CN1595780A - Control method and apparatus for series resonance DC/DC converter - Google Patents

Abstract

Translated fromChinese

本发明公开了一种串联谐振直流/直流变换器的控制方法及装置，该装置包括驱动电路、串联谐振电路、PI调节器、甄别器、脉宽调制电路和变频控制电路。所述方法为：从负载电路采样反馈信号，对该反馈信号进行比例积分变换，根据比例积分变换结果确定负载的工作状态；当确定负载电路工作在轻载或空载状态时，则将频率稳定而占空比随反馈信号变化的脉宽调制(PWM)信号作为驱动电路的驱动脉冲，使串联谐振电路工作在脉宽调制控制状态；否则，将占空比稳定而频率随反馈信号变化的脉冲信号作为所述驱动电路的驱动脉冲，使串联谐振电路工作在变频控制状态。

The invention discloses a control method and device for a series resonant direct current/direct current converter. The device comprises a drive circuit, a series resonant circuit, a PI regulator, a discriminator, a pulse width modulation circuit and a frequency conversion control circuit. The method is as follows: sampling the feedback signal from the load circuit, performing proportional-integral transformation on the feedback signal, and determining the working state of the load according to the result of the proportional-integral transformation; The pulse width modulation (PWM) signal whose duty cycle changes with the feedback signal is used as the driving pulse of the drive circuit to make the series resonant circuit work in the pulse width modulation control state; otherwise, the pulse with a stable duty cycle and a frequency that changes with the feedback signal The signal is used as a driving pulse of the driving circuit to make the series resonant circuit work in a variable frequency control state.

Description

Translated fromChinese

串联谐振直流/直流变换器的控制方法及装置Control method and device for series resonant DC/DC converter

技术领域technical field

本发明涉及直流电源变换技术，尤其涉及一种串联谐振直流/直流(DC/DC)变换器的控制方法及其装置。The invention relates to DC power conversion technology, in particular to a control method and device for a series resonant DC/DC (DC/DC) converter.

背景技术Background technique

小型化和高频化是当今电源发展的趋势，但是开关频率太高带来了开关管损耗过大的问题，这是传统BUCK变换器所解决不了的，而串联谐振变换器可以较好的解决这个问题。Miniaturization and high frequency are the development trend of power supply today, but the switching frequency is too high to bring about the problem of excessive loss of the switching tube, which cannot be solved by the traditional BUCK converter, but the series resonant converter can better solve it this problem.

串联谐振DC/DC变换器采用谐振变换技术，由于谐振元件工作在正弦谐振状态，开关管上的电压自然过零，可以实现零电压开通，电源损耗很小。这种拓扑通常采用变频调制方式，通过改变工作频率来稳定输出电压。图1是LLC串联谐振DC/DC变换器的基本形式，电源输出电压增益M与工作频率的关系为：The series resonant DC/DC converter adopts resonant conversion technology. Since the resonant element works in a sinusoidal resonant state, the voltage on the switching tube naturally crosses zero, which can realize zero-voltage turn-on, and the power loss is very small. This topology usually uses variable frequency modulation to stabilize the output voltage by changing the operating frequency. Figure 1 is the basic form of the LLC series resonant DC/DC converter. The relationship between the output voltage gain M of the power supply and the operating frequency is:

$\mathrm{<span><span>M</span>m</span>}<span><span>=</span>=</span>\frac{{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>o</span>o</span>}}}{{\mathrm{<span><span>U</span>u</span>}}_{\mathrm{<span><span>i</span>i</span>}}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>0.5</span>0.5</span>}}{\sqrt{<span><span>\{</span>\{</span>\mathrm{<span><span>1</span>1</span>}<span><span>+</span>+</span>\frac{{\mathrm{<span><span>L</span>L</span>}}_{\mathrm{<span><span>r</span>r</span>}}}{{\mathrm{<span><span>L</span>L</span>}}_{\mathrm{<span><span>p</span>p</span>}}}{<span><span>[</span>[</span>\mathrm{<span><span>1</span>1</span>}<span><span>-</span>-</span>{<span><span>(</span>(</span>\frac{{\mathrm{<span><span>f</span>f</span>}}_{\mathrm{<span><span>o</span>o</span>}}}{\mathrm{<span><span>f</span>f</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}<span><span>]</span>]</span>}^{\mathrm{<span><span>2</span>2</span>}}<span><span>+</span>+</span>{\mathrm{<span><span>Qs</span>Qs</span>}}^{\mathrm{<span><span>2</span>2</span>}}{<span><span>(</span>(</span>\frac{\mathrm{<span><span>f</span>f</span>}}{{\mathrm{<span><span>f</span>f</span>}}_{\mathrm{<span><span>o</span>o</span>}}}<span><span>-</span>-</span>\frac{{\mathrm{<span><span>f</span>f</span>}}_{\mathrm{<span><span>o</span>o</span>}}}{\mathrm{<span><span>f</span>f</span>}}<span><span>)</span>)</span>}^{\mathrm{<span><span>2</span>2</span>}}}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>1</span>1</span>}<span><span>)</span>)</span>$

