Torque control method and system based on motor current control and correction technology

Abstract

The invention relates to the technical field of motor control, in particular to a torque control method and system based on a motor current control and correction technology. According to the technical scheme, the method comprises the steps of obtaining three-phase stator current of a motor, and calculating initial electromagnetic torque through a flux linkage model after sampling and filtering; the method is characterized in that current parameters for torque calculation are dynamically corrected, including coordinate transformation, phase correction and amplitude compensation, so that corrected current parameters are generated; calculating to obtain a corrected torque value with improved precision by using the corrected parameters, and comparing the corrected torque value with a target value to generate an error signal; and finally, a driving voltage vector instruction is generated according to the error signal, and closed-loop control over the output torque of the motor is achieved through PWM. Through current dynamic correction, self-learning compensation and low-speed flux linkage estimation, high-precision self-adaptive control of the motor torque is realized, and the control stability, the response speed and the system safety are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a torque control method and system based on motor current control and correction technology. Background Technology

[0002] Motor torque control technology is one of the core components of modern motor drive systems, especially in new energy vehicle drives, electric servo control, and industrial automation equipment, where the requirements for the control accuracy and dynamic response performance of motor output torque are extremely high. Traditional torque control methods are usually based on the motor flux linkage model, calculating the electromagnetic torque by detecting stator current and rotor position signals to achieve closed-loop control of the target torque.

[0003] However, in actual operation, motor control systems generally face the following technical problems:

[0004] Due to the presence of temperature drift of the sampling resistor, bias drift of the Hall sensor, A / D conversion error and noise interference in the sampling circuit, the measured current value deviates from the true value, thus affecting the accuracy of torque calculation. This measurement error is more obvious under high-frequency PWM drive conditions.

[0005] Torque estimation error caused by phase deviation:

[0006] There is a periodic delay between current sampling, filtering, and control calculation, resulting in a phase difference between the current vector and the flux linkage vector. Without correction, the input quantities in the torque calculation model will be distorted, leading to fluctuations in the output torque and steady-state errors.

[0007] When a motor operates for a long time or under high temperature and high load conditions, the stator resistance, flux linkage constant and inductance will change dynamically. Traditional fixed parameter models cannot reflect these changes in real time, resulting in a decrease in torque control accuracy.

[0008] At zero speed or extremely low speed, the back electromotive force signal is weak, the traditional flux estimation method fails, resulting in a lack of effective feedback in the torque control circuit, and the system is prone to jitter or instability.

[0009] Existing motor control algorithms typically use static control parameters, which cannot automatically correct current or torque calculation errors based on operating conditions, leading to a gradual degradation in system accuracy after long-term operation.

[0010] To address the aforementioned issues, existing technologies have attempted to improve the situation through filtering optimization, model reference adaptive control (MRAC), or fuzzy control methods. However, these methods often involve large computational loads, complex implementations, or insufficient real-time performance, making it difficult to operate stably in industrial settings and on embedded controllers.

[0011] Therefore, we propose a torque control method and system based on motor current control and correction technology to solve the existing problems. Summary of the Invention

[0012] The purpose of this invention is to address the problems existing in the background art by proposing a torque control method and system based on motor current control and correction technology.

[0013] To achieve the above objectives, the present invention provides the following technical solution: a torque control method based on motor current control and correction technology, comprising the following steps:

[0014] S1. Acquire the three-phase stator current signal of the motor, perform real-time sampling and filtering on the current signal to obtain target current data, and calculate the initial electromagnetic torque value based on the target current data through the motor flux linkage model.

[0015] S2. The initial electromagnetic torque value is processed to improve the calculation accuracy. The core of this process is to dynamically correct the current parameters used for torque calculation in order to generate corrected current parameters. The dynamic correction includes at least one operation among coordinate transformation, phase correction and amplitude compensation of the sampled current components.

[0016] S3. Substitute the corrected current parameters into the torque calculation formula to calculate the corrected torque value after accuracy improvement. Compare the corrected torque value with the target torque value to generate a torque error signal.

[0017] S4. Based on the torque error signal, generate a drive voltage vector command for the motor and output the drive voltage vector command to the drive unit to adjust the three-phase drive voltage of the motor and realize closed-loop control of the motor output torque.

