Permanent magnet synchronous motor disturbance suppression method under direct current bias

Abstract

The invention belongs to the technical field of permanent magnet synchronous motor disturbance suppression, and particularly discloses a permanent magnet synchronous motor disturbance suppression method under direct current bias, which comprises the following steps: S1, constructing a mathematical model of a permanent magnet synchronous motor under a static coordinate system, and increasing a direct current bias error in current measurement in the mathematical model under the static coordinate system; s2, designing a second-order expansion state observer according to the mathematical model of the permanent magnet synchronous motor under the static coordinate system; and S3, designing a continuous time transfer function, and discretizing the continuous time transfer function to obtain a discretized resonance controller. On the basis of considering the direct current bias, the direct current bias is regarded as disturbance, the direct current bias is suppressed by using the extended state observer, and harmonic waves are suppressed in combination with the resonance controller. According to the method provided by the invention, the control precision is effectively improved, the influence of direct-current bias on the motor is reduced, and the control precision of the motor is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of permanent magnet synchronous motor disturbance suppression, and in particular relates to a permanent magnet synchronous motor disturbance suppression method under direct current bias. Background Art

[0002] DC bias is generated in current sensors and related circuits due to various reasons such as thermal drift, aging and nonlinearity. DC bias can cause unnecessary torque ripple, thus affecting the speed and torque control performance of permanent magnet synchronous motors.

[0003] Permanent Magnet Synchronous Motor (PMSM) is widely analyzed and used in various electromechanical energy conversion systems due to its small size, excellent performance, simple structure and high efficiency. As a core component of modern industrial systems, the PMSM is a multivariable, strongly coupled, time-varying, nonlinear system that is subject to interference from multiple sources and different characteristics. Among them, DC bias is the non-ideal DC component in the motor current or magnetic field, which will lead to increased motor iron loss, increased torque fluctuations, increased noise and vibration, and even demagnetization of permanent magnets and overheating of the system, seriously affecting the efficiency and life of the motor. Therefore, it is particularly important to consider disturbance suppression under DC bias.

[0004] Many studies have been carried out by domestic and foreign scholars on the extraction and compensation of the DC bias of current. In the existing technology, Guo Z Z et al. designed a Robust Extended Kalman Filter (REKF) in Sensorless Drive of Direct-Torque-Controlled PMSMs Based on Robust Extended Kalman Filter.in:Institute of Electrical and Electronics Engineers.2016 35th Chinese control conference:CCC 2016, Chengdu, China, 27-29 July 2016, pages 4194-5066. The linearization error in the nonlinear system model is regarded as a perturbation, and the influence of these errors on the estimation result is minimized. The goal of REKF is to ensure that the transfer function norm of the external perturbation (such as system noise and linearization error) on the estimation error is less than the preset attenuation level, avoiding the DC bias problem caused by pure integration. However, the design of REKF needs to consider multiple robustness parameters, and the sensitivity of parameter selection is relatively high, which will increase the difficulty of implementation and debugging. In the existing technology, Yang G et al. proposed a Polar-Coordinate-Multisignal-Flux Observer (PCMFO) in APolar-Coordinate-Multisignal-Flux-Observer-Based PMSM Non-PLL Sensorless Control[J].IEEE Transactions on Power Electronics, 2023, 38(9):10579-10583. The DC bias, fundamental wave and harmonic are estimated respectively through the observer with a parallel structure, so as to eliminate the influence of interference signals on the flux linkage estimation. However, PCMFO assumes that the load torque is slowly varying, so it may be affected by rapid load changes in actual working conditions.In the prior art, Wang Y R et al. proposed a voltage compensation method based on iterative learning control (ILC) in "ILC-Based Voltage Compensation Method for PMSM Sensorless Control Considering Inverter Nonlinearity and Sampling Current DC Bias" [J]. IEEE Transactions on Industrial Electronics, 2020, 67(7): 5980-5989, which eliminates the harmonic effects of inverter nonlinearity and sampling current DC bias on the estimated back electromotive force (EMF), thereby improving the estimation accuracy of position and speed. However, the convergence speed is slow. This algorithm requires 40 iterations (about 2.5 seconds) to enter the steady state under certain conditions, which may not be efficient enough under fast dynamic conditions. Moreover, implementing the ILC method requires sufficient storage and computing capabilities, which poses certain requirements on the hardware performance. In the prior art, Liu Y et al. proposed an open-loop simplified repetitive control (SRC) method in "Robust Model Predictive Control With Simplified Repetitive Control for Electrical Machine Drives" [J]. IEEE Transactions on Power Electronics, 2019, 34(5): 4524-4535 and incorporated it into model predictive control. The core of SRC is to achieve high-precision tracking of harmonic components and suppression of DC components by removing the integrator module and only retaining the resonant unit. This method can separate DC bias interference by parallel operation of different resonant units. However, this method depends on the stable operation of the system. When the operating frequency of the system changes rapidly, the compensation effect of SRC may decrease.

