Harmonic suppression method for electrolytic capacitorless permanent magnet synchronous motor drive system based on multi-port impedance optimization

Abstract

The application discloses a multi-port impedance optimization-based harmonic suppression method for a non-electrolytic capacitor permanent magnet synchronous motor driving system, and belongs to the technical field of motor control. The application is aimed at the problem that active damping control will cause the increase of machine-side harmonics when used for the network-side current harmonic suppression of a non-electrolytic capacitor motor system. The machine-side port impedance regulation voltage and the network-side port impedance regulation voltage are calculated. The entropy weight TOPSIS method is used to calculate the optimal angle of the machine-side and network-side port impedance regulation voltage, and the machine-side and network-side port impedance regulation voltage is synthesized into a cooperative voltage. The cooperative voltage is decomposed into a d-axis component and a q-axis component, and then is superimposed on the dq-axis voltage given value, so that the controlled dq-axis voltage given value is obtained. The regulated alpha-beta axis voltage given value is obtained through the inverse Park transformation link, and then the pulse control signal of the inverter is obtained through the SVPWM control, so that the machine-side and network-side harmonic suppression of the driving system is realized. The application is used for the cooperative suppression of machine-side and network-side harmonics.

Description

Technical Field

[0001] The present invention relates to a harmonic suppression method for a permanent magnet synchronous motor drive system without electrolytic capacitors based on multi-port impedance optimization, and belongs to the technical field of motor control. Background Art

[0002] The variable frequency drive system of permanent magnet synchronous motors mainly adopts an AC-DC-AC circuit structure. Generally speaking, in order to reduce the fluctuation of the bus voltage in the DC link, the bus capacitor is selected to be an aluminum electrolytic capacitor with a larger capacity. However, the life of electrolytic capacitors is greatly affected by the ambient temperature (the life is halved for every 10°C increase in temperature), which reduces the reliability of the drive system. At present, the use of small-capacitance film capacitors in the bus link can increase the service life and reduce the size. Film capacitors are less affected by ripple current and have no explosion risk. Permanent magnet synchronous motor drive systems using film capacitors have the advantages of high reliability, high power density, and low cost. In recent years, they have received widespread attention from academia and industry. At present, the drive control technology of motors without electrolytic capacitors still faces some technical challenges in harmonic suppression and stable operation.

[0003] The topology of an electroless permanent magnet synchronous motor drive system primarily consists of a diode-controlled bridge rectifier, low-capacitance thin-film capacitors, a three-phase voltage-source inverter, and a permanent magnet synchronous motor. As the DC-side capacitor value decreases, the drive system's energy coupling between the machine and grid increases, creating a series of problems for the motor drive system. For example, LC resonance caused by the filter inductor and bus capacitance exacerbates bus voltage and grid-side current harmonics. The commonly used active damping control, when used to suppress grid-side current harmonics in electroless capacitor motor systems, can increase machine-side harmonics. Summary of the Invention

[0004] To address the problem that active damping control will cause an increase in machine-side harmonics when used to suppress grid-side current harmonics in a non-electrolytic capacitor motor system, the present invention provides a harmonic suppression method for a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization.

[0005] The present invention provides a harmonic suppression method for a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization, comprising:

[0006] The machine side torque T e The pulsating component T e1 Calculate the impedance control voltage u at the machine side port tor ;

[0007] The bus voltage u dc Get its pulsating component u dc1 , combined with the setting damping coefficient g damp 、Motor d-axis current i d and the motor q-axis current i qThe grid-side port impedance control voltage u is calculated net ;

[0008] The entropy weight TOPSIS method is used to calculate the impedance control voltage u at the machine side port tor And the grid side port impedance regulation voltage u net The optimal angle θ between opti and adjust the voltage u by adjusting the impedance of the machine side port tor And the grid side port impedance regulation voltage u net Synthesize into a coordinated voltage; decompose the coordinated voltage into the coordinated voltage d-axis component u com_d and the coordinated voltage q-axis component u com_q , and then superimposed on the d-axis voltage given u dref and q-axis voltage given by u qref Thus, the d-axis voltage after control is given u dref_c After the control, the q-axis voltage is given by u qref_c ;

[0009] The d-axis voltage after control is given as u dref_c After the control, the q-axis voltage is given by u qref_c Input the inverse Park transformation link in the vector control to obtain the α-axis voltage given u after adjustment αref_c And after adjustment, the β-axis voltage is given by u βref_c , and then SVPWM control is used to obtain the pulse control signal of the inverter, thereby achieving harmonic suppression on the machine-grid side of the drive system.

