Method for configuring current of an electric machine in a derated state

Abstract

The application relates to a method for configuring current of an electric machine in a derated state, which comprises the following steps: receiving a target torque sent by a vehicle controller, the target torque being greater than a maximum value of the electric machine torque; obtaining an initial value of a target current according to the target torque; and obtaining a target current of the electric machine in a dynamic coordinate system according to the initial value of the target current and a preset boundary condition strategy, wherein the target current comprises a target excitation current and a target torque current. The application specifically divides the working conditions of the target current of the electric machine in the derated state according to the preset boundary condition strategy, so that the original allocation value of the target current can be reconfigured in any working condition of the electric machine, and then the target excitation current and the target torque current can be accurately obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, in particular to a method for configuring current of a motor in a de-rating state. BACKGROUND

[0002] In the prior art, the control method of an induction motor is usually field-oriented vector control, which has the characteristics of fast torque response, high steady-state accuracy and small torque ripple.

[0003] The field-oriented vector control scheme usually indirectly obtains the magnetic field position through stator frequency integration or flux linkage observer, and obtains target torque current and target excitation current through the solution of the target torque requested by the vehicle control unit (VCU), and then realizes indirect control of torque by using a proportional integral controller (PIC). If the maximum value of the motor torque during the operation of the motor cannot meet the target torque requested by the vehicle control unit, the motor outputs according to its maximum motor torque, and at this time the working state of the motor can be called "de-rating state". However, the control scheme in the prior art has the problem that the motor cannot accurately obtain the target torque current and the target excitation current in the de-rating state. SUMMARY

[0004] Therefore, the present application provides a method for configuring current of a motor in a de-rating state to solve the problem that the motor cannot accurately obtain the target torque current and the target excitation current in the de-rating state in the prior art.

[0005] The present application provides a method for configuring current of a motor in a de-rating state, comprising:

[0006] receiving a target torque sent by a vehicle control unit, the target torque being greater than the maximum value of the motor torque;

[0007] obtaining an initial value of a target current according to the target torque;

[0008] obtaining the target current of the motor in a dynamic coordinate system according to the initial value of the target current and a preset boundary condition strategy, wherein the target current includes a target excitation current and a target torque current.

[0009] In one embodiment, receiving a target torque sent by a vehicle control unit, previously comprises:

[0010] obtaining motor parameters, the motor parameters including bus voltage U dc , synchronous angular velocity ω s , leakage coefficient σ, stator inductance L s , and slip frequency fsl and rotor time constant T r ;

[0011] obtaining maximum allowable phase current I max and rated excitation current I sdrate ;

[0012] The mathematical expression of the boundary condition strategy is:

[0013]

[0014] wherein I sdref and I sqref are initial values of the target current;

[0015] When the boundary condition strategy is satisfied, the slip frequency obtained by obtaining the original assigned value of the target current is stepped up, and the solution value I sd_k , I sq_k of the target current is obtained according to the target torque and the slip frequency;

[0016] If the solution value I sd_k , I sq_k of the target current does not satisfy the mathematical expression: or the configured target current does not satisfy any one of the mathematical expressions: and ;

[0017] The slip frequency obtained by obtaining the original assigned value of the target current is stepped up, and the solution value I sd_l , I sq_l of the target current is obtained according to the mathematical expression: and the slip frequency;

[0018] If the solution value I sd_l , I sq_l of the target current satisfies the mathematical expression: The target current I sd , I sq is configured to be equal to the solution value I sd_l , I sq_l of the target current, and the configured target current satisfies the mathematical expression:

[0019] In one of the embodiments, if the solution value I sd_l , I sq_l of the target current does not satisfy the mathematical expression: or the configured target current does not satisfy the mathematical expression:

[0020] The slip frequency based on the original distribution value of the target current is increased step by step, and the mathematical expression is as follows: And the solution value I of the target current obtained by the slip frequency is I sd_s , sq_s The target current I is configured as I sd , sq The target current I is configured as I sd_s , sq_s And the configured target current satisfies the mathematical expression

[0021] In one embodiment, if the solution value I of the target current I sd_s , sq_s Does not satisfy the mathematical expression

[0022] The slip frequency based on the original distribution value of the target current is increased step by step, and the mathematical expression is as follows: And the solution value I of the target current obtained by the slip frequency is I sd_z , sq_z The target current I is configured as I sd , sq The target current I is configured as I sd_z , sq_z .

