Motor control method, motor driver and readable storage medium

Abstract

The invention provides a motor control method, a motor driver and a readable storage medium, and the method comprises the steps: determining the d-axis target current of a motor according to the operation signal and parameters of the motor; determining a current difference value according to the d-axis target current and the characteristic current; determining the maximum output voltage modulation coefficient of the inverter according to the current difference value; and controlling the output voltage of the inverter according to the maximum output voltage modulation coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and more particularly, to a control method for a motor, a motor driver, and a readable storage medium. Background Art

[0002] In the related art, during the operation of a motor, due to the limitation of the control scheme, it is usually impossible to achieve the maximum voltage utilization rate under the condition of the limit speed load. And the overmodulation scheme adopted to achieve the maximum voltage utilization rate sacrifices the stability of the control system, resulting in more unstable harmonics being introduced in the control in the overmodulation region, thereby reducing the stability and reliability during the operation of the motor. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0004] To this end, the first aspect of the present invention provides a control method for a motor.

[0005] The second aspect of the present invention provides a motor driver.

[0006] The third aspect of the present invention provides a motor driver.

[0007] The fourth aspect of the present invention provides a readable storage medium.

[0008] The first aspect of the present invention provides a control method for a motor, including: determining the d-axis target current according to the operation signal and parameters of the motor; determining the current difference according to the d-axis target current and the characteristic current; determining the maximum output voltage modulation coefficient of the inverter according to the current difference; and controlling the output voltage of the inverter according to the maximum output voltage modulation coefficient.

[0009] The control method for a motor provided by the present invention can be used to control the operation of the motor. Among them, the motor is connected to an inverter, and the inverter is used to provide an output voltage. That is, the motor can operate according to the output voltage provided by the inverter. Specifically, the motor may include a permanent magnet synchronous motor, and the permanent magnet synchronous motor has the advantages of high efficiency, high power density, high precision, etc.

[0010] Furthermore, during the control process of the motor, first, the characteristic current of the motor is determined according to the hardware parameters of the motor. Specifically, the characteristic current of the motor can be determined according to the permanent magnet flux linkage and the d-axis inductance of the motor. The characteristic current I is equal to the permanent magnet flux linkage Ψf of the motor divided by the d-axis inductance Ld of the motor, that is, I = Ψf ÷ Ld.

[0011] Further, during the operation of the motor, the d-axis target current of the motor can be determined according to the operation signals and parameters of the motor. The target current of the d-axis is the current required by the d-axis determined according to the required operation state of the motor during the operation of the motor.

[0012] Further, according to the d-axis target current and the characteristic current, the current difference is determined, and then according to the current difference, the maximum output voltage modulation coefficient of the inverter is determined. It can be understood that the maximum output voltage modulation coefficient of the inverter is used to indicate the maximum value of the voltage vector amplitude output by the inverter, and specifically represents the ratio of the maximum value of the output voltage vector amplitude that the output voltage of the inverter can output to the voltage value of the bus voltage connected to the inverter. The maximum output voltage modulation coefficient of the inverter is less than or equal to 1, that is, the maximum value of the output voltage vector amplitude output by the inverter is less than or equal to 2 / π times the bus voltage. The closer the maximum output voltage modulation coefficient of the inverter is to 1, the higher the voltage utilization rate of the bus voltage.

[0013] According to the current difference, the maximum output voltage modulation coefficient of the inverter is determined, so that the maximum output voltage modulation coefficient suitable for the current operation state of the motor can be determined according to the d-axis target current of the motor in actual operation and the characteristic current of the motor itself. On the one hand, it is ensured that the output voltage of the inverter will not be too large, resulting in unstable harmonics during the operation of the motor and a decrease in the operation stability of the motor. On the other hand, the voltage utilization rate can be improved under the current limit load condition, and the operation efficiency of the motor can be improved.

[0014] Further, after the maximum output voltage modulation coefficient of the inverter is determined according to the current difference, the amplitude of the output voltage vector of the inverter can be controlled according to the maximum output voltage modulation coefficient of the inverter, ensuring the stable operation of the motor, while ensuring the voltage utilization rate and improving the operation efficiency of the motor.