[0010] According to the harmonic suppression method of the electrolytic capacitor-free permanent magnet synchronous motor drive system based on multi-port impedance optimization of the present invention, the pulsating component T e1 is the machine side torque T extracted by bandpass filter BPF e The sixth harmonic of:

[0011] T e1 (s)=B(s)T e (s),

[0012] Where B(s) represents the transfer function of the bandpass filter BPF, and s is the frequency domain operator.

[0013] According to the harmonic suppression method of the electrolytic capacitor-free permanent magnet synchronous motor drive system based on multi-port impedance optimization of the present invention, the machine side port impedance controls the voltage u tor The calculation method is:

[0014] Set the generator side torque fluctuation reference value T eref =0, and the pulsating component T e1 The difference is controlled by the proportional resonant controller to obtain the impedance control voltage u at the machine side port. tor .

[0015] According to the harmonic suppression method of the electrolytic capacitor-free permanent magnet synchronous motor drive system based on multi-port impedance optimization of the present invention, the transfer function G of the proportional resonant controller is PR (s) designed to:

[0016]

[0017] Where K p is the proportional gain, K r1 is the grid-side voltage sextuple frequency resonance gain, ξ1 is the grid-side voltage sextuple frequency bandwidth, ω g is the grid-side voltage frequency.

[0018] According to the harmonic suppression method of the electrolytic capacitor-free permanent magnet synchronous motor drive system based on multi-port impedance optimization of the present invention, the pulsating component u dc1 The bus voltage harmonics extracted by high-pass filter HPF are:

[0019] u dc1 (s)=H(s)u dc (s),

[0020] Where H(s) is the transfer function of the high-pass filter HPF.

[0021] According to the harmonic suppression method of the electrolytic capacitor-free permanent magnet synchronous motor drive system based on multi-port impedance optimization of the present invention, the grid-side port impedance controls the voltage u net The calculation method is:

[0022]

[0023] According to the harmonic suppression method of the electrolytic capacitor-free permanent magnet synchronous motor drive system based on multi-port impedance optimization of the present invention, the optimal angle θ opti The calculation method is:

[0024] First, the machine-side input admittance Y is calculated based on the motor operating steady-state point parameters. m_in (s) Modeling;

[0025] Then, based on the machine side input admittance Y m_in (s) Computer-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net ;

[0026] Then based on the machine side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net Construct an evaluation matrix X, perform index standardization on the evaluation matrix X, and obtain a standardized evaluation matrix Y;

[0027] Calculate the evaluation index information entropy e based on the standardized evaluation matrix Y; and calculate the weight omega of the evaluation index from the evaluation index information entropy e;

[0028] Based on the standardized evaluation matrix Y and the weight omega of the evaluation index, a weighted evaluation matrix R is constructed, and a positive ideal solution vector s is determined + And the negative ideal solution vector s - ;

[0029] Finally, the Euclidean distance formula is used to calculate the distance of the weighted evaluation matrix R to the positive ideal solution vector s + And the negative ideal solution vector s - , and the relative closeness coefficient h is calculated; the maximum value of the relative closeness coefficient h corresponds to the optimal angle theta i As the optimal angle theta opti .

[0030] The beneficial effects of the application: the method of the application is mainly applied in electrolytic capacitor-free permanent magnet synchronous motor driving system, based on multi-port impedance optimization for harmonic suppression, to improve the performance of the driving system machine network side.