[0023] In one embodiment, the dynamic coordinate system is a two-phase rotating coordinate system.

[0024] In one embodiment, the bus voltage is collected by a voltage sensor.

[0025] In one embodiment, when the initial value of the target current is obtained according to the target torque, the assumption condition that the target excitation current is equal to the target torque current is proposed.

[0026] In one embodiment, the mathematical expression for obtaining the initial value of the target current is as follows:

[0027]

[0028] Wherein, I is the initial value of the target current, N is the number of motor pole pairs, I is the motor excitation mutual inductance, and L is the rotor inductance. sdref sqref p m r

[0029] ​​​​​The application specifically divides the working conditions of the motor in the de-rating state configured with the target current by the preset boundary condition strategy, so that the motor can reconfigure the original allocation value of the target current in any of the working conditions, and then obtain the accurate target current. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flowchart of steps for obtaining the actual current of the motor according to an embodiment of the application is shown in FIG. 6.

[0031] Figure 2 A flowchart of steps for obtaining the voltage of the motor in the stationary coordinate system according to an embodiment of the application is shown in FIG. 7.

[0032] Figure 3 A schematic diagram of the working conditions of the target current divided according to an embodiment of the application is shown in FIG. 8.

[0033] Figure 4 A flowchart of the method for configuring the current of the motor in the de-rating state according to an embodiment of the application is shown in FIG. 9. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and should not be used to limit the application.

[0035] It should be noted that the diagrams provided in the embodiments only schematically illustrate the basic concept of the application.

[0036] The structures, proportions, sizes, etc. shown in the drawings of the present specification are only used to cooperate with the content disclosed in the present specification, so that those skilled in the art can understand and read, and are not used to limit the defined conditions under which the present application can be implemented. Any modification of structure, change of proportion relationship or adjustment of size, which does not affect the effects and purposes that the present application can produce, should still fall within the scope of the technical content disclosed by the present application.

[0037] The orientations or positional relationships indicated by the terms such as "upper", "lower", "left", "right", "intermediate", "vertical", "horizontal", "inner", "outer", "radial", "circumferential", etc. in the present specification are based on the orientations or positional relationships shown in the drawings, and are only used to simplify the description, and cannot be understood as indicating or implying that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0038] Before the motor configures the target current in the dynamic coordinate system in the de-rating state, the actual current of the motor in the dynamic coordinate system is acquired, wherein the actual current includes an actual excitation current and an actual torque current.

[0039] Then the method for configuring the current of the motor in the de-rating state is used to acquire the target current of the motor in the dynamic coordinate system.

[0040] Subsequently, the target current of the motor in the dynamic coordinate system is subtracted from the actual current and subjected to proportional-integral processing to acquire the target modulation voltage of the motor in the dynamic coordinate system, and the target modulation voltage of the motor in the dynamic coordinate system and the rotor flux position are subjected to inverse Park transformation to acquire the target modulation voltage of the motor in the static coordinate system.

[0041] After that, the target modulation voltage of the motor in the static coordinate system is subjected to space vector modulation processing to acquire the three-phase pulse signal of the motor, and the three-phase pulse signal is output to the inverter for driving the motor, thereby achieving the purpose of field-oriented vector control of the motor.

[0042] As shown in Figure 1 the actual step of acquiring the actual current of the motor in the dynamic coordinate system can be step S1, which includes:

[0043] S101: presetting the mapping relationship of the stator current amplitude of the motor and the stator leakage inductance, the torque of the motor and the rotor leakage inductance, and the air gap flux and the excitation mutual inductance;

[0044] S102: collecting the three-phase current, bus voltage, stator temperature and rotor position of the motor;

[0045] S103: performing voltage reconstruction and Clarke transformation on the bus voltage to acquire the voltage of the motor in the static coordinate system;

[0046] S104: performing Clarke transformation on the three-phase current to acquire the current of the motor in the static coordinate system, and further acquiring the stator current amplitude;

[0047] S105: acquiring the stator resistance of the motor according to the temperature of the stator;

[0048] S106: acquiring the speed of the motor according to the rotor position;

