Driving control method of permanent magnet synchronous motor without electrolytic capacitor

Abstract

The invention provides a driving control method for a permanent magnet synchronous motor without an electrolytic capacitor, and the method comprises the steps: carrying out the harmonic extraction of a collected DC bus voltage value of a driving system of the permanent magnet synchronous motor without the electrolytic capacitor through a band-pass filter, and obtaining harmonic waves of different frequencies; carrying out weighted summation on the harmonic waves with different frequencies to obtain a correction coefficient; then correcting the reference voltage output by the controller of the permanent magnet synchronous motor without the electrolytic capacitor by using the correction coefficient to obtain a control voltage; and finally, modulating the control voltage by using an inverter in the non-electrolytic capacitor permanent magnet synchronous motor driving system, and generating a driving control signal to carry out driving control on the non-electrolytic capacitor permanent magnet synchronous motor. The input current quality can be effectively improved, and the system stability is improved.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet motor drive control, and in particular to a drive control method for a permanent magnet synchronous motor without an electrolytic capacitor. Background Art

[0002] The reliability, operating life and power density of the drive control system of permanent magnet motors have gradually become the focus of attention. The electrolytic capacitors in permanent magnet motors are the core components of traditional motor drivers and are used to stabilize the DC bus voltage and input current filtering, but they have problems such as large size, short life and easy explosion risk. In contrast, film capacitors have significant advantages such as long life, small size and high power density. Therefore, the development of "electrolytic capacitor-free drive system" technology and the replacement of electrolytic capacitors with small-capacity film capacitors are of great significance for extending the overall service life of the system and improving the reliability of the system. However, since the capacitance of film capacitors in electrolytic capacitor-free motor drive systems is significantly lower than that of electrolytic capacitors, the system is prone to instability under heavy load / low line impedance conditions, and the quality of input current is also significantly reduced.

[0003] In order to solve this problem, the prior art provides a control method for a permanent magnet synchronous motor without electrolytic capacitor based on active damping injection. The method is based on collecting grid input power and inverter output power, establishing an active damping control strategy, adding an RD damping circuit to the active damping control strategy, performing decoupling calculation on the RD damping circuit, obtaining decoupling parameters, and fully decoupling control of the d-axis component and the q-axis component of the synchronous motor according to the decoupling parameters; the focus of the method is to reduce the difficulty of obtaining voltage and current control instructions in the control system without affecting the control accuracy and performance of the entire system; however, when the method is used for grid-side current harmonic suppression of a non-electrolytic capacitor motor system, it will cause an increase in machine-side harmonics and its power decoupling circuit is relatively complex, increasing the size of the equipment, which is inconsistent with the development trend of low cost and miniaturization of non-electrolytic capacitor frequency conversion systems; there is also a method for controlling a permanent magnet synchronous motor without electrolytic capacitor based on multi-port impedance optimization. A harmonic suppression method for a permanent magnet synchronous motor drive system is proposed. The impedance control voltage of the machine side port and the grid side port are obtained by calculation. The entropy weight TOPSIS method is used to calculate the optimal angle of the impedance control voltage of the machine-grid side port, and the impedance control voltage of the machine-grid side port is synthesized into a coordinated voltage, which is decomposed into a coordinated voltage d-axis component and a q-axis component, and then superimposed on the dq-axis voltage setting accordingly, so as to obtain the controlled dq-axis voltage setting, and then the adjusted αβ-axis voltage setting is obtained by inverse Park transformation, and then the SVPWM control is used to obtain the pulse control signal of the inverter, so as to realize the harmonic suppression of the machine-grid side of the drive system; the focus of this method is that the proposed algorithm realizes the coordinated suppression of harmonics on the machine-grid side; but this method mainly performs impedance reshaping on the inherent harmonics near the resonant frequency, which may have limited control effect on harmonics of other frequencies, and the complex control strategy increases the complexity of the system. Summary of the invention

[0004] The present invention provides a drive control method for a permanent magnet synchronous motor without an electrolytic capacitor, the purpose of which is to improve the quality of input current and the stability of the system under heavy load / low line impedance conditions.