[0031] The application cooperatively suppresses the machine network side harmonics through machine network side port impedance cooperative optimization, so that the input power quality of the network side of the motor and the output torque harmonics of the machine side are cooperatively controlled. Based on the multi-port system impedance model with the input being the rectified voltage and the output being the motor current and the DC side current, the connection between the machine network side port impedance and the machine network side harmonics is established. At the same time, the influence of the impedance control voltage angle on the impedance optimization index is analyzed, and the optimal impedance control voltage angle is further selected by the entropy weight TOPSIS method to suppress the machine network side harmonics. Finally, under the optimal impedance control voltage angle, the impedance control voltage vector is synthesized, and the technical effect of the cooperative control of the input power quality of the network side and the output torque harmonics of the machine side is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The overall block diagram of the electrolytic capacitor-free permanent magnet synchronous motor driving system harmonic suppression method based on multi-port impedance optimization is shown in the figure; in the figure, Z net is the network side port impedance, U rect is the transfer function representing the rectified voltage, I g is the transfer function representing the DC side current flowing through L g , is the machine side input admittance after control, Z tor is the machine side port impedance, h max is the maximum value of the relative closeness coefficient; u d,q is the d-q axis motor voltage vector, i a is the a-phase current, i b is the b-phase current;

[0033] Figure 2 This is a comparison diagram of bus voltage, generator-side torque, and grid-side current waveforms before and after control using the method of the present invention and the existing active damping control method when the motor frequency is 70 Hz in a specific embodiment;

[0034] Figure 3 for Figure 2 A magnified diagram of the bus voltage, generator-side torque, and grid-side current waveforms before and after control using the method of the present invention and the existing active damping control method;

[0035] Figure 4 for Figure 2 A magnified diagram of the bus voltage and generator-side current waveforms before and after control using the method of the present invention and the existing active damping control method. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0039] Specific implementation method 1. Combination Figure 1 As shown, the present invention provides a harmonic suppression method for a permanent magnet synchronous motor drive system without electrolytic capacitors based on multi-port impedance optimization, comprising:

[0040] The machine side torque T e The pulsating component T e1 Calculate the impedance control voltage u at the machine side port tor ;

[0041] The bus voltage u dc Get its pulsating component u dc1 , combined with the setting damping coefficient g damp 、Motor d-axis current i d and the motor q-axis current i q The grid-side port impedance control voltage u is calculated net ;

[0042] The entropy weight TOPSIS method is used to calculate the impedance control voltage u at the machine side port torand grid-side port impedance regulating voltage u net between the optimal angle θ opti and grid-side port impedance regulating voltage u tor and grid-side port impedance regulating voltage u net is synthesized into a cooperative voltage; the cooperative voltage is decomposed into a d-axis component u com_d and a q-axis component u com_q of the cooperative voltage; the d-axis voltage given u dref and the q-axis voltage given u qref are superimposed on the d-axis voltage given u dref_c and the q-axis voltage given u qref_c ;

[0043] the d-axis voltage given u dref_c and the q-axis voltage given u qref_c are input into the inverse Park transformation link in vector control, to obtain the adjusted α-axis voltage given u αref_c and the adjusted β-axis voltage given u βref_c ; the pulse control signals of the inverter are obtained by using SVPWM control, so that the harmonic suppression of the machine and grid side of the drive system is realized.

[0044] As shown in Figure 1 , the electrolytic capacitor-free permanent magnet motor drive system mainly consists of three parts, one part is vector control, one part is impedance regulating voltage angle optimization, and one part is machine and grid side port impedance regulating voltage generation.

[0045] Among them, the speed loop is the outer loop because of the long working period, and the current loop is the inner loop. The speed given ω eref is subtracted from the observed speed fed back by the speed loop, and the difference is generated by the speed regulator PI to generate the q-axis current given i qref ; the observed speed is output by the speed / position observer; the q-axis current given i qref is subtracted from the feedback q-axis current i q , and the q-axis voltage given u qref is generated by the current regulator PI control; the d-axis current given i dref is subtracted from the feedback d-axis current i d , and the d-axis voltage given u dref is generated by the current regulator PI control; the output observed angle is output by the speed / position observer; the α-axis current i α and the β-axis current i β are fed back; the d-axis current i d and the q-axis current i qThe d-axis component of the coordinated voltage u com_d and the coordinated voltage q-axis component u com_q Respectively with the dq axis voltage given u d,qref Add them together to get the controlled dq axis voltage given u d,qref_c , dq axis voltage setting and observation angle The α-axis voltage u is given by the inverse Park transform output after adjustment αref_c And after adjustment, the β-axis voltage is given by u βref_c Finally, SVPWM control is used to obtain the six pulse signals output by the chip, ultimately realizing permanent magnet synchronous motor control.

