Direct torque flux linkage control method and system of dual three-phase electric drive system for electric vehicle

Abstract

The invention discloses a direct torque flux linkage control method and system of a dual three-phase electric drive system for an electric vehicle. The method comprises the following steps: carrying out direct torque flux linkage control on a # imgabs0 # sub-plane based on a # imgabs1 # coordinate axis system; observing # imgabs2 # axis current components # imgabs3 # and # imgabs4 # by utilizing a torque and flux linkage observer to obtain a real-time torque estimated value # imgabs5 # of a motor, an amplitude # imgabs6 # of a stator flux linkage estimated value and a stator flux linkage angle estimated value # imgabs7 # of the motor; performing direct torque flux linkage control on the flux linkage error to calculate # imgabs8 # shaft reference voltage; and in a # imgabs9 # sub-plane, performing closed-loop regulation on # imgabs10 # and # imgabs11 # current loops by adopting a PR controller to generate # imgabs12 # axis reference voltage. The invention aims to solve the problems of large torque pulsation and non-ideal low-speed operation of the existing direct torque control (DTC), improve the dynamic response capability and robustness of the system, reduce the stator current harmonic wave to reduce the torque pulsation of the motor, and meet the requirements of the electric vehicle field on high-precision and high-dynamic response control of the torque.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and in particular to a direct torque flux control method and system for a dual three-phase electric drive system for an electric vehicle. Background Art

[0002] The multi-phase permanent magnet electric drive system with many advantages such as low voltage and high power output, low torque pulsation, and suitable for fault-tolerant operation is more in line with the requirements of electric vehicles for high power and high reliability, and has become a new research hotspot in the electric vehicle industry. Among various types of multi-phase permanent magnet motor systems, the six-phase (double three-phase) permanent magnet motor, which is closely related to the traditional three-phase permanent magnet motor, has received extensive attention and research. Among them, the double three-phase permanent magnet synchronous motor (DTP-PMSM) with a phase shift of 30 degrees has smaller torque pulsation, and continues the advantages of high power density and high torque density of traditional three-phase permanent magnet synchronous motors, which has obvious advantages in practical engineering applications. The commonly used control methods of double three-phase permanent magnet synchronous motors are consistent with those of traditional three-phase permanent magnet synchronous motors, mainly focusing on vector control (FOC) and direct torque control (DTC). However, for multivariable, nonlinear, and strongly coupled systems such as double three-phase permanent magnet motors, FOC is easily affected by parameter dependence, resulting in slow dynamic performance and requiring complex parameter setting and decoupling algorithms. Conventional DTC has shortcomings such as large torque pulsation and unsatisfactory low-speed operation. Summary of the invention

[0003] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, a direct torque flux control method and system for a dual three-phase electric drive system for an electric vehicle are provided. The present invention aims to solve the problems of large torque pulsation and unsatisfactory low-speed operation of the existing direct torque control (DTC), improve the dynamic response capability and robustness of the system, reduce stator current harmonics to reduce motor torque pulsation, and meet the requirements of high-precision and high dynamic response control of torque in the field of electric vehicles.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: A direct torque flux control method for a dual three-phase electric drive system for an electric vehicle, comprising: Subplane based on Coordinate axis system for direct torque flux control: Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and the estimated stator flux angle ; According to the amplitude of the given stator flux , Shaft current component and The torque and flux observer observation results are used to calculate the torque and flux errors for direct torque and flux control. Axis reference voltage for controlling dual three-phase electric drive systems for electric vehicles Sub-plane converter; also includes a dual three-phase electric drive system for electric vehicles Subplane, right and The current loop uses a PR controller for closed-loop regulation. Axis reference voltage for controlling dual three-phase electric drive systems for electric vehicles Sub-plane converter.

[0005] Optionally, the amplitude of the given stator flux is According to the given torque Obtained by looking up the table using the MTPA algorithm.

[0006] Optionally, the Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and stator flux angle When the torque and flux observer is used to observe the real-time torque estimate of the motor The function expression is: , in, for The estimated real-time torque of the motor at the moment, for The real-time torque of the motor at the moment, is the sampling period, for Intermediate variables at time , for The stator flux amplitude at time , for The reference stator flux angle at time , for The stator flux angle at time , for The real-time motor speed at the moment, and the intermediate variable The calculation function expression is: , in, is the number of pole pairs of the motor, and They are The stator inductance component in the coordinate system, is the rotor flux, is the stator flux amplitude, is the load angle, and the load angle is the angle between the stator flux and the rotor flux.

