A motor torque control method and device, computer equipment and storage medium

Abstract

The application relates to a motor torque control method and device, computer equipment and a storage medium. The method comprises the following steps: collecting motor state quantities, and obtaining a stator current, a motor estimated torque and an air gap flux according to the motor state quantities; obtaining a first corresponding relationship between the stator current and a stator leakage inductance, a second corresponding relationship between the motor estimated torque and a rotor leakage inductance, and a third corresponding relationship between the air gap flux and a motor excitation mutual inductance, respectively; obtaining the stator leakage inductance according to the first corresponding relationship, obtaining the rotor leakage inductance according to the second corresponding relationship, and obtaining the motor excitation mutual inductance according to the third corresponding relationship; and obtaining a motor available torque according to the stator leakage inductance, the rotor leakage inductance and the motor excitation mutual inductance. The method can solve the problem that the torque capacity of an induction motor is difficult to fully exert.

Description

Technical Field

[0001] This application relates to the field of motor technology, and in particular to a motor torque control method, apparatus, computer equipment, and storage medium. Background Technology

[0002] Induction motors have secured a place in the field of drive motors for new energy vehicles due to their advantages such as low manufacturing cost and high reliability. The electric drive system of new energy vehicles needs to fully utilize the torque capability of induction motors. The actual torque output of an induction motor depends on the available torque limit of the electric drive system; the closer the available torque is to the torque capability, the more fully the induction motor's torque capability is utilized. However, under complex and variable operating conditions, there are currently two torque management schemes for managing motor torque: one is rotor field-oriented vector control, but due to the first-order hysteresis characteristic of the rotor flux linkage, the actual output torque of the motor cannot track the maximum available torque in real time; the other is stator field-oriented vector control, but because this scheme obtains the motor's torque capability through bench calibration, the motor torque table is calibrated based on specific operating conditions, making it difficult to guarantee that the motor will output the maximum available torque in real time. Summary of the Invention

[0003] Based on this, a motor torque control method, device, computer equipment, and storage medium are provided to solve the problem that the torque capability of induction motors is difficult to fully utilize in the prior art.

[0004] On one hand, a motor torque control method is provided, the method comprising: acquiring motor state variables, and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state variables; acquiring a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance, and obtaining the stator leakage inductance corresponding to the stator current based on the first correspondence, obtaining the rotor leakage inductance corresponding to the estimated motor torque based on the second correspondence, and obtaining the motor excitation mutual inductance corresponding to the air gap flux linkage based on the third correspondence; and obtaining the available motor torque based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance.

[0005] In one embodiment, acquiring motor state parameters and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state parameters includes: acquiring motor state parameters, wherein the motor state parameters include three-phase current, three-phase voltage, and rotor angular velocity; performing static coordinate transformation on the three-phase current and three-phase voltage respectively to obtain corresponding first current and first voltage; obtaining a fourth correspondence between the first current and first voltage, and obtaining a first stator flux linkage based on the fourth correspondence; obtaining a fifth correspondence between the first voltage and rotor angular velocity, and obtaining a second stator flux linkage based on the fifth correspondence; obtaining the stator flux linkage mixing rate between the fourth and fifth correspondences, and obtaining a corresponding mixed stator flux linkage based on the first stator flux linkage, second stator flux linkage, and stator flux linkage mixing rate; calculating the square root of the first current to obtain the stator current, and obtaining the corresponding air gap flux linkage based on the stator flux linkage and the first current.

[0006] In one embodiment, the process of acquiring motor state parameters and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state parameters further includes: obtaining a first stator flux linkage angle based on the fourth correspondence; obtaining a second stator flux linkage angle based on the fifth correspondence; obtaining a corresponding mixed stator flux linkage angle based on the first stator flux linkage angle, the second stator flux linkage angle, and the stator flux linkage mixing ratio; performing a rotational coordinate transformation on the first current based on the mixed stator flux linkage angle to obtain a second current; and obtaining the estimated motor torque based on the mixed stator flux linkage and the second current.

[0007] In one embodiment, obtaining the usable motor torque based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance includes: obtaining the motor torque based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance; calculating the derivative of the motor torque and adjusting the derivative of the motor torque according to a derivative threshold so that the derivative of the motor torque is equal to the derivative threshold, thereby obtaining a corresponding slip frequency; obtaining a target torque current and a target stator flux linkage based on the slip frequency; and obtaining the usable motor torque based on the product of the target torque current and the target stator flux linkage.

[0008] In one embodiment, obtaining the target torque current and target stator flux linkage based on the slip frequency includes: obtaining a pre-weakening stator flux linkage based on the slip frequency and the second current; obtaining a preset maximum stator flux linkage of the motor and comparing the pre-weakening stator flux linkage with the preset maximum stator flux linkage; when the pre-weakening stator flux linkage is smaller than the preset maximum stator flux linkage, using the pre-weakening stator flux linkage as the target stator flux linkage, or when the pre-weakening stator flux linkage is larger than the preset maximum stator flux linkage, using the preset maximum stator flux linkage as the target stator flux linkage.