[0046] In the impedance control voltage angle optimization part, the machine-side input admittance model is used to construct the machine-grid side port impedance optimization index λ tor and λ net , combined with the entropy weight TOPSIS method to obtain the optimal angle θ opti The relative proximity coefficient.

[0047] The generator-grid port impedance control voltage generation section uses a bandpass filter (BPF) to obtain the sixth-order harmonic of the grid-side voltage in the generator-side torque as closed-loop feedback. With 0 as the closed-loop reference, the difference between the closed-loop reference and feedback is controlled through a proportional resonance control link. The output of the proportional resonance control link is the generator-side port impedance control voltage. A high-pass filter (HPF) is used to obtain the pulsating component of the bus voltage. The motor dq axis current and bus voltage are combined with the damping current to generate the grid-side port impedance control voltage. Combined with the optimal angle θ generated by the impedance control voltage angle optimization section. opti , the impedance-controlled voltage at the generator side port and the impedance-controlled voltage at the grid side port are combined into a coordinated voltage, and then decomposed into the coordinated voltage d-axis component u com_d and the coordinated voltage q-axis component u com_q .

[0048] Figure 1 In the above, PMSM means permanent magnet motor without electrolytic capacitor, i αβ is the feedback αβ axis current, and PR is the proportional resonant controller.

[0049] Furthermore, the pulsating component T e1 is the machine side torque T extracted by bandpass filter BPF e The sixth harmonic of:

[0050] T e1 (s)=B(s)T e (s),

[0051] Where B(s) represents the transfer function of the bandpass filter BPF, and s is the frequency domain operator.

[0052] Machine side port impedance control voltage u tor The calculation method is:

[0053] Set the generator side torque fluctuation reference value T eref =0, and the pulsating component T e1 The difference is controlled by the proportional resonant controller to obtain the impedance control voltage u at the machine side port. tor .

[0054] In this embodiment, 0 is used as the closed-loop torque fluctuation value of the machine side, and the proportional resonant controller is used to control the machine side port impedance control voltage.

[0055] In this embodiment, the transfer function G of the proportional resonant controller is PR (s) designed to:

[0056]

[0057] Where K p is the proportional gain, K r1 is the grid-side voltage sextuple frequency resonance gain, ξ1 is the grid-side voltage sextuple frequency bandwidth, ω g is the grid-side voltage frequency.

[0058] Pulsation component u dc1 The bus voltage harmonics extracted by high-pass filter HPF are:

[0059] u dc1 (s)=H(s)u dc (s),

[0060] Where H(s) is the transfer function of the high-pass filter HPF.

[0061] In this embodiment, the grid-side port impedance controls the voltage u net The calculation method is:

[0062]

[0063] This embodiment extracts the pulsating component of the bus voltage and generates a damping current in combination with the damping coefficient; extracts the motor dq axis current and the bus voltage and generates a grid-side port impedance control voltage in combination with the damping current.

[0064] Furthermore, the optimal angle is obtained by combining the entropy weight TOPSIS, and the impedance control voltage of the generator side port and the impedance control voltage of the grid side port are vector-synthesized to generate a coordinated voltage vector; the optimal angle θ opti The calculation method is:

[0065] First, the machine-side input admittance Y is calculated based on the motor operating steady-state point parameters. m_in (s) Modeling;

[0066] Then, based on the machine side input admittance Y m_in (s) Computer-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net ;

[0067] Then based on the machine side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net Construct an evaluation matrix X, perform index standardization on the evaluation matrix X, and obtain a standardized evaluation matrix Y;

[0068] The evaluation index information entropy e is calculated based on the standardized evaluation matrix Y; and the weight ω of the evaluation index is calculated based on the evaluation index information entropy e;

[0069] Based on the standardized evaluation matrix Y and the weight of the evaluation index ω, the weighted evaluation matrix R is constructed and the positive ideal solution vector s is determined + and the negative ideal solution vector s - ;

[0070] Finally, the Euclidean distance formula is used to calculate the weighted evaluation matrix R to the positive ideal solution vector s + and the negative ideal solution vector s - The distance between the two sides is calculated, and the relative proximity coefficient h is calculated; the maximum value of the relative proximity coefficient h is the value of θ i As the optimal angle θ opti .