[0049] S107: performing flux observation according to the voltage and current of the motor in the static coordinate system, the stator resistance, the speed, and the stator leakage inductance, the rotor leakage inductance and the excitation mutual inductance acquired in the previous control period to acquire the torque of the motor, the air gap flux and the rotor flux position of the motor in the current control period, wherein in the first control period of the motor, the stator leakage inductance, the rotor leakage inductance and the excitation mutual inductance are all preset values;

[0050] S108: Reacquire the stator leakage inductance, rotor leakage inductance and excitation mutual inductance of the motor according to the mapping relationship, so as to obtain the motor torque, air gap flux linkage and rotor flux linkage position of the motor in the next control cycle.

[0051] S109: Perform Parker transformation on the motor current in the stationary coordinate system based on the rotor flux linkage position to obtain the actual current of the motor in the dynamic coordinate system.

[0052] In this embodiment, by way of example, the dynamic coordinate system can be a multi-dimensional coordinate system, such as a two-phase rotating coordinate system; the static coordinate system can be a multi-dimensional coordinate system, such as a two-phase stationary coordinate system.

[0053] In step S101, it is illustrated by way of example that the preset mapping relationship can be a parameter lookup table, which can be obtained through electromagnetic simulation experiments. It is understood that the mapping relationship is determined by the stator current amplitude I. amp The stator leakage inductance L can be obtained by looking up a table. ls Through the motor torque T e The rotor leakage inductance L can be obtained by looking up a table. lr Through air gap magnetic flux The excitation mutual inductance L can be obtained by looking up a table. m .

[0054] In step S102, it is illustrated by way of example that the three-phase current I of the motor can be acquired by a current sensor. A I B I C The motor bus voltage U can also be acquired through a voltage sensor. dc Furthermore, the stator temperature of the motor can be collected through a temperature sensor, and the rotor position of the motor can be collected through a rotary transformer.

[0055] like Figure 2 As shown, step S103 above, which involves voltage reconstruction and Clarke transformation of the bus voltage to obtain the motor voltage in the stationary coordinate system, includes:

[0056] S1031: Obtain the three-phase pulse signal of the motor in the previous control cycle, wherein the three-phase pulse signal is a preset value in the first control cycle of the motor;

[0057] S1032: Perform voltage reconstruction based on bus voltage and three-phase pulse signal to obtain the three-phase voltage of the motor;

[0058] S1033: Perform a Clarke transform on the three-phase voltage to obtain the motor voltage in the stationary coordinate system. In step S1031, for example, obtaining the three-phase pulse signal of the motor in the previous control cycle refers to obtaining the three-phase pulse signal t transmitted by the motor to the inverter in the previous control cycle. A tB C In the first control cycle of the motor, the preset values of the three-phase pulse signals t A B C The preset values of t A , t B , t C may be 0 or 0.5, for example, t A = 0, t B = 0.5, t C = 0.5; or t A = 0.5, t B = 0, t C = 0.5, etc.

[0059] In step S1032, the mathematical expression of the voltage reconstruction is exemplarily illustrated as follows:

[0060]

[0061] wherein U A , U B , U C are three-phase voltages.

[0062] In step S1033, after the three-phase voltages U A , U B , U C of the motor are obtained, the Clark transformation is performed on the three-phase voltages, so that the voltages U sα , U sβ of the motor in the two-phase stationary coordinate system are obtained.

[0063] In step S104, the Clark transformation is performed on the three-phase currents I A , I B , I C , so that I sα , I sβ of the motor in the two-phase stationary coordinate system are obtained, and the mathematical expression of the stator current amplitude I amp may be as follows:

[0064]

[0065] In step S105, the mathematical expression of the stator resistance of the motor according to the temperature of the stator may be as follows:

[0066] R sm = R s0 (1 + K s (t m -t0))

[0067] wherein t m is the current temperature value, R sm is the resistance of the stator at the temperature tm R0 is the stator resistance at the initial temperature t0, t0 is the initial temperature value, R s0 R0 is the stator resistance at the initial temperature t0, K s is the temperature coefficient of the material of the stator.

[0068] In step S106, it is exemplarily illustrated that the rotating speed of the motor is acquired according to the position change of the rotor within a fixed time, and the specific mathematical expression is as follows:

[0069]

[0070] Wherein, n is the rotating speed, ΔT is the fixed time, and ΔP is the position difference of the motor within the fixed time, which can be acquired by the acquired rotor position.