[0009] In one embodiment, obtaining the target torque current and target stator flux linkage based on the slip frequency further includes: obtaining a corresponding motor torque current based on the slip frequency and the target stator flux linkage; comparing the motor torque current with a motor torque current threshold, wherein the motor torque current threshold is obtained based on the peak current of the motor inverter; when the motor torque current is less than the motor torque current threshold, using the motor torque current as the target torque current, or when the motor torque current is greater than the motor torque current threshold, using the motor torque current threshold as the target torque current.

[0010] In one embodiment, after obtaining the available torque of the motor based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance, the method further includes: obtaining a fault torque reduction coefficient of the electric drive system, and obtaining the current torque of the motor based on the product of the available torque of the motor and the fault torque reduction coefficient; obtaining a target torque of the motor, and when the target torque of the motor is greater than the current torque of the motor, controlling the actual torque of the motor to be the current torque of the motor; and when the target torque of the motor is less than or equal to the current torque of the motor, controlling the actual torque of the motor to be the target torque of the motor.

[0011] On the other hand, a motor torque control device is provided, the device comprising: a data acquisition module for acquiring motor state quantities and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state quantities; a correspondence acquisition module for acquiring a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance, and obtaining the stator leakage inductance corresponding to the stator current based on the first correspondence, obtaining the rotor leakage inductance corresponding to the estimated motor torque based on the second correspondence, and obtaining the motor excitation mutual inductance corresponding to the air gap flux linkage based on the third correspondence; and an available torque evaluation module for obtaining the available motor torque based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance.

[0012] In another aspect, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it performs the following steps: acquiring motor state variables and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state variables; obtaining a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance, respectively; obtaining the stator leakage inductance corresponding to the stator current based on the first correspondence, obtaining the rotor leakage inductance corresponding to the estimated motor torque based on the second correspondence, and obtaining the motor excitation mutual inductance corresponding to the air gap flux linkage based on the third correspondence; obtaining the usable motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance; obtaining the target motor torque and comparing the target motor torque with the usable motor torque to obtain a comparison result; and controlling the actual motor torque based on the comparison result.

[0013] In another aspect, a computer-readable storage medium is provided, on which a computer program is stored, wherein when the computer program is executed by a processor, the following steps are performed: acquiring motor state quantities, and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state quantities; obtaining a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance, respectively; obtaining the stator leakage inductance corresponding to the stator current based on the first correspondence, obtaining the rotor leakage inductance corresponding to the estimated motor torque based on the second correspondence, and obtaining the motor excitation mutual inductance corresponding to the air gap flux linkage based on the third correspondence; and obtaining the available motor torque based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance.

[0014] The aforementioned motor torque control method, device, computer equipment, and storage medium acquire motor state variables and obtain stator current, estimated motor torque, and air gap flux linkage based on these variables. They then obtain a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance. Based on the first correspondence, they obtain the stator leakage inductance corresponding to the stator current; based on the second correspondence, they obtain the rotor leakage inductance corresponding to the estimated motor torque; and based on the third correspondence, they obtain the motor excitation mutual inductance corresponding to the air gap flux linkage. Finally, they obtain the usable motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance, thereby fully utilizing the torque capability of the induction motor. Attached Figure Description

[0015] Figure 1 This is an application environment diagram of the motor torque control method in one embodiment;

[0016] Figure 2 This is a flowchart illustrating a motor torque control method in one embodiment;

[0017] Figure 3 This is a structural block diagram of a motor torque control device in one embodiment;

[0018] Figure 4 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] Since the embodiments of this application involve a large number of technical terms, for ease of understanding, the relevant terms and concepts that may be involved in the embodiments of this application will be introduced below.

[0021] 1. Stator

[0022] The stator is the stationary part of the motor. It consists of three parts: the stator core, the stator windings, and the frame. Its main function is to generate a rotating magnetic field.

[0023] 2. Rotor

[0024] A rotor is a rotating body supported by bearings that rotates at high speed under the drive of a rotating magnetic field generated by the stator windings.

[0025] 3. Motor winding temperature

[0026] Electronic windings refer to the rotor coils of a motor, which generate the motor winding temperature after being energized.

[0027] 4. Three-phase current

[0028] Three-phase current is transmitted through three conductors, each conductor serving as a loop for the other two. The phase difference of its three components is one-third of a cycle or a 120° phase angle current.

[0029] 5. Three-phase voltage

[0030] Three-phase voltage refers to the voltage between phases. The three-phase voltages have equal amplitude, equal frequency, and a phase difference of 120°.

[0031] 6. Clark Transform

[0032] In a three-phase system, state variables such as voltage and current are coupled to varying degrees. By transforming the three-phase coordinates, the coupled symmetrical three-phase system can be decoupled into a two-phase system that can be controlled independently. This means mapping the state variables of the three-phase system to a static three-dimensional Euclidean space, thereby reducing the complexity of controller design.

[0033] 7. PARK Transformation

[0034] Park transformation projects the state variables, making all the state variables on the stator equivalent to the direct and quadrature axes. From the observer's perspective, the observation point has shifted from the stator to the rotor, that is, from being concerned with the rotating magnetic field generated by the three windings of the stator to being concerned with the rotating magnetic field generated by the equivalent direct and quadrature axes.

