Method for suppressing rotating speed pulsation of permanent magnet synchronous motor caused by current measurement error

Abstract

The invention discloses a method for suppressing rotation speed pulsation of a permanent magnet synchronous motor caused by a current measurement error. Acquiring state data of the permanent magnet synchronous motor; according to the acquired state data, based on a given signal and an actual three-phase current signal of the permanent magnet synchronous motor, determining a PWM wave signal for controlling the operation of the permanent magnet synchronous motor; according to the determined PWM wave signal and the constructed permanent magnet synchronous motor mathematical model; then, by optimizing a control strategy, such as a vector control method, the rotating speed of the motor can be adjusted more accurately, and pulsation caused by current measurement errors is reduced; and finally, by applying a filtering algorithm on a current measurement value, noise and interference from the sensor can be reduced, so that the measurement precision is improved. By adopting a filtering algorithm, adjustment and optimization can be carried out according to specific application and requirements so as to realize effective filtering and smooth processing of signals, thereby reducing noise and interference from the sensor and improving measurement precision.

Description

Technical Field

[0001] The invention relates to the technical field of motor control, in particular to a method for suppressing speed pulsation of a permanent magnet synchronous motor caused by current measurement errors. Background Art

[0002] Permanent magnet synchronous motors are widely used in various occasions such as electric vehicles, electric propulsion ships, precision machine tools, and household appliances due to their wide speed regulation range, large starting torque, high power density, high torque control accuracy, and strong overload capacity. Although the permanent magnet synchronous motor vector control system using traditional double closed-loop PI control can achieve good dynamic and static performance, due to the existence of non-ideal factors such as the cogging effect of the motor body, the inverter dead zone effect, and the current measurement error, the steady-state speed of the motor operation inevitably has a periodic pulsation component.

[0003] Speed ​​ripple may be acceptable for applications such as fans, pumps, and compressors. However, for applications such as precision machine tool processing and servo motors, the steady-state speed pulsation of the motor is required to be as low as possible. Current errors will cause speed mutations and torque fluctuations in the dual-armature limited-angle bearingless flux reversal motor control system, while increasing the low-order harmonic content of the phase current, which is one of the harmful factors that increase losses. Therefore, it is very meaningful to study the real-time online permanent magnet synchronous motor speed pulsation suppression method.

[0004] At present, when controlling the speed pulsation of a permanent magnet synchronous motor, the error is usually adjusted after it occurs, which causes the steady-state speed pulsation of the motor to fluctuate. The pulsation at a certain moment will be much greater than the pulsation at other moments, causing the adjustment to have a lag. Therefore, we propose a method to suppress the speed pulsation of a permanent magnet synchronous motor caused by current measurement error. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement errors, thereby solving the problem that, when controlling the speed pulsation of a permanent magnet synchronous motor, the error is usually adjusted after it occurs, resulting in fluctuations in the steady-state speed pulsation of the motor. The pulsation at a certain moment will be much greater than the pulsation at other moments, causing the adjustment to have a lag problem.

[0006] To achieve the above object, the present invention is implemented by the following technical scheme: A method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by a current measurement error comprises the following steps;

[0007] S1: Obtain the status data of the permanent magnet synchronous motor;

[0008] S2: Based on the acquired state data, a mathematical model of the permanent magnet synchronous motor and a speed adaptive harmonic expansion state observer are constructed;

[0009] S3: Construct the maximum correlation entropy factor by checking the mean and covariance of the variational Bayesian distribution and the observation factor through the observation anomaly in the filtering process;

[0010] S4: determining a PWM wave signal for controlling the operation of the permanent magnet synchronous motor based on a given signal of the permanent magnet synchronous motor and an actual three-phase current signal;

[0011] S5: according to the determined PWM wave signal and the constructed permanent magnet synchronous motor mathematical model;

[0012] S6: Then, by optimizing the control strategy, for example, by adopting a vector control method, the speed of the motor can be adjusted more accurately and the pulsation caused by the current measurement error can be reduced;

[0013] S7: Finally, by applying a filtering algorithm to the current measurement, the noise and interference from the sensor can be reduced, thereby improving the measurement accuracy.