[0015] The control method of the motor provided by the present invention determines the d-axis target current of the motor according to the operation signals and parameters of the motor during the operation of the motor. Further, the current difference is determined according to the characteristic current of the motor and the d-axis target current during the operation process, and then the maximum output voltage modulation coefficient of the inverter is determined according to the current difference. Finally, the output voltage of the inverter is controlled according to the maximum output voltage modulation coefficient of the inverter. It realizes the determination of the maximum output voltage modulation coefficient of the inverter according to the hardware parameters of the motor itself and the actual parameters during the operation process. On the one hand, it is ensured that the output voltage of the inverter will not be too large, resulting in unstable harmonics during the operation of the motor and a decrease in the operation stability of the motor. On the other hand, the voltage utilization rate can be improved under the current limit load condition, and the operation efficiency of the motor can be improved.

[0016] According to a second aspect of the present invention, a motor driver is provided, including: a determination unit configured to determine a d-axis target current of the motor according to an operating signal and parameters of the motor; and determine a current difference according to the d-axis target current and a characteristic current of the motor; and determine a maximum output voltage modulation coefficient of an inverter according to the current difference; and a control unit configured to control an output voltage of the inverter according to the maximum output voltage modulation coefficient.

[0017] In the motor driver provided by the present invention, during the operation of the motor, a d-axis target current of the motor is determined according to an operating signal and parameters of the motor. Further, a current difference is determined according to the characteristic current of the motor and the d-axis target current during the operation process, and then a maximum output voltage modulation coefficient of the inverter is determined according to the current difference. Finally, the output voltage of the inverter is controlled according to the maximum output voltage modulation coefficient of the inverter. It is realized to determine the maximum output voltage modulation coefficient of the inverter according to the hardware parameters of the motor itself and the actual parameters during the operation process. On the one hand, it is ensured that the output voltage of the inverter will not be too large, resulting in unstable harmonics during the operation of the motor and reducing the operation stability of the motor. On the other hand, the utilization rate of the voltage can be improved under the current limit load condition, and the operation efficiency of the motor can be improved.

[0018] According to a third aspect of the present invention, a motor driver is provided, including: a processor and a memory, where the memory stores a program or instruction that can run on the processor, and when the program or instruction is executed by the processor, the steps of the control method of the motor provided in the first aspect are implemented.

[0019] The motor driver provided by the present invention includes a memory and a processor, and also includes a program or instruction stored on the memory. When the program or instruction is executed by the processor, the steps of the control method of the motor in the above first aspect can be implemented. Therefore, the motor driver has all the beneficial effects of the above control method of the motor, which will not be elaborated here.

[0020] According to a fourth aspect of the present invention, a readable storage medium is provided, on which a program or instruction is stored, and when the program or instruction is executed by a processor, the control method of the motor in any one of the above technical solutions is implemented.

[0021] The readable storage medium provided by the present invention stores a program or instruction. Since the program or instruction can implement the control method of the motor in any one of the above technical solutions when executed by a processor, the storage medium has all the beneficial effects of the above control method of the motor, which will not be elaborated here.

[0022] The additional aspects and advantages of the present invention will become apparent in the following description section or be learned through the practice of the present invention. Description of the Drawings

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0024] Figure 1 A schematic flowchart of a control method for an electric motor according to an embodiment of the present invention is shown;

[0025] Figure 2 A logic block diagram of a control method for an electric motor according to an embodiment of the present invention is shown;

[0026] Figure 3 A structural block diagram of a motor driver according to an embodiment of the present invention is shown;

[0027] Wherein, Figure 3 The corresponding relationship between the reference numerals and the component names in the

[0028] 300 is a motor driver, 302 is a determination unit, and 304 is a control unit. Detailed implementation manners

[0029] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0031] The following refers to Figures 1 to 3 to describe a control method for an electric motor, a motor driver and a readable storage medium according to some embodiments of the present invention.

