0, the switch tube S is turned on_cp Otherwise, turn on the switching tube S_cN 。

If u is present_refc1 ≥V_carr Then the switch tube S is turned on_c1 Otherwise, turn on the switching tube S_c1′ 。

If u is present_refc2 ≥V_carr Then the switch tube S is turned on_c2 Otherwise, turn on the switching tube S_c2′ 。

If u is present_refc3 ≥V_carr Then the switch tube S is turned on_c3 Otherwise, turn on the switching tube S_c3′ 。

The modulation method of the 4L-HANPC-II topology is that zero crossing fundamental wave signal modulation, namely a switching tube S, is added on the basis of the modulation method shown in figure 8_aP 、S_aN 、S_bP 、S_bN 、S_cP 、S_cN Is a modulation of (a).

Example 9:

referring to fig. 10, the low frequency ripple suppression method of the hybrid active neutral point clamped four-level converter (4L-HANPC-III) includes the steps of:

1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr 。

The three-phase reference voltage signal is as follows:

u_refa ＝mV_m sin(2πf_m t) (1)

u_refb ＝mV_m sin(2πf_m t-2π/3) (2)

u_refc ＝mV_m sin(2πf_m t+2π/3) (3)

where m is a modulation factor. V (V)_m Is the voltage amplitude. f (f)_m Is the fundamental frequency. u (u)_refa 、u_refb 、u_refc Is A, B, C phase reference voltage signal.

2) Capacitor C with PI regulator₂ Voltage of (2)Adjusted to 1/3U_dc 。U_dc Is the bus voltage. The input of the PI regulator is DeltaU_C2 The output is k.

Input DeltaU of PI regulator_C2 The following is shown:

3) Calculating three-phase zero sequence voltage components, namely:

wherein u is_za 、u_zb 、u_zc Is A, B, C phase zero sequence voltage component. Voltage (V)i_a 、i_b 、i_c A, B, C phase current. A proportioner is used in the calculation of the zero sequence voltage,the proportionality coefficient is k_z ；

Three-phase zero sequence voltage component for capacitance C reduction₁ And capacitor C₃ Low frequency voltage fluctuations of (a).

4) Based on step 3), a modulation signal of the A, B, C three-phase circuit is obtained.

The modulation signal of the a-phase circuit is as follows:

u_refa1 ＝0.5u_refa –0.5min(u_refa ,u_refb ,u_refc ) (8)

u_refa2 ＝(u_refa +V_m )/k (9)

u_refa3 ＝0.5u_refa –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_za (10)

wherein u is_refa1 、u_refa2 、u_refa3 Is the modulated signal of the a-phase circuit.

The modulated signal of the B-phase circuit is as follows:

u_refb1 ＝0.5u_refb –0.5min(u_refa ,u_refb ,u_refc ) (11)

u_refb2 ＝(u_refb +V_m )/k (12)

u_refb3 ＝0.5u_refb –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zb (13)

wherein u is_refb1 、u_refb2 、u_refb3 Is a modulated signal of a B-phase circuit.

The modulation signal of the C-phase circuit is as follows:

u_refc1 ＝0.5u_refc –0.5min(u_refa ,u_refb ,u_refc ) (14)

u_refc2 ＝(u_refc +V_m )/k (15)

u_refc3 ＝0.5u_refc –0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zc (16)

wherein u is_refc1 、u_refc2 、u_refc3 Is a modulated signal of a C-phase circuit.

5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter. In particular, the method comprises the steps of,

if u is present_refa More than or equal to 0, the switch tube S is turned on_ap1 And a switch tube S_ap2 Otherwise, turn on the switching tube S_aN1 And a switch tube S_aN2 。

If the switch tube S_aN1 Switch tube S_aN2 Switch tube S_a3 All are conducted, or the switch tube S_ap1 Switch tube S_ap2 Switch tube S_a1 All are conducted, the switch tube S is conducted_aH Otherwise, switch tube S_aL 。

If u is present_refa2 ≥V_carr Then the switch tube S is turned on_a2 Otherwise, turn on the switching tube S_a2' 。

If u is present_refa3 ≥V_carr Then the switch tube S is turned on_a3 Switch tube S_a3” Otherwise, turn on the switching tube S_a3' 。

