阅读说明：本技术 基于反电动势的最大转矩电流比控制方法、装置 (Maximum torque current ratio control method and device based on back electromotive force ) 是由 陈弢文 程俊波 于 2021-08-02 设计创作，主要内容包括：本发明提供了一种基于反电动势的最大转矩电流比控制方法、装置,其中的方法包括：构建目标关系,所述目标关系表征了电机处于最大转矩电流比时,所述电机的ABC三相的反电动势与电流的关系；获取目标电机的反电动势；根据所述目标电机的反电动势以及所述目标关系,确定所述目标电机的电流。本发明通过分析目标电机的反电动势,计算出目标电机的最优电流,优化目标电机的最大输出转矩,以实现对目标电机的最大转矩电流比的控制,控制方法简单,对MCU的性能要求不高,能够使目标电机输出的效率达到最高。(The invention provides a method and a device for controlling a maximum torque current ratio based on back electromotive force, wherein the method comprises the following steps: constructing a target relation, wherein the target relation represents the relation between the back electromotive force and the current of the ABC three phases of the motor when the motor is in the maximum torque current ratio; acquiring the back electromotive force of a target motor; and determining the current of the target motor according to the counter electromotive force of the target motor and the target relation. The invention calculates the optimal current of the target motor and optimizes the maximum output torque of the target motor by analyzing the back electromotive force of the target motor so as to realize the control of the maximum torque current ratio of the target motor, has simple control method and low requirement on the performance of the MCU, and can ensure that the output efficiency of the target motor reaches the highest.)

1. A method for controlling a maximum torque current ratio based on a back electromotive force, comprising:

constructing a target relation, wherein the target relation represents the relation between the back electromotive force and the current of the ABC three phases of the motor when the motor is in the maximum torque current ratio;

acquiring the back electromotive force of a target motor;

and determining the current of the target motor according to the counter electromotive force of the target motor and the target relation.

2. The method of claim 1, wherein constructing a target relationship comprises:

determining a first relation and a second relation, wherein the first relation represents the relation among the amplitude of k-th harmonic of the back electromotive force of the ABC three phases, the electrical angle of a motor rotor and the back electromotive force; the second relation represents the relation among the amplitude of k-th harmonic of the current of the ABC three phases, the electrical angle of a motor rotor and the current;

determining a third relationship between the average output torque of the electric machine and the magnitudes of the k-th harmonic of the current and the magnitudes of the k-th harmonic of the back emf based on the first relationship and the second relationship;

determining a fourth relationship from the second relationship, the fourth relationship characterizing a relationship between the effective value of the current and the magnitude of the k-th harmonic of the current;

and determining the target relation according to the third relation and the fourth relation.

3. A method of back-emf-based maximum torque to current ratio control as set forth in claim 2 wherein said first relationship is characterized by:

the second relationship is characterized by:

wherein the content of the first and second substances,

E_a(θ)、E_b(θ)、E_c(θ) represents the back electromotive force of the ABC three phases;

E_ka magnitude representing a k-th harmonic of the back electromotive force;

I_a(θ)、I_b(θ)、I_c(θ) represents the currents of the ABC three phases;

I_krepresenting the amplitude of the k harmonic of the current;

θ p represents a phase angle of the current and the back electromotive force;

theta represents the electrical angle of the motor rotor.

4. A method of maximum torque to current ratio control based on back emf as claimed in claim 3 wherein when the phase angle is zero, the third relationship is characterized by:

when the effective values of the currents of the ABC three phases are the same, the fourth relation is characterized in that:

wherein the content of the first and second substances,

T_avecharacterizing the average output torque;

w_mcharacterizing a rotational speed of the motor;

I_rmsthe effective value of the current is characterized.

5. A back-emf-based maximum torque current ratio control method as recited in claim 2 wherein determining the target relationship from the third relationship and the fourth relationship comprises:

and solving the maximum value of the torque-current ratio according to the third relation and the fourth relation by using a Lagrange multiplier method and taking the total current value of the motor as a constant as a constraint condition to obtain the target relation.

6. A method of back-EMF-based maximum torque to current ratio control as claimed in claim 5 wherein said target relationship is characterized by:

wherein the content of the first and second substances,

γ represents the lagrange multiplier;

c represents a total current value of the motor.

7. The method of claim 1, further comprising:

and controlling the target motor according to the current of the target motor.