[0035] 8. Magnetic Linkage

[0036] Magnetic flux linkage refers to the magnetic flux linked by a conductive coil or current loop.

[0037] 9. Air gap flux

[0038] Air gap flux refers to the portion of the magnetic flux that links between the stator and rotor through the air gap.

[0039] 10. Leakage

[0040] The magnetic field lines generated by the coil cannot all pass through the secondary coil, so the inductance that produces leakage flux is called leakage inductance.

[0041] 11. Excitation

[0042] Excitation is mainly used to provide a working magnetic field for motors and other electrical equipment that works using the principle of electromagnetic induction.

[0043] The motor torque control method provided in this application can be applied to, for example... Figure 1In the application environment shown, terminal 102 and server 104 communicate via a network. First, the motor status variables are acquired through a data acquisition module. These motor status variables can be analog signals. Based on the acquired motor status variables, the stator current, estimated motor torque, and air gap flux linkage are obtained. Then, the first correspondence between stator current and stator leakage inductance, the second correspondence between estimated motor torque and rotor leakage inductance, and the third correspondence between air gap flux linkage and motor excitation inductance are obtained. Based on the first correspondence, the stator leakage inductance corresponding to the current stator current is obtained; based on the second correspondence, the rotor leakage inductance corresponding to the current estimated motor torque is obtained; and based on the third correspondence, the motor excitation inductance corresponding to the current air gap flux linkage is obtained. Based on the stator leakage inductance, rotor leakage inductance, and motor excitation inductance, corresponding calculations are performed to obtain the usable motor torque. This usable motor torque can be based on the maximum torque capacity of the electric drive system under non-fault conditions, thereby evaluating the motor's torque capability to ensure the motor fully utilizes its torque capacity and outputs maximum torque.

[0044] The terminal 102 can be, but is not limited to, various personal computers, laptops, smartphones, tablets and portable wearable devices, and the server 104 can be implemented by a standalone server or a server cluster consisting of multiple servers.

[0045] In one embodiment, such as Figure 2 As shown, a motor torque control method is provided, which is applied to... Figure 1 Taking the terminal in the example, the explanation includes the following steps:

[0046] Step 201: Collect motor state parameters and obtain stator current, estimated motor torque, and air gap flux based on the motor state parameters;

[0047] Step 202: Obtain the first correspondence between stator current and stator leakage inductance, the second correspondence between estimated motor torque and rotor leakage inductance, and the third correspondence between air gap flux and motor excitation mutual inductance, respectively. Obtain the stator leakage inductance corresponding to stator current based on the first correspondence, obtain the rotor leakage inductance corresponding to estimated motor torque based on the second correspondence, and obtain the motor excitation mutual inductance corresponding to air gap flux based on the third correspondence.

[0048] Step 203: Obtain the available torque of the motor based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance.

[0049] In step 201, for example, motor state parameters are acquired, and the stator current, estimated motor torque, and air gap flux are obtained based on these parameters. For instance, the motor state parameters can be acquired from analog signals of motor-related parameters, including the acquisition of three-phase current I through a current sensor. A I B IC DC voltage U is collected by a voltage sensor. dc The rotor position, i.e., the rotor angle θ, is acquired through a resolver and resolver decoding module. r The temperature T of the motor windings is collected by a temperature sensor. m The duty cycle t of the upper tube pulse of the three-phase bridge arm of the motor is stored through the storage module. A t B t C The corresponding motor state variables are obtained, and then the stator current, estimated motor torque, and air gap flux are calculated from the motor state variables. The stator current can be the stator current amplitude, and the air gap flux can be the air gap flux amplitude.

[0050] In step 202, for example, the first correspondence between stator current and stator leakage inductance, the second correspondence between estimated motor torque and rotor leakage inductance, and the third correspondence between air gap flux linkage and motor excitation mutual inductance are obtained respectively. The stator leakage inductance corresponding to the stator current is obtained according to the first correspondence, the rotor leakage inductance corresponding to the estimated motor torque is obtained according to the second correspondence, and the motor excitation mutual inductance corresponding to the air gap flux linkage is obtained according to the third correspondence. For example, the system's overturning slip frequency can be predicted in real time by establishing the correspondence between the corresponding motor state variables. In some implementations, a two-dimensional list of correspondences can be created based on the motor electromagnetic simulation design results and stored in a fixed storage area of ​​the software. To obtain the stator leakage inductance, a two-dimensional list relating stator current and stator leakage inductance is created based on the first correspondence. During actual operation, the stator leakage inductance value is obtained by looking up the table in real time based on the stator current. To obtain the rotor leakage inductance, a two-dimensional list relating estimated motor torque and rotor leakage inductance is created based on the second correspondence. During actual operation, the rotor leakage inductance value is obtained by looking up the table in real time based on the estimated motor torque. To obtain the motor excitation mutual inductance, a two-dimensional list relating air gap flux linkage and motor excitation mutual inductance is created based on the third correspondence. During actual operation, the motor excitation mutual inductance value is obtained by looking up the table based on the air gap flux linkage. In some implementations, the above motor state variables and the obtained motor state variables are periodically updated to ensure that the maximum available torque can be output in real time.