[0071] It can be understood that the above steps S103-S106 can be performed synchronously, and the sequential arrangement in steps is only for the convenience of description.

[0072] In step S107, it is exemplarily illustrated that the flux linkage observation can be performed on the hybrid flux linkage / torque observer according to the voltages U sα , U sβ and the currents I sα , I sβ , the stator resistance R s , the rotating speed n and the stator leakage inductance L ls , the rotor leakage inductance L lr and the excitation mutual inductance L m acquired in the last control period, so as to acquire the motor torque T e , the air gap flux linkage and the rotor flux linkage position

[0073] The mathematical model of the flux linkage observation, i.e. the hybrid flux linkage / torque observer in the embodiment, includes a voltage model (U-I) and a current model (I-ω).

[0074] The mathematical expression of the voltage model (U-I) can be as follows:

[0075]

[0076] Wherein, and are the rotor flux linkages of the motor in the two-phase static coordinate system, L r is the rotor inductance, L s is the stator inductance, and p is a differential operator; specifically, the rotor inductance L r and the stator inductance L s can be acquired according to the stator leakage inductance L lsRotor leakage inductance L lr and excitation mutual inductance L m is obtained.

[0077] The mathematical expression of the current model (I-ω) can be:

[0078]

[0079] where T r is the rotor time constant, and ω r is the rotor angular velocity; specifically, the rotor angular velocity ω r can be obtained according to the rotational speed n.

[0080] The mathematical expression of the mixing rate is:

[0081]

[0082] where γ is the mixing rate, n max is the maximum rotational speed of the motor preset, and n min is the minimum rotational speed of the motor preset.

[0083] When the motor torque T e , the air gap flux linkage , and the rotor flux linkage position in the current control cycle are obtained, the voltage model and / or the current model are selected for flux linkage observation according to the rotational speed n of the motor. Specifically, the value range of the mixing rate γ is 0-1, when the rotational speed n of the motor is less than n min , the current model (I-ω) is selected for flux linkage observation; when the rotational speed n of the motor is greater than n max , the voltage model (U-I) is selected for flux linkage observation; when the rotational speed n of the motor is between n min and n max , the current model and the voltage model are simultaneously selected for flux linkage observation.

[0084] The mathematical expression for obtaining the air gap flux linkage is:

[0085]

[0086] where is the air gap flux linkage of the motor in the two-phase stationary coordinate system.

[0087] The mathematical expression for obtaining the motor torque can be:

[0088]

[0089] where is the rotor flux linkage amplitude, and I sq* is the actual torque current of the motor in the two-phase rotating coordinate system.

[0090] In step S108, it is exemplarily illustrated that the stator current amplitude I amp , the motor torque T e and the air-gap flux linkage obtained by the motor in the present control period are respectively looked up to obtain the stator leakage inductance L ls , the rotor leakage inductance L lr and the excitation mutual inductance L m of the motor in the next control period, so as to obtain the motor torque T e , the air-gap flux linkage and the rotor flux linkage position of the motor in the next control period.

[0091] It can be understood that, since the stator leakage inductance L ls , the rotor leakage inductance L lr and the excitation mutual inductance L m are preset values in the first control period of the motor, the motor torque T e , the air-gap flux linkage and the rotor flux linkage position of the motor can be obtained by the preset values in the first control period of the motor.

[0092] In step S109, it is exemplarily illustrated that the I sα , I sβ of the motor in the two-phase static coordinate system can be Park transformed according to the rotor flux linkage position to obtain the actual current I sd* , I sq* of the motor in the two-phase rotating coordinate system.

[0093] When the motor is configured with the target current in the de-rating state, the current circle, the voltage ellipse, the excitation saturation and the leakage magnetic coefficient can be taken as the boundary conditions. For example, a schematic diagram of the working condition division of the target current is shown in Figure 3 , in which the horizontal coordinate represents the target excitation current and the vertical coordinate represents the target torque current, both in units of A.

[0094] Therefore, the boundary condition strategy can include the current circle boundary condition, which is mathematically expressed as:

[0095]

[0096] where I sdref and I sqref are initial values of the target current, and I max is the maximum allowable phase current.

