Silicon carbide device-based permanent magnet synchronous motor active disturbance rejection current harmonic suppression method

Abstract

The application provides a silicon carbide device-based permanent magnet synchronous motor active disturbance rejection current harmonic suppression method, relates to the technical field of motor control, is implemented in a motor controller / electric drive system, adopts an improved cascade extended state observer structure, performs hierarchical observation and feedforward compensation on total disturbance of a q-axis current loop, a first-stage extended state observer estimates a q-axis current and basic disturbance in real time, a second-stage extended state observer introduces a second-order resonator to model residual error signals and extract harmonic disturbance of a specific angular frequency, and the outputs of the two-stage observer are superposed to form a total disturbance estimation value, which is feedforward compensated through an active disturbance rejection control law. Without adding extra hardware sensors, the method effectively suppresses main harmonics of a motor current loop, significantly improves the harmonic suppression performance and operation stability of the permanent magnet synchronous motor current loop, has the characteristics of simple structure and convenient implementation, and is suitable for scenes such as a silicon carbide device-based motor controller or electric drive system.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and specifically to a method for suppressing harmonic currents in a permanent magnet synchronous motor based on silicon carbide devices. Background Technology

[0002] In high-performance current loop control of permanent magnet synchronous motors (PMSMs), silicon carbide (SiC) devices are being used more and more widely due to their high switching frequency, low loss and high temperature resistance. However, the high dv / dt, dead zone and on-state voltage drop caused by the hard switching of the devices significantly increase the low-order harmonics such as the 5th and 7th in the stator current. At the same time, periodic disturbances such as cogging effect of the motor body, flux linkage harmonics and DC bus fluctuations of the inverter are also superimposed on the q-axis current loop, resulting in an increase in total harmonic distortion (THD), torque ripple and noise deterioration, which directly affects the high-speed quiet operation and reliability of electric drive systems and servo systems in new energy vehicles.

[0003] Traditional PI controllers have limited ability to suppress wideband harmonics. While repetitive and resonant control can compensate for specific frequencies, they rely on accurate models and large amounts of storage resources, resulting in slow dynamic response and difficulty in handling full-speed range variations. Although single-stage extended state observers (ESOs) with active disturbance rejection controllers can estimate and compensate for total disturbances in the motor system, they have limited ability to suppress periodic harmonic disturbances at specific angular frequencies, which can easily lead to increased current harmonic components and cause torque fluctuations and noise.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] This invention provides a method for suppressing harmonic currents of permanent magnet synchronous motors based on silicon carbide devices, which can at least partially improve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for suppressing harmonic currents in a permanent magnet synchronous motor based on silicon carbide devices, comprising:

[0008] The actual q-axis current and control input of the permanent magnet synchronous motor are obtained and input into the cascaded expansion state observer for observation processing. The cascaded expansion state observer includes a first-stage observer and a second-stage observer.

[0009] The first-stage observer is used to observe the actual q-axis current and control input, and the observed q-axis current, the observed basic disturbance, and the residual signal are obtained.

[0010] The residual signal is transmitted to the second-stage observer for observation processing to obtain harmonic disturbance observation values. The basic disturbance observation values ​​and harmonic disturbance observation values ​​are superimposed to generate the total disturbance observation value.

[0011] Obtain the q-axis current setpoint, calculate the q-axis current setpoint and total disturbance observation value according to the control law to obtain the updated control quantity, and perform disturbance feedforward compensation based on the updated control quantity.

[0012] In summary, this method innovatively constructs a two-stage observation architecture in the controller structure: "basic ESO → resonator-assisted observation → cascaded fusion." It employs a cascaded expanded state observer structure to observe and compensate for the total disturbance in the motor's q-axis current loop. By proposing an improved cascaded expanded state observer structure, and through hierarchical observation and resonator compensation, it achieves simultaneous estimation and suppression of the total disturbance and specific frequency harmonic disturbances, thereby improving the harmonic suppression performance and operational stability of the permanent magnet synchronous motor's current loop. Attached Figure Description

[0013] Figure 1 This is a schematic flowchart of the self-interference rejection current harmonic suppression method for permanent magnet synchronous motors based on silicon carbide devices provided in an embodiment of the present invention.