其中，Lr为谐振电感值，Lp为主变压器励磁电感值，f为工作频率，Cr为谐振电容值，Po为输出功率，$f_o=\frac{1}{2\mathrm{\&pi;}\sqrt{\mathrm{Lr}*\mathrm{Cr}}},\mathrm{Qs}=\frac{2\mathrm{\&pi;}{f}_o{L}_r{P}_o}{{U_o}^2}.$Among them, Lr is the resonant inductance value, Lp is the excitation inductance value of the main transformer, f is the operating frequency, Cr is the resonant capacitance value, Po is the output power,$f_o=\frac{1}{2\mathrm{\&pi;}\sqrt{\mathrm{Lr}*\mathrm{Cr}}},\mathrm{Qs}=\frac{2\mathrm{\&pi;}{f}_o{L}_r{P}_o}{{u_o}^2}.$

从式(1)中可以发现工作频率越大，电压增益M越小。From formula (1), it can be found that the greater the operating frequency, the smaller the voltage gain M.

串联谐振变换器一个主要的难点问题在于在轻载和空载条件下输出电压难以稳定。串联谐振拓扑的输出电压随着开关频率升高而下降，当负载减小至轻载或空载状态时，输出电压会上升很多。这样为了稳定电压，工作频率需要升得很高，但是工作频率范围过宽会带来磁性元件难以优化的问题，而且工作频率越高，电路损耗也越大。在电源行业中，有人在输出端加上固定的负载，利用这种办法在轻载和空载条件下稳定输出电压，但这样会增加空载损耗，降低电源效率。A major difficulty of the series resonant converter is that the output voltage is difficult to stabilize under light-load and no-load conditions. The output voltage of the series resonant topology decreases as the switching frequency increases, and when the load is reduced to light load or no-load state, the output voltage will rise a lot. In this way, in order to stabilize the voltage, the operating frequency needs to be increased very high, but too wide an operating frequency range will cause the problem that the magnetic components are difficult to optimize, and the higher the operating frequency, the greater the circuit loss. In the power supply industry, some people add a fixed load to the output, and use this method to stabilize the output voltage under light load and no-load conditions, but this will increase the no-load loss and reduce the power supply efficiency.

总之，单纯的变频控制会导致工作频率范围过宽，带来磁性元件难以优化和电路损耗过大的问题，所以简单的调频控制无法满足轻载或空载时输出稳压的要求。In short, pure frequency conversion control will lead to too wide operating frequency range, which will lead to problems of difficult optimization of magnetic components and excessive circuit loss. Therefore, simple frequency modulation control cannot meet the requirements of output voltage regulation at light load or no load.

发明内容Contents of the invention

本发明的目的在于提供一种串联谐振直流/直流(DC/DC)变换器的控制方法及其装置，以解决现有技术中负载工作在轻载或空载时采用调频控制存在磁性元件难以优化和电路损耗过大的问题。The purpose of the present invention is to provide a series resonant direct current/direct current (DC/DC) converter control method and its device, in order to solve the problems in the prior art that the magnetic components are difficult to optimize when the load is under light load or no load, and the frequency modulation control is used And the problem of excessive circuit loss.

为解决上述问题，本发明提供以下技术方案：In order to solve the above problems, the present invention provides the following technical solutions:

一种串联谐振直流/直流变换器的控制方法，所述DC/DC变换器包括驱动电路和串联谐振电路，驱动电路根据接收的驱动脉冲产生控制信号，该控制信号控制串联谐振电路向负载提供功率流并使串联谐振电路的输出电压保持稳定；所述方法为：A control method for a series resonant DC/DC converter, the DC/DC converter includes a drive circuit and a series resonant circuit, the drive circuit generates a control signal according to received drive pulses, and the control signal controls the series resonant circuit to provide power to a load flow and stabilize the output voltage of the series resonant circuit; the method is:

从负载电路中采样反馈电压；Sampling the feedback voltage from the load circuit;

将所述反馈电压进行比例积分运算；performing a proportional-integral operation on the feedback voltage;

根据比例积分运算的结果判断负载是否工作在轻载或空载状态；Judging whether the load is working under light load or no load according to the result of proportional integral calculation;

如果负载工作在轻载或空载状态，则由频率稳定而占空比随反馈信号变化的脉宽调制(PWM)信号作为所述驱动电路的驱动脉冲，使串联谐振电路工作在脉宽调制控制状态；否则，由占空比稳定而频率随反馈信号变化的脉冲信号作为所述驱动电路的驱动脉冲，使串联谐振电路工作在变频控制状态。If the load works in light load or no load state, the pulse width modulation (PWM) signal whose frequency is stable and whose duty ratio changes with the feedback signal is used as the driving pulse of the driving circuit, so that the series resonant circuit works under the pulse width modulation control Otherwise, the pulse signal whose duty cycle is stable and whose frequency changes with the feedback signal is used as the driving pulse of the driving circuit, so that the series resonant circuit works in the frequency conversion control state.