8. A method of controlling a maximum torque to current ratio based on back emf as claimed in claim 1 wherein the motor comprises at least one of:

surface-mounted permanent magnet synchronous motors, embedded permanent magnet synchronous motors and switched reluctance motors.

9. A device for controlling a maximum torque current ratio based on a back electromotive force, comprising:

the relation construction module is used for constructing a target relation, and the target relation represents the relation between the back electromotive force and the current of the ABC three phases of the motor when the motor is in the maximum torque current ratio;

the data acquisition module is used for acquiring the back electromotive force of the target motor;

and the current determining module is used for determining the current of the target motor according to the counter electromotive force of the target motor and the target relation.

10. A motor control system, characterized by comprising a control module and a motor, wherein the control module is connected with the motor and is used for realizing the method for controlling the maximum torque current ratio based on the back electromotive force according to any one of claims 1 to 8.

11. An electronic device, comprising a processor and a memory,

the memory is used for storing codes and related data;

the processor is configured to execute the codes in the memory to implement the method for controlling a maximum torque-to-current ratio based on back electromotive force according to any one of claims 1 to 8.

12. A storage medium having stored thereon a computer program which, when executed by a processor, implements the back-emf-based maximum torque to current ratio control method of any one of claims 1 to 7.

Technical Field

The invention relates to the field of motor control, in particular to a method and a device for controlling a maximum torque current ratio based on back electromotive force.

Background

The permanent magnet Synchronous Motor (PMSM for short) is composed of stator, rotor and end cover, the stator is formed by laminating and pressing the lamination to reduce the iron loss generated when the Motor runs, in which a three-phase alternating current winding called armature is installed, the rotor is equipped with permanent magnet to provide excitation for the Motor, and the permanent magnet Synchronous Motor is widely applied in the fields of automobile, aerospace, industry and the like by virtue of its advantages of compact structure, high transmission efficiency, large power density and the like.

In the prior art, a PMSM control method comprises six-segment control and vector control, the six-segment control method is simple to implement, but cannot accurately control the position of a motor, and the motor vibrates obviously because the current in a motor stator is square wave; vector control can perform better position control on the motor, the current in the stator of the motor is sine wave, but when the method is used for controlling the BEMF (back electromotive force) trapezoidal wave permanent magnet synchronous motor, the output efficiency of the motor cannot reach the highest, the control is more complex, and the performance requirement on the MCU is higher.

Disclosure of Invention

The invention provides a method and a device for controlling a maximum torque-current ratio based on back electromotive force, which aim to solve the problems of low output efficiency and complex control of a motor.

According to a first aspect of the present invention, there is provided a back electromotive force-based maximum torque current ratio control method, comprising:

constructing a target relation, wherein the target relation represents the relation between the back electromotive force and the current of the ABC three phases of the motor when the motor is in the maximum torque current ratio;

acquiring the back electromotive force of a target motor;

and determining the current of the target motor according to the counter electromotive force of the target motor and the target relation.

Optionally, constructing the target relationship includes:

determining a first relation and a second relation, wherein the first relation represents the relation among the amplitude of k-th harmonic of the back electromotive force of the ABC three phases, the electrical angle of a motor rotor and the back electromotive force; the second relation represents the relation among the amplitude of k-th harmonic of the current of the ABC three phases, the electrical angle of a motor rotor and the current;

determining a third relationship between the average output torque of the electric machine and the magnitudes of the k-th harmonic of the current and the magnitudes of the k-th harmonic of the back emf based on the first relationship and the second relationship;

determining a fourth relationship from the second relationship, the fourth relationship characterizing a relationship between the effective value of the current and the magnitude of the k-th harmonic of the current;

and determining the target relation according to the third relation and the fourth relation.

Optionally, the first relationship is characterized by:

the second relationship is characterized by:

wherein the content of the first and second substances,

E_a(θ)、E_b(θ)、E_c(θ) represents the back electromotive force of the ABC three phases;

E_ka magnitude representing a k-th harmonic of the back electromotive force;

I_a(θ)、I_b(θ)、I_c(θ) represents the currents of the ABC three phases;

I_krepresenting the amplitude of the k harmonic of the current;

θ p represents a phase angle of the current and the back electromotive force;

theta represents the electrical angle of the motor rotor.