[0014] Figure 2 This is a flowchart illustrating the algorithm framework of the self-interference rejection current harmonic suppression method for permanent magnet synchronous motors based on silicon carbide devices provided in this embodiment of the invention.

[0015] Figure 3 This is a schematic diagram of the internal structure of the second-stage observer provided in an embodiment of the present invention.

[0016] Figure 4 This is a Bode plot of the traditional observer perturbation estimation error transfer function provided in an embodiment of the present invention.

[0017] Figure 5 This is a Bode plot of the error transfer function for the perturbation estimation of a conventional cascaded observer, provided in an embodiment of the present invention.

[0018] Figure 6 This is a comparison chart of the amplitude-frequency characteristics of the perturbation estimation error of ESO, cascaded ESO and improved cascaded ESO provided in the embodiments of the present invention.

[0019] Figure 7 This is a stator current spectrum analysis diagram of the traditional cascaded ESO control strategy provided in this embodiment of the invention.

[0020] Figure 8 This is a stator current spectrum analysis diagram of the improved cascaded ESO control strategy provided in this embodiment of the invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] refer to Figure 1 , Figure 2 As shown, the first embodiment of the present invention discloses a method for suppressing harmonic currents of a permanent magnet synchronous motor based on silicon carbide devices. This method can be executed by a device for suppressing harmonic currents of a permanent magnet synchronous motor based on silicon carbide devices (hereinafter referred to as the suppression device), specifically by one or more processors within the suppression device, to implement the following method:

[0023] S1, obtain the actual q-axis current and control input of the permanent magnet synchronous motor, and input them into the cascaded expansion state observer for observation processing. The cascaded expansion state observer includes a first-stage observer and a second-stage observer.

[0024] In this embodiment, the actual q-axis current iq of the motor and the control input u are first acquired and used as the input signals of the observer. After processing by the extended state observer, the current state is estimated and the disturbance components are extracted.

[0025] S2, use the first-stage observer to observe the actual q-axis current and control input, and obtain the observed q-axis current value, the observed basic disturbance value and the residual signal;

[0026] Specifically, step S2 further includes: converting the actual q-axis current i q The control input u is input to the first-stage observer to observe the q-axis current. Basic disturbance observations The first-level observer is a linearly extended state observer, whose state equation is expressed as: s is the Laplace operator, b1 and b2 are both observer bandwidth parameters, and b0 is the control gain;

[0027] For the actual q-axis current i q and q-axis current observations Perform subtraction processing to generate residual signals. The residual signal reflects the disturbance components that the first-stage observer failed to observe, and serves as the input to the second-stage observer for extracting angular frequencies of... Harmonic disturbances.

[0028] Preferably, the q-axis current observation value The transfer function is: The basic disturbance observation values The transfer function is: .

[0029] Specifically, in this embodiment, the first-stage observer uses the actual q-axis current i q Using the control input u as input, a basic ESO module is constructed. This module calculates the current observation value and the basic disturbance observation value by setting the observer bandwidth parameter. Subsequently, after the first-stage ESO completes the observation of current and disturbance, the difference between the actual current and the current observation value is calculated as the residual signal, i.e., the remaining disturbance component that the first-stage observer failed to capture. This residual signal is used as the input of the second-stage extended state observer to provide the driving signal for the subsequent extraction of harmonic disturbances. The process relies entirely on the existing sampling channel, without adding hardware or introducing additional noise by increasing the bandwidth. This ensures that subsequent harmonic compensation is based on an accurate and clean signal, thereby maintaining the beneficial effects of sinusoidal current waveform and reduced torque ripple in both steady-state and transient processes.

[0030] Please see Figure 3 S3, the residual signal is transmitted to the second-stage observer for observation processing to obtain the harmonic disturbance observation value, and the basic disturbance observation value and the harmonic disturbance observation value are superimposed to generate the total disturbance observation value.

[0031] Specifically, step S3 further includes: transmitting the residual signal R to the second-stage observer, and extracting the angular frequency of the residual signal R from the resonator built into the second-stage observer. The harmonic components are obtained, and the harmonic disturbance observations are obtained. ;

[0032] For basic disturbance observations Harmonic disturbance observations The data is overlaid to generate the total disturbance observation. .

