CN106208887B - No electrolytic capacitor motor driven systems and its control method, device - Google Patents

Abstract

The invention discloses a kind of no electrolytic capacitor motor driven systems and its control method, devices, the described method comprises the following steps：The input ac voltage of detection motor driven systems in real time；The current maximum running frequency of compressor electric motor is calculated according to input ac voltage；And compressor electric motor is controlled according to current maximum running frequency.This method calculates the current maximum running frequency of compressor electric motor according to input ac voltage, the maximum speed of compressor electric motor can be limited in time in input ac voltage cataclysm, to effectively avoid compressor electric motor out of control or motor driven systems damage, ensure compressor electric motor and motor driven systems stabilization, reliability service.

Description

Motor driving system without electrolytic capacitor and control method and device thereof

Technical Field

The invention relates to the technical field of motors, in particular to a motor driving system without electrolytic capacitors and a control method and a control device thereof.

Background

With the improvement of energy conservation requirements of consumers on electromechanical products, the permanent magnet synchronous motor with higher efficiency is more and more widely applied.

The direct current bus voltage of the conventional variable frequency driver is in a stable state, and the inversion part is relatively independent from the input alternating current voltage, so that the control of the inversion part does not need to consider the instantaneous change of the input alternating current voltage, and the control method is convenient to realize. However, this design method needs to be equipped with an electrolytic capacitor with a large capacitance value, so that the size of the driver is large, the cost is increased, the service life of the electrolytic capacitor is limited, and the effective working time of the electrolytic capacitor is often the bottleneck of the service life of the variable frequency driver.

In order to solve the problems, a strategy of replacing an electrolytic capacitor with a thin-film capacitor or a ceramic capacitor with a small capacitance value is provided in the related art, compared with a conventional variable frequency driver, a power factor correction part is omitted, and the miniaturized capacitor can reduce the cost and eliminate the service life bottleneck problem caused by the electrolytic capacitor.

However, because the capacitance value of the film capacitor or the ceramic capacitor is very small and is only 1% -2% of the capacitance value of the conventional high-voltage electrolytic capacitor, when the input alternating voltage suddenly changes, the direct-current bus voltage also changes, and if the motor cannot be controlled in time at the moment, the motor is out of control or the electric control is damaged. For example, when a compressor of an air conditioner is in a high-speed operation state, if an input ac voltage drops, a sufficient torque cannot be output due to an excessively low dc bus voltage, which may cause the compressor to step out and even damage an inverter portion, such as an IPM (Intelligent Power Module).

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.

Therefore, a first objective of the present invention is to provide a control method for an electric motor driving system without electrolytic capacitor, which calculates the current highest operating frequency of a compressor motor according to an input ac voltage, so as to limit the highest rotation speed of the compressor motor in time when the input ac voltage suddenly changes, thereby effectively avoiding the compressor motor from being out of control or the motor driving system from being damaged, and ensuring the compressor motor and the motor driving system to operate stably and reliably.

The second purpose of the invention is to provide a control device of a motor driving system without electrolytic capacitor.

A third object of the present invention is to provide an electrolytic capacitor-free motor driving system.

In order to achieve the above object, a first embodiment of the present invention provides a control method for an electrolytic capacitor-free motor driving system, including the following steps: detecting input alternating voltage of a motor driving system in real time; calculating the current highest operating frequency of a compressor motor according to the input alternating voltage; and controlling the compressor motor according to the current highest running frequency.

According to the control method of the motor driving system without the electrolytic capacitor, disclosed by the embodiment of the invention, the input alternating voltage of the motor driving system is detected in real time, the current highest running frequency of the compressor motor is calculated according to the input alternating voltage, and the compressor motor is controlled according to the current highest running frequency, so that the highest rotating speed of the compressor motor can be limited in time when the input alternating voltage suddenly changes, the compressor motor is effectively prevented from being out of control or the motor driving system is damaged, and the compressor motor and the motor driving system are ensured to run stably and reliably.

According to one embodiment of the present invention, when the input ac voltage rises, the current maximum operating frequency of the compressor motor is calculated by the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₅Is a fifth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₂<V₃<V₅。

According to one embodiment of the present invention, when the input ac voltage drops, the current highest operating frequency of the compressor motor is calculated by the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₁Is a first predetermined voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₄Is a fourth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding said pressureMaximum operating frequency of motor of compressor, and V₁<V₂<V₃<V₄。

According to an embodiment of the present invention, the controlling the compressor motor according to the current highest operating frequency includes: calculating the highest operation rotating speed of the compressor motor according to the current highest operation frequency; and acquiring a smaller value between the highest operation rotating speed and a preset given rotating speed, and controlling the compressor motor according to the smaller value.