[0097] Specifically, the target excitation current and the target torque current are limited by the limitations of the motor and the inverter and cannot be infinite, and the limitation is the maximum allowable phase current Imax In Figure 3 correspondence to the boundary condition is a circular portion.

[0098] The boundary condition strategy can further include a voltage ellipse boundary condition, which is mathematically expressed as:

[0099]

[0100] where ω s is the synchronous angular velocity, σ is the leakage coefficient, L s is the stator inductance, and U dc is the bus voltage.

[0101] Specifically, as the motor speed increases, the synchronous angular velocity increases accordingly, and the back electromotive force of the motor increases. However, the maximum linear modulation voltage in the space vector modulation is Since the influence of the stator resistance voltage drop can be ignored when the motor speed is high, the target excitation current and the target torque current can be limited by this boundary condition. In Figure 3 correspondence to the boundary condition is an elliptical portion; and it can be understood that when the synchronous angular velocity of the motor rises from ω1 to ω2, the voltage ellipse boundary condition has a converging trend.

[0102] The boundary condition strategy can further include an excitation saturation boundary condition, which is mathematically expressed as:

[0103] I sdref ≤ I sdrate

[0104] where I sdrate is the rated excitation current.

[0105] Specifically, when the target excitation current does not exceed the rated excitation current I sdrate , increasing the target excitation current can effectively increase the flux linkage and reduce the excitation loss; when the target excitation current exceeds the rated excitation current I sdrate , increasing the target excitation current will only slightly increase the flux linkage, while the excitation loss will increase sharply, ultimately causing the motor efficiency to decrease, so the target excitation current should also be limited by this boundary condition. In Figure 3 correspondence to the boundary condition is the left portion of the straight line on which the line segment AB is located.

[0106] The boundary condition strategy can further include a leakage coefficient boundary condition, which is mathematically expressed as:

[0107]

[0108] where f sl is the slip frequency of the motor, and T r is the rotor time constant.

[0109] Specifically, when the motor speed is high, it always needs to meet the voltage ellipse boundary condition, the excitation current is constantly reduced, and the slip frequency is constantly increased. When I sdref = σI sqref , the torque output reaches the maximum value, and the motor works in the best state under the target excitation current and target torque current. Figure 3 In the embodiment, the lower part of the straight line where the line segment OC is located corresponds to the boundary condition.

[0110] As shown in Figure 4 , the step of configuring the target current of the motor in the dynamic coordinate system can be step S2, which includes:

[0111] S201: receiving a target torque sent by a vehicle controller, the target torque being greater than the maximum value of the motor torque;

[0112] S202: obtaining an initial value of a target current according to the target torque;

[0113] S203: obtaining a target current of the motor in a dynamic coordinate system according to the initial value of the target current and a preset boundary condition strategy, wherein the target current includes a target excitation current and a target torque current.

[0114] In step S201, it is exemplarily illustrated that the motor in the derated state receives a target torque T eref sent by the vehicle controller. Since the target torque T eref is greater than the maximum value of the motor torque, the target excitation current and the target torque current configured by the motor can always not meet the needs of the target torque T eref , so the motor needs to be derated, and at this time the motor outputs according to the maximum value of the motor torque.

[0115] In step S202, it is exemplarily illustrated that when the motor is based on rotor field orientation, the mathematical expression of the target torque T eref is:

[0116]

[0117] Wherein, I sdref , I sqref are the initial values of the target current, N p is the number of motor pole pairs, L m is the motor excitation mutual inductance, and L r is the rotor inductance.

[0118] When obtaining the initial value of the target current according to the target torque, the assumption condition that the target excitation current is equal to the target torque current is proposed, so the initial value of the target current I sdref , Isqref The mathematical expression is:

[0119]

[0120] In step S203, it is illustrated by way of example that the initial value I of the target current is used. sdref I sqref And a preset boundary condition strategy to obtain the target current I of the motor in a two-phase rotating coordinate system. sd I sq .

[0121] like Figure 4 As shown, step S201 above, receiving the target torque sent by the vehicle controller, includes the following steps beforehand:

[0122] S200: Obtain the maximum allowable phase current I of the motor max and rated excitation current I sdrate .