[0007] Optionally, the Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and stator flux angle When the torque and flux observer is used to observe the amplitude of the stator flux estimate The function expression is: , in, and They are The estimated value of stator flux at time , Axis component, and They are The stator flux at the moment , Axis component, is the sampling period, and They are Moment Axis reference voltage , Axis component, is the stator resistance, and They are The stator current at the moment , Axis component.

[0008] Optionally, the Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and the estimated stator flux angle When the torque and flux observer is used to observe the estimated value of the stator flux angle The function expression is: , in, is the reference stator flux angle at time k, for The estimated value of the stator flux angle at time , for Always Observing The estimated value of the stator flux angle at time , for The given torque at the time, for Always Observing The estimated real-time torque of the motor at the moment, for Always Observing Intermediate variables at time The estimated value of for Always Observing The magnitude of the estimated stator flux at time , is the sampling period, for The real-time motor speed at the moment, and the intermediate variable The calculation function expression is: , in, is the number of pole pairs of the motor, and They are The stator inductance component in the coordinate system, is the rotor flux, is the stator flux amplitude, is the load angle, which is the angle between the stator flux and the rotor flux; the intermediate variable The calculation function expression of the estimated value of is: , in, for Always Observing The load angle at the moment.

[0009] Optionally, the amplitude of the given stator flux is , Shaft current component and The torque and flux observer observation results are used to calculate the torque and flux errors for direct torque and flux control. The function expression of the shaft reference voltage is: , in, and They are time Axis reference voltage , Axis component, and They are Reference to stator flux at all times , Axis component, and They are Predicted at all times The estimated value of stator flux at time , Axis component, is the stator resistance, and They are Phase current sampled at all times through After coordinate transformation, , Axis component.

[0010] Optionally, the Reference to stator flux at all times , The calculation function expression of the axis component is: , in, for The given stator flux at time, for The reference stator flux angle at time.

[0011] In addition, the present invention also provides a direct torque flux control system for a dual three-phase electric drive system for an electric vehicle, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the direct torque flux control method for the dual three-phase electric drive system for an electric vehicle.

[0012] In addition, the present invention also provides a computer-readable storage medium, which stores a computer program or instruction, and the computer program or instruction is programmed or configured to execute the direct torque flux control method of the dual three-phase electric drive system for an electric vehicle through a processor.

[0013] In addition, the present invention also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the direct torque flux control method of the dual three-phase electric drive system for an electric vehicle through a processor.

[0014] Compared with the prior art, the present invention mainly has the following advantages: in order to meet the requirements of high-precision and high dynamic response control of torque in the field of electric vehicles, on the one hand, the present invention can solve the problems of complex control, slow dynamic response, large torque pulsation, etc. in traditional dual three-phase permanent magnet synchronous motor vector control or direct torque control methods, and realize high-precision and high dynamic response control of motor speed and torque, good steady-state and dynamic performance, and small torque pulsation; on the other hand, the present invention can solve the problems of complex calculation, coupling of torque and flux, poor steady-state performance, large harmonic current, etc. in traditional zero-beat direct torque flux control strategy, and the calculation is simple, and the decoupling and precise control of torque and flux are reliable, and the engineering practicality is strong. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Schematic diagram of the control principle of the method according to an embodiment of the present invention.

[0015] Figure 2 Schematic diagram of stator current and flux vector distribution in an embodiment of the present invention.

[0016] Figure 3 Schematic diagram of the control principle of torque control in an embodiment of the present invention.

[0017] Figure 4 Schematic diagram of the control principle of stator flux control in an embodiment of the present invention.

[0018] Figure 5 The figure is a dynamic experimental result of the traditional DB-DTFC strategy used as a comparison in the embodiment of the present invention.