[0014] Preferably, the given signal of the permanent magnet synchronous motor in S4 is a stator current including AC compensation.

[0015] Preferably, the permanent magnet synchronous motor in S1 is an AC permanent magnet synchronous motor.

[0016] Preferably, the permanent magnet synchronous motor mathematical model constructed in S5 is:

[0017]

[0018]

[0019] Among them, u d represents the d-axis component of the stator voltage, u q represents the q-axis component of the stator voltage, i d represents the d-axis component of the stator current, i q represents the q-axis component of the stator current, ω r represents the rotor electrical angular velocity, R represents the stator resistance, B represents the friction coefficient, L d represents the d-axis component of the stator inductance, L q represents the q-axis component of the stator inductance, T L represents the load torque, p represents the number of pole pairs, represents permanent magnet flux and J represents the moment of inertia.

[0020] Preferably, the filtering algorithm in S7 is one of a moving average filtering method and an exponentially weighted moving average filtering method;

[0021] Moving average filtering method:

[0022]

[0023] Where g[i] is the i-th output value, N is the window size, indicating the first few data points to consider, and x[k] is the k-th input value;

[0024] Exponentially weighted moving average filtering method:

[0025] y[n]=α·x[n]+(1-α)·y[n-1] (4):

[0026] Among them, y[n] is the current output value, x[n] is the current input value, y[n-1] is the output value at the previous moment, and α is the smoothing coefficient, which controls the weight ratio of new data to old data, and its value range is usually 0≤α≤1.

[0027] Preferably, the optimization control strategy in S6 includes vector control, speed closed-loop control, model predictive control and nonlinear control;

[0028] Vector control (FOC): Vector control is an advanced control strategy that can achieve independent control of the motor, including rotor field orientation, electromagnetic torque control, etc. FOC can help reduce current fluctuations and improve the dynamic response and efficiency of the motor;

[0029] Speed ​​closed-loop control: The introduction of speed closed-loop control can measure the actual speed of the motor in real time, and achieve speed tracking by adjusting the output of the current controller, so that the speed pulsation can be compensated in time to improve stability and accuracy;

[0030] Model Predictive Control (MPC): MPC is a control strategy based on a predictive model that can predict the future behavior of the system and optimize the control input. By using MPC, nonlinear and time-varying system characteristics can be better handled and speed pulsation can be reduced;

[0031] Nonlinear control: Considering the nonlinear characteristics of permanent magnet synchronous motors, the use of appropriate nonlinear control strategies can better handle the complexity of the system and reduce control errors and fluctuations.

[0032] The present invention provides a method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement errors. Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The method for suppressing the speed pulsation of the permanent magnet synchronous motor caused by the current measurement error can be adjusted and optimized according to the specific application and requirements by adopting a filtering algorithm to achieve effective filtering and smoothing of the signal, thereby reducing the noise and interference from the sensor, thereby improving the measurement accuracy. By solving the current error, the error can be reduced, the control accuracy can be improved, and the motor operation can be made more accurate. The stable operation state can reduce the wear and damage of the motor and extend the service life of the motor.