According to an embodiment of the present invention, the controlling the compressor motor according to the current highest operating frequency further includes: acquiring a voltage instantaneous value of the input alternating voltage, and calculating a phase estimation value of the input alternating voltage according to the voltage instantaneous value; estimating a rotor position of the compressor motor to obtain a rotor angle estimate and a rotor speed estimate of the compressor motor; calculating the q-axis given current of the compressor motor according to the smaller value, the rotor speed estimated value, the shape of the input alternating voltage and the phase estimated value; calculating d-axis given current of the compressor motor according to the maximum output voltage of the inverter circuit and the output voltage amplitude of the inverter circuit; and acquiring a q-axis given voltage and a d-axis given voltage of the compressor motor according to the q-axis given current, the d-axis given current, the q-axis actual current and the d-axis actual current, generating a control signal according to the q-axis given voltage, the d-axis given voltage and the rotor angle estimation value, and controlling the compressor motor through the inverter circuit according to the control signal.

In order to achieve the above object, a control device of a motor driving system without electrolytic capacitor according to an embodiment of a second aspect of the present invention includes: the voltage detection module is used for detecting the input alternating voltage of the motor driving system in real time; the first calculation module is used for calculating the current highest running frequency of the compressor motor according to the input alternating voltage; and the control module is used for controlling the compressor motor according to the current highest running frequency.

According to the control device of the motor driving system without the electrolytic capacitor, the input alternating-current voltage of the motor driving system is detected in real time through the voltage detection module, the first calculation module calculates the current highest operation frequency of the compressor motor according to the input alternating-current voltage, and the control module controls the compressor motor according to the current highest operation frequency, so that the highest rotation speed of the compressor motor can be limited in time when the input alternating-current voltage suddenly changes, the compressor motor is effectively prevented from being out of control or the motor driving system is prevented from being damaged, and the compressor motor and the motor driving system are guaranteed to operate stably and reliably.

According to an embodiment of the present invention, when the input ac voltage rises, the first calculation module calculates a current maximum operating frequency of the compressor motor by the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₅Is a fifth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₂<V₃<V₅。

According to an embodiment of the present invention, when the input ac voltage drops, the first calculation module calculates a current maximum operating frequency of the compressor motor by the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₁Is a first predetermined voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₄Is a fourth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₁<V₂<V₃<V₄。

According to one embodiment of the invention, the control module comprises: the second calculation module is used for calculating the highest running rotating speed of the compressor motor according to the current highest running frequency; and the comparison module is used for acquiring a smaller value between the highest operation rotating speed and a preset given rotating speed so as to control the compressor motor according to the smaller value.

According to one embodiment of the invention, the control module further comprises: the phase detection phase-locked loop module is used for acquiring a voltage instantaneous value of the input alternating voltage and calculating a phase estimation value of the input alternating voltage according to the voltage instantaneous value; a position and speed estimator for estimating a rotor position of the compressor motor to obtain a rotor angle estimation value and a rotor speed estimation value of the compressor motor; the q-axis given current calculation module is used for calculating q-axis given current of the compressor motor according to the smaller value, the rotor speed estimated value, the shape of the input alternating voltage and the phase estimated value; the d-axis given current calculation module is used for calculating the d-axis given current of the compressor motor according to the maximum output voltage of the inverter circuit and the output voltage amplitude of the inverter circuit; and the current controller is used for acquiring a q-axis given voltage and a d-axis given voltage of the compressor motor according to the q-axis given current, the d-axis given current, the q-axis actual current and the d-axis actual current, generating a control signal according to the q-axis given voltage, the d-axis given voltage and the rotor angle estimation value, and controlling the compressor motor through the inverter circuit according to the control signal.

In addition, the embodiment of the invention also provides an electrolytic capacitor-free motor driving system, which comprises the control device of the electrolytic capacitor-free motor driving system.

According to the motor driving system without the electrolytic capacitor, the control device can calculate the current highest running frequency of the compressor motor according to the input alternating voltage, so that the highest rotating speed of the compressor motor can be limited in time when the input alternating voltage suddenly changes, the compressor motor is effectively prevented from being out of control or the motor driving system is damaged, and the compressor motor and the motor driving system are guaranteed to run stably and reliably.

Drawings

FIG. 1 is a schematic diagram of an electrolytic capacitor-less motor drive system according to one embodiment of the present invention;

FIG. 2 is a flow chart of a method of controlling an electrolytic capacitor-less motor drive system according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the current maximum operating frequency of the compressor motor as the input AC voltage increases, in accordance with one embodiment of the present invention;

FIG. 4 is a schematic diagram of the current maximum operating frequency of the compressor motor as the input AC voltage drops according to one embodiment of the present invention;

FIG. 5 is a flow chart of a method of controlling an electrolytic capacitor-less motor drive system according to one embodiment of the present invention;

fig. 6 is a schematic structural diagram of a control device of an electrolytic capacitor-less motor drive system according to an embodiment of the present invention;