[0005] Existing methods for suppressing DC bias, such as control strategy optimization, hardware design improvement, and signal processing methods, often have certain deficiencies. In terms of control strategies, by improving the motor drive control algorithm, the bias can be suppressed dynamically and in real time. However, these algorithms may increase the computational burden on the controller and require higher hardware performance of the controller. Secondly, hardware design improvement mainly reduces DC bias at the source by optimizing the motor structure and improving the symmetry of key components. However, this method usually comes with a high manufacturing cost. Finally, signal processing methods suppress the bias through filtering techniques, adding a high-pass filter to the current signal to filter out the DC component, or removing the drift in the measurement signal through hardware low-pass filtering. These methods are simple to implement but may affect the phase response of the signal and the dynamic performance of the system. Summary of the Invention

[0006] The present invention provides a method for suppressing disturbances in a permanent magnet synchronous motor under DC bias to solve the problem that the current DC bias can cause unnecessary torque ripple, thereby affecting the speed and torque control performance of the permanent magnet synchronous motor.

[0007] To solve the above technical problems, the technical solution of the present invention is: The method for suppressing disturbances in a permanent magnet synchronous motor under DC bias includes the following steps:

[0008] S1: Construct a mathematical model of the permanent magnet synchronous motor in the stationary coordinate system, and add the DC bias error in the current measurement to the mathematical model in the stationary coordinate system;

[0009] S2: Design a second-order extended state observer according to the mathematical model of the permanent magnet synchronous motor in the stationary coordinate system;

[0010] S3: Design a continuous-time transfer function, and discretize the continuous-time transfer function to obtain a discretized resonant controller.

[0011] In a preferred embodiment of the present invention, in step S1, the mathematical model of the permanent magnet synchronous motor in the stationary coordinate system is obtained through Equation 1:

[0012]

[0013] where V α and V β are the stator voltages in the stationary reference frame, i α and i β are the stator currents in the stationary reference frame, L s is the stator inductance, λ f is the permanent magnet flux linkage, θ r is the rotor electrical position, ω e is the electrical angular velocity, and R s is the stator winding resistance value.

[0014] In a preferred embodiment of the present invention, the d-q coordinate system mathematical model after adding the DC bias error in current measurement to the mathematical model of Equation 2 in the stationary coordinate system:

[0015]

[0016] where, i α and i β are the ideal currents on the α and β axes respectively, i α_m and i β_m are the actually measured currents on the α and β axes respectively, i α_offset and i β_offset are the DC bias errors on the α and β axes respectively, i a_offset and i b_offset are the DC bias errors on the a and b phases respectively.

[0017] In a preferred embodiment of the present invention, the DC bias error in Equation 2 is obtained through Equation 3:

[0018]

[0019] where, i d and i q are the ideal currents on the d and q axes respectively, i d_m and i q_m are the actual currents on the d and q axes respectively, i d_offset and i q_offset are the DC bias errors on the d and q axes respectively.