[0051] In step 203, it is exemplarily explained that the usable torque of the motor is obtained based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance. For example, in the single-phase equivalent circuit of an asynchronous motor, a corresponding mathematical expression of the motor torque can be obtained. This mathematical expression of the motor torque is related to the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance. After obtaining the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance, the derivative of the mathematical expression of the motor torque can be obtained. Setting this derivative equal to zero yields the slip frequency corresponding to the maximum value of the motor torque. The usable torque of the motor is then obtained through this slip frequency and the fault torque reduction coefficient. In some implementations, the mathematical expression of the motor torque is:

[0052]

[0053] Among them, T e The value of N represents the motor torque, where m represents the number of motor phases. p E represents the number of pole pairs of the motor, π represents pi, and E represents the value of a circle. s f represents the stator back electromotive force. s R represents the stator frequency. r L represents the rotor resistance. m f represents the excitation mutual inductance of the motor. sl L represents the slip frequency. s L represents the stator self-inductance. k This represents the square of the virtual inductance, L. k =L m L ls +L m L lr +L ls L lr , where L ls Indicates stator leakage inductance, L lr This indicates rotor leakage inductance.

[0054] The above method establishes a correspondence between relevant motor state variables, realizes real-time lookup table prediction and calculation of the slip frequency of the system, and evaluates the maximum value of the available torque of the motor based on the slip frequency, so that the motor can give full play to its torque capacity and output the maximum torque.

[0055] As a specific implementation of the above embodiment, the process of acquiring motor state variables and obtaining stator current, estimated motor torque, and air gap flux linkage based on these variables includes: acquiring motor state variables, wherein the motor state variables include the motor's three-phase current, three-phase voltage, and rotor angular velocity; performing static coordinate transformation on the three-phase current and three-phase voltage respectively to obtain corresponding first current and first voltage; obtaining a fourth correspondence between the first current and first voltage, and obtaining a first stator flux linkage based on the fourth correspondence; obtaining a fifth correspondence between the first voltage and rotor angular velocity, and obtaining a second stator flux linkage based on the fifth correspondence; obtaining the stator flux linkage mixing ratio between the fourth and fifth correspondences, and obtaining a corresponding mixed stator flux linkage based on the mixing ratio of the first and second stator flux linkages; calculating the square root of the first current to obtain the stator current, and obtaining the corresponding air gap flux linkage based on the stator flux linkage and the first current.

[0056] It should be noted that in some implementation processes, the three-phase voltage can be achieved by utilizing the DC voltage U. dc The voltage reconstruction is obtained by reconstructing the voltage using the duty cycle of the pulses on the upper transistors of the three-phase bridge arms. The mathematical expression for voltage reconstruction is: Among them, U A UB U C The three-phase voltages of the motor are given, and then the three-phase currents and three-phase voltages are calculated using Clark transform to obtain the first voltage U in the two-phase stationary coordinate system. sα U sβ and the first current I sα I sβ Then, based on the motor state variables calculated and updated by the system in the previous cycle, a voltage model flux linkage observation is established using the first voltage and the first current, i.e., the fourth correspondence; a current model flux linkage observation is established using the first current and the rotor angular velocity, i.e., the fifth correspondence; thereby calculating the stator flux linkage mixing rate, and based on this stator flux linkage mixing rate, a mixing flux linkage observer is constructed to observe the stator flux linkage angle and stator flux linkage, and then the first current I... sα I sβ The stator current amplitude, i.e., the stator current, is obtained by square root calculation; in some implementations, the mathematical expression of the stator flux mixing rate is: Where, n max This represents the maximum set motor speed, n. min This represents the set minimum motor speed, where n represents the actual motor speed. The stator flux mixing rate is limited to the range of 0-1. When the actual motor speed is less than n... min The time-mixed model is entirely driven by current model flux linkage observations; however, when the actual motor speed is greater than n... max The hybrid model is entirely driven by the voltage model flux linkage observations, when the actual motor speed is n min -n max In between, two models work together, namely the hybrid flux observer. The hybrid stator flux is: Therefore, the stator flux linkage angle is Stator flux linkage amplitude is In some implementation processes, the expression used for air gap flux linkage observation is: Therefore, the air gap flux linkage amplitude is That is, air gap magnetic flux.

[0057] As a specific implementation of the above embodiments, the method of collecting motor state variables and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state variables further includes: obtaining a first stator flux linkage angle based on a fourth correspondence relationship; obtaining a second stator flux linkage angle based on a fifth correspondence relationship; obtaining a corresponding mixed stator flux linkage angle based on the first stator flux linkage angle, the second stator flux linkage angle, and the stator flux linkage mixing rate; performing a rotational coordinate transformation on the first current based on the mixed stator flux linkage angle to obtain a second current; and obtaining the estimated motor torque based on the mixed stator flux linkage and the second current.

[0058] It should be noted that the first current I is calculated by performing a PARK transformation on the stator flux angle observed by the hybrid flux observer, resulting in a two-phase rotating coordinate system. sd I sq The estimated torque of the motor is obtained by combining stator flux observation. In some implementation processes, the mathematical expression of the estimated motor torque is as follows: Among them, T e1 Estimate the torque for the motor.