If u is present_refb More than or equal to 0, the switch tube S is turned on_bp1 And a switch tube S_bp2 Otherwise, turn on the switching tube S_bN1 And a switch tube S_bN2 。

If the switch tube S_bN1 Switch tube S_bN2 Switch tube S_b3 All are conducted, or the switch tube S_bp1 Switch tube S_bp2 Switch tube S_b1 All are conducted, the switch tube S is conducted_bH Otherwise, switch tube S_bL 。

If u is present_refb1 ≥V_carr Then the switch tube S is turned on_b1 Otherwise, turn on the switching tube S_b1' Switch tube S_b1” 。

If u is present_refb2 ≥V_carr Then the switch tube S is turned on_b2 Otherwise, turn on the switching tube S_b2' 。

If u is present_refb3 ≥V_carr Then the switch is turned on Tube S_b3 Switch tube S_b3” Otherwise, turn on the switching tube S_b3' 。

If u is present_refc More than or equal to 0, the switch tube S is turned on_cp1 And a switch tube S_cp2 Otherwise, turn on the switching tube S_cN1 And a switch tube S_cN2 。

If the switch tube S_cN1 Switch tube S_cN2 Switch tube S_c3 All are conducted, or the switch tube S_cp1 Switch tube S_cp2 Switch tube S_c1 All are conducted, the switch tube S is conducted_cH Otherwise, switch tube S_cL 。

If u is present_refc1 ≥V_carr Then the switch tube S is turned on_c1 Otherwise, turn on the switching tube S_c1' Switch tube S_c1” 。

If u is present_refc2 ≥V_carr Then the switch tube S is turned on_c2 Otherwise, turn on the switching tube S_c2' 。

If u is present_refc3 ≥V_carr Then the switch tube S is turned on_c3 Switch tube S_c3” Otherwise, turn on the switching tube S_c3' 。

Claims (5)

1. The hybrid cascade four-level converter is characterized by comprising the following circuit structure:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ ；

N₁ End series capacitor C₁ Rear connection switch tube S_a1 A drain electrode of (2); switch tube S_a1 The grid electrode of the upper part is suspended; switch tube S_a1 Source series switching tube S_a1' A drain electrode of (2); switch tube S_a1 The end of the source electrode is the A phase output end;

switch tube S_a1' The grid electrode of the upper part is suspended; switch tube S_a1' Source series switching tube S_a2' A drain electrode of (2);

switch tube S_a2' The grid electrode of the upper part is suspended; switch tube S_a2' Source series switching tube S_a3' A drain electrode of (2);

switch tube S_a3' The grid electrode of the upper part is suspended; switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ An end;

N₁ end series capacitor C₁ Rear connection switch tube S_b1 A drain electrode of (2); switch tube S_b1 The grid electrode of the upper part is suspended; switch tube S_b1 Source series switching tube S_b1' A drain electrode of (2); switch tube S_b1 The end of the source electrode is a B phase output end;

switch tube S_b1' The grid electrode of the upper part is suspended; switch tube S_b1' Source series switching tube S_b2' A drain electrode of (2);

switch tube S_b2' The grid electrode of the upper part is suspended; switch tube S_b2' Source series switching tube S_b3' A drain electrode of (2);

switch tube S_b3' The grid electrode of the upper part is suspended; switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ An end;

N₁ end series capacitor C₁ Rear connection switch tube S_c1 A drain electrode of (2); switch tube S_c1 The grid electrode of the upper part is suspended; switch tube S_c1 Source series switching tube S_c1' A drain electrode of (2); switch tube S_c1 The end of the source electrode is a C-phase output end;

switch tube S_c1' The grid electrode of the upper part is suspended; switch tube S_c1' Source series switching tube S_c2' A drain electrode of (2);

switch tube S_c2' The grid electrode of the upper part is suspended; switch tube S_c2' Source series switching tube S_c3' A drain electrode of (2);

switch tube S_c3' The grid electrode of the upper part is suspended; switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ An end;

N₁ end series switching tube S_a2 A drain electrode of (2); switch tube S_a2 The grid electrode of the upper part is suspended; switch tube S_a2 Source series switching tube S_a2' A drain electrode of (2);