[0123] In step S200, the maximum permissible phase current I is illustrated by way of example. max The value depends on the insulation and heat dissipation capabilities of the motor and inverter, and can be obtained through electromagnetic simulation testing; rated excitation current I sdrate The rated parameters can be obtained from the motor's rated parameters, which include rated voltage, rated current, rated frequency, rated slip frequency, and rated speed.

[0124] like Figure 3 As shown, step S203 above may include a first working condition:

[0125] When the initial value of the target current I sdref and I sqref When the voltage elliptic boundary condition is not satisfied, in other words, the mathematical expression of the boundary condition strategy is:

[0126]

[0127] When the target torque is satisfied, the slip frequency is increased step by step based on the original distribution value of the target current, and the solution value I of the target current is obtained according to the target torque and slip frequency. sd_k I sq_k Specifically, to obtain the solution value I of the target current. sd_k I sq_k The mathematical expression is:

[0128]

[0129] Among them, f sl1 f is the slip frequency corresponding to the original allocation value of the target current. sl_kk is 1, 2, 3, …, and the slip frequency corresponding to the solution value of the target current is denoted as ωk.

[0130] If there is no solution value of the target current I sd_k , I sq_k satisfying the mathematical expression: i.e., there is no solution value of the target current I sd_k , I sq_k satisfying the voltage ellipse boundary condition, or the configured target current does not satisfy the mathematical expression: and i.e., the configured target current does not satisfy any one of the current circle boundary condition and the excitation saturation boundary condition.

[0131] On the basis of the slip frequency obtained by the original allocation value of the target current, the slip frequency is increased step by step, and the solution value of the target current I sd_l , I sq_l is obtained according to the mathematical expression: and the slip frequency, and specifically, the mathematical expression for obtaining the solution value of the target current I sd_l , I sq_l is:

[0132]

[0133] wherein, l is 1, 2, 3, ….

[0134] If there is a solution value of the target current I sd_l , I sq_l satisfying the mathematical expression: In other words, if there is a solution value of the target current I sd_l , I sq_l satisfying the voltage ellipse boundary condition, the configured target current I sd , I sq is equal to the solution value of the target current I sd_l , I sq_l , and the configured target current satisfies the mathematical expression: In other words, the configured target current satisfies the excitation saturation boundary condition. It can be understood that the configured target current is located on the BC arc segment in Figure 3 .

[0135] The above step S203 can further include a second working condition:

[0136] If the above first condition does not exist, the solution value of the target current I sd_l , I sq_l satisfies the mathematical expression: Or the configured target current does not meet the mathematical expression:

[0137] Based on the slip frequency obtained from the initial distribution value of the target current, the slip frequency is increased in steps, and according to the mathematical expression: And the solution value I of the target current obtained from the slip frequency. sd_s I sq_s Specifically, to obtain the solution value I of the target current. sd_s I sq_s The mathematical expression is:

[0138]

[0139] Configure target current I sd I sq The solution value I equals the target current. sd_s I sq_s And the configured target current satisfies the mathematical expression In other words, the configured target current satisfies the current circle boundary condition. This can be understood as the configured target current being located at... Figure 3 On line segment OC in the middle.

[0140] The above step S203 may also include a third working condition:

[0141] If the target current I is calculated in the second working condition described above sd_s I sq_s Not satisfied with mathematical expression

[0142] Based on the slip frequency obtained from the initial distribution value of the target current, the slip frequency is increased in steps, and according to the mathematical expression: And the solution value I of the target current obtained from the slip frequency. sd_z I sq_z Specifically, to obtain the solution value I of the target current. sd_z I sq_z The mathematical expression is:

[0143]

[0144] Configure target current I sd I sq The solution value I equals the target current. sd_z I sq_z Understandably, the configured target current is located at... Figure 3 Point C in the diagram.

[0145] The application specifically divides the working condition of the motor in the de-rating state configured with the target current into three kinds through the boundary condition strategy composed of the current circle, the voltage ellipse, the excitation saturation and the leakage coefficient, so that the motor can reconfigure the original allocation value of the target current in any of the above working conditions, and then accurately obtain the target torque current and the target excitation current.