[0059] As a specific implementation of the above embodiments, obtaining the usable torque of the motor based on stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance includes: obtaining the motor torque based on stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance; calculating the derivative of the motor torque and adjusting the derivative of the motor torque according to a derivative threshold so that the derivative of the motor torque equals the derivative threshold, thereby obtaining the corresponding slip frequency; obtaining the target torque current and target stator flux linkage based on the slip frequency; obtaining the second usable torque of the motor based on the product of the target torque current and the target stator flux linkage; obtaining the fault torque reduction coefficient of the electric drive system and obtaining the usable torque of the motor based on the product of the second usable torque of the motor and the fault torque reduction coefficient.

[0060] It should be noted that when an asynchronous motor adopts a stator field-oriented vector control strategy, for a given stator flux linkage, there exists a slip frequency that maximizes the motor torque. This slip frequency is called the overturning slip frequency. Specifically, the derivative of the motor torque can be calculated by differentiating the mathematical expression of the motor torque. The derivative threshold can be 0, i.e., setting the derivative equal to 0, so that the slip frequency corresponding to the maximum motor torque is the overturning slip frequency. In stator field-oriented vector control, the stator flux linkage and torque current are direct control quantities, while the slip frequency is an indirect output quantity. It is necessary to ensure that the actual slip frequency does not exceed the overturning slip frequency to ensure system stability. In some implementations, the mathematical expression of the available torque of the motor is: Among them, T eAvb The available torque for the motor, For the target stator flux linkage, I sqAvb Given the target torque current, the available torque of the motor is the maximum capable torque of the electric drive system under non-fault operating conditions. In other implementations, the mathematical expression of the motor's current torque is: T eAvbF =T eAvb *K ft , where K ft For fault-related torque reduction coefficient, T eAvbF This represents the current torque of the motor.

[0061] As a specific implementation of the above embodiments, obtaining the target torque current and target stator flux linkage based on the slip frequency includes: obtaining the pre-weakening stator flux linkage based on the slip frequency and the second current; obtaining the preset maximum stator flux linkage of the motor and comparing the pre-weakening stator flux linkage with the preset maximum stator flux linkage; when the pre-weakening stator flux linkage is less than the preset maximum stator flux linkage, using the pre-weakening stator flux linkage as the target stator flux linkage, or when the pre-weakening stator flux linkage is greater than the preset maximum stator flux linkage, using the preset maximum stator flux linkage as the target stator flux linkage.

[0062] It should be noted that, in order to avoid the decrease in motor efficiency caused by magnetic saturation, the preset maximum stator flux linkage of the motor is set to the maximum stator flux linkage of the motor. Under any operating condition, the stator flux linkage will not exceed the preset maximum stator flux linkage; the maximum stator flux linkage under the current operating conditions and space vector modulation constraints, i.e., the pre-weakening stator flux linkage, is mathematically expressed as: in, For pre-weakening stator flux linkage, U ph R is the maximum allowable phase voltage amplitude of the system. s For stator resistance, f re U is the electric frequency of the motor rotor. In some implementations, U... ph Based on DC voltage U dc Based on the characteristic that the space vector modulation module always operates in the linear modulation region, and considering the limitations of DC voltage and space vector linear modulation, its output voltage cannot be infinitely large. Therefore, the mathematical expression for the maximum allowable phase voltage amplitude of the system is: In some implementations, the mathematical expression for stator resistance is: R s =R s0 (1+K s (t m -t0)), where t m t0 is the current temperature value, t0 is the preset temperature value, K s R is the temperature coefficient of the stator resistance material. s0 R is the stator resistance at temperature t0, where t0 and R s0 This is based on electromagnetic simulation results. In some implementation processes, the motor rotor frequency can be calculated using the angular difference between rotor positions within a preset time threshold. Specifically, the mathematical expression for the motor rotor frequency is: Where ΔT is the preset time threshold, and Δθ r This is the difference in rotor angle of the motor.

[0063] In one embodiment, once the pre-weakening stator flux linkage and the preset maximum stator flux linkage are determined, based on system limitations, it is necessary to compare the sizes of the pre-weakening stator flux linkage and the preset maximum stator flux linkage, and determine the smaller value as the target stator flux linkage.

[0064] As a specific implementation of the above embodiments, obtaining the target torque current and target stator flux linkage based on the slip frequency further includes: obtaining the corresponding motor torque current based on the slip frequency and target stator flux linkage; comparing the motor torque current with a motor torque current threshold, wherein the motor torque current threshold is obtained based on the peak current of the motor inverter; when the motor torque current is less than the motor torque current threshold, using the motor torque current as the target torque current, or when the motor torque current is greater than the motor torque current threshold, using the motor torque current threshold as the target torque current.

[0065] It should be noted that, while ensuring the stator flux linkage is within the usable range, the slip frequency is overturned to obtain the torque current corresponding to the maximum motor torque. Therefore, the motor torque current refers to the maximum torque current under the conditions of pre-weakening stator flux linkage, preset maximum stator flux linkage, and overturned slip frequency limitation. The mathematical expression of the motor torque current is: Among them, I sqm This refers to the motor torque current. For the target stator flux linkage, ω slm The critical slip angular velocity is set as follows: In order to ensure the safe operation of the inverter, the motor torque current threshold is set as the maximum allowable torque current under the maximum peak current limit of the inverter. Therefore, due to the above limitations, the motor torque current and the motor torque current threshold are compared, and the smaller value is determined as the target torque current.