Optionally, when the phase angle is zero, the third relationship is characterized by:

when the effective values of the currents of the ABC three phases are the same, the fourth relation is characterized in that:

wherein the content of the first and second substances,

T_avecharacterizing the average output torque;

w_mcharacterizing a rotational speed of the motor;

I_rmsthe effective value of the current is characterized.

Optionally, determining the target relationship according to the third relationship and the fourth relationship includes:

and solving the maximum value of the torque-current ratio according to the third relation and the fourth relation by using a Lagrange multiplier method and taking the total current value of the motor as a constant as a constraint condition to obtain the target relation.

Optionally, the target relationship is characterized by:

wherein the content of the first and second substances,

γ represents the lagrange multiplier;

c represents a total current value of the motor.

Optionally, the method further includes:

and controlling the target motor according to the current of the target motor.

Optionally, the motor comprises at least one of:

surface-mounted permanent magnet synchronous motors, embedded permanent magnet synchronous motors and switched reluctance motors.

According to a second aspect of the present invention, there is provided a counter-electromotive force-based maximum torque current ratio control device including:

the relation construction module is used for constructing a target relation, and the target relation represents the relation between the back electromotive force and the current of the ABC three phases of the motor when the motor is in the maximum torque current ratio;

the data acquisition module is used for acquiring the back electromotive force of the target motor;

and the current determining module is used for determining the current of the target motor according to the counter electromotive force of the target motor and the target relation.

According to a third aspect of the present invention, there is provided a motor control system comprising a control module, a motor, the control module being connected to the motor, the control module being configured to implement the maximum torque current ratio control method based on back electromotive force according to the first aspect of the present invention and its alternatives.

According to a fourth aspect of the present invention, there is provided an electronic device, comprising a processor and a memory,

the memory is used for storing codes and related data;

the processor is configured to execute the codes in the memory to implement the method for controlling a maximum torque-to-current ratio based on back electromotive force according to the first aspect of the present invention and its alternatives.

According to a fifth aspect of the present invention, there is provided a storage medium having stored thereon a computer program which, when executed by a processor, implements the back-emf-based maximum torque-to-current ratio control method of the first aspect of the present invention and its alternatives.

The method and the device for controlling the maximum torque current ratio based on the back electromotive force construct the relationship between the back electromotive force and the optimal current, further calculate the optimal current of the target motor by analyzing the back electromotive force of the target motor when controlling the motor, and optimize the maximum output torque of the target motor so as to realize the control of the maximum torque current ratio of the target motor; compared with vector control in partial schemes, the control method is simple, has low requirements on the performance of the MCU, and can ensure that the output efficiency of the target motor reaches the highest; meanwhile, compared with a six-segment control method, the position of the target motor can be accurately controlled.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a first flowchart illustrating a method for controlling a ratio of maximum torque to current based on back EMF according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating step S101 according to an embodiment of the present invention;

FIG. 3 is a flowchart illustrating step S1014 according to an embodiment of the present invention;

FIG. 4 is a second flowchart illustrating a method for controlling the ratio of maximum torque to current based on back EMF according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a motor controlled by a vector control method in the prior art;

FIG. 6 is a waveform diagram illustrating a counter electromotive force of a sine wave in the prior art;

FIG. 7 is a waveform diagram illustrating a non-sinusoidal back EMF in the prior art;

FIG. 8 is a waveform of back EMF in an embodiment of the present invention;

FIG. 9 is a waveform diagram of the back EMF after FFT in accordance with an embodiment of the present invention;

FIG. 10 is a schematic diagram of a current waveform in accordance with an embodiment of the present invention;

FIG. 11 is a waveform illustrating the back EMF when the motor is running according to an embodiment of the present invention;

FIG. 12 is a waveform illustrating the current of the average output torque according to an embodiment of the present invention;

FIG. 13 is a first block diagram of a process for back EMF based maximum torque to current ratio control in accordance with an embodiment of the present invention;

FIG. 14 is a second block diagram of a process for back EMF based maximum torque to current ratio control in accordance with an embodiment of the present invention;

fig. 15 is a schematic structural diagram of an electronic device in an embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

Referring to fig. 1, a method for controlling a maximum torque current ratio based on a back electromotive force includes:

s101: constructing a target relation;

the target relation represents the relation between the back electromotive force and the current of the ABC three phases of the motor when the motor is at the maximum torque current ratio;

the current can be understood as the current injected in the stator of the motor, and the counter electromotive force can be understood as the ratio of the maximum torque current to the average output torque to the stator current in the process of rotating the permanent magnet on the rotor of the motor;

the magnetic linkage moves on the stator winding to cause the change of the magnetic field so as to generate induced electromotive force, and then the relation between the counter electromotive force and the circuit when the motor is in the maximum torque current ratio is analyzed through experimental data so as to obtain a target relation.