根据上述方法：将比例积分运算的结果与一参考信号进行比较来判断负载是否工作在轻载或空载状态，该参考信号根据所述负载的电气特性确定。According to the above method: the result of the proportional integral operation is compared with a reference signal to determine whether the load is operating in a light load or no-load state, and the reference signal is determined according to the electrical characteristics of the load.

根据比例积分运算的结果控制脉冲信号的频率；根据比例积分运算的结果与所述参考信号的差值来控制脉宽调制(PWM)信号的占空比。The frequency of the pulse signal is controlled according to the result of the proportional integral operation; the duty ratio of the pulse width modulation (PWM) signal is controlled according to the difference between the result of the proportional integral operation and the reference signal.

将占空比稳定而频率变化的脉冲信号作为同步信号，将所述差值的反相信号作为控制信号来产生驱动脉冲；当负载工作在轻载或空载状态时，产生占空比稳定而频率与所述同步信号相同的驱动脉冲；否则产生频率稳定而占空比随所述差值信号变化的驱动脉冲。The pulse signal with a stable duty cycle and variable frequency is used as a synchronous signal, and the inversion signal of the difference is used as a control signal to generate a driving pulse; when the load is working in a light-load or no-load state, a stable and A drive pulse with the same frequency as the synchronization signal; otherwise, a drive pulse with a stable frequency and a duty cycle that varies with the difference signal.

一种串联谐振直流/直流(DC/DC)变换器，包括驱动电路和串联谐振电路，该驱动电路根据接收的驱动脉冲向串联谐振电路输出控制信号，串联谐振电路在所述控制信号的控制下将变换后的电源提供给负载电路；其中所述变换器还包括：A series resonant direct current/direct current (DC/DC) converter, comprising a drive circuit and a series resonant circuit, the drive circuit outputs a control signal to the series resonant circuit according to a received drive pulse, and the series resonant circuit is controlled by the control signal The converted power supply is provided to the load circuit; wherein the converter also includes:

比例积分调节器，将从负载电路采样的反馈信号进行比例积分；Proportional-integral regulator, which proportionally integrates the feedback signal sampled from the load circuit;

甄别器，输入端与所述比例积分调节器连接，根据比例积分调节器输出信号确定负载电路的负载状态；A discriminator, the input end of which is connected to the proportional-integral regulator, determines the load state of the load circuit according to the output signal of the proportional-integral regulator;

脉宽调制电路，与所述甄别器连接，根据甄别器的输出信号产生频率稳定而占空比变化的驱动脉冲并提供给驱动电路；A pulse width modulation circuit, connected to the discriminator, generates a drive pulse with a stable frequency and variable duty ratio according to the output signal of the discriminator and provides it to the drive circuit;

变频控制电路，与所述甄别器和驱动电路连接，根据甄别器的输出信号产生占空比稳定而频率变化的驱动脉冲并输出给驱动电路。The frequency conversion control circuit is connected with the discriminator and the driving circuit, generates a driving pulse with a stable duty ratio and variable frequency according to the output signal of the discriminator, and outputs it to the driving circuit.

根据上述变换器：According to the above converter:

所述甄别器包括：反相器，将比例积分调节器的输出信号反相；减法器，将反相器输出的信号与一参考信号比较并输出控制信号。The discriminator includes: an inverter, which inverts the output signal of the proportional integral regulator; a subtractor, which compares the signal output by the inverter with a reference signal and outputs a control signal.

所述比例积分调节器与减法器之间还连接有反相器，所述变频控制电路的输入端与该反向的输出端连接，所述脉宽调制电路的输入端与减法器的输出端连接。An inverter is also connected between the proportional-integral regulator and the subtractor, the input terminal of the frequency conversion control circuit is connected to the reversed output terminal, and the input terminal of the pulse width modulation circuit is connected to the output terminal of the subtractor. connect.

所述变频控制电路包括压频振器和三角波发生器。The frequency conversion control circuit includes a voltage frequency oscillator and a triangular wave generator.

变频控制电路的驱动脉冲输出端与脉宽调制电路的同步端连接，脉宽调制电路根据该同步端的输入信号和所述减法器的输出信号产生占空比稳定而频率与所述同步信号相同的驱动脉冲或频率稳定而占空比随控制信号变化的驱动脉冲。The drive pulse output terminal of the frequency conversion control circuit is connected to the synchronous terminal of the pulse width modulation circuit, and the pulse width modulation circuit generates a signal with a stable duty cycle and the same frequency as the synchronous signal according to the input signal of the synchronous terminal and the output signal of the subtractor. Driving pulse or driving pulse whose frequency is stable and whose duty cycle varies with the control signal.