[0066] As a specific implementation of the above embodiments, after obtaining the available torque of the motor based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance, the method further includes: obtaining the fault torque reduction coefficient of the electric drive system, and obtaining the current torque of the motor based on the product of the available torque of the motor and the fault torque reduction coefficient; obtaining the target torque of the motor, and controlling the actual torque of the motor based on the comparison result, including: when the target torque of the motor is greater than the available torque of the motor, controlling the actual torque of the motor to be the available torque of the motor; when the target torque of the motor is less than or equal to the available torque of the motor, controlling the actual torque of the motor to be the target torque of the motor.

[0067] It should be understood that, although Figure 2 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 herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 2At 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.

[0068] In one embodiment, such as Figure 3 As shown, a motor torque control device is provided, including: a data acquisition module, a correspondence acquisition module, an available torque acquisition module, a torque comparison module, and a torque control module, wherein:

[0069] The data acquisition module is used to collect motor state parameters and obtain stator current, estimated motor torque, and air gap flux based on the motor state parameters.

[0070] The correspondence acquisition module is used to acquire the first correspondence between stator current and stator leakage inductance, the second correspondence between estimated motor torque and rotor leakage inductance, and the third correspondence between air gap flux and motor excitation mutual inductance, respectively. Based on the first correspondence, the stator leakage inductance corresponding to the stator current is obtained; based on the second correspondence, the rotor leakage inductance corresponding to the estimated motor torque is obtained; and based on the third correspondence, the motor excitation mutual inductance corresponding to the air gap flux is obtained.

[0071] The available torque assessment module is used to obtain the available torque of the motor based on stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance.

[0072] Optionally, the data acquisition module is also used to acquire motor state variables, including the motor's three-phase current, three-phase voltage, and rotor angular velocity; perform static coordinate transformation on the three-phase current and three-phase voltage respectively to obtain the corresponding first current and first voltage; obtain the fourth correspondence between the first current and the first voltage, and obtain the first stator flux linkage based on the fourth correspondence; obtain the fifth correspondence between the first voltage and the rotor angular velocity, and obtain the second stator flux linkage based on the fifth correspondence; obtain the stator flux linkage mixing rate between the fourth and fifth correspondences, and obtain the corresponding mixed stator flux linkage based on the mixing rate of the first stator flux linkage and the second stator flux linkage; calculate the square root of the first current to obtain the stator current, and obtain the corresponding air gap flux linkage based on the stator flux linkage and the first current.

[0073] Optionally, the data acquisition module is also used to obtain the first stator flux linkage angle according to the fourth correspondence; obtain the second stator flux linkage angle according to the fifth correspondence; obtain the corresponding mixed stator flux linkage angle according to the first stator flux linkage angle, the second stator flux linkage angle and the stator flux linkage mixing rate; perform a rotational coordinate transformation on the first current according to the mixed stator flux linkage angle to obtain the second current; and obtain the estimated torque of the motor according to the mixed stator flux linkage and the second current.

[0074] Optionally, the correspondence acquisition module is also used to obtain the motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance; calculate the derivative of the motor torque, and adjust the derivative of the motor torque according to the derivative threshold so that the derivative of the motor torque is equal to the derivative threshold, thereby obtaining the corresponding slip frequency; obtain the target torque current and target stator flux linkage based on the slip frequency; and obtain the usable torque of the motor based on the product of the target torque current and the target stator flux linkage.

[0075] Optionally, the correspondence acquisition module is also used to obtain the pre-weakening stator flux linkage based on the slip frequency and the second current; obtain the preset maximum stator flux linkage of the motor, and compare the pre-weakening stator flux linkage with the preset maximum stator flux linkage; when the pre-weakening stator flux linkage is less than the preset maximum stator flux linkage, the pre-weakening stator flux linkage is used as the target stator flux linkage, or when the pre-weakening stator flux linkage is greater than the preset maximum stator flux linkage, the preset maximum stator flux linkage is used as the target stator flux linkage.

[0076] Optionally, the correspondence acquisition module is also used to obtain the corresponding motor torque current based on the slip frequency and the target stator flux linkage; compare the motor torque current with the motor torque current threshold, wherein the motor torque current threshold is obtained based on the current peak value of the motor inverter; when the motor torque current is less than the motor torque current threshold, the motor torque current is used as the target torque current, or when the motor torque current is greater than the motor torque current threshold, the motor torque current threshold is used as the target torque current.

[0077] Optionally, the torque evaluation module can also be used to control the actual torque of the motor to be the current torque of the motor when the target torque of the motor is greater than the current torque of the motor; and to control the actual torque of the motor to be the target torque of the motor when the target torque of the motor is less than or equal to the current torque of the motor.

[0078] Specific limitations regarding the motor torque control device can be found in the limitations of the motor torque control method described above, and will not be repeated here. Each module in the aforementioned motor torque control device 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.

[0079] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 4As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a motor torque control method. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse.

[0080] Those skilled in the art will understand that Figure 4 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.

