Permanent magnet synchronous motor torque ripple suppression method, device, equipment and medium

Abstract

The invention discloses a permanent magnet synchronous motor torque ripple suppression method and device, equipment and a medium, relates to the technical field of permanent magnet synchronous motor control, and is used for solving the problem of low torque ripple suppression precision in related technologies. The method comprises the following steps: acquiring a permanent magnet flux linkage actual value of the permanent magnet synchronous motor at the current magnet temperature; determining a d-axis flux linkage compensation amount and a q-axis flux linkage compensation amount under the rotating coordinate system based on a difference value between the permanent magnet flux linkage actual value and a pre-stored permanent magnet flux linkage reference value; according to the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, respectively compensating a pre-stored d-axis reference flux linkage and a q-axis reference flux linkage to obtain a d-axis target flux linkage and a q-axis target flux linkage; and based on the d-axis target flux linkage and the q-axis target flux linkage, generating a harmonic current instruction for counteracting the torque ripple, and injecting the harmonic current instruction into a current control loop of the permanent magnet synchronous motor.

Description

Technical Field

[0001] This application relates to the field of permanent magnet synchronous motor control technology, and in particular to a method, device, equipment and medium for suppressing torque fluctuations in permanent magnet synchronous motors. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in high-precision drive fields such as electric vehicles, industrial servos, and aerospace due to their high power density, high efficiency, and excellent dynamic performance. However, the inherent cogging torque, magnetic flux spatial harmonics, and magnetic circuit saturation nonlinearity of PMSMs can cause periodic fluctuations in output torque. These fluctuations manifest as speed fluctuations at low speeds, and in precision control applications, they can directly affect the positioning accuracy and operational stability of the system.

[0003] To suppress torque ripple, harmonic current injection is commonly used in related technologies. The basic principle of this method is as follows: under specific operating conditions (such as constant room temperature and a specific current point), the main flux harmonic components causing torque ripple under no-load conditions are identified through offline testing or finite element analysis, and their amplitude and phase are fixedly stored as compensation reference parameters. Then, during motor operation, harmonic currents of corresponding frequency and amplitude are calculated and injected based on these fixed reference parameters, aiming to generate an additional torque to counteract the inherent torque ripple.

[0004] However, the fixed parameter compensation strategy described above will cause the flux linkage harmonic parameters to change when the actual operating conditions of the motor (especially the temperature rise caused by long-term operation or large load changes) deviate from the calibrated operating conditions. However, the injected harmonic current parameters cannot be adjusted accordingly, resulting in a significant decrease in torque fluctuation suppression accuracy. Summary of the Invention

[0005] Based on this, a method, device, equipment, and medium for suppressing torque fluctuations in permanent magnet synchronous motors are provided to solve the problem that fixed parameter compensation strategies in related technologies can lead to a significant decrease in torque fluctuation suppression accuracy when the actual operating conditions of the motor deviate from the calibrated operating conditions.

[0006] In a first aspect, this application provides a method for suppressing torque ripple in a permanent magnet synchronous motor, the method comprising: Obtain the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; Based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage, the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system are determined. Based on the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, the pre-stored d-axis reference flux linkage and q-axis reference flux linkage are compensated respectively to obtain the d-axis target flux linkage and the q-axis target flux linkage. Based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, a harmonic current command is generated to counteract torque fluctuations, and the harmonic current command is injected into the current control circuit of the permanent magnet synchronous motor.

[0007] By using the above method, the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature is obtained in real time. After comparing it with the reference value, the flux linkage of the d-axis and q-axis is dynamically compensated. Then, based on the compensated target flux linkage, a harmonic current command to offset torque fluctuation is generated and injected into the current control loop. This effectively suppresses torque fluctuation caused by flux linkage fluctuation due to changes in magnet temperature, and improves the motor control accuracy and operating stability.

[0008] In one embodiment, the actual value of the permanent magnet flux linkage is the first DC component of the permanent magnet flux linkage along the d-axis, and the reference value of the permanent magnet flux linkage is the reference flux linkage along the d-axis and the reference flux linkage along the q-axis at the reference flux linkage temperature.

[0009] Using the above method, the first DC component of the permanent magnet's flux linkage in the d-axis is extracted and monitored in real time as the actual flux linkage value, and then compared with the reference flux linkage in the dq-axis at the reference magnet temperature. Since the temperature change of the permanent magnet flux linkage amplitude is mainly reflected in the offset of the first DC component, dq-axis flux linkage compensation based on this difference can accurately correspond to the flux linkage amplitude change, thereby generating accurate harmonic current commands, effectively suppressing torque pulsation caused by magnet temperature fluctuations, and improving the consistency and stability of motor torque output.

[0010] In one embodiment, determining the d-axis flux linkage compensation and q-axis flux linkage compensation in a rotating coordinate system based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage includes: The d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount are determined based on the difference using a preset flux linkage temperature coupling model. The magnetic flux temperature coupling model includes the mapping relationship between the change of the first DC component and the d-axis magnetic flux compensation and the q-axis magnetic flux compensation.

[0011] By employing the above method, a pre-defined flux linkage temperature coupling model is introduced. This model maps and decomposes the single difference between the actual value of the permanent magnet flux linkage (first DC component) and the reference value into mutually coupled d-axis and q-axis flux linkage compensation quantities in a rotating coordinate system. This model accurately characterizes the combined impact of changes in the first DC component of the d-axis flux linkage on the d- and q-axis flux linkages. This ensures that the subsequent harmonic current commands generated based on the compensation quantities can more comprehensively and accurately offset the torque fluctuations caused by temperature-induced flux linkage changes, thereby improving the effectiveness of the compensation strategy and the control accuracy.

[0012] In one embodiment, determining the d-axis flux linkage compensation and the q-axis flux linkage compensation based on the difference using a preset flux linkage temperature coupling model includes: The difference is input into the magnetic flux temperature coupling model; In the flux linkage temperature coupling model, the difference is multiplied by the preset d-axis gain coefficient and q-axis gain coefficient respectively to obtain the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, wherein the d-axis gain coefficient and q-axis gain coefficient are obtained by fitting motor flux linkage data.

[0013] By multiplying the temperature difference of the permanent magnet flux linkage by the preset d-axis and q-axis gain coefficients, the precise decoupling and quantitative allocation from the total flux linkage change to the d-axis and q-axis magnetic field changes in the rotating coordinate system are achieved, providing accurate feedforward compensation for subsequent torque fluctuation suppression based on temperature compensation.