[0018] Preferably, the dynamic correction in S2 includes:

[0019] The phase current signal is transformed to obtain the direct-axis current component and quadrature-axis current component in the synchronous rotating coordinate system, as well as the motor operating status signal, to determine the phase deviation in the current measurement; the current component is corrected according to the phase deviation angle so that the corrected current vector is in phase with the flux linkage vector and the amplitude of the direct-axis current component and quadrature-axis current component is compensated.

[0020] Preferably, the compensation amount used for amplitude compensation of the direct-axis current component and the quadrature-axis current component is obtained by querying a pre-built correction coefficient table. The correction coefficient table is built based on the historical torque error data of the motor under different operating conditions. The index parameters of the correction coefficient table include at least one of motor temperature and DC bus voltage to achieve multi-parameter fusion correction.

[0021] Preferably, the method further includes the steps of: real-time monitoring of the torque control error of the motor, and dynamically updating the parameters in the correction coefficient table based on the torque control error using a self-learning algorithm, wherein the self-learning algorithm is based on the mean square value of the torque error within multiple sampling periods and corrects the current control gain coefficient in real time according to the parameter update formula.

[0022] Preferably, when the motor is running at low speed, the motor flux is estimated by a flux observer, and the initial electromagnetic torque and the correction current parameter are compensated based on the estimated flux value. The flux observer uses a high-frequency signal injection method to estimate the flux at zero speed and extremely low speed.

[0023] Preferably, the driving signal for adjusting the motor is specifically obtained by inputting the torque error signal to a proportional-integral controller to generate a voltage regulation amount, and generating a three-phase PWM waveform to drive the motor based on the voltage regulation amount using space vector pulse width modulation technology.

[0024] A torque control system based on motor current control and correction technology is characterized by comprising:

[0025] The signal acquisition module is used to acquire the stator current signal and speed signal of the motor.

[0026] The current processing module is used to filter and transform the sampled current to output the target current data.

[0027] The torque calculation module is used to calculate the initial electromagnetic torque based on the target current data and the flux linkage model.

[0028] The current correction module is used to correct the initial current component based on the phase deviation angle and amplitude error;

[0029] An adaptive compensation module is used to dynamically correct current control parameters based on historical errors;

[0030] The control output module is used to adjust the drive voltage vector according to the corrected torque value to realize closed-loop control of the motor torque. The control output module outputs a modulation signal through the PWM inverter unit, which generates a three-phase drive waveform according to the corrected voltage vector command.

[0031] Preferably, the current correction module includes a phase detection unit, a compensation calculation unit, and a feedback correction unit, wherein the compensation calculation unit generates a correction current command based on the correction formula.

[0032] Preferably, the adaptive compensation module includes an error extraction unit and a coefficient adjustment unit, wherein the error extraction unit is used to obtain the torque deviation within a continuous sampling period; and the coefficient adjustment unit adjusts the control parameters in real time based on the error gradient according to the parameter update rule.

[0033] Preferably, the system further includes a status monitoring module, which is connected to the control output module. The status monitoring module is used to detect the motor temperature, current deviation and flux change rate in real time. When the detected value exceeds a set threshold, a safety torque limiting strategy is triggered to reduce the amplitude of the drive command voltage.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] By performing coordinate transformation, phase correction, and amplitude compensation on the current sampling signal, the errors caused by measurement delay and amplitude drift are eliminated, and the current vector and flux linkage vector are kept in phase, which significantly improves the accuracy of torque calculation.

[0036] A multi-dimensional correction strategy based on operating status is adopted, and the current correction coefficient is dynamically adjusted in combination with parameters such as motor temperature and bus voltage, so that the control algorithm can automatically adapt to different operating conditions and reduce the impact of model parameter mismatch on control performance.

[0037] This invention achieves adaptive optimization of control parameters by real-time monitoring of the mean square value of torque error and using a self-learning algorithm to update the correction coefficient table and control gain online, enabling the system to maintain high-precision control even after long-term operation.

[0038] Under low-speed or zero-speed conditions, the flux linkage is estimated by using a flux linkage observer combined with a high-frequency signal injection method, which effectively compensates for the failure of the back EMF method at low speeds and ensures the continuity and stability of torque control.

[0039] By combining proportional-integral controller with space vector pulse width modulation (SVPWM) technology, precise voltage vector commands are generated to achieve high-precision modulation of the motor's three-phase PWM waveform, resulting in faster dynamic response and smaller steady-state fluctuations in output torque.