[0081] 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. When the processor executes the computer program, it performs the following steps: acquiring motor state variables and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state variables; obtaining a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance, respectively; obtaining the stator leakage inductance corresponding to the stator current based on the first correspondence, obtaining the rotor leakage inductance corresponding to the estimated motor torque based on the second correspondence, and obtaining the motor excitation mutual inductance corresponding to the air gap flux linkage based on the third correspondence; and obtaining the usable motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance.

[0082] In one embodiment, when the processor executes the computer program, it further performs the following steps: acquiring motor state variables, wherein the motor state variables include the three-phase current, three-phase voltage, and rotor angular velocity of the motor; performing static coordinate transformation on the three-phase current and three-phase voltage respectively to obtain the corresponding first current and first voltage; obtaining a fourth correspondence between the first current and the first voltage, and obtaining a first stator flux linkage based on the fourth correspondence; obtaining a fifth correspondence between the first voltage and the rotor angular velocity, and obtaining a second stator flux linkage based on the fifth correspondence; obtaining the stator flux linkage mixing rate between the fourth and fifth correspondences, and obtaining a corresponding mixed stator flux linkage based on the mixing rate of the first and second stator flux linkages; obtaining a corresponding stator flux linkage based on the stator flux linkage mixing rate; calculating the square root of the first current to obtain the stator current, and obtaining a corresponding air gap flux linkage based on the stator flux linkage and the first current.

[0083] In one embodiment, when the processor executes the computer program, it further performs the following steps: obtaining a first stator flux linkage angle according to a fourth correspondence; obtaining a second stator flux linkage angle according to a fifth correspondence; obtaining a corresponding mixed stator flux linkage angle according to the first stator flux linkage angle, the second stator flux linkage angle, and the stator flux linkage mixing rate; performing a rotational coordinate transformation on the first current according to the mixed stator flux linkage angle to obtain a second current; and obtaining the estimated torque of the motor according to the mixed stator flux linkage and the second current.

[0084] In one embodiment, when the processor executes the computer program, it further performs the following steps: obtaining the motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance; calculating the derivative of the motor torque and adjusting the derivative of the motor torque according to a derivative threshold so that the derivative of the motor torque is equal to the derivative threshold, thereby obtaining the corresponding slip frequency; obtaining the target torque current and the target stator flux linkage based on the slip frequency; and obtaining the usable torque of the motor based on the product of the target torque current and the target stator flux linkage.

[0085] In one embodiment, when the processor executes the computer program, it further implements the following steps: obtaining the pre-weakening stator flux linkage based on the slip frequency and the second current; obtaining the preset maximum stator flux linkage of the motor and comparing the pre-weakening stator flux linkage with the preset maximum stator flux linkage; when the pre-weakening stator flux linkage is less than the preset maximum stator flux linkage, using the pre-weakening stator flux linkage as the target stator flux linkage, or when the pre-weakening stator flux linkage is greater than the preset maximum stator flux linkage, using the preset maximum stator flux linkage as the target stator flux linkage.

[0086] In one embodiment, when the processor executes the computer program, it further performs the following steps: obtaining the corresponding motor torque current based on the slip frequency and the target stator flux linkage; comparing the motor torque current with a motor torque current threshold, wherein the motor torque current threshold is obtained based on the peak current of the motor inverter; when the motor torque current is less than the motor torque current threshold, using the motor torque current as the target torque current, or when the motor torque current is greater than the motor torque current threshold, using the motor torque current threshold as the target torque current.

[0087] In one embodiment, when the processor executes the computer program, it further implements the following steps: when the target torque of the motor is greater than the current torque of the motor, the actual torque of the motor is controlled to be the current torque of the motor; when the target torque of the motor is less than or equal to the current torque of the motor, the actual torque of the motor is controlled to be the target torque of the motor.

[0088] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, it performs the following steps: acquiring motor state variables and obtaining stator current, estimated motor torque, and air gap flux linkage based on the motor state variables; acquiring a first correspondence between stator current and stator leakage inductance, a second correspondence between estimated motor torque and rotor leakage inductance, and a third correspondence between air gap flux linkage and motor excitation mutual inductance, respectively; obtaining the stator leakage inductance corresponding to the stator current based on the first correspondence, obtaining the rotor leakage inductance corresponding to the estimated motor torque based on the second correspondence, and obtaining the motor excitation mutual inductance corresponding to the air gap flux linkage based on the third correspondence; obtaining the usable motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance; acquiring the target motor torque and comparing the target motor torque with the usable motor torque to obtain a comparison result; and controlling the actual motor torque based on the comparison result.

[0089] 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, and when executed, it 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 can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various 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.

[0090] 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.

[0091] 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 controlling motor torque, characterized in that, include: Collect motor state parameters and obtain stator current, estimated motor torque, and air gap flux based on the motor state parameters; The first correspondence between stator current and stator leakage inductance, the second correspondence between estimated motor torque and rotor leakage inductance, and the third correspondence between air gap flux and motor excitation mutual inductance are obtained respectively. The stator leakage inductance corresponding to the stator current is obtained according to the first correspondence, the rotor leakage inductance corresponding to the estimated motor torque is obtained according to the second correspondence, and the motor excitation mutual inductance corresponding to the air gap flux is obtained according to the third correspondence. Obtaining the usable torque of the motor based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance includes: obtaining the motor torque based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance; calculating the derivative of the motor torque, and adjusting the derivative of the motor torque according to a derivative threshold so that the derivative of the motor torque is equal to the derivative threshold, thereby obtaining the corresponding slip frequency; obtaining the target torque current and the target stator flux linkage based on the slip frequency; and obtaining the usable torque of the motor based on the product of the target torque current and the target stator flux linkage.