本发明具有以下有益效果：The present invention has the following beneficial effects:

1、能够实现调频与PWM两种控制方式，在电源工作频率较低时采用变频控制，电源工作频率过高时引入PWM控制方式，从而解决了串联谐振变换器的难点问题，即轻载和空载时工作频率太高和电路损耗过大的问题；1. It can realize two control methods of frequency modulation and PWM, adopt frequency conversion control when the power supply operating frequency is low, and introduce PWM control mode when the power supply operating frequency is too high, thus solving the difficult problem of the series resonant converter, that is, light load and no-load The operating frequency is too high and the circuit loss is too large during load;

2、调频与PWM两种功能电路在逻辑上是并联关系，实现方式采用串联关系，实现电路避免了许多逻辑选通器件和多路PI调节器的使用，电路非常简单；而且两种控制切换平滑，其可靠性和动态特性非常好；2. The two functional circuits of frequency modulation and PWM are logically connected in parallel, and the realization method adopts a series relationship. The realization circuit avoids the use of many logic gating devices and multi-channel PI regulators, and the circuit is very simple; and the two control switching is smooth , its reliability and dynamic characteristics are very good;

3、本发明对全桥LC、半桥LC和LLC等串联谐振的变形拓扑都适用，有较强的工程意义。3. The present invention is applicable to series resonance deformation topologies such as full-bridge LC, half-bridge LC and LLC, and has strong engineering significance.

附图说明Description of drawings

图1为现有技术的串联谐振电路原理图；Fig. 1 is the schematic diagram of series resonant circuit of prior art;

图2A、图2B为本发明直流/直流变换器的原理框图；2A and 2B are schematic block diagrams of the DC/DC converter of the present invention;

图3为本发明的变频控制电路和PWM控制电路的原理框图；Fig. 3 is the functional block diagram of frequency conversion control circuit and PWM control circuit of the present invention;

图4为图3变频控制电路和PWM控制电路的电路原理图；Fig. 4 is the circuit principle diagram of Fig. 3 frequency conversion control circuit and PWM control circuit;

图5为本发明的反馈信号与频率的关系示意图；Fig. 5 is a schematic diagram of the relationship between the feedback signal and the frequency of the present invention;

图6为驱动脉冲波形图。Fig. 6 is a driving pulse waveform diagram.

具体实施方式Detailed ways

本发明将调频控制和脉宽调制(PWM)控制相结合来控制串联谐振电路，在电源工作频率较低时采用变频控制，电源工作频率过高时引入PWM控制方式，以此来避免负载工作在轻载或空载时频率上升过高和电路损耗过大的问题。The present invention combines frequency modulation control and pulse width modulation (PWM) control to control the series resonant circuit, adopts frequency conversion control when the operating frequency of the power supply is low, and introduces PWM control mode when the operating frequency of the power supply is too high, so as to prevent the load from working at The problem of excessive frequency rise and excessive circuit loss at light load or no load.

参阅图2A所示，DC/DC变换器包括驱动电路、串联谐振电路、PI调节器、甄别器、脉宽调制电路和变频控制电路。驱动电路根据接收的驱动脉冲向串联谐振电路输出控制信号，串联谐振电路在所述控制信号的控制下将整流后输入的直流电源变换后提供给负载电路。Referring to FIG. 2A, the DC/DC converter includes a drive circuit, a series resonant circuit, a PI regulator, a discriminator, a pulse width modulation circuit and a frequency conversion control circuit. The driving circuit outputs a control signal to the series resonant circuit according to the received driving pulse, and the series resonant circuit converts the rectified input DC power supply to the load circuit under the control of the control signal.

PI调节器的输入端与负载电路连接，用于将从负载电路采样反馈电压与给定电压进行比例积分运算。The input end of the PI regulator is connected with the load circuit, and is used for performing proportional integral operation on the feedback voltage sampled from the load circuit and the given voltage.

甄别器的输入端与PI调节器的输出端连接，根据PI调节器的比例积分运算结果确定负载电路是否工作在轻载或空载状态(即判断负载电路状态)并输出相应的控制信号。The input terminal of the discriminator is connected with the output terminal of the PI regulator, and according to the proportional-integral operation result of the PI regulator, it is determined whether the load circuit is working in a light-load or no-load state (that is, to judge the state of the load circuit) and output a corresponding control signal.

脉宽调制电路，与甄别器和驱动电路连接，根据甄别器输出的控制信号产生频率稳定而占空比变化的驱动脉冲输出给驱动电路。The pulse width modulation circuit is connected with the discriminator and the drive circuit, generates a drive pulse with a stable frequency and variable duty ratio according to the control signal output by the discriminator, and outputs it to the drive circuit.

变频控制电路，与甄别器和驱动电路连接，根据甄别器输出的控制信号产生占空比稳定而频率变化的驱动脉冲并输出给驱动电路。The frequency conversion control circuit is connected with the discriminator and the drive circuit, generates a drive pulse with a stable duty ratio and variable frequency according to the control signal output by the discriminator, and outputs it to the drive circuit.

频率和占空比的变化受反馈信号控制，即随反馈信号变化而变化。The change of frequency and duty cycle is controlled by the feedback signal, that is, it changes with the change of the feedback signal.