N₁ end series switching tube S_b2 A drain electrode of (2); switch tube S_b2 The grid electrode of the upper part is suspended; switch tube S_b2 Source series switching tube S_b2' A drain electrode of (2);

N₁ end series switching tube S_c2 A drain electrode of (2); switch tube S_c2 The grid electrode of the upper part is suspended; switch tube S_c2 Source series switching tube S_c2' A drain electrode of (2);

N₂ end series switching tube S_a3 A drain electrode of (2); switch tube S_a3 The grid electrode of the upper part is suspended; switch tube S_a3 Source series switching tube S_a3' A drain electrode of (2);

N₂ end series switching tube S_b3 A drain electrode of (2); switch tube S_b3 The grid electrode of the upper part is suspended; switch tube S_b3 Source series switching tube S_b3' A drain electrode of (2);

N₂ end series switching tube S_c3 A drain electrode of (2); switch tube S_c3 The grid electrode of the upper part is suspended; switch tube S_c3 Source series switching tube S_c3' Is formed on the drain electrode of the transistor.

2. The hybrid cascade four-level converter is characterized by comprising the following circuit structure:

recording capacitor C₂ And capacitor C₁ One end connected with N₁ And capacitor C₃ One end connected with N₂ ；

N₁ End series capacitor C₁ Rear connection switch tube S_a1 A drain electrode of (2); switch tube S_a1 The grid electrode of the upper part is suspended; switch tube S_a1 Source series switching tube S_a1' A drain electrode of (2); switch tube S_a1 Source series switching tube S_a2 A drain electrode of (2);

switch tube S_a1' The grid electrode of the upper part is suspended; switch tube S_a1' Source connection N of (2)₁ An end;

switch tube S_a2 The grid electrode of the upper part is suspended; switch tube S_a2 Source electrode of (C) is connected with switch tube S_a2' A drain electrode of (2); switch tube S_a2 Source electrode of (C) is connected with switch tube S_a3 A drain electrode of (2);

Switch tube S_a2' The grid electrode of the upper part is suspended; switch tube S_a2' Source connection N of (2)₂ An end;

switch tube S_a3 The grid electrode of the upper part is suspended; switch tube S_a3 Source electrode of (C) is connected with switch tube S_a3' A drain electrode of (2); switch tube S_a3 The end of the source electrode is the A phase output end;

switch tube S_a3' The grid electrode of the upper part is suspended; switch tube S_a3' Source series capacitance C of (2)₃ Rear connection N₂ An end;

N₁ end series capacitor C₁ Rear connection switch tube S_b1 A drain electrode of (2); switch tube S_b1 The grid electrode of the upper part is suspended; switch tube S_b1 Source series switching tube S_b1' A drain electrode of (2); switch tube S_b1 Source series switching tube S_b2 A drain electrode of (2);

switch tube S_b1' The grid electrode of the upper part is suspended; switch tube S_b1' Source connection N of (2)₁ An end;

switch tube S_b2 The grid electrode of the upper part is suspended; switch tube S_b2 Source electrode of (C) is connected with switch tube S_b2' A drain electrode of (2); switch tube S_b2 Source electrode of (C) is connected with switch tube S_b3 A drain electrode of (2);

switch tube S_b2' The grid electrode of the upper part is suspended; switch tube S_b2' Source connection N of (2)₂ An end;

switch tube S_b3 The grid electrode of the upper part is suspended; switch tube S_b3 Source electrode of (C) is connected with switch tube S_b3' A drain electrode of (2); switch tube S_b3 The end of the source electrode is a B phase output end;

switch tube S_b3' The grid electrode of the upper part is suspended; switch tube S_b3' Source series capacitance C of (2)₃ Rear connection N₂ An end;