[0019] Figure 6 The following are the dynamic experimental results of the method of the embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0021] The control principle of the direct torque flux control method for the dual three-phase electric drive system of an electric vehicle of the present invention is as follows: Figure 1 As shown, see Figure 1 Based on the traditional vector space decoupling (VSD) technology, the direct torque flux control method of the dual three-phase electric drive system for electric vehicles in this embodiment includes: Subplane based on Coordinate axis system for direct torque flux control: Shaft current component and The torque and flux observer (Torque & Flux Observer) is used to obtain the real-time torque estimate of the motor. , the magnitude of the estimated stator flux and the estimated stator flux angle ; According to the amplitude of the given stator flux , Shaft current component and The torque and flux observer observation results are used to perform direct torque flux control (DB-DTFC) using the torque and flux errors to calculate Axis reference voltage for controlling dual three-phase electric drive systems for electric vehicles Sub-plane converter; also includes a dual three-phase electric drive system for electric vehicles Subplane, right and The current loop uses a PR (proportional resonant) controller for closed-loop regulation. Axis reference voltage for controlling dual three-phase electric drive systems for electric vehicles Sub-plane converter.

[0022] See also Figure 1 In this embodiment, direct torque flux control (DB-DTFC) is used to replace the PI regulator in the traditional FOC control or the hysteresis comparison link in the traditional DTC control. and flux given , the current real-time speed of the motor , Shaft current component and , combined with the flux torque observer to obtain the real-time torque of the motor , stator flux amplitude and stator flux angle The required voltage vector is calculated using information such as torque and flux errors. Then, through SVPWM technology, the basic voltage space vector modulation is used to output the required arbitrary voltage vector, replacing the voltage vector lookup table output in the traditional DTC, which can reduce torque and flux pulsation and fix the switching frequency of the controller. In addition, the torque and flux observer can observe the real-time torque, flux amplitude and flux vector position for closed-loop control of torque and flux. Subplane, right and The current loop uses a PR controller for closed-loop regulation to suppress the 5th and 7th current harmonics generated by dead zone, stator winding asymmetry and back electromotive force distortion to reduce the motor torque ripple. Figure 1 As shown, the amplitude of the given stator flux in this embodiment is According to the given torque It is obtained by looking up the existing MTPA (maximum torque per current ratio) algorithm to achieve optimal efficiency control.

[0023] Figure 2 is a schematic diagram of stator current and flux vector distribution in an embodiment of the present invention, Figure 2 The two-phase stationary coordinate system ( ), two-phase rotating coordinate system with rotor field orientation ( ) and the stator field oriented two-phase rotating coordinate system ( ) relationship, where is the stator flux, is the rotor flux, is the stator current, and are the stator flux and rotor flux speeds respectively, and are the stator flux angle and the rotor flux angle respectively, It is the angle between the stator flux and the rotor flux, also called the load angle; and is the stator current , Axis component, and is the stator current , Axis component. Based on VSD coordinate transformation, In the stationary coordinate system, the stator flux equation of the dual three-phase permanent magnet synchronous motor in the dual three-phase electric drive system for electric vehicles can be expressed as: , (1) , (2) in, , They are Axis and Stator flux component on the shaft; , They are Axis and Stator voltage component on the shaft; , They are Axis and The stator current component on the shaft, is the stator resistance.

[0024] According to formula (1), The estimated value of stator flux at time can be expressed as: , (3) in, is the sampling period.

[0025] In digital control systems, there is a one-step delay in updating the PWM duty cycle. In addition, it is difficult to measure the armature voltage at the motor terminals for inverter-powered motor drive systems. and , usually using a reference voltage , To estimate the stator flux. Assume that there is no error between the reference voltage and the actual sampled voltage, that is, , , then in the The stator flux at the end of a PWM cycle can be expressed as: , (4) In order to achieve zero-beat control of the stator flux, the estimated stator flux , Need to follow the reference stator flux , , then in the The control input at the end of a PWM cycle can be calculated by the following formula: , (5) In formula (4), , and , Use them separately Prediction value at time , , , Instead, the reference voltage vector can be further obtained as follows: , (6) In this embodiment, according to the amplitude of the given stator flux , Shaft current component and The torque and flux observer observation results are used to calculate the torque and flux errors for direct torque and flux control. The functional expression of the shaft reference voltage is equation (6), where: and They are time Axis reference voltage , Axis component, and They are Reference to stator flux at all times , Axis component, and They are Predicted at all times The estimated value of stator flux at time , Axis component, is the stator resistance, and They are Phase current sampled at all times through After coordinate transformation, , Axis component, Reference to stator flux at all times , The calculation function expression of the axis component is: , (7) in, is the given stator flux at time k, is the reference stator flux angle at time k, and the reference stator flux angle can be obtained by the torque control in DB-DTFC.