[0020] In a preferred embodiment of the present invention, the parameters k and φ in Equation 3 are obtained through Equation 4:

[0021]

[0022] where, i a_offset and i b_offset are the DC bias errors on the a and b phases respectively.

[0023] In a preferred embodiment of the present invention, in step S2, the extended state observer is obtained through Equation 5 and

[0024] Equation 6:

[0025]

[0026] where, β1 and β2 are the gains of the ESO, and are the observed values of the αβ-axis currents, e α and e β are the measurement errors, and is the estimated value of the stator voltage in the stationary reference frame, is the estimated value of the resistance, and are the observations of the disturbances on the α and β axes respectively, and L q is the q-axis inductance.

[0027] In a preferred embodiment of the present invention, the gain coefficients in Equation 5 and Equation 6 are obtained through Equation 7:

[0028]

[0029] where ω0 is the bandwidth of the linear extended state observer.

[0030] In a preferred embodiment of the present invention, in step S4, the continuous-time transfer function is converted into a discrete-time transfer function through the bilinear transformation method, that is, the resonant controller is discretized.

[0031] In a preferred embodiment of the present invention, the continuous-time transfer function is obtained through Equation 8:

[0032]

[0033] where ω c is the resonant bandwidth, and k R is the resonant gain.

[0034] In a preferred embodiment of the present invention, the discrete-time transfer function is obtained through Equation 9:

[0035]

[0036] where b0, b1, b2 are the numerator coefficients of the discrete system, and a1, a2 are the denominator coefficients of the discrete system.

[0037] The technical solution provided by the present invention has the following advantages compared with the prior art:

[0038] On the basis of considering the DC bias, the present invention regards the DC bias as a disturbance and uses an extended state observer to suppress it. Combining with a resonant controller, the harmonics are suppressed. The method proposed by the present invention effectively improves the control accuracy, reduces the influence of the DC bias on the motor, and improves the control accuracy of the motor. Description of the Drawings

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0040] Figure 1 It is the control flowchart of the permanent magnet synchronous motor in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0041] Figure 2 It is the motor vector control drive system diagram of the permanent magnet synchronous motor in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0042] Figure 3 It is the comparative Bode diagram of the ideal resonant controller and the continuous-time transfer function in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0043] Figure 4 It is the speed and tracking curve diagram of the traditional PI control in the prior art;

[0044] Figure 5 It is the speed tracking curve diagram considering DC bias in the prior art;

[0045] Figure 6 It is the three-phase current diagram of the PI control with DC bias added in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0046] Figure 7 It is the three-phase current diagram of the new control with DC bias added in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0047] Figure 8 It is the torque diagram of the PI control after adding DC bias in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0048] Figure 9 It is the three-phase current diagram of the new control for suppressing DC bias in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0049] Figure 10 It is the extraction diagram of the DC bias by the extended state observer in a method for suppressing disturbances of a permanent magnet synchronous motor under DC bias according to an embodiment of the present invention;

[0050] Figure 11 It is a comparison diagram of the actual value and the read value of the dq-axis current in a permanent magnet synchronous motor disturbance suppression method under DC bias according to an embodiment of the present invention;

[0051] Figure 12 It is a current Fourier transform decomposition diagram of PI control in the prior art;

[0052] Figure 13 It is a current Fourier transform decomposition diagram of a new controller for a permanent magnet synchronous motor disturbance suppression method under DC bias according to an embodiment of the present invention. Specific embodiments

[0053] For the sake of easy understanding, the following describes a permanent magnet synchronous motor disturbance suppression method under DC bias in combination with embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0054] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation and positional relationship shown in the drawings. It is 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 should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0055] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0056] For the sake of easy understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in the present invention. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0057] As Figure 1 shown, the present invention discloses a permanent magnet synchronous motor disturbance suppression method under DC bias, which includes the following steps.