[0032] As Figure 1 shown, according to an embodiment of the present invention, a control method for an electric motor is proposed, including:

[0033] S102, determining a d-axis target current of the electric motor according to an operating signal and parameters of the electric motor;

[0034] S104, determining a current difference according to the d-axis target current and a characteristic current of the electric motor;

[0035] S106, determining a maximum output voltage modulation coefficient of an inverter according to the current difference;

[0036] S108, controlling an output voltage of the inverter according to the maximum output voltage modulation coefficient.

[0037] The control method of the motor provided by the present invention can be used to control the operation of the motor. Among them, the motor is connected to an inverter, and the inverter is used to provide an output voltage. That is, the motor can operate according to the output voltage provided by the inverter. Specifically, the motor can include a permanent magnet synchronous motor, which has the advantages of high efficiency, high power density, high precision, etc.

[0038] Further, in the control process of the motor, first, according to the hardware parameters of the motor, the characteristic current of the motor is determined. Specifically, the characteristic current of the motor can be determined according to the permanent magnet flux linkage and the d-axis inductance of the motor. The characteristic current I is equal to the permanent magnet flux linkage Ψf of the motor divided by the d-axis inductance Ld of the motor, that is, I = Ψf ÷ Ld.

[0039] Further, during the operation of the motor, the d-axis target current of the motor can be determined according to the operation signal and parameters of the motor. Among them, the target current of the d-axis is the current required by the d-axis determined according to the required operation state of the motor during the operation of the motor.

[0040] Further, according to the d-axis target current and the characteristic current, the current difference is determined, and then according to the current difference, the maximum output voltage modulation coefficient of the inverter is determined. It can be understood that the maximum output voltage modulation coefficient of the inverter is used to indicate the maximum value of the output voltage vector amplitude output by the inverter, specifically representing the ratio of the maximum value of the output voltage vector amplitude that the output voltage of the inverter can output to the voltage value of the bus voltage connected to the inverter. The maximum output voltage modulation coefficient of the inverter is less than or equal to 1. That is, the maximum value of the output voltage vector amplitude output by the inverter is less than or equal to 2 / π times the bus voltage. The closer the maximum output voltage modulation coefficient of the inverter is to 1, the higher the voltage utilization rate of the bus voltage.

[0041] According to the current difference, the maximum output voltage modulation coefficient of the inverter is determined, so that the maximum output voltage modulation coefficient suitable for the current operating state of the motor can be determined according to the d-axis target current of the motor in actual operation and the characteristic current of the motor itself. On the one hand, it is ensured that the output voltage of the inverter will not be too large, resulting in unstable harmonics during the operation of the motor and reducing the operating stability of the motor. On the other hand, the voltage utilization rate can be improved under the current limit load conditions, and the operating efficiency of the motor can be improved.

[0042] Further, after determining the maximum output voltage modulation coefficient of the inverter according to the current difference, the output voltage vector amplitude of the inverter can be controlled according to the maximum output voltage modulation coefficient of the inverter to ensure the stable operation of the motor, while ensuring the voltage utilization rate and improving the operating efficiency of the motor.

[0043] The control method of the motor provided by the present invention determines the d-axis target current of the motor according to the operation signal and parameters of the motor during the operation of the motor. Further, the current difference is determined according to the characteristic current of the motor and the d-axis target current during the operation, and then the maximum output voltage modulation coefficient of the inverter is determined according to the current difference. Finally, the output voltage of the inverter is controlled according to the maximum output voltage modulation coefficient of the inverter. It realizes the determination of the maximum output voltage modulation coefficient of the inverter according to the hardware parameters of the motor itself and the actual parameters during the operation. On the one hand, it ensures that the output voltage of the inverter will not be too large, resulting in unstable harmonics during the operation of the motor and reducing the operation stability of the motor. On the other hand, it can improve the utilization rate of the voltage under the current limit load condition and improve the operation efficiency of the motor.

[0044] In some embodiments, optionally, determining the maximum output voltage modulation coefficient of the inverter according to the current difference includes: when the current difference is greater than the preset current value, controlling the maximum output voltage modulation coefficient of the inverter to be the coefficient threshold; when the current difference is less than or equal to the preset current value, determining the target value of the maximum output voltage modulation coefficient according to the current difference, the preset current value and the coefficient threshold.