[0014] In one embodiment, based on the d-axis target flux linkage and the q-axis target flux linkage, a harmonic current command for offsetting torque fluctuations is generated, including: Obtain the second DC components of the d-axis and q-axis currents; Based on the d-axis target flux linkage, the q-axis target flux linkage, the second DC component, and the preset electromagnetic torque model, a torque fluctuation function is constructed with harmonic current components of a preset order as variables; wherein, the electromagnetic torque model includes a temperature effect term, and the flux linkage parameters in the temperature effect term are the d-axis target flux linkage and the q-axis target flux linkage; With the goal of minimizing the value of the torque fluctuation function within a preset electrical cycle, the amplitude and phase of the harmonic current component are solved to generate the harmonic current command.

[0015] By using the above method, a torque fluctuation function with harmonic current as the variable is constructed, and the value of the torque fluctuation function within a preset electrical cycle is minimized as the optimization objective to solve the harmonic current command. This allows for the systematic analysis of the optimal harmonic current amplitude and phase required to offset a specific number of torque fluctuations.

[0016] In one embodiment, the step of minimizing the value of the torque ripple function within a preset electrical cycle and solving for the amplitude and phase of the harmonic current component includes: Within a preset range of amplitude and phase values, multiple initial solutions for harmonic current components of the preset order are generated. The harmonic current corresponding to each initial solution is superimposed with the second DC component to calculate the torque fluctuation value within the preset electrical cycle; With the goal of minimizing the torque fluctuation value, the initial solution is optimized based on a preset optimization algorithm until the torque fluctuation value meets the preset convergence condition, and the final solution is used as the amplitude and phase of the harmonic current component.

[0017] By using the above method, based on multiple initial solutions, and combining optimization algorithms, the optimal harmonic current parameters that minimize torque fluctuations are found. This ensures that the generated compensation current command is the globally optimal solution for torque fluctuations under actual operating conditions, thereby significantly enhancing the robustness and adaptability of torque fluctuation suppression.

[0018] In one embodiment, the method is executed periodically in an event-triggered manner.

[0019] Using the above method, the flux compensation and harmonic current calculation process can be automatically started when specific conditions are met. This ensures continuous tracking and compensation for flux drift caused by slowly changing factors such as temperature, while effectively avoiding the waste of controller computing resources caused by continuous calculation, thus achieving an optimized balance between control performance and computing efficiency.

[0020] Secondly, this application provides a torque ripple suppression device for a permanent magnet synchronous motor, the device comprising: The acquisition module is used to acquire the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; The determination module is used to determine the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage. The compensation module is used to compensate the pre-stored d-axis reference flux and q-axis reference flux according to the d-axis flux compensation amount and q-axis flux compensation amount, respectively, to obtain the d-axis target flux and q-axis target flux. The fluctuation suppression module is used to generate a harmonic current command to counteract torque fluctuations based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, and to inject the harmonic current command into the current control loop of the permanent magnet synchronous motor.

[0021] Thirdly, this application provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the torque fluctuation suppression method for permanent magnet synchronous motors described in the first aspect.

[0022] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the torque ripple suppression method for permanent magnet synchronous motors described in the first aspect.

[0023] The technical effects of each of the second to fourth aspects mentioned above, as well as the technical effects that each aspect may achieve, are described above with reference to the technical effects that can be achieved for the first aspect or the various possible solutions in the first aspect, and will not be repeated here. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating a method for suppressing torque fluctuations in a permanent magnet synchronous motor in one embodiment. Figure 2 This is a schematic diagram of the torque fluctuation suppression device for a permanent magnet synchronous motor in one embodiment. Figure 3 This is a schematic diagram of the internal structure of a computer device in one embodiment. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The specific operational methods in the method embodiments can also be applied to the device embodiments or system embodiments. It should be noted that in the description of this application, "multiple" is understood as "at least two". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing together, or B existing alone. A connected to B can represent: A and B directly connected, or A and B connected through C. Furthermore, in the description of this application, terms such as "first" and "second" are used only for distinguishing the purpose of description and should not be construed as indicating or implying relative importance or order.

[0026] Before introducing the torque fluctuation suppression method for permanent magnet synchronous motors provided in the embodiments of this application, the technical background of this application will be described in detail below for ease of understanding.

[0027] To suppress torque ripple, harmonic current injection is commonly used in related technologies. The basic principle of this method is as follows: under specific operating conditions (such as constant room temperature and a specific current point), the main flux harmonic components causing torque ripple under no-load conditions are identified through offline testing or finite element analysis, and their amplitude and phase are fixedly stored as compensation reference parameters. Then, during motor operation, harmonic currents of corresponding frequency and amplitude are calculated and injected based on these fixed reference parameters, aiming to generate an additional torque to counteract the inherent torque ripple.

[0028] However, the fixed parameter compensation strategy described above will cause the flux linkage harmonic parameters to change when the actual operating conditions of the motor (especially the temperature rise caused by long-term operation or large load changes) deviate from the calibrated operating conditions. However, the injected harmonic current parameters cannot be adjusted accordingly, resulting in a significant decrease in torque fluctuation suppression accuracy.

[0029] In view of this, this application provides a method, device, equipment and medium for suppressing torque fluctuations in a permanent magnet synchronous motor. It introduces a flux linkage compensation mechanism based on the current magnet temperature. By correcting the flux linkage reference required for harmonic current injection, the compensation current can adaptively follow the changes in electromagnetic parameters of the motor caused by temperature rise, thereby maintaining a high-precision torque fluctuation suppression effect across the entire operating temperature range and improving the control accuracy and operational stability of the system.

[0030] The technical solution provided in this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 The following is a flowchart illustrating a method for suppressing torque fluctuations in a permanent magnet synchronous motor, comprising the following steps: S101, Obtain the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; S102, Based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage, determine the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system; S103, based on the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, compensate the pre-stored d-axis reference flux linkage and q-axis reference flux linkage respectively to obtain the d-axis target flux linkage and the q-axis target flux linkage; S104 generates a harmonic current command to counteract torque fluctuations based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, and injects the harmonic current command into the current control loop of the permanent magnet synchronous motor.