[0146] After the step of configuring the target current of the motor in the dynamic coordinate system is completed, the target current I sd of the motor in the dynamic coordinate system can be obtained by subtracting the actual current I sq . sd* sq* from the actual current I sd , I sq , and then transmitting it to a proportional-integral controller for proportional-integral processing, and then obtaining the target modulation voltage U sdref of the motor in the two-phase rotating coordinate system sqref . Then, the target modulation voltage U sdref of the motor in the two-phase rotating coordinate system sqref is subjected to inverse Park transformation according to the rotor flux position to obtain the target modulation voltage U αref of the motor in the two-phase static coordinate system βref .

[0147] After that, the target modulation voltage U αref of the motor in the two-phase static coordinate system βref can be subjected to vector modulation processing by using a seven-segment space vector modulation strategy to obtain the three-phase pulse signal t A , t B , t C ; after obtaining the three-phase pulse signal t A , t B , t C , it can be transmitted to an inverter for driving the motor, thereby completing the entire control process of the motor. At the same time, the three-phase pulse signal t A , t B , t C is also used for voltage reconstruction of the three-phase voltage U A , U B , U C in the next control period.

[0148] The technical features of the above embodiments can be combined in any way. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0149] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific and detailed manner, but should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are all within the scope of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A method for configuring the current of a motor in a derating state, characterized in that, Comprising: Receiving a target torque sent by a vehicle controller, the target torque being greater than a maximum value of a motor torque; Obtaining an initial value of a target current according to the target torque; Obtaining a target current of the motor in a dynamic coordinate system according to the initial value of the target current and a preset boundary condition strategy, wherein the target current comprises a target excitation current and a target torque current; Receiving a target torque sent by a vehicle controller, the target torque being greater than a maximum value of a motor torque; acquiring motor parameters, the motor parameters comprising a bus voltage of the motor , a synchronous angular velocity , a leakage coefficient , a stator inductance , a slip frequency and a rotor time constant ; acquiring a maximum allowed phase current of the electric machine and a rated excitation current ; The mathematical expression of the boundary condition strategy is: ； wherein and is an initial value of the target current; when the boundary condition strategy is satisfied, stepping up a slip frequency based on a slip frequency obtained when obtaining a raw allocation value of the target current, and obtaining a solution value of the target current according to the target torque and the slip frequency 、 ; if there is no solution value of the target current , satisfies the mathematical expression: , or the target current configured does not satisfy any one of the mathematical expressions: and . The slip frequency is increased step by step based on the slip frequency obtained by acquiring the original distribution value of the target current, and the mathematical expression is: and the slip frequency acquires the solution value of the target current 、 ; if there is a solution value of the target current , satisfies the mathematical expression: , the target current is configured , is equal to the solved value of the target current , , and the configured target current satisfies the mathematical expression: 。 2. The method for configuring the current of the motor in the de-rating state according to claim 1, characterized in that, if there is no solution value of the target current , satisfies the mathematical expression: , or the target current configured does not satisfy the mathematical expression: ； The slip frequency obtained by acquiring the original distribution value of the target current is increased step by step, and the mathematical expression is: The slip frequency is configured to obtain the solution value of the target current 、 The target current is configured 、 The target current is equal to the solution value of the target current 、 , and the configured target current satisfies the mathematical expression 。 3. The method for configuring the current of the motor in the de-rating state according to claim 2, characterized in that, if the solution value of the target current , does not satisfy the mathematical expression ; The slip frequency is increased step by step based on the slip frequency obtained by acquiring the original distribution value of the target current, and the mathematical expression is: And the slip frequency acquires the solution value of the target current 、 , the target current is configured 、 Equal to the solution value of the target current 、 .

4. The method for configuring the current of the motor in the de-rating state according to claim 1, characterized in that, The dynamic coordinate system is a two-phase rotating coordinate system.

5. The method for configuring the current of the motor in the de-rating state according to claim 1, characterized in that, The bus voltage is collected by a voltage sensor.

6. The method for configuring the current of the motor in the de-rating state according to claim 1, characterized in that, When obtaining the initial value of the target current according to the target torque, a hypothesis condition that the target excitation current is equal to the target torque current is proposed.

7. The method for configuring the current of the motor in the de-rating state according to claim 1, characterized in that, The mathematical expression for obtaining the initial value of the target current is: ； wherein, , is an initial value of the target current, is the number of motor pole pairs, is the motor excitation mutual inductance, is the rotor inductance.

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