[0045] In this embodiment, the maximum output voltage modulation coefficient of the inverter can be determined by the specific value of the current difference. Specifically, when the current difference is greater than the preset current value, the maximum output voltage modulation coefficient of the inverter can be controlled to be the coefficient threshold. That is, when the current difference is greater than the preset current value, the maximum output voltage modulation coefficient of the inverter is set to the coefficient threshold to ensure that there is a certain difference between the output voltage of the inverter and the bus voltage, and further, the output voltage of the inverter is too large, resulting in a decrease in the operation stability of the motor.

[0046] Specifically, the coefficient threshold can be set to 0.9068 to 0.9523. That is, when the current difference is greater than the preset current value, the maximum output voltage modulation coefficient of the inverter can take a value between 0.9068 and 0.9523, and the specific value can be determined according to the actual operation situation of the motor and the actual situation such as the operation environment. In addition, the preset current value can also be determined according to the actual operation situation or the operation environment situation of the motor.

[0047] Further, when the current difference is less than or equal to the preset current value, the target value of the maximum output voltage modulation coefficient can be determined according to the current difference, the preset current value, and the coefficient threshold. That is, when the current difference is less than or equal to the preset current value, the maximum output voltage modulation coefficient of the inverter can be dynamically adjusted according to the change process of the current difference, so as to ensure that the output voltage of the inverter can change according to the actual parameter changes during the operation of the motor. On the basis of ensuring the stable operation of the motor, the utilization rate of the voltage is improved, and thus the operation efficiency of the motor is improved.

[0048] Further, determining the target value of the maximum output voltage modulation coefficient according to the current difference, the preset current value, and the coefficient threshold includes: according to the preset formula: The target value of the maximum output voltage modulation coefficient;

[0049] where M1 is the target value, M2 is the coefficient threshold, I1 is the preset current value, and △I is the current difference.

[0050] Specifically, when the current difference is less than or equal to the preset current value, the target value of the maximum output voltage modulation coefficient can be determined according to the current difference, the preset current value, and the coefficient threshold.

[0051] Specifically, the target value of the maximum output voltage modulation coefficient can be determined according to the preset formula:

[0052]

[0053] where M1 is the target value, M2 is the coefficient threshold, I1 is the preset current value, and △I is the current difference.

[0054] In some embodiments, optionally, controlling the output voltage of the inverter according to the maximum output voltage modulation coefficient includes: when the motor is running, obtaining the actual voltage modulation coefficient of the inverter; when the actual voltage modulation coefficient is less than the coefficient threshold, controlling the inverter to output voltage according to the actual voltage modulation coefficient; when the actual voltage modulation coefficient reaches the coefficient threshold, obtaining the current difference; when the current difference is greater than the preset current value, controlling the inverter to output voltage according to the actual voltage modulation coefficient or according to the coefficient threshold; when the current difference is less than or equal to the preset current value, controlling the inverter to output voltage according to the target value of the maximum output voltage modulation coefficient.

[0055] In this embodiment, when the motor is running, the output voltage of the inverter is determined according to the determined maximum output voltage modulation coefficient of the inverter. Specifically, during the operation of the motor, first, the actual voltage modulation coefficient of the inverter is obtained, and then the actual voltage modulation coefficient of the motor is compared with the coefficient threshold. If the actual voltage modulation coefficient of the motor is less than the coefficient threshold, the inverter is controlled to output voltage with the current actual voltage modulation coefficient, so as to ensure that the output voltage will not be too high and cause the reduction of the motor operation stability.

[0056] If the actual voltage modulation coefficient of the motor reaches the coefficient threshold, the current difference in the actual operation of the motor is obtained according to the d-axis target current and the characteristic current during the current motor operation. If the current difference in the current operation of the motor is greater than the preset current value, it means that the current difference between the current d-axis current value and the characteristic current is large. At this time, if the maximum output voltage modulation coefficient of the inverter is increased, it may cause the motor operation to be unstable. Therefore, at this time, the maximum output voltage modulation coefficient of the inverter can be set to the coefficient threshold, that is, the maximum output voltage modulation coefficient of the inverter is maintained at the coefficient threshold to ensure the motor operation stability. At this time, the output voltage of the inverter can be output according to the actual voltage modulation coefficient of the inverter, that is, the current output voltage modulation coefficient of the inverter is maintained, or the actual voltage modulation coefficient of the inverter is adjusted to the coefficient threshold, and the voltage is output according to the coefficient threshold.