[0005] In order to achieve the above object, the present invention provides a drive control method for a permanent magnet synchronous motor without an electrolytic capacitor, comprising:

[0006] Step 1, collecting the DC bus voltage value of the electrolytic capacitor-free permanent magnet synchronous motor drive system;

[0007] Step 2: Using a bandpass filter to extract harmonics from the DC bus voltage value to obtain harmonics of different frequencies;

[0008] Step 3, performing weighted summation on harmonics of different frequencies to obtain a correction coefficient;

[0009] Step 4, using the correction coefficient to correct the reference voltage output by the electrolytic capacitor-free permanent magnet synchronous motor controller to obtain a control voltage;

[0010] Step 5: Use the inverter in the electrolytic capacitor-free permanent magnet synchronous motor drive system to modulate the control voltage to generate a drive control signal to drive and control the electrolytic capacitor-free permanent magnet synchronous motor.

[0011] Furthermore, the bandpass filter has a center frequency of 6kf. g The transfer function of the bandpass filter is G BPF,k (s) is:

[0012]

[0013] Where s represents the Laplace operator, ω c，k represents the bandwidth frequency of the kth harmonic bandpass filter, ω g Indicates the input / grid angular frequency, represents the compensation phase for the kth harmonic, k=1,2,3,….

[0014] Furthermore, the DC bus voltage value is subjected to harmonic extraction using a bandpass filter, and the calculation expressions for harmonics of different frequencies are obtained as follows:

[0015] u dck =G BPF,k (s)u dc

[0016] Among them, u dck represents the kth harmonic of the DC bus voltage, u dc Indicates the DC bus voltage.

[0017] Further, the calculation expression of the correction coefficient is:

[0018]

[0019] Where γ represents the correction factor, g k represents the weighting coefficient of the kth harmonic, and N represents the frequency of the harmonic.

[0020] More specifically, step 4 includes:

[0021] When the non-electrolytic capacitor permanent magnet synchronous motor controller is implemented on the dq axis, the reference voltage output by the dq axis is corrected by using the correction coefficient to obtain the control voltage of the dq axis;

[0022] When the non-electrolytic capacitor permanent magnet synchronous motor controller is implemented on the αβ axis, the reference voltage output by the αβ axis is corrected by using the correction coefficient to obtain the control voltage of the αβ axis.

[0023] Furthermore, the calculation expression of the control voltage of the dq axis is:

[0024]

[0025] in, Respectively represent the reference voltage of dq axis output, Represent the control voltage of dq axis respectively.

[0026] Furthermore, the calculation expression of the control voltage of the αβ axis is:

[0027]

[0028] in, Respectively represent the reference voltage output of α and β axes, They represent the control voltages of the α and β axes respectively.

[0029] More specifically, the electrolytic capacitor-free permanent magnet synchronous motor controller includes:

[0030] A first PI control unit, a second PI control unit, and a third PI control unit;

[0031] The first PI control unit is used to process the expected speed of the permanent magnet synchronous motor without electrolytic capacitor and the actual speed of the permanent magnet synchronous motor without electrolytic capacitor to obtain a q-axis current reference value;

[0032] The second PI control unit is used to process the q-axis current and the q-axis current reference value of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system to obtain a reference voltage of the q-axis output;

[0033] The third PI control unit is used to process the d-axis current and the d-axis current reference value of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system to obtain a reference voltage of the d-axis output.

[0034] Furthermore, the q-axis current and d-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system are obtained by transforming the input current of the permanent magnet synchronous motor without electrolytic capacitor. The transformation expression is:

[0035]

[0036] Among them, i u 、i v 、i w They represent the input current of each phase of the permanent magnet synchronous motor without electrolytic capacitor, θ represents the rotor flux angle, i d 、i q They respectively represent the d-axis current and g-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system.