[0058] S1: Construct the mathematical model of the permanent magnet synchronous motor in the stationary coordinate system, and add the DC bias error in the current measurement to the mathematical model in the stationary coordinate system.

[0059] Before constructing the d-q coordinate mathematical model of the PMSM, the following assumptions are made for the surface-mounted permanent magnet synchronous motor:

[0060] (1) The air gap distribution is sufficiently uniform;

[0061] (2) There is no iron core saturation;

[0062] (3) There are no cogging effects and end effects;

[0063] (4) There are no hysteresis losses and eddy current losses;

[0064] (5) The three-phase windings are in a symmetric relationship and are evenly distributed;

[0065] Based on the above assumptions, the PMSM mathematical model is as follows:

[0066] Voltage equation of the permanent magnet synchronous motor in the rotating coordinate system (d, q):

[0067]

[0068] where, U d , U q are the d-axis and q-axis voltages respectively; R s is the stator winding resistance value; L d , L q are the inductance values on the d-axis and q-axis; i d , i q are the d-axis and q-axis currents respectively; ω e is the electrical angular velocity; ψ f is the permanent magnet rotor flux linkage.

[0069] In the stationary reference frame, the voltage equation of the permanent magnet synchronous motor is:

[0070]

[0071] where, V αβ is the stator voltage in the stationary reference frame, i αβ is the stator current in the stationary reference frame; L s is the stator inductance, λ f is the permanent magnet flux linkage, θ r is the rotor electrical position.

[0072] The inverse Park transformation can be expressed as:

[0073]

[0074] The motor vector control drive system of a permanent magnet synchronous motor considering DC bias is as Figure 2 shown. The three-phase currents are balanced, i.e., i c =-(i a +i b ). Therefore, the three-phase currents including DC bias can be expressed as:

[0075]

[0076] where i a_m and i b_m are the measured phase-a current and phase-b current respectively; i a_offset and i b_offset are the DC biases of phase-a and phase-b respectively.

[0077] These current errors can be presented in the stationary reference frame as:

[0078]

[0079] where i α_m and i β_m are the α-axis and β-axis currents respectively. i α_offset and i β_offset are the DC bias errors of the α-axis and β-axis respectively.

[0080] These current errors can be presented in the d-q coordinate system as:

[0081]

[0082] where k and φ can be expressed as:

[0083]

[0084] It can be inferred from Equation (3) that the current bias contains an AC value in the d-q coordinate system, and its frequency is the same as the motor operating frequency.

[0085] If three current sensors are used to measure the phase currents, the three-phase currents may have independent DC biases. The α-axis and β-axis offset errors in Equation (3) will still have DC components. Therefore, if the traditional method is used to suppress the current fluctuations caused by current sampling errors without eliminating the DC bias, only the corresponding current fluctuation components will disappear in the current feedback value, while the actual current will completely contain the current measurement error under the action of feedback control.

[0086] Electromagnetic torque equation:

[0087]

[0088] where T e is the electromagnetic torque; p is the number of pole pairs of the motor.

[0089] S2: Design a second - order extended state observer according to the mathematical model of the permanent - magnet synchronous motor in the stationary coordinate system.

[0090] Regarding the DC bias as a disturbance, the extended state observer can estimate the disturbance in the system in real - time and regard it as part of the extended state, and then perform dynamic compensation through the controller. This method does not require an accurate disturbance model and only needs the input - output data of the system to achieve compensation.

[0091] By using Equation (1), we can obtain:

[0092]

[0093] Therefore, in order to extract and suppress the DC bias, the second - order extended state observer can be designed as:

[0094]

[0095] Among them, β1 and β2 are the gains of the ESO. To ensure the system stability, Gao Zhiqiang et al. proposed to tune the parameters of the linear extended state observer. Let the bandwidth of the linear extended state observer be ω0, so the gain coefficient of the extended state observer is:

[0096]

[0097] S3: Design a continuous - time transfer function and discretize the continuous - time transfer function to obtain a discretized resonant controller.