[0040] The system integrates a status monitoring module to detect motor temperature, current deviation, and flux change rate in real time. When the detected value exceeds the safety threshold, the torque limiting strategy is automatically triggered to reduce the drive voltage amplitude and effectively prevent system overload and overheating.

[0041] The method of this invention can be implemented based on existing motor control platforms, does not rely on external complex sensors, has a moderate computational load, and is easy to integrate into industrial frequency converters, servo controllers, and electric drive systems for new energy vehicles. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0043] Figure 2 This is a schematic diagram of the system framework of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] like Figure 1 As shown, the torque control method based on motor current control and correction technology proposed in this invention has the core idea of ​​correcting the phase deviation and amplitude error in the torque calculation of the traditional flux linkage model through dynamic correction of current signal and adaptive compensation algorithm, so as to improve the accuracy of torque calculation and control. This method is applicable to torque control scenarios of various types of motors such as permanent magnet synchronous motors, induction motors, and direct drive servo motors.

[0047] The torque control method includes the following steps:

[0048] S1. Signal Acquisition and Initial Torque Calculation

[0049] The three-phase stator current signal of the motor is acquired, and the current signal is sampled and filtered in real time to obtain the target current data. Based on the target current data, the initial electromagnetic torque value is calculated through the motor flux linkage model.

[0050] Specifically, the signal sampling period is set to 100μs to 1ms to meet the requirements of high-speed control. The acquired signal is processed by a digital low-pass filter or a moving average filter algorithm to reduce electromagnetic interference and switching noise.

[0051] Subsequently, the control system calls upon the built-in motor flux linkage model to calculate the initial electromagnetic torque value. Taking a permanent magnet synchronous motor as an example, the torque calculation formula is as follows:

[0052]

[0053] in,

[0054] p is the number of pole pairs of the motor;

[0055] ψ f For permanent magnet flux linkage;

[0056] I d I q These are the direct-axis and quadrature-axis current components, respectively;

[0057] L d L q For the d-axis and q-axis inductance.

[0058] The torque calculation result serves as the basis for subsequent current correction and compensation.

[0059] S2, Current Dynamic Correction

[0060] The key to improving the accuracy of the initial electromagnetic torque value lies in the dynamic correction of the current parameters used for torque calculation, in order to generate corrected current parameters. Dynamic correction includes three sub-steps:

[0061] Coordinate transformation: The current signal in the three-phase stationary coordinate system is transformed to the synchronous rotating coordinate system through Clarke transformation and Park transformation to obtain the direct-axis current component I. d and cross-axis current component I q .

[0062] Phase correction: Based on the motor's operating status signals (such as speed and voltage), determine the phase deviation angle Δθ in the current measurement and correct the current component.

[0063] I' d =I d cos(Δθ)-I q sin(Δθ)

[0064] I' q =I d sin(Δθ)+I q cos(Δθ)

[0065] Make the corrected current vector in phase with the flux linkage vector.

[0066] Amplitude compensation: Amplitude compensation is performed on the direct-axis current component and the quadrature-axis current component. The compensation amount is obtained by querying a pre-built correction coefficient table. The correction coefficient table is built based on the historical torque error data of the motor under different operating conditions. The index parameters include at least one of the motor temperature and DC bus voltage to achieve multi-parameter fusion correction. The correction formula is as follows:

[0067] I″ d =K c ×I′ d

[0068] I″ q =K c ×I′ q

[0069] Among them, K c This is a compensation factor.

[0070] S3, Corrected Torque Calculation and Error Generation

[0071] Correct the current parameter I″ d ,I″q Substituting into the torque calculation formula, the corrected torque value T after accuracy improvement is obtained. ec , will T ec With the target torque value T ref By comparison, the torque error signal is obtained:

[0072] ΔT=T ref -T ec

[0073] This error signal is used as input to the controller for closed-loop regulation.

[0074] S4, Torque Closed-Loop Control

[0075] Based on the torque error signal, a drive voltage vector command for the motor is generated and output to the drive unit to adjust the three-phase drive voltage of the motor and realize closed-loop control. Specifically, the torque error signal is input to the proportional-integral controller (PI controller) to generate the voltage regulation amount, and a three-phase PWM waveform is generated based on space vector pulse width modulation (SVPWM) technology to drive the motor.