FIG. 7 is a block diagram of a phase detection PLL module according to one embodiment of the present invention; and

fig. 8 is a schematic structural diagram of a control device of an electrolytic capacitor-less motor drive system according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

An electrolytic capacitor-free motor drive system and a control method and apparatus thereof according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of an electrolytic capacitor-less motor drive system according to an embodiment of the present invention. As shown in fig. 1, the motor driving system without electrolytic capacitor includes: the circuit comprises an input inductor 1, a rectifying circuit 2, a direct current link part 3, an inverter circuit 4 and a control part 5, wherein the rectifying circuit 2 performs full-wave rectification on an input alternating current power supply AC; the dc link section 3 includes a thin film capacitor EC connected in parallel to the output side of the rectifier circuit 2, and outputs a pulsating dc voltage V after passing through the thin film capacitor EC_dc(i.e., dc bus voltage); the inverter circuit 4 uses the switching tubes S1-S6 to output the pulsating dc voltage V from the dc link unit 3_dcAfter being converted into alternating current, the alternating current is supplied to a compressor motor 6 (which can be a permanent magnet synchronous motor); the control part 5 controls the switching tubes S1-S6 in the inverter circuit 4 to normally operate the compressor motor 6.

Fig. 2 is a flowchart of a control method of an electrolytic capacitor-less motor driving system according to an embodiment of the present invention. As shown in fig. 2, the control method of the electrolytic capacitor-less motor driving system includes the steps of:

s1, detecting the input alternating voltage V of the motor driving system in real time_ac。

S2, according to the input AC voltage V_acCalculating the current maximum operating frequency F of the compressor motor_max。

According to one embodiment of the invention, when an AC voltage V is input_acWhen rising, the current maximum operating frequency F of the compressor motor is calculated by the following formula (1)_max：

Wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsFor an effective value of the input AC voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₅Is a fifth predetermined voltage, F_max1Is a V₂Maximum operating frequency, F, of the corresponding compressor motor_max2Is a V₃Maximum operating frequency of the corresponding compressor motor, and V₂<V₃<V₅。

Specifically, as shown in FIG. 3, when an AC voltage V is inputted_acWhen rising, if the effective value V of the AC voltage is input_rms<V₂Then, it indicates the input AC voltage V_acIs smaller, at the moment, the starting of the compressor motor is forbidden, namely the current highest running frequency F_max0; if V₂≤V_rms<V₃The compressor motor is allowed to start running, and the effective value V of the input alternating voltage can be used_rmsCalculating the current highest operating frequency F_maxI.e. F_max＝(F_max2-F_max1)*(V_rms-V₂)/(V₃-V₂)+F_max1(ii) a If V₃≤V_rms≤V₅The compressor motor is allowed to be in a high-speed running state all the time, i.e. F_max＝F_max2(ii) a If V_rms>V₅Then it indicates the current input AC voltage V_acToo high, at which time compression needs to be controlledThe electromechanical machine stops working. Therefore, the current highest running frequency of the compressor motor is dynamically adjusted according to the input alternating voltage detected in real time, so that when the input alternating voltage rises, the highest rotating speed of the compressor motor can be limited in time, the compressor motor is effectively prevented from being out of control or a motor driving system is prevented from being damaged, and the compressor motor and the driving motor system are ensured to run stably and reliably.

According to one embodiment of the invention, when an AC voltage V is input_acWhen descending, the current highest operation frequency F of the compressor motor is calculated by the following formula (2)_max：

Wherein, V₁Is a first predetermined voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₄Is a fourth predetermined voltage, and V₁<V₂<V₃<V₄。

Specifically, as shown in FIG. 4, when an AC voltage V is inputted_acWhen dropping, if the effective value V of the AC voltage is input_rms>V₄Then the compressor motor is controlled to stop working, namely the current highest running frequency F_max0; if V₃≤V_rms≤V₄The compressor motor is allowed to be in a high-speed running state all the time, i.e. F_max＝F_max2(ii) a If V₂≤V_rms<V₃According to the effective value V of the input AC voltage_rmsTo calculate the current highest operating frequency F_maxI.e. F_max＝(F_max2-F_max1)*(V_rms-V₂)/(V₃-V₂)+F_max1(ii) a If V₁≤V_rms<V₂The compressor motor is allowed to be in a low speed running state all the time, i.e. F_max＝F_max1(ii) a If V_rms<V₁Then the motor of the compressor is controlled to stop working, namely, the current highestOperating frequency F_max0. Thereby can come to carry out dynamic adjustment to the current highest operating frequency of compressor motor according to real-time detection's input alternating voltage, with when input alternating voltage falls, can in time restrict the highest rotational speed of compressor motor, effectively avoid compressor motor out of control or motor drive system to damage, for example, can effectively avoid the compressor of air conditioner when being in high-speed operation, because of the too low problem that makes the compressor motor step-out of moment that leads to of direct current bus voltage, thereby guarantee compressor motor and motor drive system stable, the reliable operation.