In one embodiment, the electric machine comprises at least one of:

surface-mounted permanent magnet synchronous motors, embedded permanent magnet synchronous motors and switched reluctance motors.

Referring to fig. 2, in one embodiment, the step S101 includes:

s1011: determining a first relationship and a second relationship;

the first relation represents the relation among the amplitude of k-th harmonic of the back electromotive force of the ABC three phases, the electrical angle of a motor rotor and the back electromotive force;

the second relation represents the relation among the amplitude of k-th harmonic of the current of the ABC three phases, the electrical angle of a motor rotor and the current;

in one example, the first relationship may be obtained by fourier transforming the back emf to obtain the amplitude of the k-th harmonic of the back emf, the electrical angle of the motor rotor, and the relationship between said back emf, i.e. the back emf may be represented by a superposition of sinusoidal signals of different frequencies and amplitudes;

by way of further example, the first relationship may be expressed as:

similarly, the second relationship may be expressed as:

wherein the content of the first and second substances,

E_a(θ)、E_b(θ)、E_c(θ) represents the back electromotive force of the ABC three phases;

E_ka magnitude representing a k-th harmonic of the back electromotive force;

I_a(θ)、I_b(θ)、I_c(θ) represents the currents of the ABC three phases;

I_krepresenting the amplitude of the k harmonic of the current;

θ p represents the phase angle of the current and the counter electromotive force, i.e. the phase difference of the counter electromotive force and the current is characterized in degrees;

theta represents the electrical angle of the motor rotor.

S1012: determining a third relationship between the average output torque of the electric machine and the magnitudes of the k-th harmonic of the current and the magnitudes of the k-th harmonic of the back emf based on the first relationship and the second relationship;

the average output torque can be understood as the ratio of the average output power to the rotating speed of the motor, and the average output power can be obtained by the back electromotive force and the current;

by way of further example, when the phase angle is zero, the motor may be guaranteed to output at maximum average power, and the relationship between the average output torque of the motor and the magnitudes of the k-th harmonic of the current and the k-th harmonic of the back electromotive force may be expressed as:

by simplifying the above equation (3), the following third relationship can be obtained:

wherein the content of the first and second substances,

T_avecharacterizing the average output torque;

w_mcharacterizing a rotational speed of the motor;

as can be seen from the third relation represented by the above formula (4), the obtained relation in an embodiment of the present invention is the relation between the average output torque and the amplitude of the back electromotive force harmonic and the amplitude of the current harmonic, and is not the relation between the average output torque and the back electromotive force and the current in some schemes, and further, when the back electromotive force contains a large amount of harmonics, but not sinusoidal waves, the maximum output torque-current ratio can be provided for the motor, so as to ensure that the output power of the motor reaches the maximum.

S1013: determining a fourth relationship according to the second relationship;

the fourth relationship characterizes a relationship between an effective value of the current and an amplitude of a k-th harmonic of the current;

in a further example, when the effective values of the currents of the ABC three phases are the same, the fourth relationship is characterized as:

wherein, I_rmsThe effective value of the current is characterized.

S1014: and determining the target relation according to the third relation and the fourth relation.

By way of further example, step S1014 includes:

s10141: and solving the maximum value of the torque-current ratio according to the third relation and the fourth relation by using a Lagrange multiplier method and taking the total current value of the motor as a constant as a constraint condition to obtain the target relation.

In one example, the maximum torque to current ratio can be characterized by the following equation:

wherein MTPA characterizes the maximum torque to current ratio;

the total current value of the motor can be represented as a constant by the following equation:

wherein C represents a total current value of the motor.

For formulas (6) and (7), the relationship between the current and the back electromotive force obtained by the lagrangian multiplier method and the relationship between the lagrangian multiplier and the amplitude of the back electromotive force harmonic wave are utilized, so that in practical application, the lagrangian multiplier is obtained by analyzing the back electromotive force harmonic wave, and then the current is obtained according to the back electromotive force, so that the maximum torque-current ratio of the motor is realized.

In one example, the target relationship is characterized by:

wherein the content of the first and second substances,

γ represents the lagrange multiplier.