[0026] The torque equation of the dual three-phase permanent magnet synchronous motor shown in equation (2) can be expressed as follows after coordinate transformation: , (8) in, and They are The stator inductance component in the coordinate system, is the number of motor pole pairs. Therefore, the torque change rate can be expressed as: , (9) Among them, A and B are intermediate variables, and there are: , (10) Usually, the second term on the right side of equation (9) is much smaller than the first term and can be ignored. Therefore, equation (9) can be expressed as: , (11) According to formula (11), The torque at the end of a PWM cycle can be expressed as: , (12) In order to achieve torque zero-beat control, the estimated torque needs to follow the reference torque , so the The reference stator flux angle at the end of a PWM cycle can be expressed as: , (13) Similarly, At the end of each PWM cycle, the stator flux angle, torque, and stator flux are substituted into their respective The predicted value at the sampling time, assuming that the motor speed is remains unchanged over time, that is Therefore, formula (13) can be rewritten as: , (14) In summary, we can establish The control strategy of DB-DTFC in the coordinate system includes two stages: torque control and stator flux control. The control principle diagrams are as follows: Figure 3 and Figure 4 As shown. Among them, , After calibration, Shaft current , The results are obtained by looking up the table to avoid the impact of motor parameter changes on control performance.

[0027] In this embodiment, Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and stator flux angle When the torque and flux observer is used to observe the real-time torque estimate of the motor The functional expression of is the above formula (12), where for The estimated real-time torque of the motor at the moment, for The real-time torque of the motor at the moment, is the sampling period, for Intermediate variables at time , for The stator flux amplitude at time , for The reference stator flux angle at time , for The stator flux angle at time , for The real-time motor speed at the moment.

[0028] like Figure 4 As shown, in this embodiment, Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and stator flux angle When the torque and flux observer is used to observe the amplitude of the stator flux estimate The functional expression of is the above formula (4), where and They are The estimated value of stator flux at time , Axis component, and They are The stator flux at the moment , Axis component, is the sampling period, and They are Moment Axis reference voltage , Axis component, is the stator resistance, and They are The stator current at the moment , Axis component.

[0029] like Figure 3 As shown, in this embodiment, Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and the estimated stator flux angle When the torque and flux observer is used to observe the estimated value of the stator flux angle The functional expression of is the above formula (14), where is the reference stator flux angle at time k, for The estimated value of the stator flux angle at time , for Always Observing The estimated value of the stator flux angle at time , for The given torque at the time, for Always Observing The estimated real-time torque of the motor at the moment, for Always Observing Intermediate variables at time The estimated value of for Always Observing The magnitude of the estimated stator flux at time , is the sampling period, for The real-time motor speed at the moment, and the intermediate variable The calculation function expression of is shown in the above formula (10); for Always Observing The magnitude of the estimated stator flux at time is Predicted at all times The estimated value of stator flux at time , Axis Component and The sum of the squares of the two; the intermediate variable The calculation function expression of the estimated value of is: , (15) in, for Always Observing Intermediate variables at time , for Always Observing The load angle at time , see Figure 3 , in the torque control link, the function expression of the observed load angle is: , (16) in, For observation The load angle at the moment is Always Observing Moment .

[0030] In order to verify the direct torque flux control method of the dual three-phase electric drive system for electric vehicles in this embodiment, all experiments in this embodiment are tested on a dual three-phase permanent magnet synchronous motor platform powered by two three-phase voltage source inverters. The dual three-phase permanent magnet synchronous motor and experimental control parameters are shown in Table 1. The method of this embodiment is compared with the FOC (vector control) and traditional DB-DTFC strategies in the prior art. The final experimental data are shown in Table 2.

[0031] Table 1: Dual three-phase permanent magnet synchronous motor and experimental control parameters

[0032] In Table 1, K p , Kr and are the proportional gain coefficient, resonant gain coefficient and resonant frequency of the PR controller respectively, is the reference frequency.