[0057] If the current difference in the current operation of the motor is less than or equal to the preset current value, it means that the current difference between the current d-axis current value and the characteristic current will not cause the motor operation state to be unstable. At this time, the output voltage of the inverter can be controlled according to the determined maximum output voltage modulation coefficient of the inverter, that is, the maximum output voltage modulation coefficient is determined according to the current difference, the preset current value and the coefficient threshold. To improve the voltage utilization rate of the motor and improve the motor efficiency.

[0058] That is, according to the preset formula: The maximum output voltage modulation coefficient is determined.

[0059] In the specific implementation process, such as Figure 2As shown, the actual voltage modulation coefficient of the motor can be combined with the vector angle of the voltage. The vector angle of the voltage θ1 can be obtained through Park transformation from the actual vector angle θ acquired during the operation of the motor. Through space vector pulse width modulation (SVPWM) combined with a dual-mode overmodulation method, the maximum output voltage modulation coefficient of the inverter is modulated. The vector angle of the voltage can be determined through Park transformation during the actual operation of the motor. Specifically, if the actual voltage modulation coefficient of the motor is less than the coefficient threshold, the inverter is controlled to output voltage with the current actual voltage modulation coefficient, so as to ensure that the output voltage will not be too high and cause a reduction in the stability of the motor operation. The current actual voltage modulation coefficient of the inverter can be between 0.9068 and 0.9523. If the actual voltage modulation coefficient of the motor is less than the coefficient threshold and the current difference in the current during the current operation of the motor is less than or equal to the preset current value, the maximum output voltage modulation coefficient of the inverter is calculated according to the above formula, and the maximum output voltage of the inverter is controlled. At this time, the maximum output voltage modulation coefficient of the inverter is between 0.9523 and 1.

[0060] In some embodiments, optionally, obtaining the actual voltage modulation coefficient of the inverter includes: obtaining the input voltage of the inverter and the electrical angular velocity of the motor; determining the q-axis target current of the motor according to the electrical angular velocity; determining the q-axis target voltage of the motor according to the q-axis target current; determining the d-axis target voltage of the motor according to the d-axis target current; and determining the actual voltage modulation coefficient according to the input voltage, the q-axis target voltage, and the d-axis target voltage.

[0061] In this embodiment, during the operation of the motor, the actual voltage modulation coefficient of the inverter can be determined according to the input voltage of the inverter, that is, the bus voltage, as well as the electrical angular velocity of the motor, the d-axis target voltage of the motor, and the q-axis target voltage of the motor.

[0062] Specifically, as Figure 2 shown, first, during the operation of the motor, the input voltage of the inverter and the electrical angular velocity of the motor are obtained. The electrical angular velocity of the motor can be determined by using a current loop PI controller according to the target electrical angular velocity ω1 indicated by the speed command corresponding to the motor operation and the actual electrical angular velocity ω of the motor. The actual electrical angular velocity ω of the motor can be collected by sensors such as a position sensor or a position observer. Then, the q-axis target current of the motor is determined according to the electrical angular velocity of the motor, and further, the q-axis target voltage of the motor is determined according to the q-axis target current of the motor. Then, the d-axis target voltage of the motor is determined according to the d-axis target current of the motor.

[0063] It should be noted that as Figure 2As shown, the q-axis target voltage V2 of the motor can be determined by using a current-loop PI controller based on the q-axis target current Iq of the motor and the actual q-axis current iq during the operation of the motor. Correspondingly, the d-axis target voltage V1 of the motor can be determined by using a current-loop PI controller based on the d-axis target current Id of the motor and the actual d-axis current id during the operation of the motor. Among them, the actual q-axis current iq and the actual d-axis current id can be determined by Clarke transformation and Park transformation based on the three-phase current Iabc output by the inverter.