[0071] The details are as follows:

[0072] Input admittance Y on the machine side m_in (s) Modeling:

[0073]

[0074] Where I inv is the average value of the inverter input current, U dc is the average bus voltage, U d is the average d-axis voltage, ω e is the average electrical angular velocity of the rotor, L d is the d-axis inductance, I q is the average value of the q-axis current, I d is the average d-axis current, R s is the stator phase resistance, U dref is the average value of the d-axis reference voltage, L q is the q-axis inductance, K pq is the proportional gain of the q-axis current regulator, K iq is the integral gain of the q-axis current regulator, n p is the number of motor pole pairs, ψf is the permanent magnet flux, θ is the optimal angle process value, U qref is the average value of the q-axis reference voltage, K pd is the proportional gain of the d-axis current regulator, K id is the integral gain of the d-axis current regulator, U q is the average value of q-axis voltage;

[0075] Based on the machine side input admittance Y m_in (s) Computer-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net for:

[0076]

[0077] Where U g is the effective value of the grid phase voltage, C dc is the capacitance of the small-value film capacitor, L g is the DC side inductance, R g is the DC side resistance;

[0078]

[0079] Based on the machine-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net The constructed evaluation matrix X is:

[0080] X=(λ tor_i ,λ net_i ) 101×2 , i=0,1,2,…,100,

[0081] Where λ tor_i is the machine-side port impedance optimization index obtained in the i-th iteration, λ net_i is the grid-side port impedance optimization index obtained in the i-th iteration; θ i is the optimal angle process value obtained in the i-th iteration, θ i =1.8×i;

[0082] The evaluation matrix X is normalized, and the obtained standardized evaluation matrix Y is:

[0083]

[0084] Where λ tor_nor_i is λ tor_i The standardized value of λ net_nor_i is λ net_i The normalized value of max1 is all λ tor_i The maximum value among all λ net_i The maximum value in .

[0085] The calculation method of the evaluation index information entropy e of the standardized value is:

[0086]

[0087] Where e tor is the information entropy of the machine-side port impedance optimization index, e net The information entropy of the network-side port impedance optimization index;

[0088] The method for calculating the weight ω of the evaluation index from the evaluation index information entropy e is:

[0089]

[0090] Where ω tor is the weight of the machine-side port impedance optimization index, ω net The weight of the grid-side port impedance optimization index;

[0091] Construct the weighted evaluation matrix R and determine the positive ideal solution vector s + and the negative ideal solution vector s - :

[0092]

[0093] Where r tor_i is the machine-side port impedance optimization index evaluation matrix, r net_i is the grid-side port impedance optimization index evaluation matrix, is the ideal positive solution vector on the machine side, is the positive ideal solution vector on the grid side, is the negative ideal solution vector on the machine side, is the negative ideal solution vector on the net side;

[0094] Using the Euclidean distance formula, calculate the weighted evaluation matrix R to the positive ideal solution vector s + and the negative ideal solution vector s - The distance and calculate the relative proximity coefficient h:

[0095]

[0096] In the formula From the weighted evaluation matrix R to the positive ideal solution vector s + distance, is the weighted evaluation matrix R to the negative ideal solution vector s - distance;

[0097] The maximum value of the relative closeness coefficient h corresponds to θ i As the optimal angle θ opti .

[0098] Furthermore, the coordinated voltage d-axis component u com_d and the coordinated voltage q-axis component u com_q The calculation method is:

[0099] Specific embodiment:

[0101] The effectiveness of the method of the present invention is verified by this example:

[0102] The effectiveness of the harmonic suppression strategy proposed in this paper was verified on a non-electrolytic capacitor permanent magnet synchronous motor drive system platform. The various parameters of the experimental platform were set as follows: grid voltage 380V, grid frequency 50Hz (at this time, the main harmonics of the bus voltage are 300Hz and 600Hz), DC bus capacitor is a film capacitor with a capacitance of 30μF, d-axis inductance 7.5mH, q-axis inductance 17.2mH, back EMF constant 210V, rotor pole pair number 3, rated power 5.5kW, rated frequency 75Hz, and stator resistance 0.265Ω. All control algorithms in the experiment were implemented in TMS320F28075. The switching and current and voltage sampling value update frequency were both set to 8kHz, and the switching period was 1.25e-4s.