[0033] Preferably, the resonator built into the second-stage observer is a second-order resonator, and its state equation is: ,in, and These are all internal state variables of the resonator. and These are all output weighting coefficients; the center frequency of the resonator can be adjusted by adjusting the parameters. and Configure it to meet the suppression requirements of harmonic disturbances at different frequencies.

[0034] Preferably, the total disturbance observation value The transfer function is expressed as: ,in, and Both are transfer functions with respect to s, and they correspond to the actual q-axis current i, respectively. q The impact of the control input u on the total disturbance observation.

[0035] Please see Figure 2 In this embodiment, a resonator module is introduced into the second-stage extended state observer. The resonator is composed of a second-order oscillation structure, used for oscillations with an angular frequency of... The disturbance is modeled. At the output of the resonator, m2 is weighted by parameters k1 and k2 to obtain the estimated value of the harmonic disturbance, thereby realizing the estimation of the disturbance component at a specific frequency.

[0036] Specifically, the residual signal R is directly fed into the second-stage observer, which has a built-in second-order resonator with internal states m1 and m2. By adjusting k1 and k2, the center frequency can be determined. No additional hardware is required to align with the harmonic angular frequency to be suppressed; the resonator filters R in each control cycle and outputs the harmonic disturbance observation value. Furthermore, to further correct the system state, a new observation state is set after introducing the resonator. , This modified state is used to ensure the dynamic coupling relationship between the second-level ESO and the first-level ESO.

[0037] Subsequently, within the same period, the harmonic disturbance observations are added to the fundamental disturbance observations obtained in the first stage to form the total disturbance observation. This disturbance estimate includes both the fundamental disturbance and specific harmonic disturbance components, and can be used as the compensation input for the controller. The full influence of the actual q-axis current and control input on the total disturbance is preserved. This superposition step allows the controller to simultaneously cancel low-frequency disturbances and angular frequencies with only one subtraction in the subsequent control law. It eliminates harmonic disturbances, smooths the current waveform, reduces THD, and has a very short algorithm time and minimal storage footprint, balancing real-time performance with ease of implementation.

[0038] S4. Obtain the q-axis current setpoint, calculate the q-axis current setpoint and total disturbance observation value according to the control law to obtain the updated control quantity, and perform disturbance feedforward compensation based on the updated control quantity.

[0039] Specifically, step S4 further includes: the formula for the updated control quantity is: ,in, This is the proportional gain of the controller. This is the given value for the q-axis current.

[0040] Under the control law, the formula for the closed-loop disturbance transfer function of the current to the disturbance is: , , , The q-axis current i of the motor q The Laplace transform of the system represents the system output. The actual disturbance f acting on the motor current loop q The Laplace transform of represents the disturbance input of the system, where the closed-loop disturbance transfer function is in It has a zero point to achieve a diagonal frequency of Suppression of harmonic disturbances.

[0041] Specifically, in this embodiment, in the controller section, an active disturbance rejection control law is constructed based on the total disturbance observation value of the improved cascaded extended state observer, and the updated control quantity is calculated. This formula uses the same proportional coefficient to take into account both tracking speed and stability, and the operation only requires one multiplication and subtraction, without the need for additional parameter tuning. Through this relationship, the influence of disturbances on the current loop can be compensated in real-time operation.

[0042] Specifically, since the q-axis current setpoint has already accounted for the basic disturbance and the angular frequency of... Harmonic disturbances are combined, and the control quantity, after being sent to the module, constitutes feedforward compensation, making the closed-loop transfer function of the current to the disturbance equal to the closed-loop disturbance transfer function. The zero point appears at the point, which precisely cancels out the harmonic components; this demonstrates the beneficial effects of rapid, accurate, and easy-to-implement single-step update of "given value - disturbance - control quantity".

[0043] Please see Figures 4 to 8 In this embodiment, the entire operation flow of this method is as follows: the actual motor current and the control quantity are input into the first-stage ESO, which outputs the current estimate and the basic disturbance; the residual signal enters the resonator module of the second-stage ESO, which outputs the harmonic disturbance estimate; the two are superimposed in the disturbance synthesis module to obtain the total disturbance estimate; finally, the total disturbance estimate is substituted into the control law to calculate the new control input signal, thereby completing the disturbance suppression of the current loop. Through the above steps, the improved cascaded extended state observer of this invention realizes complete observation and disturbance compensation of the motor current loop. In implementation, it is only necessary to set the first-stage ESO, the second-stage ESO, and the disturbance synthesis and control law module in sequence in the control system to realize the function of the method.