[0034] (2) The method for suppressing the speed pulsation of the permanent magnet synchronous motor caused by the current measurement error can more accurately adjust the speed of the motor and reduce the pulsation caused by the current measurement error by optimizing the control strategy. The use of a suitable nonlinear control strategy can better handle the complexity of the system, reduce control errors and fluctuations, and better handle nonlinear and time-varying system characteristics, reduce speed pulsation. At the same time, by establishing a model to optimize the control of future behavior, the speed pulsation of the permanent magnet synchronous motor is maintained in a relatively stable operating state. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flowchart of the overall process of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0037] Embodiment 1:

[0038] A method for suppressing speed pulsation of a permanent magnet synchronous motor caused by current measurement error comprises the following steps:

[0039] S1: Obtain the status data of the permanent magnet synchronous motor;

[0040] The permanent magnet synchronous motor is an AC permanent magnet synchronous motor;

[0041] S2: Based on the acquired state data, a mathematical model of the permanent magnet synchronous motor and a speed adaptive harmonic expansion state observer are constructed;

[0042] S3: Construct the maximum correlation entropy factor by checking the mean and covariance of the variational Bayesian distribution and the observation factor through the observation anomaly in the filtering process;

[0043] S4: determining a PWM wave signal for controlling the operation of the permanent magnet synchronous motor based on a given signal of the permanent magnet synchronous motor and an actual three-phase current signal;

[0044] The given signal of the permanent magnet synchronous motor is the stator current with AC compensation;

[0045] S5: according to the determined PWM wave signal and the constructed permanent magnet synchronous motor mathematical model;

[0046] The mathematical model of permanent magnet synchronous motor is:

[0047]

[0048]

[0049] Among them, u d represents the d-axis component of the stator voltage, u q represents the q-axis component of the stator voltage, i d represents the d-axis component of the stator current, i q represents the q-axis component of the stator current, ω r represents the rotor electrical angular velocity, R represents the stator resistance, B represents the friction coefficient, L d represents the d-axis component of the stator inductance, L q represents the q-axis component of the stator inductance, T L represents the load torque, p represents the number of pole pairs, represents permanent magnet flux, J represents moment of inertia;

[0050] S6: Then, by optimizing the control strategy, for example, by adopting a vector control method, the speed of the motor can be adjusted more accurately and the pulsation caused by the current measurement error can be reduced;

[0051] Optimization control strategies include vector control, speed closed-loop control, model predictive control and nonlinear control;

[0052] Vector control (FOC): Vector control is an advanced control strategy that enables independent control of the motor. Using rotor field orientation, FOC can help reduce current fluctuations and improve the dynamic response and efficiency of the motor.

[0053] Rotor field orientation technology:

[0054] Vector control: Vector control is a control method based on magnetic field orientation. By measuring the current and position information of the motor, it can achieve precise control of the direction of the rotor magnetic field, thereby achieving high efficiency and high performance operation;

[0055] Space vector modulation: Using space vector modulation technology, the direction and size of the motor's magnetic field are controlled by changing the vector and amplitude of the motor's phase current, thus achieving precise control of the motor.

[0056] Direct torque control: Direct torque control is a control method based on rotor magnetic field orientation. It directly measures the current and position information of the motor and changes the magnetic field orientation of the motor instantly to achieve precise torque control.

[0057] Field Oriented Observer: Use the field oriented observer to estimate the motor rotor position and magnetic field direction, thereby achieving closed-loop control and ensuring system stability and accuracy;

[0058] Speed ​​closed-loop control: The introduction of speed closed-loop control can measure the actual speed of the motor in real time, and achieve speed tracking by adjusting the output of the current controller, so that the speed pulsation can be compensated in time to improve stability and accuracy;

[0059] Model Predictive Control (MPC): MPC is a control strategy based on a predictive model that can predict the future behavior of the system and optimize the control input. By using MPC, nonlinear and time-varying system characteristics can be better handled and speed pulsation can be reduced;

[0060] Nonlinear control: Considering the nonlinear characteristics of permanent magnet synchronous motors, the use of appropriate nonlinear control strategies can better handle the complexity of the system and reduce control errors and fluctuations.

[0061] S7: Finally, by applying a filtering algorithm to the current measurement value, the noise and interference from the sensor can be reduced, thereby improving the measurement accuracy;

[0062] The filtering algorithm is moving average filtering;

[0063] The formula used by the moving average filter method is:

[0064]

[0065] Where y[i] is the i-th output value, N is the window size, representing the first few data points to consider, and x[k] is the k-th input value.