在图2A所示的方案中，变频控制和脉宽调制控制从逻辑关系上是并联关系而电路实现上是串联关系。当甄别器确定负载电路工作在轻载或空载状态时，甄别器控制脉宽调制电路向驱电路输出驱动脉冲，使串联谐振电路工作在PWM控制方式；否则，甄别器控制变频控制电路向驱动电路输出驱动脉冲，使串联谐振电路工作在变频控制方式。In the scheme shown in FIG. 2A , the frequency conversion control and the pulse width modulation control are connected in parallel logically and connected in series in circuit implementation. When the discriminator determines that the load circuit is working in light load or no-load state, the discriminator controls the pulse width modulation circuit to output drive pulses to the drive circuit, so that the series resonant circuit works in PWM control mode; otherwise, the discriminator controls the frequency conversion control circuit to drive The circuit outputs driving pulses, so that the series resonant circuit works in the frequency conversion control mode.

参阅图2B所示，变频控制和脉宽调制控制在逻辑是并联关系，但在电路实现上为串联关系。变频控制电路输出端与PWM控制电路的输入端连接，将变频控制电路输出的信号作PWM控制电路的同步信号，而甄别器输出的信号作为PWM控制电路的比较信号。当负载工作在轻载或空载状态时，比较信号使PWM控制电路产生占空比稳定而频率与所述同步信号相同的驱动脉冲；否则产生频率稳定而占空比随控制信号变化的驱动脉冲。As shown in FIG. 2B , the frequency conversion control and the pulse width modulation control are connected in parallel in logic, but in series in circuit implementation. The output terminal of the frequency conversion control circuit is connected with the input terminal of the PWM control circuit, and the signal output by the frequency conversion control circuit is used as a synchronous signal of the PWM control circuit, and the signal output by the discriminator is used as a comparison signal of the PWM control circuit. When the load is working in light load or no-load state, the comparison signal makes the PWM control circuit generate a drive pulse with a stable duty cycle and the same frequency as the synchronization signal; otherwise, it generates a drive pulse with a stable frequency and a duty cycle that varies with the control signal .

以下主要以图2B所示的方案为例进行说明：The following mainly takes the scheme shown in FIG. 2B as an example for illustration:

参阅图3所示(即图2B所示的方案)，甄别器包括反相器，以及与该反向器输出端连接的减法器。比例积分器将给定电压与输入的采样电压做比例积分运算；反相器将比例积分运算(PI)结果大小反相；减法器将参考电压Vref与反相后的PI运算结果相减得到差值信号，并将该差值信号输出给PWM控制电路。其中参考电压Vref根据负载的电气特性及其它参数确定，以保证能够区分负载的轻载和空载状态与正常的负载状态。Referring to FIG. 3 (that is, the scheme shown in FIG. 2B ), the discriminator includes an inverter and a subtractor connected to the output terminal of the inverter. The proportional integrator performs a proportional integral operation on the given voltage and the input sampling voltage; the inverter inverts the result of the proportional integral operation (PI); the subtractor subtracts the reference voltage Vref from the inverted PI operation result to obtain the difference value signal, and output the difference signal to the PWM control circuit. The reference voltage Vref is determined according to the electrical characteristics of the load and other parameters, so as to ensure that the light-load and no-load states of the load can be distinguished from the normal load state.

变频控制电路包括压频振荡器和三角波发生器，压频振荡器的输入端与反相器的输出端连接，由PI调节器输出的信号控制变频控制电路产生频率变化的脉冲信号。压频振荡器将电压信号变为输出频率变化的方波信号，三角波发器接收该频率变化的方波信号产生频率变化的三角波信号并输出至PWM控制电路。The frequency conversion control circuit includes a voltage frequency oscillator and a triangular wave generator. The input terminal of the voltage frequency oscillator is connected to the output terminal of the inverter, and the signal output by the PI regulator controls the frequency conversion control circuit to generate a pulse signal of frequency change. The voltage frequency oscillator converts the voltage signal into a square wave signal with variable output frequency, and the triangular wave generator receives the square wave signal with variable frequency to generate a triangular wave signal with variable frequency and outputs it to the PWM control circuit.

PWM控制电路包括PWM产生器和锁相电路，PWM产生器根据比较电压信号决定驱动脉冲的占空比，锁相电路对PWM产生器输出的驱动脉冲锁相。The PWM control circuit includes a PWM generator and a phase-lock circuit. The PWM generator determines the duty ratio of the driving pulse according to the comparison voltage signal, and the phase-lock circuit locks the phase of the driving pulse output by the PWM generator.

当减法器输出的差值大于PWM产生器输入的三角波峰值时，控制PWM控制电路输出的驱动脉冲的占空比不再变换，只有频率变化，即进入调频控制；当所述差值低于PWM的三角波峰值时，驱动脉冲的频率基本保持不变，只有占空比变化，即进入PWM控制。When the difference output by the subtractor is greater than the peak value of the triangle wave input by the PWM generator, the duty ratio of the driving pulse output by the control PWM control circuit is no longer changed, and only the frequency changes, that is, it enters the frequency modulation control; when the difference is lower than the PWM When the peak value of the triangular wave, the frequency of the driving pulse remains basically unchanged, only the duty cycle changes, that is, it enters the PWM control.