[0032] This application applies to permanent magnet synchronous motors (PMSMs) with a power range of 15-255 kW and a rated speed of 3000-15000 rpm. The control cycle is set to 50 microseconds (μs), matching a pulse width modulation frequency of 20 kHz, thus ensuring real-time control. Furthermore, the magnet temperature range is 25-65 degrees Celsius (°C).

[0033] For example, the actual value of the permanent magnet flux linkage of the PMSM at the current magnet temperature is obtained. The permanent magnet flux linkage is a core parameter for calculating electromagnetic torque, and its value changes significantly with temperature. Accurately obtaining the actual value of the permanent magnet flux linkage at the current magnet temperature is a prerequisite for achieving high-precision torque control. Methods for obtaining the current magnet temperature include, but are not limited to: Direct temperature measurement method: This method directly measures the real-time temperature of the permanent magnet by using a temperature sensor (such as a thermistor or thermocouple) on or inside the permanent magnet. This method offers high accuracy and fast response, but requires additional sensors and specific installation techniques.

[0034] Thermal network model estimation method: Based on the PMSM thermal network model, this method estimates the permanent magnet temperature in real time by measuring easily obtainable temperature points (such as stator winding temperature, casing temperature, cooling medium temperature, etc.) and known losses (copper loss, iron loss), combined with thermal resistance and thermal capacity parameters. This method does not require direct installation of sensors on the magnet and has high reliability.

[0035] In practical applications, the appropriate method can be selected based on system cost, accuracy requirements, and packaging conditions.

[0036] The motor controller stores a reference value for the permanent magnet flux linkage, calibrated at a reference magnet temperature (typically 25°C) or determined by the motor design parameters. The actual permanent magnet flux linkage value is compared to this reference value to obtain the difference. This difference reflects the change in the air gap magnetic field caused by temperature variations. Since changes in the permanent magnet flux linkage affect both the d-axis and q-axis magnetic fields of the rotating coordinate system through magnetic circuit coupling, to accurately reflect the actual spatial distribution of the magnetic field changes, the above difference needs to be appropriately allocated to the d-axis and q-axis, thereby calculating the corresponding d-axis flux linkage compensation and q-axis flux linkage compensation.

[0037] In addition, the motor controller pre-stores d-axis and q-axis reference flux linkages corresponding to the permanent magnet flux linkage reference values. This set of reference flux linkages characterizes the ideal magnetic field distribution at the reference magnet temperature. Based on the d-axis and q-axis flux linkage compensation amounts, the aforementioned reference flux linkages are compensated respectively to obtain d-axis and q-axis target flux linkages that better match the current actual magnetic field state.

[0038] For example, the d-axis flux compensation is added to the d-axis reference flux to obtain the d-axis target flux; the q-axis flux compensation is added to the q-axis reference flux to obtain the q-axis target flux.

[0039] Based on the target flux linkages of the d-axis and q-axis, and combined with a preset electromagnetic torque model, the d-axis harmonic current commands and q-axis harmonic current commands required to offset specific harmonic torque fluctuations (such as the 6th and 12th harmonics) can be derived more accurately through reverse engineering. The core principle is: by injecting specific harmonic currents, the resulting compensation torque is made equal in amplitude and opposite in phase to the harmonic components of the inherent torque fluctuations caused by parameter changes, inherent defects, or magnetic field distortion of the motor, thereby achieving smoothing of the total torque. The preset electromagnetic torque model includes a temperature-affected term, where the flux linkage parameters are the target flux linkages of the d-axis and q-axis.

[0040] Finally, the calculated harmonic current command is superimposed with the fundamental current command (from the upper speed loop or torque loop) to form the final dq-axis current command. This command is sent to the current loop controller, where it is space vector pulse width modulated to generate the switching signal for driving the inverter, thereby accurately generating the required harmonic components in the actual motor current.

[0041] By using the above method, the change in permanent magnet flux due to temperature changes is acquired and compensated in real time, thereby accurately calculating the target flux of the d-axis and q-axis that matches the actual magnetic field state. Based on this, a harmonic current command injection current control loop is generated to counteract the torque fluctuation of specific harmonics, thereby effectively suppressing torque fluctuations and significantly improving the smoothness and control accuracy of motor operation.

[0042] In one embodiment, it is illustrated by way of example that the d-axis reference flux linkage and q-axis reference flux linkage at reference magnet temperature can be measured by the no-load back EMF method (typically calibrated during the factory testing phase after the motor is manufactured).

[0043] When the PMSM is running under no-load conditions, the current is zero. At this time, the no-load back electromotive force induced in the stator winding is entirely generated by the rotating magnetic field of the permanent magnet. Therefore, by measuring this back electromotive force, the equivalent flux linkage of the permanent magnet can be deduced.

[0044] For example, first, the peak value E0 of the three-phase no-load back electromotive force is measured at the motor terminals, which is related to the total magnetic flux linkage λ of the permanent magnet. PM and electric angular velocity ω e Between , where ω e =2πf, where f is the fundamental frequency of the back electromotive force. This formula establishes the directly measurable external electrical quantities (E0 and ω). e ) and λ PM The connection between them.

[0045] Then, the three-phase no-load back electromotive force is converted to the dq axis using the Park transformation, and its d-axis component and q-axis component (E) are obtained. d E q This component is related to the dq flux linkage (λ). d , λ q The following relationship exists between E and E: d =-ω e λ q E q =ω e λ d Therefore, the magnetic flux linkage λ can be calculated. d =E q / ω e , λ q =-E d / ω e .

[0046] Therefore, during the PMSM factory test, the PMSM is placed at a reference magnet temperature and driven to a specified speed to obtain ω. e And simultaneously measure E0 or directly obtain E d E q The d-axis and q-axis reference flux linkages at the reference magnet temperature can be calculated using the above formula and used as pre-stored reference parameters in the controller.

[0047] Using the above method, based on the back electromotive force and electric angular velocity measured during no-load operation, the reference flux linkages of the d-axis and q-axis were accurately calibrated at the reference magnet temperature during the factory testing phase after the motor is manufactured. This provides accurate and reliable initial reference parameters for the controller to perform real-time compensation of magnetic field state and suppression of torque fluctuations in subsequent operation.