[0103] Figures 2 to 4 The experimental results at 70Hz are obtained by using the existing active damping control method and then the method of the present invention. Figure 2 After applying the existing active damping strategy, the bus voltage fluctuation amplitude dropped from 150.2V to 133.8V. With the method of the present invention, it slightly rebounded to 137.5V. Simultaneously, the electromagnetic torque fluctuation amplitude increased from 5.7Nm to 9.6Nm, then decreased to 7.1Nm. Furthermore, the grid-side current THD dropped from an initial 57.3% to 43.2%, and then to 45.6%. Figure 3 The magnified images of the experimental waveforms in three states are shown. Figure 4 The changes in motor current under three conditions are shown. Compared with a system using an active damping strategy, the system using the method of the present invention improves the performance of the drive system on the machine side while maintaining the grid-side power quality under the active damping strategy. Specifically, the machine-side current THD is reduced from 7.38% to 5.86%. This shows that the method of the present invention can achieve coordinated optimization of the machine-grid side port impedance and coordinated suppression of machine-grid side harmonics.

[0104] The method of the present invention is introduced in detail above, and the principle and implementation method of the method of the present invention are explained by using specific embodiments. The above embodiments are only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A harmonic suppression method for a permanent magnet synchronous motor drive system without electrolytic capacitors based on multi-port impedance optimization, characterized in that: include: The machine side torque T e The pulsating component T e1 Calculate the impedance control voltage u at the machine side port tor ; The bus voltage u dc Get its pulsating component u dc1 , combined with the setting damping coefficient g damp 、Motor d-axis current i d and the motor q-axis current i q The grid-side port impedance control voltage u is calculated net ; The entropy weight TOPSIS method is used to calculate the impedance control voltage u at the machine side port tor And the grid side port impedance regulation voltage u net The optimal angle θ between opti And adjust the voltage u by adjusting the impedance of the machine side port tor And the grid side port impedance regulation voltage u net Synthesize into a coordinated voltage; decompose the coordinated voltage into the coordinated voltage d-axis component u com_d and the coordinated voltage q-axis component u com_q , and then superimposed on the d-axis voltage given u dref and q-axis voltage given by u qref Thus, the d-axis voltage after control is given u dref_c After the control, the q-axis voltage is given by u qref_c ; The d-axis voltage after control is given as u dref_c After the control, the q-axis voltage is given by u qref_c Input the inverse Park transformation link in the vector control to obtain the α-axis voltage given u after adjustment αref_c And after adjustment, the β-axis voltage is given by u βref_c , and then use SVPWM control to obtain the pulse control signal of the inverter, thereby achieving harmonic suppression on the machine-grid side of the drive system; Machine side port impedance control voltage u tor The calculation method is: Set the generator side torque fluctuation reference value T eref =0, and the pulsating component T e1 The difference is controlled by the proportional resonant controller to obtain the impedance control voltage u at the machine side port. tor ; Grid-side port impedance control voltage u net The calculation method is: Optimal angle θ opti The calculation method is: First, the machine-side input admittance Y is calculated based on the motor operating steady-state point parameters. m_in (s) is used for modeling; s is a frequency domain operator; Then, based on the machine side input admittance Y m_in (s) Computer-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net ; Then based on the machine side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net Construct an evaluation matrix X, perform index standardization on the evaluation matrix X, and obtain a standardized evaluation matrix Y; The evaluation index information entropy e is calculated based on the standardized evaluation matrix Y; and the weight ω of the evaluation index is calculated based on the evaluation index information entropy e; Based on the standardized evaluation matrix Y and the weight of the evaluation index ω, the weighted evaluation matrix R is constructed and the positive ideal solution vector s is determined + and the negative ideal solution vector s - ; Finally, the Euclidean distance formula is used to calculate the weighted evaluation matrix R to the positive ideal solution vector s + and the negative ideal solution vector s - The distance between the two sides is calculated, and the relative proximity coefficient h is calculated; the maximum value of the relative proximity coefficient h is the value of θ i As the optimal angle θ opti .