S3, according to the current highest operation frequency F_maxThe compressor motor is controlled.

According to one embodiment of the invention, the current highest operating frequency F is used_maxControlling a compressor motor, comprising: according to the current highest operating frequency F_maxCalculating the maximum operation speed omega of the compressor motor_max(ii) a Obtaining the highest running speed omega_maxWith a preset given rotational speedSmaller value therebetweenAccording to a smaller value(as ω_ref) The compressor motor is controlled.

Further, as shown in FIG. 5, according to the current highest operating frequency F_maxControl the compressor motor, still include:

s101, acquiring a voltage instantaneous value V of an input alternating voltage_geAnd based on the instantaneous value V of the voltage_geCalculating a phase estimate θ of an input AC voltage_ge。

Specifically, as shown in fig. 7, the instantaneous value V is calculated from the voltage_geCalculating input ACPhase estimate of pressure θ_geThe method comprises the following steps: performing cosine calculation on the phase estimation value of the input alternating voltage in the previous calculation period to obtain a first calculation value; instantaneous value V of voltage_geMultiplying the first calculated value by a second calculated value; low-pass filtering the second calculated value to obtain a third calculated value, wherein the bandwidth of the low-pass filtering is smaller than the input AC voltage frequency omega_g1/5 of (1); performing PI (Proportional Integral) adjustment on the third calculated value to obtain a fourth calculated value; for the fourth calculated value and the frequency omega of the input AC voltage_gThe sum is subjected to integral calculation to obtain a phase estimation value theta of the input alternating voltage of the current calculation period_ge。

S102, estimating the rotor position of the compressor motor to obtain the rotor angle estimated value theta of the compressor motor_estAnd rotor speed estimate ω_est。

Specifically, the rotor angle estimation value θ of the compressor motor can be obtained by flux linkage observation_estAnd rotor speed estimate ω_est. Specifically, the voltage V on the two-phase stationary coordinate system can be first determined_α、V_βAnd current I_α、I_βAnd calculating the estimated value of the effective magnetic flux of the compressor motor in the axial directions of the two-phase static coordinate systems α and β, wherein the specific calculation formula is as follows:

wherein,andan estimate of the effective flux, V, in the direction of the α and β axes of the compressor motor, respectively_αAnd V_βVoltage in the direction of the α and β axes, I_αAnd I_βα and β in the axial direction, respectivelyR is the stator resistance, L_qIs the q-axis flux linkage of the compressor motor.

Then, a rotor angle estimation value θ of the compressor motor is calculated according to the following equation (4)_estAnd rotor speed estimate ω_est：

Wherein, K_{p_pll}And K_{i_pll}Respectively, a proportional integral parameter, theta_errAs an estimate of the deviation angle, ω_fThe bandwidth of the velocity low pass filter.

S103, according to the smaller value omega_refRotor speed estimate ω_estShape and phase estimation value theta of input alternating voltage_geCalculating the q-axis given current I of the compressor motor_qref。

Specifically, as shown in fig. 6, according to a smaller value ω_refRotor speed estimate ω_estShape and phase estimation value theta of input alternating voltage_geCalculating the q-axis given current I of the compressor motor_qrefThe method comprises the following steps: for the minimum value omega_refWith rotor speed estimate omega_estThe difference between them is PI regulated to obtain a given T of torque amplitude₀(ii) a Estimating value theta according to shape and phase of input alternating voltage_geGenerating an output variable W_f(ii) a Will output variable W_fAnd torque amplitude given T₀Multiplying and dividing by the compressor motor torque coefficient K_tTo obtain an initial value I of a given q-axis current_q0(ii) a According to the phase estimation value theta_geGenerating a compensation current I_qcom(ii) a Will compensate the current I_qcomSuperimposed on the q-axis set current initial value I_q0To obtain a given q-axis current I_qref。

Wherein the output variable may be generated by the following equation (5):

wherein, W_f(θ_ge) As an output variable, V_θdFor input of alternating voltage with a phase theta within a half period_dVoltage of time, V_mFor the voltage amplitude of the input AC voltage, theta_dThe phase corresponding to the current dead zone.

The compensation current may be generated by the following equation (6):

wherein, I_qcomFor compensating current, C is capacitance value of capacitor connected in parallel between input ends of inverter circuit, theta_d1The phase parameter is a predetermined phase parameter, and the value thereof can be a phase theta corresponding to the current dead zone_dSpecifically, the range of 0.1 to 0.2rad can be used.