In the above embodiment, it can be seen from the obtained target relationship that, in an embodiment of the present invention, the current is related to the counter electromotive force and the harmonic of the counter electromotive force, and further, while the counter electromotive force of the motor is controlled to be a trapezoidal wave, the output efficiency of the motor can be controlled to be the highest, and the control method is simple and has no high requirement on the MCU.

S102: acquiring the back electromotive force of a target motor;

s103: and determining the current of the target motor according to the counter electromotive force of the target motor and the target relation.

In a further example, in step S103, when determining the current of the target motor, the obtained back electromotive force of the target motor needs to be subjected to fast fourier transform to obtain multiple harmonic components of the back electromotive force of the target motor, and then the current of the target motor is determined according to the obtained harmonic components and the back electromotive force.

Referring to fig. 4, in one embodiment, the method further includes:

s104: and controlling the target motor according to the current of the target motor.

The invention further provides a motor control system, which comprises a control module and a motor, wherein the control module is connected with the motor and is used for realizing the maximum torque current ratio control method based on the back electromotive force in the first aspect and the optional aspects of the invention.

The following describes the positive effects of the method according to an embodiment of the present invention in detail with reference to fig. 5 to 12:

fig. 5 is a schematic diagram of controlling a motor by a vector control method in the prior art, and the specific control process is as follows:

by giving reference currents (e.g. I in FIG. 5) in the direct (d) and alternating (q) axes_{d_Ref}And I_{q_Ref}) Comparing the given reference current with the current sample value in the stator of the motor (wherein, the current sample value is converted into I by CLARK_αAnd I_βIs shown by_αAnd I_βIs transformed by PARK to obtain I_dAnd I_q) An error signal is generated which generates d-axis and q-axis reference voltages (e.g., U in FIG. 5) via a PI controller_{d_Ref}And U_{q_Ref}) And generating a reference voltage (U) under an alpha-beta coordinate system by performing inverse PARK transformation on the generated reference voltage_{α_Ref}And U_{β_Ref}) Finally, according to the reference voltage under the α - β coordinate system, the space vector modulation algorithm may generate corresponding PWM signals (e.g., PWM 1-6 in fig. 5) to drive the inverter to control the motor, and finally, the current flowing through the stator of the motor is a sine wave by selecting reasonable relevant parameters of the PI controller.

In fig. 5, the expression for the average output torque of the motor is:

wherein, theta is the electrical angle of the motor rotor, E_x(theta) and I_x(theta) is the back electromotive force and phase current of any phase of the motor, w_mThe mechanical rotation speed of the motor.

From Fourier series expansion, E_x(theta) and I_x(θ) is the superposition of sinusoidal signals of different frequencies and amplitudes.

Based on the orthogonality of the sine function, for the motor with sine-wave back electromotive force (for example, as shown in fig. 6, where A, B, C corresponds to sine-wave waveforms of three-phase back electromotive force of the motor respectively), at this time, injecting sine current into the stator of the motor can provide the maximum output torque current ratio, so that the motor efficiency is optimized;

for a motor with non-sinusoidal back electromotive force (for example, as shown in fig. 7, the sinusoidal waves corresponding to A, B, C are waveforms of back electromotive forces of three phases of the motor), the back electromotive force contains a large amount of harmonics, and if a sinusoidal current with a frequency of fundamental waves is injected into the motor at this time, the maximum output torque current ratio cannot be provided, and further the motor cannot achieve the maximum output efficiency.

In an embodiment of the invention, a target relation representing the relation between the current and the counter electromotive force is constructed through analysis of the counter electromotive force and the current, namely, as shown in formula (8), and further, when the current is injected into the motor, the optimal stator current capable of achieving the maximum torque current ratio is calculated through analysis of the harmonic wave of the counter electromotive force of the motor, so that the control of the motor is realized.