[0048] In one embodiment, exemplarily illustrated, the actual value of the permanent magnet flux linkage characterizes the real-time state of the total magnetic flux generated by the permanent magnet itself as a function of temperature. Along the dq axis, the permanent magnet magnetic field is primarily represented by the first DC component of the d-axis flux linkage (in Weber). Therefore, the actual value of the permanent magnet flux linkage can be characterized and obtained through the first DC component of the d-axis flux linkage. The methods for obtaining this value include, but are not limited to: Direct or indirect measurement method based on no-load back electromotive force: Under no-load conditions, the first DC component of the permanent magnet flux linkage and the d-axis flux linkage are equal. By measuring the no-load back electromotive force at different magnet temperatures, the actual value of the permanent magnet flux linkage at the corresponding magnet temperature can be indirectly obtained. This method can establish the correspondence between magnet temperature and the first DC component by changing the magnet temperature and repeating the measurement under steady-state conditions.

[0049] Formula-based calculation method based on temperature characteristic curves: For permanent magnet materials with well-defined temperature characteristics (such as neodymium iron boron), the change in magnetic flux density with temperature can be described using empirical formulas. For example: , where λ d，T0 To reference the first DC component of the d-axis flux linkage at flux linkage temperature T0, α is the temperature coefficient of the permanent magnet. Some permanent magnet manufacturers provide this coefficient or a flux linkage-temperature fitting curve. In actual operation, after obtaining the current magnet temperature, the actual value of the permanent magnet flux linkage at the current magnet temperature can be calculated in real time using this formula.

[0050] The above method characterizes the actual value of permanent magnet flux linkage as the first DC component of d-axis flux linkage, and provides two acquisition methods: an indirect measurement method based on no-load back electromotive force and a formula calculation method based on material temperature characteristic curve. This enables real-time and effective characterization and acquisition of the total magnetic flux state of permanent magnets as it changes with temperature, thus laying a key parameter foundation for accurate magnetic field compensation and torque fluctuation suppression.

[0051] In one embodiment, it is exemplarily illustrated that the d-axis flux linkage compensation and q-axis flux linkage compensation in a rotating coordinate system are determined based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage, including but not limited to: The d-axis flux linkage compensation and q-axis flux linkage compensation are determined based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage using a preset flux linkage temperature coupling model. The flux linkage temperature coupling model includes the mapping relationship between the change of the first DC component of the d-axis flux linkage and the d-axis flux linkage compensation and q-axis flux linkage compensation.

[0052] Using the above method, based on the preset magnetic flux temperature coupling model, the total magnetic flux change of the permanent magnet caused by temperature change is decoupled and mapped into d-axis and q-axis magnetic flux compensation amounts. This accurately quantifies the specific influence of temperature on the d-axis and q-axis magnetic fields, providing key intermediate variables for subsequent targeted magnetic field compensation and accurate harmonic current command generation.

[0053] In one embodiment, it is exemplarily illustrated that the d-axis flux linkage compensation and the q-axis flux linkage compensation are determined based on the difference using a preset flux linkage temperature coupling model, including but not limited to: The difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage. Input the preset flux linkage temperature coupling model; in this flux linkage temperature coupling model, Each is compared with the preset d-axis gain coefficient k d With q-axis gain coefficient k q Multiplying them together yields the d-axis flux compensation. Compensation amount with q-axis flux , where k d With k q The weights of the influence of permanent magnet flux change on the d-axis and q-axis flux are obtained by fitting motor flux data.

[0054] For example, this magnetic flux temperature coupling model is a linear model and satisfies the following expression: .

[0055] The linear model described above is based on the following physical assumption: within a certain range of temperature and current variations, the coupling effect of permanent magnet flux linkage changes on the d-axis and q-axis flux linkages can be approximated as a linear relationship. This model is simple in structure, easy to implement in engineering, and can well reflect the flux linkage coupling characteristics of most permanent magnet synchronous motors within their normal operating range.

[0056] k d With k q Calibration is typically completed during the motor design phase, and calibration methods include, but are not limited to: Finite element simulation calibration: Simulating different permanent magnet temperatures (corresponding to different λ values) using finite element simulation. m The magnetic field distribution under different load currents was analyzed, and the d-axis and q-axis flux linkage data were extracted. Then, k was obtained through linear regression fitting. d With k q .

[0057] Experimental test calibration: In the motor bench test, the set of coefficients is directly fitted by controlling the magnet temperature and measuring the d and q axis flux linkages under the corresponding operating conditions (e.g., based on back electromotive force or flux linkage observer).

[0058] Where, k d With k q The coefficient values ​​of different motors vary significantly depending on the specific electromagnetic design of the PMSM, especially the rotor structure (such as surface-mount, built-in, V-type, etc.), the arrangement of permanent magnets, and the saturation characteristics of silicon steel sheets.

[0059] For example, for an internal permanent magnet synchronous motor, if its d-axis magnetic circuit is more significantly affected by the temperature of the permanent magnet, and the q-axis magnetic circuit exhibits certain coupling changes due to cross-saturation, then it may be possible to fit k. d =1.2, k q =0.8. This combination indicates that for every 1 unit decrease in the permanent magnet flux linkage, the d-axis flux linkage decreases by 1.2 units and the q-axis flux linkage decreases by 0.8 units, reflecting the non-uniform redistribution of flux linkage between the two axes under temperature changes.

[0060] Based on the above flux linkage temperature coupling model, the required d-axis and q-axis flux linkage compensation amounts can be accurately and quickly calculated according to the real-time detected or estimated changes in the permanent magnet flux linkage, laying the foundation for subsequent high-precision torque fluctuation suppression.

[0061] In one embodiment, it is exemplarily illustrated that, based on the d-axis target flux linkage and the q-axis target flux linkage, a harmonic current command for offsetting torque fluctuations is generated, including but not limited to: Obtain the second DC components of the d-axis and q-axis currents; based on the target flux linkage of the d-axis, the target flux linkage of the q-axis, the second DC components, and the preset electromagnetic torque model, construct a torque ripple function with harmonic current components of a preset order as variables; with the goal of minimizing the value of the torque ripple function within a preset electrical cycle, solve for the amplitude and phase of the harmonic current components to generate harmonic current commands.