[0037] The above scheme of the present invention has the following beneficial effects:

[0038] The present invention uses a bandpass filter to extract harmonics from a DC bus voltage value of a collected electrolytic capacitor-free permanent magnet synchronous motor drive system to obtain harmonics of different frequencies; then weighted summation is performed on the harmonics of different frequencies to obtain a correction coefficient; then the correction coefficient is used to correct a reference voltage output by a controller of the electrolytic capacitor-free permanent magnet synchronous motor to obtain a control voltage; finally, the control voltage is modulated by an inverter in the electrolytic capacitor-free permanent magnet synchronous motor drive system to generate a drive control signal to drive and control the electrolytic capacitor-free permanent magnet synchronous motor; compared with the prior art, the present invention extracts different harmonic components of the DC bus voltage, calculates the voltage reference correction coefficient, and uses the correction coefficient to adjust the original reference voltage of the motor controller, thereby broadening the stability domain of the electrolytic capacitor-free drive system under low line impedance / heavy load conditions, and can effectively improve the input current quality and enhance the system stability.

[0039] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a driving control flow chart of an embodiment of the present invention;

[0041] Figure 2 A topological structure diagram of a permanent magnet synchronous motor drive system without electrolytic capacitors in an embodiment of the present invention;

[0042] Figure 3 This is a control block diagram of a permanent magnet synchronous motor without electrolytic capacitor in an embodiment of the present invention;

[0043] Figure 4 This is a simulation result diagram of the permanent magnet synchronous motor drive control method without using electrolytic capacitors;

[0044] Figure 5 This is a simulation result diagram of the drive control method of a permanent magnet synchronous motor without electrolytic capacitor. DETAILED DESCRIPTION

[0045] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] In view of the existing problems, the present invention provides a drive control method for a permanent magnet synchronous motor without an electrolytic capacitor.

[0050] like Figure 1 As shown, an embodiment of the present invention provides a drive control method for a permanent magnet synchronous motor without an electrolytic capacitor, comprising:

[0051] Step 1, collecting the DC bus voltage value of the electrolytic capacitor-free permanent magnet synchronous motor drive system;

[0052] Step 2: Using a bandpass filter to extract harmonics from the DC bus voltage value to obtain harmonics of different frequencies;

[0053] Step 3, performing weighted summation on harmonics of different frequencies to obtain a correction coefficient;

[0054] Step 4, using the correction coefficient to correct the reference voltage output by the electrolytic capacitor-free permanent magnet synchronous motor controller to obtain a control voltage;

[0055] Step 5: Use the inverter in the electrolytic capacitor-free permanent magnet synchronous motor drive system to modulate the control voltage to generate a drive control signal to drive and control the electrolytic capacitor-free permanent magnet synchronous motor.

[0056] The electrolytic capacitor-free permanent magnet synchronous motor in the embodiment of the present invention is a three-phase synchronous motor, and the topological structure of its drive system includes a three-phase voltage source on the grid side, a filter inductor L f , uncontrolled rectifier bridge, DC inductor L dc , DC resistance R dc 、Film capacitor C dc , three-phase inverter, such as Figure 2 As shown;

[0057] The negative terminals of the three-phase voltage sources on the grid side are connected to the output terminals of the three-phase grid, and the positive terminals of the three-phase voltage sources on the grid side are connected to the filter inductor L f The input terminal is connected to the filter inductor L f The output end is connected to the midpoint of the bridge arm of the uncontrolled rectifier bridge, and one end of the bridge arm of the uncontrolled rectifier bridge is connected to the DC inductor L dc The first end of the DC inductor L dc The second end of the DC resistor R dc The first end is connected to the DC resistor R dc The second end of the film capacitor C dc The first end of the three-phase inverter is connected to the first end of the three-phase inverter, and the other end of the bridge arm of the uncontrolled rectifier bridge is connected to the film capacitor C dc The second end of the three-phase inverter is connected to the second end of the three-phase inverter, the three-phase output end of the three-phase inverter is connected to the three-phase input end of the electrolytic capacitor-free permanent magnet synchronous motor, and the control end of the three-phase inverter is connected to the output end of the electrolytic capacitor-free permanent magnet synchronous motor controller.