Referring to fig. 8, in an example, when the rotation speed of the motor is 1200rpm, the back electromotive force of the motor is obtained, and the back electromotive force is subjected to fast fourier transform to obtain a component of multiple harmonics of the back electromotive force, which may be shown in fig. 9,

as can be seen from fig. 9, the amplitude of the fundamental component of the back electromotive force is 11.257V, the amplitude of the third harmonic component is 1.334V, and the amplitude of the fifth harmonic component is-0.36V, and according to the target relationship characterized in equation (8), the current of the motor at the maximum torque current ratio can be calculated, and the waveform of the current can be, for example, I in fig. 10₂Corresponding waveform, I₁The corresponding waveform is a sine wave;

as can be seen from fig. 10, the amplitude of the fundamental component of the current is 0.991A, the amplitude of the third harmonic component is 0.127A, the amplitude of the fifth harmonic component is-0.032A,

fig. 11 shows a waveform of counter electromotive force during operation of the motor, and an average output torque of the motor can be obtained from the current and the counter electromotive force, and the average output torque can be shown in fig. 12, for example, where the waveform with a lower gradation value is a waveform corresponding to the average output torque when a sine wave is input to the stator, the average output torque is 1.065N.M, and the waveform with a higher gradation value is a waveform corresponding to the average output torque when a current obtained by the formula (8) is input to the stator, and the average output torque is 1.086N.M, and it can be seen that when the current obtained by the present invention is injected into the stator, the average output torque is improved by 2% compared to when a sine wave is injected into the stator.

It should be noted that the method provided by the embodiment of the present invention can be used not only for controlling the motor, but also for analyzing the torque ripple of the motor.

Referring to fig. 13, an embodiment of the present invention further provides a device 2 for controlling a maximum torque-to-current ratio based on back electromotive force, including:

the relation construction module 201 is configured to construct a target relation, where the target relation represents a relation between back electromotive force and current of three ABC phases of the motor when the motor is at a maximum torque-to-current ratio;

the data acquisition module 202 is used for acquiring the back electromotive force of the target motor;

and a current determining module 203, configured to determine the current of the target motor according to the target relationship and the counter electromotive force of the target motor.

Optionally, the relationship building module 201 is specifically configured to:

determining a first relation and a second relation, wherein the first relation represents the relation among the amplitude of k-th harmonic of the back electromotive force of the ABC three phases, the electrical angle of a motor rotor and the back electromotive force; the second relation represents the relation among the amplitude of k-th harmonic of the current of the ABC three phases, the electrical angle of a motor rotor and the current;

determining a third relationship between the average output torque of the electric machine and the magnitudes of the k-th harmonic of the current and the magnitudes of the k-th harmonic of the back emf based on the first relationship and the second relationship;

determining a fourth relationship from the second relationship, the fourth relationship characterizing a relationship between the effective value of the current and the magnitude of the k-th harmonic of the current;

and determining the target relation according to the third relation and the fourth relation.

Optionally, the first relationship is characterized by:

the second relationship is characterized by:

wherein the content of the first and second substances,

E_a(θ)、E_b(θ)、E_c(θ) represents the back electromotive force of the ABC three phases;

E_ka magnitude representing a k-th harmonic of the back electromotive force;

I_a(θ)、I_b(θ)、I_c(θ) represents the currents of the ABC three phases;

I_krepresenting the amplitude of the k harmonic of the current;

θ p represents a phase angle of the current and the back electromotive force;

theta represents the electrical angle of the motor rotor.

Optionally, when the phase angle is zero, the third relationship is characterized by:

when the effective values of the currents of the ABC three phases are the same, the fourth relation is characterized in that:

wherein the content of the first and second substances,

T_avecharacterizing the average output torque;

w_mcharacterizing a rotational speed of the motor;

I_rmsthe effective value of the current is characterized.

Optionally, determining the target relationship according to the third relationship and the fourth relationship includes:

and solving the maximum value of the torque-current ratio according to the third relation and the fourth relation by using a Lagrange multiplier method and taking the total current value of the motor as a constant as a constraint condition to obtain the target relation.

Optionally, the target relationship is characterized by:

wherein the content of the first and second substances,

γ represents the lagrange multiplier;

c represents a total current value of the motor.

Referring to fig. 14, in an embodiment, the apparatus further includes:

and a motor control module 204, configured to control the target motor according to the current of the target motor.

Optionally, the motor comprises at least one of:

surface-mounted permanent magnet synchronous motors, embedded permanent magnet synchronous motors and switched reluctance motors.

Referring to fig. 15, the present invention further provides an electronic device 30, which includes

A processor 31; and the number of the first and second groups,

a memory 32 for storing executable instructions for the processor;

wherein the processor 31 is configured to perform the above-mentioned method via execution of executable instructions.

The processor 31 is capable of communicating with the memory 32 via a bus 33.

Embodiments of the present invention also provide a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements the above-mentioned method.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.