[0062] For example, firstly, an accurate electromagnetic torque model considering temperature changes is established, and its equation is: , where: T e，T The electromagnetic torque at magnet temperature T (unit: Nm); P is the number of pole pairs of the motor; L dq The dq-axis inductance matrix is ​​in the form of L d For the d-axis inductance, L q For q-axis inductance; i dq The dq-axis current vector is in the form of i d Let i be the d-axis current. q λ is the q-axis current; dq，T The target flux linkages along the d-axis and q-axis are in the form of: θ is the rotor electrical angle; T is the rate of change of the target magnetic flux with respect to the electric angle. cog This represents the cogging torque (unit: Newton-meter). This model fully describes the following torque components: Reluctance torque: caused by the difference in inductance between the d and q axes; Permanent magnet torque (current-magnetic flux coupling term): generated by the interaction between the target magnetic flux and the current; Position-magnetic flux-current coupled torque: generated by the coupling of the magnetic flux with the current as the rotor position changes.

[0063] Methods for obtaining key model parameters include, but are not limited to: L d and L q During the motor design phase, a finite element model is established using electromagnetic simulation software, and the results are obtained through electromagnetic field simulation calculations.

[0064] i d and i q During motor operation, the three-phase stator current is measured by a current sensor and converted into i-axis current in a synchronous rotating coordinate system via Parker transformation. d with i q .

[0065] θ: The rotor mechanical angle θ is measured by a position sensor (such as a rotary transformer). m Then, convert P to electrical angle θ = P × θ m .

[0066] Tcog (θ): During the motor design phase, the cogging torque at different rotor positions is calculated through electromagnetic simulation to obtain its curve as a function of electrical angle, which serves as a known periodic disturbance.

[0067] Then, the dq-axis current is decomposed into a second DC component (used to generate average torque) and a harmonic component (used to cancel out fluctuations): , where i dq0 The second DC component is represented by k, where k is the harmonic order (e.g., 6th, 12th, etc.), and i dqk，T Let be the kth harmonic current used to minimize torque ripple at time T, in the form of: i dk，T and i qk，T The amplitude of the harmonic current. and This represents the phase of the harmonic current. dq0 The methods of obtaining it include, but are not limited to: Calculation based on target average torque: Based on the desired output target average torque T... avg Neglecting torque fluctuations (i.e., considering only the DC component), the electromagnetic torque equation can be simplified and solved inversely to obtain the equation satisfying T. avg i dq0 ; Experimental or simulation calibration: Directly obtain the i that enables the motor to output the desired average torque through experimental or simulation methods. d0 and i q0 Combination. This method is more direct and better suits the actual characteristics of the motor. The specific method of obtaining the information depends on the situation and is not limited here.

[0068] Subsequently, by substituting the above current expression and the target magnetic flux into the preset electromagnetic torque model, the instantaneous torque T within a preset electrical cycle (such as one electrical cycle, the specific cycle depending on the situation, is not limited here) can be calculated. e (θ). And define the torque ripple function as the peak-to-peak or root-mean-square value of the torque within this period.

[0069] Finally, the objective is to minimize the value of the torque ripple function, and with i dk，T i qk，T , and To optimize the variables, a solution is found within one electrical cycle. Optimization algorithms (such as sequential quadratic programming or genetic algorithms) can be used to search for the solution under set constraints (such as the harmonic current amplitude not exceeding a specific proportion of the rated current). The obtained harmonic current command is then superimposed with the second DC component to form a complete current command, which is injected into the current control loop to achieve precise compensation for torque fluctuations.

[0070] Using the above method, an accurate electromagnetic torque model incorporating temperature influence is established. The dq-axis current is decomposed into DC and harmonic components. An optimization problem is constructed with a specific harmonic current as the variable and the goal of minimizing the torque fluctuation function value within one electrical cycle. Finally, the optimal harmonic current amplitude and phase command are obtained by solving the problem. This achieves high-precision active suppression of torque fluctuations caused by multiple factors such as temperature changes, magnetic circuit nonlinearity, and cogging effect, significantly improving the smooth operation performance of the motor.

[0071] In one embodiment, it is exemplarily illustrated that the amplitude and phase of the harmonic current components are solved with the objective of minimizing the value of the torque ripple function within a preset electrical cycle, including but not limited to: Within a preset range of amplitude and phase values, multiple initial solutions for harmonic current components of preset orders are generated. The range of harmonic current amplitude values ​​must be considered in conjunction with the motor's rated current I. rated The harmonic current amplitude is determined by factors such as heat dissipation limitations and the actual need to suppress torque fluctuations. From the perspective of safe motor operation, the harmonic current amplitude cannot be too large, otherwise it will lead to excessive current in the motor windings, generating too much heat, affecting the motor's lifespan, or even damaging the motor. Generally, the harmonic current amplitude should be less than or equal to I. rated A specific proportion, such as an upper limit of amplitude of 0.2I. rated -0.3I rated The amplitude is non-negative, meaning the lower limit of the amplitude is 0. The phase is a periodic variable, and its range is usually set to [0, 2π) radians.

[0072] The harmonic current corresponding to each initial solution is superimposed with the second DC component to calculate the torque fluctuation value within one electrical cycle. The goal is to minimize this torque fluctuation value. The initial solutions are optimized using a preset optimization algorithm until the torque fluctuation value meets a preset convergence condition. The final solution is then used as the amplitude and phase of the harmonic current component. The preset convergence condition can be that the torque fluctuation value is less than a preset threshold, or that the maximum number of iterations has been reached. Considering the limitations of computer resources such as computing power and memory, too many iterations will lead to excessively long computation times, which is detrimental to engineering applications. Generally, a large initial number of iterations (e.g., 200-500) can be set first, and then adjusted according to the actual convergence results.

[0073] Taking the genetic algorithm as an example, within the preset range of amplitude and phase values, N sets of initial solutions (i.e. chromosomes) are randomly generated. Each set of solutions contains the amplitude and phase corresponding to all harmonic orders (k=1 to n).

[0074] For each initial solution, its corresponding harmonic currents are compared with i. dq0 Superimpose to obtain the complete i dq Combined with the target magnetic flux λ at time T dq，TSubstituting the values ​​into the preset electromagnetic torque model, the maximum value of the electromagnetic torque (max(T)) within one electrical cycle is calculated. e，T ) and minimum value min(T) e，T This allows us to obtain the peak-to-peak torque ΔT. e，T =max(T e，T )-min(T e，T ).