S104, according to the maximum output voltage V of the inverter circuit_maxAnd the output voltage amplitude V of the inverter circuit₁Calculating d-axis given current I of compressor motor_dref。

Specifically, as shown in fig. 6, according to the maximum output voltage V of the inverter circuit_maxAnd the output voltage amplitude V of the inverter circuit₁Calculating d-axis given current I of compressor motor_drefThe method comprises the following steps: maximum output voltage V to inverter circuit_maxAnd the output voltage amplitude V of the inverter circuit₁The difference is subjected to field weakening control to obtain an initial value I of a d-axis given current_d0(ii) a Setting an initial value of current I for d-axis_d0Performing a clipping process to obtain a d-axis set current I_dref。

Wherein the initial value I of the d-axis given current can be calculated by the following formula (7)_d0：

Wherein, K_iIn order to integrate the control coefficients of the motor,V_dand V_qD-axis actual voltage and q-axis actual voltage, V, of the compressor motor, respectively_dcIs the dc bus voltage of the compressor motor.

Then, an initial value I is given according to the current_d0And calculating d-axis given current I by the following formula (8)_dref：

Wherein, I_demagAnd the current limit value is the demagnetization current limit value of the motor of the compressor.

S105, setting current I according to q axis_qrefD-axis given current I_drefQ-axis actual current I_qAnd d-axis actual current I_dObtaining a given q-axis voltage V of a compressor motor_qrefAnd d-axis given voltage V_drefAnd a voltage V is given according to the q-axis_qrefD-axis given voltage V_drefRotor angle estimation value theta_estAnd generating a control signal, and controlling the compressor motor through the inverter circuit according to the control signal.

Specifically, the q-axis given voltage V can be calculated by the following formula (9)_qrefAnd d-axis given voltage V_dref：

Wherein, I_qIs the q-axis actual current, I_dIs d-axis actual current, K_pdAnd K_idProportional gain and integral gain, K, respectively, for d-axis current control_pqAnd K_iqControl the proportional gain and the q-axis current respectivelyIntegral gain, ω is the speed of the compressor motor, K_eIs the back electromotive force coefficient, L, of the compressor motor_dAnd L_qRespectively a d-axis inductance and a q-axis inductance,denotes the integral of x (τ) over time.

Obtaining a given voltage V of q axis_qrefAnd d-axis given voltage V_drefThen, the rotor angle estimate θ can be used_estGiven voltage V to q-axis_qrefAnd d-axis given voltage V_drefCarrying out Park inverse transformation to obtain the voltage V on the two-phase static coordinate system_α、V_βThe concrete transformation formula is as follows:

further, the voltage V on the two-phase static coordinate system is compared_α、V_βPerforming Clark inverse transformation to obtain three-phase voltage command V_u、V_v、V_wThe concrete transformation formula is as follows:

then, the voltage V can be obtained according to the DC bus_dcAnd three-phase voltage command V_u、V_v、V_wDuty ratio calculation is carried out to obtain a duty ratio control signal, namely a three-phase duty ratio D_u、D_v、D_wThe specific calculation formula is as follows:

finally, according to the three-phase duty ratio D_u、D_v、D_wThe switching tube of the inverter circuit is controlled to realize the compressorAnd controlling the motor.

In summary, according to the control method of the motor driving system without the electrolytic capacitor of the embodiment of the invention, the input ac voltage of the motor driving system is detected in real time, the current highest operating frequency of the compressor motor is calculated according to the input ac voltage, and the compressor motor is controlled according to the current highest operating frequency, so that the highest rotating speed of the compressor motor can be limited in time when the input ac voltage suddenly changes, thereby effectively avoiding the out-of-control of the compressor motor or the damage of the motor driving system, and ensuring the stable and reliable operation of the compressor motor and the motor driving system.

Fig. 8 is a schematic structural diagram of a control device of an electrolytic capacitor-less motor drive system according to an embodiment of the present invention. As shown in fig. 8, the control device includes: a voltage detection module 10, a first calculation module 20 and a control module 30.

Specifically, the voltage detection module 10 is used for detecting the input ac voltage V of the motor drive system in real time_ac. The first calculating module 20 is used for calculating the AC voltage V according to the input AC voltage_acCalculating the current maximum operating frequency F of the compressor motor_max。

According to one embodiment of the invention, when an AC voltage V is input_acWhen rising, the first calculation module 20 calculates the current maximum operating frequency F of the compressor motor by the above equation (1)_max。

Specifically, as shown in FIG. 3, when an AC voltage V is inputted_acWhen rising, if the effective value V of the AC voltage is input_rms<V₂Then, it indicates the input AC voltage V_acIs smaller, at the moment, the starting of the compressor motor is forbidden, namely the current highest running frequency F_max0; if V₂≤V_rms<V₃The compressor motor is allowed to start running, and the effective value V of the input alternating voltage can be used_rmsCalculating the current highest operating frequency F_maxI.e. F_max＝(F_max2-F_max1)*(V_rms-V₂)/(V₃-V₂)+F_max1(ii) a If V₃≤V_rms≤V₅The compressor motor is allowed to be in a high-speed running state all the time, i.e. F_max＝F_max2(ii) a If V_rms>V₅Then it indicates the current input AC voltage V_acAnd if the temperature is too high, the motor of the compressor needs to be controlled to stop working. Therefore, the current highest running frequency of the compressor motor is dynamically adjusted according to the input alternating voltage detected in real time, so that when the input alternating voltage rises, the highest rotating speed of the compressor motor can be limited in time, the compressor motor is effectively prevented from being out of control or a motor driving system is prevented from being damaged, and the compressor motor and the driving motor system are ensured to run stably and reliably.