[0058] In the embodiment of the present invention, the filter inductor L f It is composed of three inductors, the first end of each inductor is connected to each phase of the grid-side voltage source, and the second end of each inductor is connected to the midpoint of the bridge arm of the uncontrolled rectifier bridge.

[0059] In the embodiment of the present invention, the uncontrolled rectifier bridge includes six diodes, two diodes form a group of bridge arms, forming three groups of bridge arms, and the midpoint of each group of bridge arms is connected to the filter inductor L f The first output terminal.

[0060] In the embodiment of the present invention, the three-phase inverter includes six switch tubes, and every two switch tubes form a group of bridge arms, and the midpoint of each bridge arm is respectively connected to one-phase input end of the electrolytic capacitor-free permanent magnet synchronous motor.

[0061] Most preferably, the bandpass filter has a center frequency at 6kf g The transfer function of the bandpass filter is G BPF,k (s) is:

[0062]

[0063] Among them, s represents the Laplace operator, ω c，k represents the bandwidth frequency of the kth harmonic bandpass filter, ω g Indicates the input / grid angular frequency, ω g =2πf g , f g Indicates input / grid frequency, represents the compensation phase for the kth harmonic, k=1,2,3,….

[0064] Specifically, the DC bus voltage value is subjected to harmonic extraction using a bandpass filter, and the calculation expressions for harmonics of different frequencies are obtained as follows:

[0065] u dck =G BPF,k (s)u dc

[0066] Among them, u dck represents the kth harmonic of the DC bus voltage, u dc Indicates the DC bus voltage.

[0067] In the embodiment of the present invention, each harmonic of each frequency is multiplied by an adjustable constant gain. These gains can be adjusted according to the needs of the system to optimize the stability and response speed of the system. The harmonic signals of each frequency after gain adjustment are added to obtain a total compensation signal. The summed compensation signal is used as a correction coefficient. The correction coefficient reflects the response and adjustment of the system to different harmonics. The calculation expression of the correction coefficient is:

[0068]

[0069] Where γ is the correction factor, g k represents the weighting coefficient of the kth harmonic, g k>0, N represents the frequency of harmonics.

[0070] In the embodiment of the present invention, the weighting coefficient g k The larger the value of is, the stronger the corresponding k-th harmonic suppression capability is. It should be noted that due to the physical constraints of the actual controller (not infinite output) and stability requirements, the weighting coefficient g k The choice needs to be designed and debugged according to the actual situation.

[0071] Specifically, step 4 includes:

[0072] When the non-electrolytic capacitor permanent magnet synchronous motor controller is implemented on the dq axis, the reference voltage output by the dq axis is corrected by using the correction coefficient to obtain the control voltage of the dq axis;

[0073] When the non-electrolytic capacitor permanent magnet synchronous motor controller is implemented on the αβ axis, the reference voltage output by the αβ axis is corrected by using the correction coefficient to obtain the control voltage of the αβ axis.

[0074] Specifically, the calculation expression of the control voltage of the dq axis is:

[0075]

[0076] in, Respectively represent the reference voltage of dq axis output, Represent the control voltage of dq axis respectively.

[0077] Specifically, the calculation expression of the control voltage of the αβ axis is:

[0078]

[0079] in, Respectively represent the reference voltage output of α and β axes, They represent the control voltages of the α and β axes respectively.

[0080] Specifically, if Figure 3 As shown, the electrolytic capacitor-free permanent magnet synchronous motor controller includes:

[0081] A first PI control unit, a second PI control unit, and a third PI control unit;

[0082] The first PI control unit is used to process the expected speed of the permanent magnet synchronous motor without electrolytic capacitor and the actual speed of the permanent magnet synchronous motor without electrolytic capacitor to obtain the q-axis current reference value The calculation expression is:

[0083]

[0084] Among them, K pωrepresents the proportional gain of the first PI control unit, K iω represents the integral gain of the first PI control unit, ω * represents the expected speed of the permanent magnet synchronous motor without electrolytic capacitor, ω represents the actual speed of the permanent magnet synchronous motor without electrolytic capacitor, which can be obtained by the angle / speed encoder or the sensorless algorithm;