[0075] With ΔT e，T The reciprocal (or negative) of the value is used as the fitness value; the smaller the value, the greater the fluctuation and the worse the fitness. Selection, crossover, and mutation operations are performed based on the fitness to generate a new generation of solutions. Fitness evaluation and population updates are repeated until the maximum number of iterations is reached, or the fitness value is less than a first preset threshold, or the fitness change value is less than a second preset threshold (the specific threshold depends on the situation and is not limited here). The solution with the largest final fitness value is used as the amplitude and phase of the harmonic current command.

[0076] Using the above method, the range of harmonic current amplitude and phase values ​​is set based on the motor's safety and performance requirements. Then, using an optimization algorithm, multiple initial solutions of harmonic current are iteratively searched and evaluated within one electrical cycle with the goal of minimizing torque fluctuation. Finally, the optimal combination of harmonic current amplitude and phase is solved, thereby effectively suppressing torque fluctuation while ensuring the safe operation of the motor.

[0077] In one embodiment, S101 to S104 can be executed periodically in an event-triggered manner, thereby balancing the computational load while ensuring real-time performance. The triggering and execution mechanism includes, but is not limited to: The parameter optimization process is triggered periodically by an enable signal. The sending period and validity determination mechanism of this signal are as follows: Transmission Cycle: The enable signal is transmitted according to the target cycle. The determination of this target cycle needs to comprehensively consider the dynamic characteristics of the system: if the motor operating conditions or magnet temperature change rapidly, the target cycle should be set shorter (e.g., synchronized with the control cycle or an integer multiple thereof) to achieve rapid tracking and optimization. Computational Resource Constraints: An excessively short target cycle will lead to excessively high optimization calculation frequency, potentially consuming too many processor resources and affecting the execution of critical real-time control tasks such as the current loop. Therefore, the target cycle needs to strike a balance between dynamic response requirements and available computing power.

[0078] For example, for a PMSM with a control period of 50μs and a modulation frequency of 20kHz, the transmission period can be set to the order of several milliseconds to tens of milliseconds.

[0079] Sender and Receiver: The transmission path of the enable signal depends on the system architecture. For example, in centralized control, the main control unit (such as the motor controller) can generate and send the enable signal to the signal processing module at regular intervals. In a hierarchical system, the upper-level management module (such as the vehicle controller) can send optimization instructions to the lower-level motor control module when specific conditions are met.

[0080] Furthermore, the validity of the enable signal is determined by the system state and is only valid when specific conditions are met. For example, the enable signal is valid when the system detects torque fluctuations or current harmonic content exceeding a set threshold, significant changes occur in motor load, speed, or magnet temperature (the change exceeds a threshold), a preset timing optimization point is reached, or an external forced optimization command is received. Conversely, the enable signal is invalid when the system is running smoothly, torque fluctuations are within allowable limits, motor operating conditions and flux linkage parameters do not change significantly, the preset transmission cycle has not been reached, or the system is in a fault or abnormal operating state.

[0081] When the enable signal is valid, the system executes the complete S101-S104 process and updates the harmonic current amplitude and phase obtained from this solution to the system parameter memory. When the enable signal is invalid, the complete S101-S104 process is not executed. Instead, the previously stored harmonic current amplitude and phase are directly called, and the current fundamental current command is combined with the current command to calculate and output the dq axis current command. This significantly saves computational resources while maintaining system stability, and is especially suitable for operation phases with stable operating conditions and slow parameter changes.

[0082] The above mechanism ensures the adaptability and real-time performance of harmonic compensation, while avoiding unnecessary online optimization calculations, thus guaranteeing the overall efficiency and reliability of the control system.

[0083] In one embodiment, it is exemplarily illustrated that this method can be used to perform complete optimization calculations at different typical magnet temperatures during the motor manufacturing or controller matching stage, constructing a mapping table between magnet temperature, harmonic current amplitude, and phase. In actual operation, only the magnet temperature needs to be acquired or estimated in real time, and the corresponding harmonic current command can be quickly obtained and injected by looking up the table, greatly reducing the online calculation burden and improving response speed.

[0084] In one embodiment, it is exemplarily illustrated that before applying the aforementioned method for suppressing torque fluctuations in a permanent magnet synchronous motor, the motor control system needs to be calibrated to ensure the accuracy of the basic sensor data and motor model parameters. Calibration includes, but is not limited to, current sensor calibration and position sensor zero-bias calibration.

[0085] In current sensor calibration, current measurement deviations mainly originate from sensor zero drift, gain error, nonlinearity, and system electromagnetic interference. Model-based or adaptive methods are typically used to correct these deviations.

[0086] Model-based current measurement deviation correction: Based on the measured three-phase current and the theoretical three-phase current, a three-phase current deviation is constructed, and the sum of the three-phase current deviations is equal to 0.

[0087] Based on this, using the motor voltage equation, and based on the actual applied voltage v along the dq axis... d v q The theoretical value of the current i is calculated. d，cal and i q，cal The motor voltage equation is as follows: Among them, R s For stator resistance; L d L q For dq axis inductance; Electric angular velocity; This is a constant flux linkage generated solely by the rotor permanent magnet. Then, a Parker transformation is performed on the measured three-phase current to obtain the measured current i along the dq axis. d_mea with i q_mea , change i d_mea with i d_cal i q_mea with i q_cal The difference between the two values ​​is used to obtain the current deviation Δi. d With Δi q And based on Δi d With Δi q For i respectively d_mea with i q_mea The correction is performed to obtain the corrected dq-axis current, and then the corrected dq-axis current is converted into the corrected three-phase current through the Parker inverse transformation.

[0088] Current measurement deviation correction based on adaptive correction law: Assuming the estimated value of the current deviation is... and Then the adaptive correction law can be designed as follows: ; where k p k i These are adaptive gains, used to eliminate the instantaneous and steady-state errors of the estimation, respectively. Based on the estimated... and For i respectively d_mea with i q_mea The corrected dq-axis current is obtained by performing a correction, and then the corrected dq-axis current is converted into a corrected three-phase current through the Parker inverse transform. The specific method for correcting the current measurement deviation depends on the situation and is not limited here.

[0089] In position sensor zero-offset calibration, to eliminate mechanical zero-position deviations in the installation of position sensors such as rotary transformers or encoders, an automatic calibration method combining i / f open-loop control and a sliding mode observer can be used. To operate the PMSM in open-loop i / f mode: Given the d-axis current i d_ref (Generally a constant, used to produce a certain excitation or demagnetization effect), the q-axis current follows a preset law with respect to the electric angular velocity ω. e Increase, i q_ref =f(ω) e ), where ω e The slope gradually increases from zero with a fixed slope, i.e., ω e (t)=ω0+kt, where ω0 is the initial electric angular velocity, k is the slope of the angular velocity increase, and t is the time constant, thus ensuring that the motor starts smoothly and enters a steady state.