[0064] Finally, based on the input voltage of the inverter, the q-axis target voltage and the d-axis target voltage of the motor, the actual output voltage modulation coefficient of the inverter during the operation of the motor can be determined. Furthermore, based on the magnitude relationship between the actual output voltage modulation coefficient of the inverter and the coefficient threshold, the output voltage of the inverter can be controlled according to the maximum output voltage modulation coefficient of the inverter.

[0065] Furthermore, based on the input voltage of the inverter, the q-axis target voltage and the d-axis target voltage of the motor, the actual output voltage modulation coefficient of the inverter during the operation of the motor is determined. Specifically, it can be determined according to the preset formula:

[0066]

[0067] Determine the actual output voltage modulation coefficient, where M3 is the actual voltage modulation coefficient, V1 is the d-axis target voltage, V2 is the q-axis target voltage, and V3 is the input voltage.

[0068] In some embodiments, optionally, based on the operation signal and parameters of the motor, the d-axis target current of the motor is determined, including: obtaining the operation state of the motor; in the case where the motor operates in the constant torque region, calculating the d-axis target current through a first algorithm; in the case where the motor operates in the constant power region, calculating the d-axis target current through a second algorithm.

[0069] In this embodiment, during the operation of the motor, it is also necessary to determine the d-axis target current of the motor according to the actual operation state of the motor. Among them, the operation state of the motor can include operating in the constant torque region or operating in the constant power region.

[0070] Specifically, in the case where the motor operates in the constant torque region, the d-axis target current of the motor can be calculated through a first algorithm. Specifically, the first algorithm can be the maximum torque per ampere algorithm (MTPA).

[0071] In the case where the motor operates in the constant power region, the d-axis target current of the motor can be calculated through a second algorithm. Specifically, the second algorithm can be the field weakening algorithm.

[0072] Furthermore, as Figure 2As shown, according to the d-axis target current and the characteristic current, the current difference is determined. Specifically, it can be determined according to the preset formula: ΔI = K × (I3 - |I4|), where ΔI is the current difference, I3 is the characteristic current, I4 is the d-axis target current, and K is the preset coefficient.

[0073] It should be noted that the characteristic current I3 is equal to the permanent magnet flux linkage Ψf of the motor divided by the d-axis inductance Ld of the motor, that is, I3 = Ψf ÷ Ld. The coefficient K can be set according to the actual operating state or operating environment of the motor.

[0074] According to the second aspect of the present invention, as Figure 3 shown, a motor driver 300 is proposed, including: a determination unit 302, configured to determine the d-axis target current of the motor according to the operating signal and parameters of the motor; and determine the current difference according to the d-axis target current and the characteristic current of the motor; and determine the maximum output voltage modulation coefficient of the inverter according to the current difference; a control unit 304, configured to control the output voltage of the inverter according to the maximum output voltage modulation coefficient.

[0075] The motor driver 300 provided by the present invention determines the d-axis target current of the motor according to the operating signal and parameters of the motor during the operation of the motor. Further, the current difference is determined according to the characteristic current of the motor and the d-axis target current during the operation process, and then the maximum output voltage modulation coefficient of the inverter is determined according to the current difference. Finally, the output voltage of the inverter is controlled according to the maximum output voltage modulation coefficient of the inverter. It realizes determining the maximum output voltage modulation coefficient of the inverter according to the hardware parameters of the motor itself and the actual parameters during the operation process. On the one hand, it ensures that the output voltage of the inverter will not be too large, resulting in unstable harmonics during the operation of the motor and reducing the operation stability of the motor. On the other hand, it can improve the utilization rate of the voltage under the current limit load condition and improve the operation efficiency of the motor.

[0076] Further, the determination unit 302 is specifically configured to: when the current difference is greater than the preset current value, control the maximum output voltage modulation coefficient of the inverter to be the coefficient threshold; when the current difference is less than or equal to the preset current value, determine the target value of the maximum output voltage modulation coefficient according to the current difference, the preset current value, and the coefficient threshold.

[0077] Further, the determination unit 302 is specifically configured to: according to the preset formula: determine the target value of the maximum output voltage modulation coefficient; where M1 is the target value, M2 is the coefficient threshold, I1 is the preset current value, and ΔI is the current difference.