2. The harmonic suppression method of a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization according to claim 1 is characterized in that: Pulsation component T e1 is the machine side torque T extracted by bandpass filter BPF e The sixth harmonic of: T e1 (s)=B(s)T e (s), Where B(s) represents the transfer function of the bandpass filter BPF.

3. The harmonic suppression method of a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization according to claim 2 is characterized in that: The transfer function G of the proportional resonant controller PR (s) designed to: Where K p is the proportional gain, K r1 is the grid-side voltage sextuple frequency resonance gain, ξ1 is the grid-side voltage sextuple frequency bandwidth, ω g is the grid-side voltage frequency.

4. The harmonic suppression method of a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization according to claim 3 is characterized in that: Pulsation component u dc1 The bus voltage harmonics extracted by high-pass filter HPF are: u dc1 (s)=H(s)u dc (s), Where H(s) is the transfer function of the high-pass filter HPF.

5. The harmonic suppression method of a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization according to claim 4 is characterized in that: Input admittance Y on the machine side m_in (s) Modeling: Where I inv is the average value of the inverter input current, U dc is the average bus voltage, U d is the average d-axis voltage, ω e is the average electrical angular velocity of the rotor, L d is the d-axis inductance, I q is the average value of the q-axis current, I d is the average d-axis current, R s is the stator phase resistance, U dref is the average value of the d-axis reference voltage, L q is the q-axis inductance, K pq is the proportional gain of the q-axis current regulator, K iq is the integral gain of the q-axis current regulator, n p is the number of motor pole pairs, ψ f is the permanent magnet flux, θ is the optimal angle process value, U qref is the average value of the q-axis reference voltage, K pd is the proportional gain of the d-axis current regulator, K id is the integral gain of the d-axis current regulator, U q is the average value of q-axis voltage; Based on the machine side input admittance Y m_in (s) Computer-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net for: Where U g is the effective value of the grid phase voltage, C dc is the capacitance of the small-value film capacitor, L g is the DC side inductance, R g is the DC side resistance; Based on the machine-side port impedance optimization index λ tor and the grid-side port impedance optimization index λ net The constructed evaluation matrix X is: X=(λ tor_i ,l net_i ) 101×2 ,i=0,1,2,…,100, Where λ tor_i is the machine-side port impedance optimization index obtained in the i-th iteration, λ net_i is the grid-side port impedance optimization index obtained in the i-th iteration; θ i is the optimal angle process value obtained in the i-th iteration, θ i =1.8×i; The evaluation matrix X is normalized, and the obtained standardized evaluation matrix Y is: Where λ tor_nor_i is λ tor_i The standardized value of λ net_nor_i is λ net_i The normalized value of max1 is all λ tor_i The maximum value among all λ net_i The maximum value in .

6. The harmonic suppression method of a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization according to claim 5, characterized in that: The calculation method of the evaluation index information entropy e of the standardized value is: Where e tor is the information entropy of the machine-side port impedance optimization index, e net The information entropy of the network-side port impedance optimization index; The method for calculating the weight ω of the evaluation index from the evaluation index information entropy e is: Where ω tor is the weight of the machine-side port impedance optimization index, ω net The weight of the grid-side port impedance optimization index; Construct the weighted evaluation matrix R and determine the positive ideal solution vector s + and the negative ideal solution vector s - : Where r tor_i is the machine-side port impedance optimization index evaluation matrix, r net_i is the grid-side port impedance optimization index evaluation matrix, is the ideal positive solution vector on the machine side, is the positive ideal solution vector on the grid side, is the negative ideal solution vector on the machine side, is the negative ideal solution vector on the net side; Using the Euclidean distance formula, calculate the weighted evaluation matrix R to the positive ideal solution vector s + and the negative ideal solution vector s - The distance and calculate the relative proximity coefficient h: In the formula From the weighted evaluation matrix R to the positive ideal solution vector s + distance, is the weighted evaluation matrix R to the negative ideal solution vector s - distance; The maximum value of the relative closeness coefficient h corresponds to θ i As the optimal angle θ opti .

7. The harmonic suppression method of a non-electrolytic capacitor permanent magnet synchronous motor drive system based on multi-port impedance optimization according to claim 6, characterized in that: Coordinated voltage d-axis component u com_d and the coordinated voltage q-axis component u com_q The calculation method is:

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