[0090] Simultaneously, a sliding mode observer is designed using the dq-axis current as the state variable: ;in, and The observed dq-axis current; denoted as ω0, where ω0 is the observed electric angular velocity; k1 and k2 are the sliding mode gains; and sgn(·) is the sign function.

[0091] The mechanical rotation speed can then be calculated from the output of the sliding mode observer. and rotor position : , , where P is the number of pole pairs of the motor.

[0092] Based on this, the calibration process is as follows: Initialize the i / f control parameters and sliding mode observer; start i / f control to make the PMSM accelerate uniformly to the target speed range (usually 10%-30% of the rated speed) and maintain stable operation. Within the steady-state operating range, synchronously record the actual rotor position θ read by the position sensor. sen The observed rotor position output by the sliding mode observer .

[0093] Calculate the average position deviation over m electrical cycles, where m is an integer greater than 1. Use this average position deviation as the zero-position offset calibration value for the position sensor. Change the operating speed (e.g., 15% of rated speed, 20% of rated speed, 25% of rated speed, etc.) and repeat the above process to verify the consistency of the average position deviation. If the average position deviation is stable, the calibration is valid; otherwise, the convergence of the diaphragm observer or the control parameters need to be checked.

[0094] This calibration process is usually performed automatically before leaving the factory or during the system power-on initialization phase. It is an important prerequisite for achieving high-precision torque fluctuation suppression and lays a solid foundation for the effectiveness and robustness of the control algorithm in real systems.

[0095] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order in which these steps are executed, and they can be performed in other orders. Furthermore, Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0096] In one embodiment, such as Figure 2 As shown, a torque fluctuation suppression device for a permanent magnet synchronous motor is provided, comprising: an acquisition module 201, a determination module 202, a compensation module 203, and a fluctuation suppression module 204, wherein: The acquisition module 201 is used to acquire the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; The determination module 202 is used to determine the d-axis flux compensation amount and the q-axis flux compensation amount in the rotating coordinate system based on the difference between the actual value of the permanent magnet flux and the pre-stored reference value of the permanent magnet flux. The compensation module 203 is used to compensate the pre-stored d-axis reference flux and q-axis reference flux according to the d-axis flux compensation amount and the q-axis flux compensation amount, respectively, to obtain the d-axis target flux and the q-axis target flux. The fluctuation suppression module 204 is used to generate a harmonic current command to offset torque fluctuations based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, and inject the harmonic current command into the current control loop of the permanent magnet synchronous motor.

[0097] Specific limitations regarding the torque fluctuation suppression device for permanent magnet synchronous motors can be found in the limitations of the torque fluctuation suppression method for permanent magnet synchronous motors mentioned above, and will not be repeated here. Each module in the aforementioned torque fluctuation suppression device for permanent magnet synchronous motors can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the corresponding operations of each module.

[0098] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as shown below. Figure 3 As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores torque ripple suppression data for permanent magnet synchronous motors. The network interface communicates with external terminals via a network connection. When the processor executes the computer program, it implements a method for suppressing torque ripple in permanent magnet synchronous motors. The display screen can be an LCD screen or an e-ink display screen. The input device can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device casing, or an external keyboard, touchpad, or mouse.

[0099] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0100] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to perform the following steps: Obtain the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; Based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage, the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system are determined. Based on the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, the pre-stored d-axis reference flux linkage and q-axis reference flux linkage are compensated respectively to obtain the d-axis target flux linkage and the q-axis target flux linkage. Based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, a harmonic current command is generated to counteract torque fluctuations, and the harmonic current command is injected into the current control loop of the permanent magnet synchronous motor.

[0101] In one embodiment, the processor, when executing a computer program, also performs the following steps: Based on the difference, the d-axis flux compensation amount and the q-axis flux compensation amount are determined by using a preset flux temperature coupling model. The flux linkage temperature coupling model includes the mapping relationship between the change of the first DC component and the d-axis flux linkage compensation and the q-axis flux linkage compensation.

[0102] In one embodiment, the processor, when executing a computer program, also performs the following steps: Input the difference into the magnetic flux temperature coupling model; In the flux linkage temperature coupling model, the difference is multiplied by the preset d-axis gain coefficient and q-axis gain coefficient respectively to obtain the d-axis flux linkage compensation amount and q-axis flux linkage compensation amount. The d-axis gain coefficient and q-axis gain coefficient are obtained by fitting the motor flux linkage data.

[0103] In one embodiment, the processor, when executing a computer program, also performs the following steps: Obtain the second DC components of the d-axis and q-axis currents; Based on the d-axis target flux linkage, the q-axis target flux linkage, the second DC component, and the preset electromagnetic torque model, a torque fluctuation function is constructed with harmonic current components of a preset order as variables; wherein, the electromagnetic torque model includes a temperature effect term, and the flux linkage parameters in the temperature effect term are the d-axis target flux linkage and the q-axis target flux linkage; With the goal of minimizing the value of the torque ripple function within a preset electrical cycle, the amplitude and phase of the harmonic current components are solved to generate harmonic current commands.

[0104] In one embodiment, the processor, when executing a computer program, also performs the following steps: Within the preset amplitude and phase range, generate initial solutions for multiple sets of preset harmonic current components; The harmonic current corresponding to each initial solution is superimposed with the second DC component to calculate the torque fluctuation value within the preset electrical cycle. With the goal of minimizing torque fluctuation, the initial solution is optimized based on a preset optimization algorithm until the torque fluctuation meets the preset convergence condition, and the final solution is used as the amplitude and phase of the harmonic current component.

[0105] In one embodiment, the processor, when executing a computer program, also performs the following steps: A method for suppressing torque fluctuations in permanent magnet synchronous motors is executed periodically in a way that is triggered by events.

[0106] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor: Obtain the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; Based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage, the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system are determined. Based on the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, the pre-stored d-axis reference flux linkage and q-axis reference flux linkage are compensated respectively to obtain the d-axis target flux linkage and the q-axis target flux linkage. Based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, a harmonic current command is generated to counteract torque fluctuations, and the harmonic current command is injected into the current control loop of the permanent magnet synchronous motor.