[0078] Further, the control unit 304 is specifically configured to: when the motor is operating, obtain the actual voltage modulation coefficient of the inverter; when the actual voltage modulation coefficient is less than the coefficient threshold, control the inverter to output voltage according to the actual voltage modulation coefficient; when the actual voltage modulation coefficient reaches the coefficient threshold, obtain the current difference; when the current difference is greater than the preset current value, control the inverter to output voltage according to the coefficient threshold; when the current difference is less than or equal to the preset current value, control the inverter to output voltage according to the target value of the maximum output voltage modulation coefficient.

[0079] Further, the control unit 304 is further configured to: obtain the input voltage of the inverter and the electrical angular velocity of the motor; determine the q-axis target current of the motor according to the electrical angular velocity; determine the q-axis target voltage of the motor according to the q-axis target current; determine the d-axis target voltage of the motor according to the d-axis target current; determine the actual voltage modulation coefficient according to the input voltage, the q-axis target voltage, and the d-axis target voltage.

[0080] Further, the control unit 304 is further configured to: according to the preset formula: determine the actual voltage modulation coefficient; where M3 is the actual voltage modulation coefficient, V1 is the d-axis target voltage, V2 is the q-axis target voltage, and V3 is the input voltage.

[0081] Further, the determining unit 302 is specifically further configured to: obtain the operating state of the motor; when the motor is operating in the constant torque region, calculate the d-axis target current through the first algorithm; when the motor is operating in the constant power region, calculate the d-axis target current through the second algorithm.

[0082] Further, the determining unit 302 is further configured to: according to the preset formula: △I = K × (I3 - ∣I4∣), determine the current difference; where △I is the current difference, I3 is the characteristic current, I4 is the d-axis target current, and K is the preset coefficient.

[0083] According to the third aspect of the present invention, a motor driver is provided, including: a processor and a memory, the memory stores a program or instruction that can run on the processor, and when the program or instruction is executed by the processor, the steps of the control method of the motor provided in the first aspect are implemented.

[0084] The motor driver provided by the present invention includes a memory and a processor, and further includes a program or instruction stored on the memory. When the program or instruction is executed by the processor, the steps of the control method of the motor in the above first aspect can be implemented. Therefore, the motor driver has all the beneficial effects of the above control method of the motor, which will not be elaborated here.

[0085] According to a fourth aspect of the present invention, a readable storage medium is provided, on which a program or instructions are stored. When the program or instructions are executed by a processor, the control method of the motor as described in any one of the above technical solutions is implemented.

[0086] The readable storage medium provided by the present invention stores a program or instructions. When the program or instructions are executed by a processor, the control method of the motor as described in any one of the above technical solutions can be implemented. Therefore, this storage medium has all the beneficial effects of the above control method of the motor, which will not be elaborated here.

[0087] Among them, the method can be implemented in various different ways according to specific features and / or example applications. For example, these methods can be implemented by a combination of hardware, firmware, and / or software. For example, in a hardware implementation, the processor can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, electronic devices, other device units for performing the above functions, and / or combinations thereof.

[0088] A computer-readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. A computer-readable storage medium can be an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the above devices, but is not limited thereto. A non-exhaustive list of more specific examples of computer-readable storage media includes: portable computer floppy disks, hard disks, random access memories (RAMs), read-only memories (ROMs), erasable programmable read-only memories (EPROMs or flash memories), static random access memories (SRAMs), portable compact disc read-only memories (CD-ROMs), digital versatile discs (DVDs), memory cards, floppy disks, coding mechanical devices (such as punched cards or grooves with raised structures recording instructions), and any suitable combination of the above devices. The computer-readable storage medium used herein should not be construed as a signal itself, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagated through waveguides or other transmission media, or electrical signals transmitted through wires.