[0076] Adaptive compensation and low-speed processing

[0077] Adaptive compensation: Real-time monitoring of torque control error, and dynamic updating of the correction coefficient table based on the error using a self-learning algorithm. The control system calculates the mean square value of torque error over multiple sampling periods.

[0078]

[0079] When E exceeds the set threshold, the parameter update module is triggered, and the current control gain coefficient is corrected in real time according to the parameter update formula. The gain update formula is:

[0080]

[0081] Where E is the mean square error and η is the learning rate.

[0082] Low-speed compensation: When the motor is running at low speed, the flux linkage of the motor is estimated by a flux linkage observer, and the initial electromagnetic torque and correction current parameters are compensated based on the estimated value. The flux linkage observer uses a high-frequency signal injection method to estimate the flux linkage at zero speed and extremely low speed to ensure stable torque output.

[0083] Example 2

[0084] like Figure 2 As shown, the torque control system based on motor current control and correction technology proposed in this invention adopts a modular design and consists of the following functional modules:

[0085] Signal acquisition module

[0086] This module is responsible for acquiring the three-phase stator current signal and speed signal of the motor.

[0087] The three-phase current signal is obtained by a Hall current sensor or a sampling resistor and input to the controller via an analog-to-digital converter circuit.

[0088] The speed signal is provided by an encoder or a magnetoelectric speed sensor;

[0089] The acquisition module is equipped with an isolated power supply and an anti-interference filter circuit to ensure signal stability.

[0090] Current processing module

[0091] This module performs filtering, transformation, and normalization processing on the sampled signal;

[0092] A digital low-pass filter is used to eliminate high-frequency noise, and the Clarke and Park transform algorithms are used to convert the three-phase stationary coordinate system signal into an I-mode signal in a rotating coordinate system. d and I q The data is then transmitted to the torque calculation module.

[0093] Torque Calculation Module

[0094] This module calls the motor flux linkage model and calculates the initial electromagnetic torque based on the input current data. The module supports parameter configuration for different motor types and can load different flux linkage characteristic curves through the software interface.

[0095] Current correction module

[0096] This module performs phase and amplitude correction on the current component and includes:

[0097] Phase detection unit: Real-time detection of the phase difference between current and magnetic flux;

[0098] Compensation calculation unit: Generates correction current based on the correction formula.

[0099] Feedback correction unit: Feeds the correction results back to the torque calculation module to achieve current closed-loop correction.

[0100] Adaptive compensation module

[0101] This module includes an error extraction unit and a coefficient adjustment unit:

[0102] Error extraction unit: Acquires torque deviation signals over multiple consecutive sampling periods;

[0103] Coefficient adjustment unit: Based on the error change trend, dynamically corrects the control gain, correction coefficient table or PI parameters according to the update rules. The update cycle of this module can be configured according to the system's computing power, generally 10ms to 100ms.

[0104] Control output module

[0105] This module generates a drive voltage vector command based on torque error. The control output module has an embedded proportional-integral control algorithm, which, combined with the SVPWM modulation algorithm, generates a three-phase PWM waveform signal and outputs it to the inverter drive unit to achieve real-time drive control of the motor.

[0106] Status monitoring module

[0107] Used to monitor the motor's operating status in real time, including stator temperature, current deviation, and flux change rate. When any monitored parameter exceeds the safety threshold, the module triggers the "torque limiting protection strategy," which automatically reduces the amplitude of the PWM output voltage or shuts off the control output to prevent the motor from overheating or vibrating abnormally.

[0108] PWM inverter unit

[0109] This unit is the power drive section, consisting of a three-phase full bridge. It receives PWM signals from the control output module and controls the power switching devices (such as IGBTs and MOSFETs) to turn on, thereby achieving precise modulation of the three-phase voltage of the motor.

[0110] This system integrates current signal correction, real-time torque calculation, self-learning compensation, and safety monitoring in its structure, which can significantly improve the torque output accuracy and dynamic response performance of the motor. It is especially suitable for high-performance servo control and electric drive systems for new energy vehicles.