[0107] In one embodiment, when the computer program is executed by a processor, it also performs the following steps: Based on the difference, the d-axis flux compensation amount and the q-axis flux compensation amount are determined by using a preset flux temperature coupling model. The flux linkage temperature coupling model includes the mapping relationship between the change of the first DC component and the d-axis flux linkage compensation and the q-axis flux linkage compensation.

[0108] In one embodiment, when the computer program is executed by a processor, it also performs the following steps: Input the difference into the magnetic flux temperature coupling model; In the flux linkage temperature coupling model, the difference is multiplied by the preset d-axis gain coefficient and q-axis gain coefficient respectively to obtain the d-axis flux linkage compensation amount and q-axis flux linkage compensation amount. The d-axis gain coefficient and q-axis gain coefficient are obtained by fitting the motor flux linkage data.

[0109] In one embodiment, when the computer program is executed by a processor, it also performs the following steps: Obtain the second DC components of the d-axis and q-axis currents; Based on the d-axis target flux linkage, the q-axis target flux linkage, the second DC component, and the preset electromagnetic torque model, a torque fluctuation function is constructed with harmonic current components of a preset order as variables; wherein, the electromagnetic torque model includes a temperature effect term, and the flux linkage parameters in the temperature effect term are the d-axis target flux linkage and the q-axis target flux linkage; With the goal of minimizing the value of the torque ripple function within a preset electrical cycle, the amplitude and phase of the harmonic current components are solved to generate harmonic current commands.

[0110] In one embodiment, when the computer program is executed by a processor, it also performs the following steps: Within the preset amplitude and phase range, generate initial solutions for multiple sets of preset harmonic current components; The harmonic current corresponding to each initial solution is superimposed with the second DC component to calculate the torque fluctuation value within the preset electrical cycle. With the goal of minimizing torque fluctuation, the initial solution is optimized based on a preset optimization algorithm until the torque fluctuation meets the preset convergence condition, and the final solution is used as the amplitude and phase of the harmonic current component.

[0111] In one embodiment, when the computer program is executed by a processor, it also performs the following steps: A method for suppressing torque fluctuations in permanent magnet synchronous motors is executed periodically in a way that is triggered by events.

[0112] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0113] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for suppressing torque ripple in a permanent magnet synchronous motor, characterized in that, The method includes: Obtain the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; Based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage, the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system are determined. Based on the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, the pre-stored d-axis reference flux linkage and q-axis reference flux linkage are compensated respectively to obtain the d-axis target flux linkage and the q-axis target flux linkage. Based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, a harmonic current command is generated to counteract torque fluctuations, and the harmonic current command is injected into the current control circuit of the permanent magnet synchronous motor.

2. The method according to claim 1, characterized in that, The actual value of the permanent magnet flux linkage is the first DC component of the permanent magnet flux linkage along the d-axis, and the reference values ​​of the permanent magnet flux linkage are the reference flux linkage along the d-axis and the reference flux linkage along the q-axis at the reference flux linkage temperature.

3. The method according to claim 2, characterized in that, The determination of the d-axis flux linkage compensation and q-axis flux linkage compensation in the rotating coordinate system based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage includes: The d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount are determined based on the difference using a preset flux linkage temperature coupling model. The magnetic flux temperature coupling model includes the mapping relationship between the change of the first DC component and the d-axis magnetic flux compensation and the q-axis magnetic flux compensation.

4. The method according to claim 3, characterized in that, The step of determining the d-axis flux linkage compensation and the q-axis flux linkage compensation based on the difference using a preset flux linkage temperature coupling model includes: The difference is input into the magnetic flux temperature coupling model; In the flux linkage temperature coupling model, the difference is multiplied by the preset d-axis gain coefficient and q-axis gain coefficient respectively to obtain the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount, wherein the d-axis gain coefficient and q-axis gain coefficient are obtained by fitting motor flux linkage data.

5. The method according to claim 1, characterized in that, The step of generating a harmonic current command to counteract torque fluctuations based on the d-axis target flux linkage and the q-axis target flux linkage includes: Obtain the second DC components of the d-axis and q-axis currents; Based on the d-axis target flux linkage, the q-axis target flux linkage, the second DC component, and the preset electromagnetic torque model, a torque fluctuation function is constructed with harmonic current components of a preset order as variables; wherein, the electromagnetic torque model includes a temperature effect term, and the flux linkage parameters in the temperature effect term are the d-axis target flux linkage and the q-axis target flux linkage; With the goal of minimizing the value of the torque fluctuation function within a preset electrical cycle, the amplitude and phase of the harmonic current component are solved to generate the harmonic current command.

6. The method according to claim 5, characterized in that, The step of minimizing the value of the torque fluctuation function within a preset electrical cycle and solving for the amplitude and phase of the harmonic current component includes: Within a preset range of amplitude and phase values, multiple initial solutions for harmonic current components of the preset order are generated. The harmonic current corresponding to each initial solution is superimposed with the second DC component to calculate the torque fluctuation value within the preset electrical cycle; With the goal of minimizing the torque fluctuation value, the initial solution is optimized based on a preset optimization algorithm until the torque fluctuation value meets the preset convergence condition, and the final solution is used as the amplitude and phase of the harmonic current component.

7. The method according to claim 1, characterized in that, The method is executed periodically in an event-triggered manner.

8. A torque ripple suppression device for a permanent magnet synchronous motor, characterized in that, The device includes: The acquisition module is used to acquire the actual value of the permanent magnet flux linkage of the permanent magnet synchronous motor at the current magnet temperature; The determination module is used to determine the d-axis flux linkage compensation amount and the q-axis flux linkage compensation amount in the rotating coordinate system based on the difference between the actual value of the permanent magnet flux linkage and the pre-stored reference value of the permanent magnet flux linkage. The compensation module is used to compensate the pre-stored d-axis reference flux and q-axis reference flux according to the d-axis flux compensation amount and q-axis flux compensation amount, respectively, to obtain the d-axis target flux and q-axis target flux. The fluctuation suppression module is used to generate a harmonic current command to offset torque fluctuations based on the target flux linkage on the d-axis and the target flux linkage on the q-axis, and to inject the harmonic current command into the current control loop of the permanent magnet synchronous motor.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1 to 7.

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