参阅图4所示，压频振荡器和三角波发生器由集成电路CD4046实现，PWM产生器和锁相电路由集成电路SG3525实现，PI调节器、减法器和甄别器由运算放器LM358实现。Referring to Figure 4, the voltage frequency oscillator and triangular wave generator are implemented by integrated circuit CD4046, the PWM generator and phase-locked circuit are implemented by integrated circuit SG3525, and the PI regulator, subtractor and discriminator are implemented by operational amplifier LM358.

PI调节器的运算结果经反相后一路送给压频振荡电路，产生频率变化的锯齿波；另一路与参考电压Vref做减法运算后，作为比较电压Vcomp，与PWM电路输入的锯齿波做比较运算。The operation result of the PI regulator is sent to the voltage-frequency oscillation circuit one way after inversion to generate a sawtooth wave with frequency change; the other way is subtracted from the reference voltage Vref and used as a comparison voltage Vcomp to compare with the sawtooth wave input by the PWM circuit operation.

当PI调节器的输出电压大于或等于参考电压Vref时，说明负载工作在具有一定负载的状态，即电路应工作在变频控制方式，将减法器输出做限辐处理后作为集成电路SG3525的比较电压Vcomp，由于比较电压Vcomp(即限辐值)大于集成电路SG3525同步端SYNC输入的三角波峰值，脉冲占空比为50％，脉冲经锁相后输出为频率变化的方波信号作为驱动脉冲。When the output voltage of the PI regulator is greater than or equal to the reference voltage Vref, it means that the load is working with a certain load, that is, the circuit should work in the frequency conversion control mode, and the output of the subtractor will be used as the comparison voltage of the integrated circuit SG3525 after radiation-limiting processing Vcomp, because the comparison voltage Vcomp (that is, the limited amplitude value) is greater than the peak value of the triangular wave input by the synchronous terminal SYNC of the integrated circuit SG3525, the pulse duty cycle is 50%, and the pulse is output as a square wave signal with variable frequency as the driving pulse after being phase-locked.

当PI调节器的输出电压小于参考电压Vref时，说明负载工作在轻载或空载状态，即电路应工作在PWM控制方式，集成电路SG3525的工作频率仍与集成电路CD4046的输出同步，减法器输出信号作为PWM产生器SG3525的比较信号Vcomp，与同步端SYNC输入的锯齿波比较运算来决定输出占空比的变化，占空比变化的PWM信号再经锁相电路后输出作为驱动脉冲。When the output voltage of the PI regulator is lower than the reference voltage Vref, it means that the load is working in a light-load or no-load state, that is, the circuit should work in the PWM control mode, and the operating frequency of the integrated circuit SG3525 is still synchronized with the output of the integrated circuit CD4046, and the subtractor The output signal is used as the comparison signal Vcomp of the PWM generator SG3525, which is compared with the sawtooth wave input by the synchronous terminal SYNC to determine the change of the output duty cycle, and the PWM signal with the duty cycle change is output as a driving pulse after passing through the phase-locked circuit.

参阅图5所示，它反映了PI调节器输出电压V与工作频率f的函数关系，电压V1为参考电压，电压V2为PI调节器输出的最大电压(如，12V)，当V1＜V＜V2时，V-f是线性对应的关系，变换器工作在变频控制状态；当0＜V＜V1时，工作频率将稳定在f2，而PWM控制开始起作用，将根据电压PI环的输出调节驱动脉冲的占空比大小，直至电压稳定。Referring to Figure 5, it reflects the functional relationship between the output voltage V of the PI regulator and the operating frequency f, the voltage V1 is the reference voltage, and the voltage V2 is the maximum output voltage of the PI regulator (for example, 12V), when V1<V< When V2, V-f is a linear corresponding relationship, and the converter works in the frequency conversion control state; when 0<V<V1, the working frequency will be stable at f2, and the PWM control will start to work, and the drive pulse will be adjusted according to the output of the voltage PI loop The size of the duty cycle until the voltage is stable.

结合图4与图5，在图4中，甄别器将采样电压作PI运算后的输出结果V_PI与参考电压V1进行比较判断，若V1＜V_PI＜V2，说明变换器工作在非轻载状态，驱动脉冲为频率变化而占空比不变的方波，变换器利用变频方式来稳定输出电压；若是0＜V_PI＜V1，说明变换器工作在轻载或空载状态，输出脉冲频率稳定在f2，电源通过脉冲PWM来稳定输出电压。Combining Figure 4 and Figure 5, in Figure 4, the discriminator compares and judges the output result V_PI after PI operation of the sampling voltage with the reference voltage V1, if V1<V_PI <V2, it means that the converter is working under non-light load state, the drive pulse is a square wave whose frequency changes and the duty ratio remains constant, and the converter uses frequency conversion to stabilize the output voltage; if 0<V_PI <V1, it means that the converter is working in a light-load or no-load state, and the output pulse frequency Stabilized at f2, the power supply stabilizes the output voltage through pulse PWM.