According to one embodiment of the invention, when an AC voltage V is input_acWhen descending, the first calculation module 20 calculates the current highest operating frequency F of the compressor motor by the above formula (2)_max。

Specifically, as shown in FIG. 4, when an AC voltage V is inputted_acWhen dropping, if the effective value V of the AC voltage is input_rms>V₄Then the compressor motor is controlled to stop working, namely the current highest running frequency F_max0; if V₃≤V_rms≤V₄The compressor motor is allowed to be in a high-speed running state all the time, i.e. F_max＝F_max2(ii) a If V₂≤V_rms<V₃According to the effective value V of the input AC voltage_rmsTo calculate the current highest operating frequency F_maxI.e. F_max＝(F_max2-F_max1)*(V_rms-V₂)/(V₃-V₂)+F_max1(ii) a If V₁≤V_rms<V₂The compressor motor is allowed to be in a low speed running state all the time, i.e. F_max＝F_max1(ii) a If V_rms<V₁Then the compressor motor is controlled to stop working, namely the current highest running frequency F_max0. So that the current highest operating frequency of the compressor motor can be acted upon according to the input AC voltage detected in real timeThe state adjustment to when input alternating voltage falls, can in time restrict the highest rotational speed of compressor motor, effectively avoid compressor motor out of control or motor drive system to damage, for example, can effectively avoid when the compressor of air conditioner is in high-speed operation, because of the compressor motor step-out problem that the moment that direct current bus voltage leads to excessively hangs down is not enough and makes, thereby guarantees compressor motor and motor drive system stable, the reliable operation.

The control module 30 is used for controlling the maximum current operating frequency F_maxThe compressor motor is controlled.

According to one embodiment of the present invention, as shown in fig. 8, the control module 30 includes: a second calculation module 31 and a comparison module 32, wherein the second calculation module 31 is used for calculating the current highest operating frequency F_maxCalculating the maximum operation speed omega of the compressor motor_max(ii) a The comparison module 32 is used to obtain the maximum operating speed ω_maxWith a preset given rotational speedSmaller value therebetweenAccording to a smaller value(as ω_ref) The compressor motor is controlled.

Further, as shown in fig. 6, the control module 30 further includes: a phase detection phase-locked loop module 33, a position velocity estimator 34, a q-axis given current calculation module 35, a d-axis given current calculation module 36, and a current controller 37.

Wherein, the phase detection pll module 33 is used for obtaining the instantaneous voltage V of the input ac voltage_geAnd based on the instantaneous value V of the voltage_geCalculating a phase estimate θ of an input AC voltage_ge。

Specifically, as shown in fig. 7, the phase detection lockThe phase loop module 33 includes: a cosine calculator 331, a first multiplier 332, a low pass filter 333, a first PI regulator 334, and an integrator 335. The cosine calculator 331 is configured to perform cosine calculation on the phase estimation value of the input ac voltage in the previous calculation period to obtain a first calculation value; the first multiplier 332 converts the instantaneous value V of the voltage_geMultiplying the first calculated value by a second calculated value; the low pass filter 333 performs a low pass filtering process on the second calculated value to obtain a third calculated value, wherein the bandwidth of the low pass filter 333 is smaller than the input ac voltage frequency ω_g1/5 of (1); the first PI adjuster 334 PI-adjusts the third calculated value to obtain a fourth calculated value; integrator 335 calculates the fourth value and the frequency ω of the input ac voltage_gThe sum is subjected to integral calculation to obtain a phase estimation value theta of the input alternating voltage of the current calculation period_ge。

The position and speed estimator 34 is used to estimate the rotor position of the compressor motor to obtain a rotor angle estimate and a rotor speed estimate of the compressor motor.