[0098] The transfer function of the ideal resonant controller is:

[0099]

[0100] Among them, k R is the resonant gain; ω0 is the resonant angular frequency.

[0101] It can be seen from Equation (16) that the ideal resonant controller only acts on the resonant angular frequency at ω0. However, during the actual operation of the system, due to the error of the sampling circuit and the precision limitation of the digital control system, the actual fundamental frequency of the motor will fluctuate around its ideal value. Therefore, it is difficult for the ideal resonant controller to achieve a good harmonic suppression effect. By improving Equation (16), we can get:

[0102]

[0103] Among them, ω c is the resonant bandwidth. Among them, the numerator represents the dynamic gain characteristic of the system, and the denominator contains the influence of the damping ratio and the resonant frequency.

[0104] For GR (s) and G QR Perform Bode plot analysis on (s) and G Figure 3 As shown, in the magnitude response curve, compared with G R (s), the magnitude peak value of G QR (s) is significantly lower and smoother, indicating that G QR (s) introduces additional damping, thus suppressing the resonance intensity of the system. The phase response curve shows the trend of the phase change of the G R (s) and G QR (s) systems with frequency. In the low-frequency band, the phases of both systems remain close to 0°. As the frequency approaches the resonant frequency, the system phase drops rapidly. In the high-frequency band, the phases of both systems eventually tend to 90°. In particular, the phase transition region of G QR (s) starts earlier and the transition is smoother compared to G R (s). This characteristic indicates that the G QR (s) system exhibits a faster phase adjustment ability in dynamic response, which helps to improve the stability and control performance of the system.

[0105] To implement this system in a digital controller, it needs to be converted to the discrete-time domain.

[0106] Use the bilinear transformation method (Tustin method) to convert the continuous-time transfer function G QR (s) to the discrete-time transfer function G QR (z). The basic formula of the Tustin method is as follows:

[0107]

[0108] Substitute equation (17) into G QR (s), and after expanding and simplifying the numerator and denominator, finally obtain the form of G QR (z) as:

[0109]

[0110] where, b0, b1, b2 are the numerator coefficients of the discrete system, and a1, a2 are the denominator coefficients of the discrete system.

[0111] To verify the feasibility of the method proposed above, the present invention builds a control system model through Matlab / Simulink simulation software. The specific simulation parameters of the motor are shown in Table 1.

[0112] Table 1 PMSM parameters

[0113]

[0114] Starting without load at t = 0, with a given rotational speed of 2000 r / min. At t = 0.4 s, the load torque suddenly changes to 10 N·m. At t = 0.7 s, the rotational speed suddenly decreases by -1500 N. To verify the effectiveness of the controller, the traditional PI control and the method proposed in the present invention are compared, and the results are as Figure 4 and Figure 5 shown.

[0115] From Figure 4 and Figure 5 it can be seen that, compared with the traditional PI control, the system using the extended state observer to suppress the direct current bias has better disturbance rejection ability, and the rotational speed tracking curve is smoother, weakening the chattering.

[0116] To verify the effectiveness of the method proposed in the present invention, a bias current of 0.5 A is added to the A and B phase currents in the traditional PI control, that is, offset = 0.5 A. The three-phase currents and torque are as Figure 6 and Figure 8 shown. After adding a bias current of 0.5 A, the three-phase currents of the system under the traditional PI controller show obvious offsets; at the same time, the motor also has very large torque ripples, with a fluctuation amplitude of ±1.15. And as the direct current bias current increases, the offset of the three-phase currents will be more obvious, and the torque ripple will be larger.

[0117] To reduce the influence of the direct current bias on the system, the extended state observer is used to extract the direct current bias, and the extraction results are as Figure 10 shown. The extracted direct current bias is compensated. From Figure 7 and Figure 9 it can be seen that for the system compensated by the extended state observer, the offset of the current is significantly reduced, and the torque ripple is reduced to ±0.3, effectively improving the dynamic performance and control accuracy of the motor. At the same time, from Figure 11 it can be seen that the read values of the d and q axis currents can well track the actual current values.