[0089] In the description of the present invention, the term "a plurality of" means two or more, unless otherwise clearly defined. The orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention; terms such as "connection", "installation", "fixation", etc. should all be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0090] In the description of this specification, the description of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0091] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method for an electric motor, characterized in that, comprising: determining a d-axis target current of the electric motor according to an operating signal and parameters of the electric motor; determining a current difference according to the d-axis target current and a characteristic current of the electric motor; determining a maximum output voltage modulation coefficient of an inverter according to the current difference; controlling an output voltage of the inverter according to the maximum output voltage modulation coefficient.

2. The control method according to claim 1, characterized in that, the determining the maximum output voltage modulation coefficient of the inverter according to the current difference comprises: when the current difference is greater than a preset current value, controlling the maximum output voltage modulation coefficient of the inverter to be a coefficient threshold; when the current difference is less than or equal to the preset current value, determining a target value of the maximum output voltage modulation coefficient according to the current difference, the preset current value and the coefficient threshold.

3. The control method according to claim 2, characterized in that, the determining the target value of the maximum output voltage modulation coefficient according to the current difference, the preset current value and the coefficient threshold comprises: According to a preset formula: Determine the target value of the maximum output voltage modulation coefficient; wherein, M1 is the target value, M2 is the coefficient threshold, I1 is the preset current value, and △I is the current difference.

4. The control method according to claim 2, characterized in that, the controlling the output voltage of the inverter according to the maximum output voltage modulation coefficient comprises: when the electric motor is operating, obtaining an actual voltage modulation coefficient of the inverter; when the actual voltage modulation coefficient is less than the coefficient threshold, controlling the inverter to output a voltage according to the actual voltage modulation coefficient; when the actual voltage modulation coefficient reaches the coefficient threshold, obtaining the current difference; when the current difference is greater than the preset current value, controlling the inverter to output a voltage according to the actual voltage modulation coefficient or to output a voltage according to the coefficient threshold; when the current difference is less than or equal to the preset current value, controlling the inverter to output a voltage according to the target value of the maximum output voltage modulation coefficient.

5. The control method according to claim 4, characterized in that, the obtaining the actual voltage modulation coefficient of the inverter comprises: obtaining an input voltage of the inverter and an electrical angular velocity of the electric motor; determining a q-axis target current of the electric motor according to the electrical angular velocity; determining a q-axis target voltage of the electric motor according to the q-axis target current; determining a d-axis target voltage of the electric motor according to the d-axis target current; determining the actual voltage modulation coefficient according to the input voltage, the q-axis target voltage and the d-axis target voltage.

6. The control method according to claim 5, characterized in that, the determining the actual voltage modulation coefficient according to the input voltage, the q-axis target voltage and the d-axis target voltage comprises: According to a preset formula: determine the actual voltage modulation coefficient; wherein, M3 is the actual voltage modulation coefficient, V1 is the d-axis target voltage, V2 is the q-axis target voltage, and V3 is the input voltage.

7. The control method according to any one of claims 1 to 6, wherein, determining the d-axis target current of the motor according to the operating signal and parameters of the motor includes: obtaining the operating state of the motor; when the motor operates in the constant torque region, calculating the d-axis target current through a first algorithm; when the motor operates in the constant power region, calculating the d-axis target current through a second algorithm.

8. The control method according to any one of claims 1 to 6, wherein, determining a current difference according to the d-axis target current and the characteristic current of the motor includes: determining the current difference according to a preset formula: △I = K × (I3 - |I4|); wherein, △I is the current difference, I3 is the characteristic current, I4 is the d-axis target current, and K is a preset coefficient.

9. A motor driver, wherein, comprising: a determining unit configured to determine the d-axis target current of the motor according to the operating signal and parameters of the motor; and determining a current difference according to the d-axis target current and the characteristic current of the motor; and determining a maximum output voltage modulation coefficient of the inverter according to the current difference; a control unit configured to control the output voltage of the inverter according to the maximum output voltage modulation coefficient.

10. A motor driver, wherein, comprising: a processor and a memory, the memory storing a program or instruction executable on the processor, and when the program or instruction is executed by the processor, the steps of the control method of the motor according to any one of claims 1 to 8 are implemented.

11. A readable storage medium, wherein, a program or instruction is stored on the readable storage medium, and when the program or instruction is executed by a processor, the steps of the control method of the motor according to any one of claims 1 to 8 are implemented.

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