Specifically, the rotor angle estimation value θ of the compressor motor can be obtained by flux linkage observation_estAnd rotor speed estimate ω_est. Specifically, the voltage V on the two-phase stationary coordinate system can be first determined_α、V_βAnd current I_α、I_βThe estimated values of the effective magnetic fluxes of the compressor motor in the axial directions of the two-phase stationary coordinate systems α and β are calculated as shown in the above equation (3), and then the estimated value of the rotor angle θ of the compressor motor is calculated according to the above equation (4)_estAnd rotor speed estimate ω_est。

The q-axis given current calculation module 35 is used for calculating a given current according to the smaller value omega_refRotor speed estimate ω_estShape and phase estimation value theta of input alternating voltage_geCalculating the q-axis given current I of the compressor motor_qref。

Specifically, as shown in fig. 6, the q-axis given current calculation module 35 includes: second PI regulator 351 and waveform generator 352. An initial current calculation unit 353, a capacitance current compensation unit 354, and a superposition unit 355. Wherein the second PI regulator 351 is used for regulating the minimum value omega_refWith rotor speed estimate omega_estThe difference between them is PI regulated to obtain a given T of torque amplitude₀(ii) a The waveform generator 352 is used to estimate the value theta according to the shape and phase of the input AC voltage_geGenerating an output variable W_f(ii) a The initial current calculating unit 353 outputs the variable W_fAnd torque amplitude given T₀Multiplying and dividing by the compressor motor torque coefficient K_tTo obtain an initial value I of a given q-axis current_q0(ii) a The capacitance current compensation unit 354 is used for estimating the value theta according to the phase_geGenerating a compensation current I_qcom(ii) a The superposition unit 355 is used for adding the compensation current I_qcomSuperimposed on the q-axis set current initial value I_q0To obtain a given q-axis current I_qref. Wherein the waveform generator 352 may generate the output variable W by equation (5) above_f. The capacitance current compensation unit 354 may generate the compensation current I by the above equation (6)_qcom。

The d-axis given current calculation module 36 is configured to calculate a d-axis given current of the compressor motor according to the maximum output voltage of the inverter circuit 4 and the output voltage amplitude of the inverter circuit 4.

Specifically, as shown in fig. 6, the d-axis given current calculation module 36 includes: a flux weakening controller 361 and a limiting unit 362, wherein the flux weakening controller 361 is used for the maximum output voltage V of the inverter circuit 4_maxAnd the output voltage amplitude V of the inverter circuit 4₁The difference is subjected to field weakening control to obtain an initial value I of a d-axis given current_d0(ii) a The clipping unit 362 is used to give an initial value of current I to the d-axis_d0Performing a clipping process to obtain a d-axis set current I_dref. Wherein the field-weakening controller 361 can calculate the initial value I of the d-axis given current by the above formula (7)_d0. Then, the clipping unit 362 calculates the d-axis given current I by the above equation (8)_dref。

The current controller 37 is used for giving a current I according to a q axis_qrefD-axis given current I_drefQ-axis actual current I_qAnd d-axis actual current I_dObtaining a given q-axis voltage V of a compressor motor_qrefAnd d-axis given voltage V_drefAnd a voltage V is given according to the q-axis_qrefD-axis given voltage V_drefRotor angle estimation value theta_estGenerates a control signal and controls the compressor motor through the inverter circuit 4 according to the control signal.

Specifically, the current controller 37 may calculate the q-axis given voltage V by the above-described equation (9)_qrefAnd d-axis given voltage V_dref. Obtaining a given voltage V of q axis_qrefAnd d-axis given voltage V_drefThen, the rotor angle estimate θ can be used_estGiven voltage V to q-axis_qrefAnd d-axis given voltage V_drefCarrying out Park inverse transformation to obtain the voltage V on the two-phase static coordinate system_α、V_βThe concrete transformation formula is as the above formula (10). Then, the voltage V on the two-phase static coordinate system is compared_α、V_βPerforming Clark inverse transformation to obtain three-phase voltage command V_u、V_v、V_wThe concrete transformation formula is as shown in the above formula (11). Then, the duty ratio calculating unit 38 calculates the duty ratio based on the dc bus voltage V_dcAnd three-phase voltage command V_u、V_v、V_wDuty ratio calculation is carried out to obtain a duty ratio control signal, namely a three-phase duty ratio D_u、D_v、D_wThe specific calculation formula is as the above formula (12). Finally, according to the three-phase duty ratio D_u、D_v、D_wAnd controlling a switching tube of the inverter circuit to realize the control of the compressor motor.

It is to be understood that the first calculation module 20 and the control module 30 in the control apparatus of the embodiment of the present invention may be integrated in the control portion 5 shown in fig. 1.

According to the control device of the motor driving system without the electrolytic capacitor, the input alternating-current voltage of the motor driving system is detected in real time through the voltage detection module, the first calculation module calculates the current highest operation frequency of the compressor motor according to the input alternating-current voltage, and the control module controls the compressor motor according to the current highest operation frequency, so that the highest rotation speed of the compressor motor can be limited in time when the input alternating-current voltage suddenly changes, the compressor motor is effectively prevented from being out of control or the motor driving system is prevented from being damaged, and the compressor motor and the motor driving system are guaranteed to operate stably and reliably.

In addition, the embodiment of the invention also provides an electrolytic capacitor-free motor driving system, which comprises the control device of the electrolytic capacitor-free motor driving system.