N₁ end series capacitor C₁ Rear connection switch tube S_c1 A drain electrode of (2); switch tube S_c1 The grid electrode of the upper part is suspended; switch tube S_c1 Source series switching tube S_c1' A drain electrode of (2); switch tube S_c1 Source series switching tube S_c2 A drain electrode of (2);

switch tube S_c1' The grid electrode of the upper part is suspended; switch tube S_c1' Source connection N of (2)₁ An end;

switch tube S_c2 The grid electrode of the upper part is suspended; switch tube S_c2 Source electrode of (C) is connected with switch tube S_c2' A drain electrode of (2); switch tube S_c2 Source electrode of (C) is connected with switch tube S_c3 A drain electrode of (2);

switch tube S_c2' The grid electrode of the upper part is suspended; switch tube S_c2' Source connection N of (2)₂ An end;

switch tube S_c3 The grid electrode of the upper part is suspended; switch tube S_c3 Source electrode of (C) is connected with switch tube S_c3' A drain electrode of (2); switch tube S_c3 The end of the source electrode is a C-phase output end;

switch tube S_c3' The grid electrode of the upper part is suspended; switch tube S_c3' Source series capacitance C of (2)₃ Rear connection N₂ And (3) an end.

3. The low frequency ripple suppression method of the four-level converter according to any one of claims 1 to 2, characterized by comprising the steps of:

1) Determining a three-phase reference voltage signal and a triangular carrier signal V_carr ；

The three-phase reference voltage signal is as follows:

u_refa ＝mV_m sin(2πf_m t) (1)

u_refb ＝mV_m sin(2πf_m t-2π/3) (2)

u_refc ＝mV_m sin(2πf_m t+2π/3) (3)

wherein m is a modulation factor; v (V)_m Is the voltage amplitude; f (f)_m Is the fundamental frequency; u (u)_refa 、u_refb 、u_refc A, B, C phase reference voltage signals, respectively;

2) Using PI regulators to regulate the voltage U of the capacitor C2_C2 Adjusted to 1/3U_dc ；U_dc Is the bus voltage; the input of the PI regulator is DeltaU_C2 The output is k;

input DeltaU of PI regulator_C2 The following is shown:

ΔU_C2 ＝1/3U_sc -U_C2 (4)

3) Calculating three-phase zero sequence voltage components, namely:

Wherein u is_za 、u_zb 、u_zc A, B, C phase zero sequence voltage component; deltaU_C13 Representing the voltage; i.e_a 、i_b 、i_c A, B, C phase current; k (k)_z Scaling factor for a scaling factor for calculating zero sequence voltage;

4) Acquiring a modulation signal of the A, B, C three-phase circuit based on the step 3);

the modulation signal of the a-phase circuit is as follows:

u_refa1 ＝0.5u_refa -0.5min(u_refa ,u_refb ,u_refc ) (8)

u_refa2 ＝(u_refa +V_m )/k (9)

u_refa3 ＝0.5u_refa -0.5max(u_refa ,u_refb ,u_refc )+V_m +u_za (10)

wherein u is_refa1 、u_refa2 、u_refa3 A modulation signal for the a-phase circuit;

the modulated signal of the B-phase circuit is as follows:

u_refb1 ＝0.5u_refb -0.5min(u_refa ,u_refb ,u_refc ) (11)

u_refb2 ＝(u_refb +V_m )/k (12)

u_refb3 ＝0.5u_refb -0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zb (13)

wherein u is_refb1 、u_refb2 、u_refb3 A modulation signal for a B-phase circuit;

the modulation signal of the C-phase circuit is as follows:

u_refc1 ＝0.5u_refc -0.5min(u_refa ,u_refb ,u_refc ) (14)

u_refc2 ＝(u_refc +V_m )/k (15)

u_refc3 ＝0.5u_refc -0.5max(u_refa ,u_refb ,u_refc )+V_m +u_zc (16)

wherein u is_refc1 、u_refc2 、u_refc3 A modulation signal for a C-phase circuit;

5) According to the modulated signal of A, B, C three-phase circuit and the triangular carrier signal V_carr And controlling the on-off of all switching tubes in the four-level converter.

4. A method of low frequency ripple suppression in a four-level converter according to claim 3, characterized in that three-phase zero sequence voltage components are used to reduce capacitance C₁ And capacitor C₃ Low frequency fluctuations of (a).

5. A method for suppressing low frequency ripple of a four-level converter according to claim 3, wherein the voltage Δu is_C13 ＝U_C1 -U_C3 。