参阅图6所示，波形a是变频控制下的50％占空比驱动波形；波形b是PWM控制下的驱动波形，电源会根据输出电压调节占空比的宽度，直至占空比为零。Referring to Figure 6, waveform a is a 50% duty cycle driving waveform under variable frequency control; waveform b is a driving waveform under PWM control, and the power supply will adjust the width of the duty cycle according to the output voltage until the duty cycle is zero.

本发明在工作频率较低时，变换器工作在变频控制方式；而在工作频率较高时，变换器工作在PWM控制方式，工作频率不变，电路中的PI环的结果将调节驱动脉冲的占空比大小，直至电压稳定，这样就避免了空载和轻载条件下，开关频率太高的问题。变频控制与PWM控制在逻辑上是并联关系，但在电路实现上却是串联关系。一次PI运算就可以满足两种控制的需要，这就避免了两套控制方法对应两套PI运算电路，而且避免了很多逻辑选通器件和多路PI调节器的使用，大大简化了电路结构。同时从图4可以看到，由于集成电路CD4046与SG3525是频率同步的，二者是串联的关系，这样当电路在PWM与调频两个状态切换时，切换是平滑的，这就保证了电路工作的可靠性。In the present invention, when the working frequency is low, the converter works in the frequency conversion control mode; when the working frequency is high, the converter works in the PWM control mode, the working frequency remains unchanged, and the result of the PI loop in the circuit will adjust the driving pulse The duty cycle is large until the voltage is stable, thus avoiding the problem of too high switching frequency under no-load and light-load conditions. Frequency conversion control and PWM control are connected in parallel in logic, but they are connected in series in circuit implementation. One PI operation can meet the needs of two kinds of control, which avoids two sets of control methods corresponding to two sets of PI operation circuits, and avoids the use of many logic gating devices and multi-channel PI regulators, greatly simplifying the circuit structure. At the same time, it can be seen from Figure 4 that since the integrated circuit CD4046 and SG3525 are frequency-synchronized, the two are connected in series, so when the circuit switches between the PWM and frequency modulation states, the switching is smooth, which ensures that the circuit works reliability.

本发明中的串联谐振电路可为全桥LC、半桥LC和LLC等串联谐振及其变形拓扑。The series resonant circuit in the present invention can be a series resonant topology such as full bridge LC, half bridge LC and LLC and its deformation.

本发明的PWM、变频控制和甄别电路也可以通过软件来实现，这部分工作是本领域的普通技术人员根据上述的技术方案很容易推导出的。The PWM, frequency conversion control and discrimination circuits of the present invention can also be realized by software, and this part of work can be easily deduced by those skilled in the art according to the above-mentioned technical solutions.

Claims (10)