[0066] Embodiment 2:

[0067] A method for suppressing speed pulsation of a permanent magnet synchronous motor caused by current measurement error comprises the following steps:

[0068] S1: Obtain the status data of the permanent magnet synchronous motor;

[0069] The permanent magnet synchronous motor is an AC permanent magnet synchronous motor;

[0070] S2: Based on the acquired state data, a mathematical model of the permanent magnet synchronous motor and a speed adaptive harmonic expansion state observer are constructed;

[0071] S3: Construct the maximum correlation entropy factor by checking the mean and covariance of the variational Bayesian distribution and the observation factor through the observation anomaly in the filtering process;

[0072] S4: determining a PWM wave signal for controlling the operation of the permanent magnet synchronous motor based on a given signal of the permanent magnet synchronous motor and an actual three-phase current signal;

[0073] The given signal of the permanent magnet synchronous motor is the stator current with AC compensation;

[0074] S5: according to the determined PWM wave signal and the constructed permanent magnet synchronous motor mathematical model;

[0075] The mathematical model of permanent magnet synchronous motor is:

[0076]

[0077]

[0078] Among them, u d represents the d-axis component of the stator voltage, u q represents the q-axis component of the stator voltage, i d represents the d-axis component of the stator current, i q represents the q-axis component of the stator current, ω r represents the rotor electrical angular velocity, R represents the stator resistance, B represents the friction coefficient, L d represents the d-axis component of the stator inductance, L q represents the q-axis component of the stator inductance, T L represents the load torque, p represents the number of pole pairs, represents permanent magnet flux, J represents moment of inertia;

[0079] S6: Then, by optimizing the control strategy, for example, by adopting a vector control method, the speed of the motor can be adjusted more accurately and the pulsation caused by the current measurement error can be reduced;

[0080] Optimization control strategies include vector control, speed closed-loop control, model predictive control and nonlinear control;

[0081] Vector control (FOC): Vector control is an advanced control strategy that can achieve independent control of the motor. Using electromagnetic torque control, FOC can help reduce current fluctuations and improve the dynamic response and efficiency of the motor.

[0082] Electromagnetic torque control:

[0083] Field-oriented control: By controlling the direction of the motor's magnetic field to keep it consistent with the direction of rotation of the rotor, efficient torque control can be achieved;

[0084] Current control: According to the motor's operating status and load requirements, the motor's phase current and phase are adjusted to achieve precise control of the electromagnetic torque;

[0085] Feedback control: Use sensors or observers to monitor the status and operation information of the motor in real time, so as to perform closed-loop control of the electromagnetic torque and maintain system stability and performance.

[0086] Speed ​​closed-loop control: The introduction of speed closed-loop control can measure the actual speed of the motor in real time, and achieve speed tracking by adjusting the output of the current controller, so that the speed pulsation can be compensated in time to improve stability and accuracy;

[0087] Model Predictive Control (MPC): MPC is a control strategy based on a predictive model that can predict the future behavior of the system and optimize the control input. By using MPC, nonlinear and time-varying system characteristics can be better handled and speed pulsation can be reduced;

[0088] Nonlinear control: Considering the nonlinear characteristics of permanent magnet synchronous motors, the use of appropriate nonlinear control strategies can better handle the complexity of the system and reduce control errors and fluctuations.

[0089] S7: Finally, by applying a filtering algorithm to the current measurement value, the noise and interference from the sensor can be reduced, thereby improving the measurement accuracy;

[0090] The filtering algorithm is the exponentially weighted moving average filtering method;

[0091] The formula used by the exponentially weighted moving average filter method is:

[0092] y[n]=α·x[n]+(1-α)·y[n-1] (4);

[0093] Among them, y[n] is the current output value, x[n] is the current input value, y[n-1] is the output value at the previous moment, and α is the smoothing coefficient, which controls the weight ratio of new data to old data, and its value range is usually 0≤α≤1.