[0118] Taking the rotational speed of 2000 r / min and the rated load condition as an example, the fundamental wave frequency is 133.33 Hz. Comparing the fast Fourier transform (FFT) decomposition diagrams of the A phase current of the system under the PI controller and the Figure 12 and Figure 13 under the suppression of the direct current bias by the extended state observer. It can be seen that the method proposed in the present invention effectively reduces the direct current component.

[0119] On the basis of considering the DC bias, the DC bias is regarded as a disturbance and suppressed by using an extended state observer. Combining with a resonant controller, the harmonics are suppressed. Simulation verification is carried out in Matlab / Simulink. The method proposed by the present invention effectively improves the control accuracy, reduces the influence of the DC bias on the motor, and improves the control accuracy of the motor.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for suppressing disturbance of a permanent magnet synchronous motor under DC bias, characterized in that: The following steps are involved: S1: Construct a mathematical model of the permanent magnet synchronous motor in a stationary coordinate system, and add a DC bias error in current measurement to the mathematical model in the stationary coordinate system; S2: Design a second-order extended state observer based on the mathematical model of the permanent magnet synchronous motor in a stationary coordinate system; S3: Design a continuous-time transfer function, and discretize the continuous-time transfer function to obtain a discrete resonant controller.

2. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 1, characterized in that: In step S1, the mathematical model of the permanent magnet synchronous motor in a stationary coordinate system is obtained by formula 1: Among them, V α and V β is the stator voltage in the stationary reference frame, i α and i β is the stator current in the stationary reference frame, L s is the stator inductance, λ f is the permanent magnet flux, θ r is the rotor electrical position, ω e is the electrical angular velocity, R s is the stator winding resistance.

3. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 2, characterized in that: The dq coordinate coefficient mathematical model is obtained by adding the DC bias error in current measurement to the mathematical model in the stationary coordinate system through equation 2: Among them, i α and i β are the ideal currents in the α and β axes, i α_m and i β_m The actual measured current of α and β axes, i α_offset and i β_offset are the DC bias errors of the α and β axes, respectively, i a_offset and i b_offset are the DC offset errors of phase a and phase b respectively.

4. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 3 is characterized in that: The DC offset error in Equation 2 is obtained by Equation 3: Among them, i d 、i q are the ideal currents of d and q axes respectively, i d_m and i q_m The actual current of d and q axis, i d_offset and i q_offset are the DC offset errors of the d and q axes, respectively.

5. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 4, characterized in that: The parameter k·φ in Equation 3 is obtained by Equation 4: Among them, i a_offset and i b_offset are the DC offset errors of phase a and phase b respectively.

6. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 1, characterized in that: In step S2, the extended state observer is obtained by equation 5 and equation 6: Among them, β1 and β2 are the gains of ESO, and is the observed value of the αβ axis current, e α and e β is the measurement error, and is the estimated value of the stator voltage in the stationary reference frame, is the estimated value of the resistor, and are the observations of the α and β axis disturbances, respectively, L q is the q-axis inductance.

7. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 6, characterized in that: The gain coefficients in Equation 5 and Equation 6 are obtained by Equation 7: Where ω0 is the bandwidth of the linear extended state observer.

8. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 1, characterized in that: In the step S4, the continuous-time transfer function is converted into a discrete-time transfer function, namely a discretized resonant controller, by a bilinear transformation method.

9. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 8, characterized in that: The continuous-time transfer function is obtained by equation 8: Among them, ω c is the resonant bandwidth, k R is the resonance gain.

10. The method for suppressing disturbance of a permanent magnet synchronous motor under DC bias according to claim 9, characterized in that: The discrete-time transfer function is obtained by equation 9: Among them, b0, b1, b2 are the numerator coefficients of the discrete system, and a1, a2 are the denominator coefficients of the discrete system.

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