[0111] The above specific embodiments are merely several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

[0112] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A torque control method based on motor current control and correction technology, characterized in that, Includes the following steps: S1. Acquire the three-phase stator current signal of the motor, perform real-time sampling and filtering on the current signal to obtain target current data, and calculate the initial electromagnetic torque value based on the target current data through the motor flux linkage model. S2. The initial electromagnetic torque value is processed to improve the calculation accuracy. The core of this process is to dynamically correct the current parameters used for torque calculation in order to generate corrected current parameters. The dynamic correction includes at least one operation among coordinate transformation, phase correction and amplitude compensation of the sampled current components. S3. Substitute the corrected current parameters into the torque calculation formula to calculate the corrected torque value after accuracy improvement. Compare the corrected torque value with the target torque value to generate a torque error signal. S4. Based on the torque error signal, generate a drive voltage vector command for the motor and output the drive voltage vector command to the drive unit to adjust the three-phase drive voltage of the motor and realize closed-loop control of the motor output torque.

2. The torque control method based on motor current control and correction technology according to claim 1, characterized in that: The dynamic correction in S2 includes: The phase current signal is transformed to obtain the direct-axis current component and quadrature-axis current component in the synchronous rotating coordinate system, as well as the motor operating status signal, to determine the phase deviation in the current measurement; the current component is corrected according to the phase deviation angle so that the corrected current vector is in phase with the flux linkage vector and the amplitude of the direct-axis current component and quadrature-axis current component is compensated.

3. The torque control method based on motor current control and correction technology according to claim 2, characterized in that: The compensation amount used for amplitude compensation of the direct-axis current component and the quadrature-axis current component is obtained by querying a pre-built correction coefficient table. The correction coefficient table is built based on the historical torque error data of the motor under different operating conditions. The index parameters of the correction coefficient table include at least one of the motor temperature and DC bus voltage to achieve multi-parameter fusion correction.

4. The torque control method based on motor current control and correction technology according to claim 3, characterized in that: The method also includes the steps of: real-time monitoring of the torque control error of the motor, and dynamic updating of the parameters in the correction coefficient table based on the torque control error through a self-learning algorithm, wherein the self-learning algorithm is based on the mean square value of the torque error within multiple sampling periods and corrects the current control gain coefficient in real time according to the parameter update formula.

5. The torque control method based on motor current control and correction technology according to claim 2, characterized in that: When the motor is running at low speed, the flux linkage of the motor is estimated by a flux linkage observer, and the initial electromagnetic torque and the correction current parameter are compensated based on the estimated flux linkage value. The flux linkage observer uses a high-frequency signal injection method to estimate the flux linkage at zero speed and extremely low speed.

6. The torque control method based on motor current control and correction technology according to claim 1, characterized in that: Specifically, the driving signal for the motor is to input the torque error signal to the proportional-integral controller to generate a voltage regulation amount, and based on the voltage regulation amount, to generate a three-phase PWM waveform to drive the motor using space vector pulse width modulation technology.

7. The torque control system based on motor current control and correction technology according to claim 1, characterized in that, include: The signal acquisition module is used to acquire the stator current signal and speed signal of the motor. The current processing module is used to filter and transform the sampled current to output the target current data. The torque calculation module is used to calculate the initial electromagnetic torque based on the target current data and the flux linkage model. The current correction module is used to correct the initial current component based on the phase deviation angle and amplitude error; An adaptive compensation module is used to dynamically correct current control parameters based on historical errors; The control output module is used to adjust the drive voltage vector according to the corrected torque value to realize closed-loop control of the motor torque. The control output module outputs a modulation signal through the PWM inverter unit, which generates a three-phase drive waveform according to the corrected voltage vector command.

8. The torque control system based on motor current control and correction technology according to claim 7, characterized in that: The current correction module includes a phase detection unit, a compensation calculation unit, and a feedback correction unit. The compensation calculation unit generates a correction current command based on the correction formula.

9. The torque control system based on motor current control and correction technology according to claim 7, characterized in that: The adaptive compensation module includes an error extraction unit and a coefficient adjustment unit. The error extraction unit is used to obtain the torque deviation within a continuous sampling period. The coefficient adjustment unit adjusts the control parameters in real time based on the error gradient according to the parameter update rule.

10. The torque control system based on motor current control and correction technology according to claim 7, characterized in that: The system further includes a status monitoring module, which is connected to the control output module. The status monitoring module is used to detect the motor temperature, current deviation and flux change rate in real time. When the detected value exceeds the set threshold, a safety torque limiting strategy is triggered to reduce the amplitude of the drive command voltage.

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