According to the motor driving system without the electrolytic capacitor, the control device can calculate the current highest running frequency of the compressor motor according to the input alternating voltage, so that the highest rotating speed of the compressor motor can be limited in time when the input alternating voltage suddenly changes, the compressor motor is effectively prevented from being out of control or the motor driving system is damaged, and the compressor motor and the motor driving system are guaranteed to run stably and reliably.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (9)

1. A control method of a motor driving system without electrolytic capacitor is characterized by comprising the following steps:

detecting input alternating voltage of a motor driving system in real time;

calculating the current highest operating frequency of a compressor motor according to the input alternating voltage; and

controlling the compressor motor according to the current highest operating frequency, wherein,

when the input ac voltage rises, calculating a current maximum operating frequency of the compressor motor by the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₅Is a fifth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₂<V₃<V₅。

2. The control method according to claim 1, wherein when the input ac voltage decreases, a current highest operating frequency of the compressor motor is calculated by the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₁Is a first predetermined voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₄Is a fourth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₁<V₂<V₃<V₄。

3. The control method of claim 1, wherein said controlling the compressor motor according to the current highest operating frequency comprises:

calculating the highest operation rotating speed of the compressor motor according to the current highest operation frequency;

and acquiring a smaller value between the highest operation rotating speed and a preset given rotating speed, and controlling the compressor motor according to the smaller value.

4. The control method of claim 3, wherein said controlling the compressor motor according to the current highest operating frequency further comprises:

acquiring a voltage instantaneous value of the input alternating voltage, and calculating a phase estimation value of the input alternating voltage according to the voltage instantaneous value;

estimating a rotor position of the compressor motor to obtain a rotor angle estimate and a rotor speed estimate of the compressor motor;

calculating the q-axis given current of the compressor motor according to the smaller value, the rotor speed estimated value, the shape of the input alternating voltage and the phase estimated value;

calculating d-axis given current of the compressor motor according to the maximum output voltage of the inverter circuit and the output voltage amplitude of the inverter circuit;

and acquiring a q-axis given voltage and a d-axis given voltage of the compressor motor according to the q-axis given current, the d-axis given current, the q-axis actual current and the d-axis actual current, generating a control signal according to the q-axis given voltage, the d-axis given voltage and the rotor angle estimation value, and controlling the compressor motor through the inverter circuit according to the control signal.

5. A control apparatus of an electrolytic capacitor-less motor drive system, comprising:

the voltage detection module is used for detecting the input alternating voltage of the motor driving system in real time;

the first calculation module is used for calculating the current highest running frequency of the compressor motor according to the input alternating voltage; and

a control module, configured to control the compressor motor according to the current highest operating frequency, wherein when the input ac voltage increases, the first calculation module calculates the current highest operating frequency of the compressor motor according to the following formula:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₅Is a fifth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₂<V₃<V₅。

6. The control apparatus of claim 5, wherein the first calculation module calculates a current maximum operating frequency of the compressor motor when the input AC voltage drops by:

wherein, F_maxIs the current highest operating frequency, V, of the compressor motor_rmsIs the effective value of the input AC voltage, V₁Is a first predetermined voltage, V₂Is a second predetermined voltage, V₃Is a third predetermined voltage, V₄Is a fourth predetermined voltage, F_max1Is the said V₂Corresponding maximum operating frequency, F, of the compressor motor_max2Is the said V₃Corresponding to the maximum operating frequency of the compressor motor, and V₁<V₂<V₃<V₄。

7. The control device of claim 5, wherein the control module comprises:

the second calculation module is used for calculating the highest running rotating speed of the compressor motor according to the current highest running frequency;

and the comparison module is used for acquiring a smaller value between the highest operation rotating speed and a preset given rotating speed so as to control the compressor motor according to the smaller value.

8. The control device of claim 7, wherein the control module further comprises:

the phase detection phase-locked loop module is used for acquiring a voltage instantaneous value of the input alternating voltage and calculating a phase estimation value of the input alternating voltage according to the voltage instantaneous value;

a position and speed estimator for estimating a rotor position of the compressor motor to obtain a rotor angle estimation value and a rotor speed estimation value of the compressor motor;

the q-axis given current calculation module is used for calculating q-axis given current of the compressor motor according to the smaller value, the rotor speed estimated value, the shape of the input alternating voltage and the phase estimated value;

the d-axis given current calculation module is used for calculating the d-axis given current of the compressor motor according to the maximum output voltage of the inverter circuit and the output voltage amplitude of the inverter circuit;

and the current controller is used for acquiring a q-axis given voltage and a d-axis given voltage of the compressor motor according to the q-axis given current, the d-axis given current, the q-axis actual current and the d-axis actual current, generating a control signal according to the q-axis given voltage, the d-axis given voltage and the rotor angle estimation value, and controlling the compressor motor through the inverter circuit according to the control signal.

9. An electrolytic capacitor-less motor drive system characterized by comprising the control device of the electrolytic capacitor-less motor drive system according to any one of claims 5 to 8.