[0085] The second PI control unit is used to process the q-axis current and the q-axis current reference value of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system to obtain the reference voltage of the q-axis output The calculation expression is:

[0086]

[0087] Among them, K pq represents the proportional gain of the third PI control unit, K iq represents the integral gain of the third PI control unit, It represents the d-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system, which can be obtained by the field weakening controller or the maximum torque per ampere (MTPA) controller;

[0088] The third PI control unit is used to process the d-axis current and the d-axis current reference value of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system to obtain the reference voltage of the d-axis output The calculation expression is:

[0089]

[0090] Among them, K pd represents the proportional gain of the third PI control unit, K id represents the integral gain of the third PI control unit, It represents the d-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system, which can be obtained by the weak magnetic field controller or the maximum torque per ampere controller.

[0091] Specifically, the q-axis current and d-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system are obtained by Park transformation of the input current of the permanent magnet synchronous motor without electrolytic capacitor. The transformation expression is:

[0092]

[0093] Among them, i u 、i v 、i w They represent the input current of each phase of the permanent magnet synchronous motor without electrolytic capacitor, θ represents the rotor flux angle, which can be obtained by the angle / speed encoder or the sensorless algorithm, id 、i q They respectively represent the d-axis current and q-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system.

[0094] In order to verify the effectiveness of the method, the present invention is carried out according to Figure 2 The topology diagram shown in the figure is used to build the simulink simulation diagram. The grid side parameter is the amplitude U of the three-phase voltage source. sm =311V, input grid frequency f g =50Hz, inductance L in =0.2175mH, resistance R in =0.039432Ω, capacitance C x =1.6uF; DC inductor L dc =43uH, film capacitor C dc =80uF; load side parameter is stator phase resistance R s =0.083Ω, inductance L q =1.8mH, L d =1.37mH, magnetic flux Φ = 0.1448Wb, inertia J = 0.00433kg.m 2 , the number of pole pairs p = 3, and the simulation test is carried out with the above-set parameters. The test results are as follows Figure 4 and Figure 5 As shown:

[0095] like Figure 4 FIG. 4 shows the simulation results without using the method provided by the embodiment of the present invention. Figure 4 (a) and (b) respectively show the simulation waveforms of the DC bus voltage and the grid-side input current. From the simulation results, it can be seen that when the method provided by the embodiment of the present invention is not used, the peak-to-peak value of the DC bus voltage reaches 700V, and the peak-to-peak value of the grid-side input current reaches 100A.

[0096] like Figure 4 FIG. 4 shows the simulation results of the method provided by the embodiment of the present invention. Figure 5 (a) and (b) respectively show the simulation waveforms of the DC bus voltage and the grid-side input current. It can be seen from the simulation results that when the method provided by the embodiment of the present invention is used, the peak-to-peak value of the DC bus voltage is only 475V, and the peak-to-peak value of the grid-side input current is only 70A; this shows that the method provided by the embodiment of the present invention expands the stability domain of the system and improves the reliability of the system.

[0097] The embodiment of the present invention uses a bandpass filter to extract harmonics from the collected DC bus voltage value of the electrolytic capacitor-free permanent magnet synchronous motor drive system to obtain harmonics of different frequencies; then weighted summation is performed on the harmonics of different frequencies to obtain a correction coefficient; then the correction coefficient is used to correct the reference voltage output by the electrolytic capacitor-free permanent magnet synchronous motor controller to obtain a control voltage; finally, the control voltage is modulated by the inverter in the electrolytic capacitor-free permanent magnet synchronous motor drive system to generate a drive control signal to drive and control the electrolytic capacitor-free permanent magnet synchronous motor; compared with the prior art, the embodiment of the present invention can broaden the stability domain of the electrolytic capacitor-free drive system under low line impedance / heavy load conditions by extracting different harmonic components of the DC bus voltage, calculating the voltage reference correction coefficient, and using the correction coefficient to adjust the original reference voltage of the motor controller, and can effectively improve the input current quality and enhance the system stability.