[0094] In another embodiment, speed pulsations are reduced by using model predictive control (MPC):

[0095] Establish an accurate predictive dynamic model, which includes aspects such as mechanical systems, control systems, and sensors, to accurately describe the dynamic behavior of the system and the source of speed pulsation, and then set the control goals you want to achieve, such as reducing the amplitude and frequency of speed pulsation, improving system stability and performance, and achieve the goals by optimizing control inputs.

[0096] In each control cycle, MPC uses the current system state and model to predict the system response in the future, and then calculates the optimal control input sequence through the optimization algorithm to make the system tend to the desired state in the future. The optimized control input calculated by MPC is implemented in the system, and the control system adjusts the system state according to the optimized input to reduce speed pulsation, monitor the system response and adjust the MPC parameters as needed to further optimize the control effect and reduce speed pulsation.

[0097] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0098] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0099] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for suppressing speed pulsation of a permanent magnet synchronous motor caused by current measurement error, characterized in that: The steps include: S1: Obtain the status data of the permanent magnet synchronous motor; S2: Based on the acquired state data, a mathematical model of the permanent magnet synchronous motor and a speed adaptive harmonic expansion state observer are constructed; S3: Construct the maximum correlation entropy factor by checking the mean and covariance of the variational Bayesian distribution and the observation factor through the observation anomaly in the filtering process; S4: determining a PWM wave signal for controlling the operation of the permanent magnet synchronous motor based on a given signal of the permanent magnet synchronous motor and an actual three-phase current signal; S5: according to the determined PWM wave signal and the constructed permanent magnet synchronous motor mathematical model; S6: Then, by optimizing the control strategy, for example, by adopting a vector control method, the speed of the motor can be adjusted more accurately and the pulsation caused by the current measurement error can be reduced; S7: Finally, by applying a filtering algorithm to the current measurement, the noise and interference from the sensor can be reduced, thereby improving the measurement accuracy.

2. The method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement error according to claim 1, characterized in that: The given signal of the permanent magnet synchronous motor in S4 is the stator current with AC compensation.

3. The method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement error according to claim 1, characterized in that: The permanent magnet synchronous motor in S1 is an AC permanent magnet synchronous motor.

4. The method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement error according to claim 1, characterized in that: The mathematical model of the permanent magnet synchronous motor constructed in S5 is: Among them, u d represents the d-axis component of the stator voltage, u q represents the q-axis component of the stator voltage, i d represents the d-axis component of the stator current, i q represents the q-axis component of the stator current, ω r represents the rotor electrical angular velocity, R represents the stator resistance, B represents the friction coefficient, L d represents the d-axis component of the stator inductance, L q represents the q-axis component of the stator inductance, T L represents the load torque, p represents the number of pole pairs, represents permanent magnet flux and J represents the moment of inertia.

5. The method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement error according to claim 1, characterized in that: The filtering algorithm in S7 is one of a moving average filtering method and an exponentially weighted moving average filtering method; The formula used in the moving average filtering method is: Where y[i] is the i-th output value, N is the window size, representing the first few data points to consider, and x[k] is the k-th input value.

6. The method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement error according to claim 1, characterized in that: The optimization control strategies in S6 include vector control, speed closed-loop control, model predictive control and nonlinear control.

7. The method for suppressing the speed pulsation of a permanent magnet synchronous motor caused by current measurement error according to claim 5, characterized in that: The formula used by the exponentially weighted moving average filtering method is: y[n]=α·x[n]+(1-α)·y[n-1] (4); Among them, y[n] is the current output value, x[n] is the current input value, y[n-1] is the output value at the previous moment, and α is the smoothing coefficient, which controls the weight ratio of new data to old data, and its value range is usually 0≤α≤1.

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