[0044] In summary, this method is implemented in a motor controller / electric drive system. The first-stage extended state observer is used to estimate the q-axis current and fundamental disturbance. The second-stage extended state observer introduces a second-order resonator to model the residual signal, used to extract harmonic disturbances at specific angular frequencies. The outputs of the two observers are superimposed to form the total disturbance estimate, and a control law is introduced to achieve feedforward compensation. Through these steps, real-time disturbance estimation of the motor current loop and effective suppression of major harmonics (such as the 5th and 7th harmonics) can be achieved without adding additional hardware sensors. Please refer to [link to relevant documentation]. Figure 7 , Figure 8 As shown in the figure, Matlab / Simulink simulation verification shows that this invention can reduce the total harmonic distortion (THD) of the stator current from 5.37% to 2.79%, significantly improving the harmonic suppression performance and operational stability of the current loop of the permanent magnet synchronous motor. It features a simple structure and convenient implementation. Designed to improve the suppression capability and stability of the current loop under harmonic and periodic disturbance environments, it can be widely applied in scenarios requiring high-precision current control, such as new energy vehicle drives, motor controllers, electric drive systems, and motor servo control.

[0045] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for suppressing harmonic currents in a permanent magnet synchronous motor based on silicon carbide devices, characterized in that, include: The actual q-axis current and control input of the permanent magnet synchronous motor are obtained and input into the cascaded expansion state observer for observation processing. The cascaded expansion state observer includes a first-stage observer and a second-stage observer. The first-stage observer is used to observe the actual q-axis current and control input, obtaining the observed q-axis current value, the observed basic disturbance value, and the residual signal, specifically: The actual q-axis current i q The control input u is input to the first-stage observer to observe the q-axis current. Basic disturbance observations The first-level observer is a linearly extended state observer, whose state equation is expressed as: s is the Laplace operator, b1 and b2 are both observer bandwidth parameters, and b0 is the control gain; For the actual q-axis current i q and q-axis current observations Perform subtraction processing to generate residual signals. ; The residual signal is transmitted to the second-stage observer for observation processing to obtain harmonic disturbance observation values. The basic disturbance observation values ​​and harmonic disturbance observation values ​​are superimposed to generate the total disturbance observation value. Obtain the q-axis current setpoint, calculate the q-axis current setpoint and total disturbance observation value according to the control law to obtain the updated control quantity, and perform disturbance feedforward compensation based on the updated control quantity; The q-axis current observation The transfer function is: The basic disturbance observation values The transfer function is: ; The residual signal is transmitted to the second-stage observer for observation processing to obtain harmonic disturbance observation values. The basic disturbance observation values ​​and harmonic disturbance observation values ​​are then superimposed to generate the total disturbance observation value, specifically: The residual signal R is transmitted to the second-stage observer, and the angular frequency of the residual signal R is extracted by the resonator built into the second-stage observer. The harmonic components are obtained, and the harmonic disturbance observations are obtained. ; For basic disturbance observations Harmonic disturbance observations The data is overlaid to generate the total disturbance observation. ; The resonator built into the second-stage observer is a second-order resonator, and its state equation is: ,in, and These are all internal state variables of the resonator. and All are output weighting coefficients; The total disturbance observation value The transfer function is expressed as: ,in, and Both are transfer functions with respect to s, and they correspond to the actual q-axis current i, respectively. q The impact of the control input u on the total disturbance observation.

2. The method for suppressing harmonic current of a permanent magnet synchronous motor based on silicon carbide devices according to claim 1, characterized in that, The formula for the updated control quantity is: ,in, This is the proportional gain of the controller. This is the given value for the q-axis current.

3. The method for suppressing harmonic current of a permanent magnet synchronous motor based on silicon carbide devices according to claim 2, characterized in that, Under the control law, the formula for the closed-loop disturbance transfer function of the current to the disturbance is: , , , The q-axis current i of the motor q The Laplace transform of the system represents the system output. The actual disturbance f acting on the motor current loop q The Laplace transform of represents the disturbance input of the system, where the closed-loop disturbance transfer function is in It has a zero point to achieve a diagonal frequency of Suppression of harmonic disturbances.

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