Translated fromChinese

1、一种串联谐振直流/直流变换器的控制方法，所述直流/直流(DC/DC)变换器包括驱动电路和串联谐振电路，驱动电路根据接收的驱动脉冲产生控制信号，该控制信号控制串联谐振电路向负载提供功率流并使串联谐振电路的输出电压保持稳定；其特征在于所述方法为：1. A control method for a series resonant DC/DC converter, the DC/DC (DC/DC) converter includes a drive circuit and a series resonant circuit, the drive circuit generates a control signal according to the received drive pulse, and the control signal controls The series resonant circuit provides power flow to the load and keeps the output voltage of the series resonant circuit stable; characterized in that the method is:从负载电路中采样反馈电压；Sampling the feedback voltage from the load circuit;将所述反馈电压进行比例积分运算；performing a proportional-integral operation on the feedback voltage;根据比例积分运算的结果判断负载是否工作在轻载或空载状态；Judging whether the load is working under light load or no load according to the result of proportional integral calculation;如果负载工作在轻载或空载状态，则由频率稳定而占空比随反馈信号变化的脉宽调制(PWM)信号作为所述驱动电路的驱动脉冲，使串联谐振电路工作在脉宽调制控制状态；否则，由占空比稳定而频率随反馈信号变化的脉冲信号作为所述驱动电路的驱动脉冲，使串联谐振电路工作在变频控制状态。If the load works in light load or no load state, the pulse width modulation (PWM) signal whose frequency is stable and whose duty ratio changes with the feedback signal is used as the driving pulse of the driving circuit, so that the series resonant circuit works under the pulse width modulation control Otherwise, the pulse signal whose duty cycle is stable and whose frequency changes with the feedback signal is used as the driving pulse of the driving circuit, so that the series resonant circuit works in the frequency conversion control state.2、如权利要求1所述的方法，其特征在于，将比例积分运算的结果与一参考信号进行比较来判断负载是否工作在轻载或空载状态，该参考信号根据所述负载的电气特性确定。2. The method according to claim 1, characterized in that the result of the proportional integral operation is compared with a reference signal to determine whether the load is operating at a light load or no-load state, and the reference signal is based on the electrical characteristics of the load Sure.3、如权利要求2所述的方法，其特征在于，根据比例积分运算的结果控制脉冲信号的频率；根据比例积分运算的结果与所述参考信号的差值来控制脉宽调制(PWM)信号的占空比。3. The method according to claim 2, wherein the frequency of the pulse signal is controlled according to the result of the proportional integral operation; the pulse width modulation (PWM) signal is controlled according to the difference between the result of the proportional integral operation and the reference signal duty cycle.4、如权利要求3所述的方法，其特征在于，将占空比稳定而频率变化的脉冲信号作为同步信号，将所述差值作为控制信号来产生驱动脉冲；当负载工作在轻载或空载状态时，产生占空比稳定而频率与所述同步信号相同的驱动脉冲；否则产生频率稳定而占空比随所述差值信号变化的驱动脉冲。4. The method according to claim 3, characterized in that the pulse signal with a stable duty ratio and variable frequency is used as a synchronous signal, and the difference is used as a control signal to generate a driving pulse; when the load is working at light load or In the no-load state, a driving pulse with a stable duty ratio and the same frequency as the synchronous signal is generated; otherwise, a driving pulse with a stable frequency and a duty ratio that varies with the difference signal is generated.5、一种串联谐振直流/直流变换器，包括驱动电路和串联谐振电路，该驱动电路根据接收的驱动脉冲向串联谐振电路输出控制信号，串联谐振电路在所述控制信号的控制下将变换后的电源提供给负载电路；其特征在于所述变换器还包括：5. A series resonant DC/DC converter, comprising a drive circuit and a series resonant circuit, the drive circuit outputs a control signal to the series resonant circuit according to the received drive pulse, and the series resonant circuit converts the transformed The power supply is provided to the load circuit; it is characterized in that the converter also includes:比例积分调节器，将从负载电路采样的反馈信号进行比例积分；Proportional-integral regulator, which proportionally integrates the feedback signal sampled from the load circuit;甄别器，输入端与所述比例积分调节器连接，根据比例积分调节器输出信号确定负载电路的负载状态；A discriminator, the input end of which is connected to the proportional-integral regulator, determines the load state of the load circuit according to the output signal of the proportional-integral regulator;脉宽调制电路，与所述甄别器连接，根据甄别器的输出信号产生频率稳定而占空比变化的驱动脉冲并提供给驱动电路；A pulse width modulation circuit, connected to the discriminator, generates a drive pulse with a stable frequency and variable duty ratio according to the output signal of the discriminator and provides it to the drive circuit;变频控制电路，与所述甄别器和驱动电路连接，根据甄别器的输出信号产生占空比稳定而频率变化的驱动脉冲并输出给驱动电路。The frequency conversion control circuit is connected with the discriminator and the driving circuit, generates a driving pulse with a stable duty ratio and variable frequency according to the output signal of the discriminator, and outputs it to the driving circuit.6、如权利要求5所述的变换器，其特征在于，所述甄别器包括：6. The converter of claim 5, wherein the discriminator comprises:反相器，将比例积分调节器的输出信号反相；an inverter, which inverts the output signal of the proportional-integral regulator;减法器，将反相器输出的信号与一参考信号比较并输出控制信号。The subtractor compares the signal output by the inverter with a reference signal and outputs a control signal.7、如权利要求67所述的变换器，其特征在于，变频控制电路的输入端与所述反相器的输出端连接，脉宽调制电路的输入端与所述减法器的输出端连接。7. The converter according to claim 67, wherein the input terminal of the frequency conversion control circuit is connected to the output terminal of the inverter, and the input terminal of the pulse width modulation circuit is connected to the output terminal of the subtractor.8、如权利要求7所述的变换器，其特征在于，所述变频控制电路包括压频振荡器和三角波发生器，所述压频振荡器将所述反相器输出的电压信号转变为频率变化的方波信号，所述三角波发器根据压频振荡器输出的方波信号产生并输出三角波信号。8. The converter according to claim 7, wherein the frequency conversion control circuit includes a voltage frequency oscillator and a triangular wave generator, and the voltage frequency oscillator converts the voltage signal output by the inverter into a frequency A changing square wave signal, the triangular wave generator generates and outputs a triangular wave signal according to the square wave signal output by the voltage frequency oscillator.9、如权利要求5至8任一所述的变换器，其特征于，所述脉宽调制电路包括脉宽调制产生器和锁相电路。9. The converter according to any one of claims 5 to 8, wherein the pulse width modulation circuit comprises a pulse width modulation generator and a phase-lock circuit.10、如权利要求9所述的变换器，其特征在于，变频控制电路的驱动脉冲输出端与脉宽调制电路的同步端连接，脉宽调制电路根据该同步端的输入信号和所述减法器的输出信号产生占空比稳定而频率与所述同步信号相同的驱动脉冲或频率稳定而占空比随控制信号变化的驱动脉冲。10. The converter according to claim 9, characterized in that, the drive pulse output terminal of the frequency conversion control circuit is connected to the synchronous terminal of the pulse width modulation circuit, and the pulse width modulation circuit is based on the input signal of the synchronous terminal and the The output signal generates a driving pulse with a stable duty ratio and the same frequency as the synchronous signal or a driving pulse with a stable frequency and a duty ratio that varies with the control signal.

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