[0098] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A drive control method for a permanent magnet synchronous motor without electrolytic capacitor, characterized in that: include: Step 1, collecting the DC bus voltage value of the electrolytic capacitor-free permanent magnet synchronous motor drive system; Step 2, using a bandpass filter to perform harmonic extraction on the DC bus voltage value to obtain harmonics of different frequencies; Step 3, performing weighted summation on harmonics of different frequencies to obtain a correction coefficient; Step 4, using the correction coefficient to correct the reference voltage output by the electrolytic capacitor-free permanent magnet synchronous motor controller to obtain a control voltage; Step 5: Use the inverter in the electrolytic capacitor-free permanent magnet synchronous motor drive system to modulate the control voltage to generate a drive control signal to drive and control the electrolytic capacitor-free permanent magnet synchronous motor.

2. The drive control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 1, characterized in that: The bandpass filter has a center frequency of 6kf g The transfer function of the bandpass filter is G BPF,k (s) is: Among them, s represents the Laplace operator, ω c，k represents the bandwidth frequency of the kth harmonic bandpass filter, ω g Indicates the input / grid angular frequency, represents the compensation phase for the kth harmonic, k=1,2,3,….

3. The drive control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 2, characterized in that: The DC bus voltage value is subjected to harmonic extraction using a bandpass filter, and the calculation expressions for harmonics of different frequencies are obtained as follows: u dck =G BPF,k (s)u dc Among them, u dck represents the kth harmonic of the DC bus voltage, u dc Indicates the DC bus voltage.

4. The drive control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 3, characterized in that: The calculation expression of the correction coefficient is: Where γ represents the correction factor, g k represents the weighting coefficient of the kth harmonic, and N represents the frequency of the harmonic.

5. The drive control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 4, characterized in that: The step 4 comprises: When the non-electrolytic capacitor permanent magnet synchronous motor controller is implemented on the dq axis, the reference voltage output by the dq axis is corrected by using the correction coefficient to obtain the control voltage of the dq axis; When the electrolytic capacitor-free permanent magnet synchronous motor controller is implemented on the αβ axis, the reference voltage output by the αβ axis is corrected by using the correction coefficient to obtain the control voltage of the αβ axis.

6. The driving control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 5, characterized in that: The calculation expression of the control voltage of the dq axis is: in, Respectively represent the reference voltage of dq axis output, Represent the control voltage of dq axis respectively.

7. The drive control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 5, characterized in that: The calculation expression of the control voltage of the αβ axis is: in, Respectively represent the reference voltage output of α and β axes, They represent the control voltages of the α and β axes respectively.

8. The driving control method of a permanent magnet synchronous motor without electrolytic capacitor according to claim 1, characterized in that: The electrolytic capacitor-free permanent magnet synchronous motor controller comprises: A first PI control unit, a second PI control unit, and a third PI control unit; The first PI control unit is used to process the expected speed of the electrolytic capacitor-free permanent magnet synchronous motor and the actual speed of the electrolytic capacitor-free permanent magnet synchronous motor to obtain a q-axis current reference value; The second PI control unit is used to process the q-axis current of the electrolytic capacitor-free permanent magnet synchronous motor in the dq coordinate system and the q-axis current reference value to obtain a reference voltage output by the q-axis; The third PI control unit is used to process the d-axis current of the electrolytic capacitor-free permanent magnet synchronous motor in the dq coordinate system and the d-axis current reference value to obtain a reference voltage of the d-axis output.

9. The driving control method of the electrolytic capacitor-free permanent magnet synchronous motor according to claim 8, characterized in that: The q-axis current and d-axis current of the electrolytic capacitor-free permanent magnet synchronous motor in the dq coordinate system are obtained by transforming the input current of the electrolytic capacitor-free permanent magnet synchronous motor, and the transformation expression is: Among them, i u 、i v 、i w They represent the input current of each phase of the permanent magnet synchronous motor without electrolytic capacitor, θ represents the rotor flux angle, i d 、i q They respectively represent the d-axis current and q-axis current of the permanent magnet synchronous motor without electrolytic capacitor in the dq coordinate system.

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