2. The motor torque control method as described in claim 1, characterized in that, Collect motor state parameters and obtain stator current, estimated motor torque, and air gap flux linkage based on the motor state parameters, including: Collect motor state parameters, including the motor's three-phase current, three-phase voltage, and rotor angular velocity; Perform static coordinate transformations on the three-phase currents and three-phase voltages respectively to obtain the corresponding first current and first voltage; Obtain the fourth correspondence between the first current and the first voltage, and obtain the first stator flux linkage based on the fourth correspondence; Obtain the fifth correspondence between the first current and the rotor angular velocity, and obtain the second stator flux linkage based on the fifth correspondence; Obtain the stator flux mixing rate between the fourth and fifth correspondences, and obtain the corresponding mixed stator flux based on the first stator flux, the second stator flux, and the stator flux mixing rate; The stator current is obtained by calculating the square root of the first current, and the corresponding air gap flux is obtained based on the mixed stator flux and the first current.

3. The motor torque control method as described in claim 2, characterized in that, The system collects motor state parameters and obtains stator current, estimated motor torque, and air gap flux linkage based on these parameters. It also includes: The first stator flux linkage angle is obtained according to the fourth correspondence. The second stator flux linkage angle is obtained based on the fifth correspondence. The corresponding mixed stator flux angle is obtained based on the first stator flux angle, the second stator flux angle, and the stator flux mixing rate; The first current is obtained by performing a rotational coordinate transformation on the first current based on the hybrid stator flux angle; The estimated torque of the motor is obtained based on the hybrid stator flux and the second current.

4. The motor torque control method as described in claim 3, characterized in that, Obtaining the target torque current and target stator flux linkage based on the slip frequency includes: The pre-weakening stator flux linkage is obtained based on the slip frequency and the second current; Obtain the preset maximum stator flux linkage of the motor, and compare the pre-weakening stator flux linkage with the preset maximum stator flux linkage; When the pre-weakening stator is smaller than the preset maximum stator flux linkage, the pre-weakening stator flux linkage is taken as the target stator flux linkage; or, when the pre-weakening stator flux linkage is greater than the preset maximum stator flux linkage, the preset maximum stator flux linkage is taken as the target stator flux linkage.

5. The motor torque control method as described in claim 4, characterized in that, Obtaining the target torque current and target stator flux linkage based on the slip frequency also includes: Based on the slip frequency and the target stator flux linkage, the corresponding motor torque current is obtained; The motor torque current is compared with the motor torque current threshold, wherein the motor torque current threshold is obtained based on the peak current of the motor inverter; When the motor torque current is less than the motor torque current threshold, the motor torque current is used as the target torque current; or, when the motor torque current is greater than the motor torque current threshold, the motor torque current threshold is used as the target torque current.

6. The motor torque control method as described in claim 1, characterized in that, After obtaining the usable torque of the motor based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance, the method further includes: Obtain the fault torque reduction coefficient of the electric drive system, and obtain the current torque of the motor based on the product of the available torque of the motor and the fault torque reduction coefficient; Obtain the target torque of the motor; when the target torque of the motor is greater than the current torque of the motor, control the actual torque of the motor to be the current torque of the motor. When the target torque of the motor is less than or equal to the current torque of the motor, the actual torque of the motor is controlled to be the target torque of the motor.

7. A motor torque control device, characterized in that, include: The data acquisition module is used to collect motor state parameters and obtain stator current, estimated motor torque, and air gap flux based on the motor state parameters. The correspondence acquisition module is used to acquire the first correspondence between stator current and stator leakage inductance, the second correspondence between estimated motor torque and rotor leakage inductance, and the third correspondence between air gap flux and motor excitation mutual inductance, respectively. Based on the first correspondence, the stator leakage inductance corresponding to the stator current is obtained; based on the second correspondence, the rotor leakage inductance corresponding to the estimated motor torque is obtained; and based on the third correspondence, the motor excitation mutual inductance corresponding to the air gap flux is obtained. The available torque evaluation module is used to obtain the available torque of the motor based on the stator leakage inductance, the rotor leakage inductance, and the motor excitation mutual inductance. The module includes: obtaining the motor torque based on the stator leakage inductance, rotor leakage inductance, and motor excitation mutual inductance; calculating the derivative of the motor torque and adjusting the derivative of the motor torque according to a derivative threshold so that the derivative of the motor torque equals the derivative threshold, thereby obtaining the corresponding slip frequency; obtaining the target torque current and the target stator flux linkage based on the slip frequency; and obtaining the available torque of the motor based on the product of the target torque current and the target stator flux linkage.

8. 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 steps of the method according to any one of claims 1 to 6.

9. 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 steps of the method according to any one of claims 1 to 6.

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