[0033] Table 2: Comparison of experimental data of different control strategies under steady-state operation

[0034] As shown in Table 2, compared with FOC (vector control) and traditional DB-DTFC strategies, the torque ripple and current harmonics of the direct torque flux control method for the dual three-phase electric drive system for electric vehicles in this embodiment are smaller, and the program execution time is greatly shortened, which has high engineering application value. In addition, dynamic experiments are also carried out in this embodiment. The dynamic experiment is carried out by increasing and decreasing the load torque. r / min At a speed of T e From 50 Nm Increase to 100 Nm Then from 100 Nm Reduce to 50 Nm The experimental results of the conventional DB-DTFC and the direct torque flux control method for the dual three-phase electric drive system for electric vehicles in this embodiment are shown in Figure 5 and Figure 6 As shown, speed Indicates the real-time speed of the motor. i A and i D The A and D phase currents of the dual three-phase electric drive system for electric vehicles are Figure 5 and Figure 6 It can be seen that, compared with the traditional DB-DTFC strategy, the direct torque flux control method of the dual three-phase electric drive system for electric vehicles in this embodiment has good torque and stator current control performance under different conditions, and the torque pulsation is smaller. In addition, when the load torque changes, the speed can also quickly return to stability. Therefore, the direct torque flux control method of the dual three-phase electric drive system for electric vehicles in this embodiment can meet the requirements of high-precision and high-dynamic response control of torque in the field of electric vehicles. It should be noted that although the direct torque flux control strategy in the method of this embodiment can be used based on dual Coordinate transformation, standard vector control based on VSD or traditional DTC algorithm based on hysteresis comparison can be used as an alternative, but the control is more complicated and has poor robustness. The deadbeat direct torque flux control method based on the coordinate system can be used in other Coordinate system or based on Coordinate system torque and flux control method, but the calculation is complex, it is difficult to achieve torque and flux decoupling, and the system steady-state and dynamic performance are poor. The electronic voltage component on the coordinate system realizes the decoupling and deadbeat control of stator flux and torque, and combines the real-time prediction of torque flux and the real-time table lookup of inductance parameters with the Compared with traditional FOC (vector control) or DTC control, the strategy has the following advantages when combined with sub-plane PR harmonic suppression: (1) The calculation complexity of the stator voltage in this strategy is lower than that of the traditional DB-DTFC strategy, which can greatly reduce the calculation burden of the control chip; (2) This strategy reduces the total harmonic distortion of the stator flux and current, and effectively suppresses the motor torque pulsation; (3) This strategy has good steady-state and dynamic performance, achieves high-precision control of the motor speed and torque, has high parameter robustness, and has high engineering application value. In addition, this embodiment also provides a direct torque flux control system for a dual three-phase electric drive system for an electric vehicle, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the direct torque flux control method for the dual three-phase electric drive system for an electric vehicle.

[0035] In addition, this embodiment also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the direct torque flux control method of the dual three-phase electric drive system for the electric vehicle through a processor.

[0036] In addition, this embodiment also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the direct torque flux control method of the dual three-phase electric drive system for an electric vehicle through a processor.

[0037] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A direct torque flux control method for a dual three-phase electric drive system for an electric vehicle, characterized in that: Including dual three-phase electric drive systems for electric vehicles Subplane based on Coordinate axis system for direct torque flux control: Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and the estimated stator flux angle ; According to the amplitude of the given stator flux , Shaft current component and The torque and flux observer observation results are used to calculate the torque and flux errors for direct torque and flux control. Axis reference voltage for controlling dual three-phase electric drive systems for electric vehicles Sub-plane converter; also includes a dual three-phase electric drive system for electric vehicles Subplane, right and The current loop uses a PR controller for closed-loop regulation. Axis reference voltage for controlling dual three-phase electric drive systems for electric vehicles Sub-plane converter.

2. The direct torque flux control method for a dual three-phase electric drive system for an electric vehicle according to claim 1, characterized in that: The amplitude of the given stator flux is According to the given torque Obtained by looking up the table using the MTPA algorithm.

3. The direct torque flux control method for a dual three-phase electric drive system for an electric vehicle according to claim 1, characterized in that: The Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and stator flux angle When the torque and flux observer is used to observe the real-time torque estimate of the motor The function expression is: ， in, for The estimated real-time torque of the motor at the moment, for The real-time torque of the motor at the moment, is the sampling period, for Intermediate variables at time , for The stator flux amplitude at time , for The reference stator flux angle at time , for The stator flux angle at time , for The real-time motor speed at the moment, and the intermediate variable The calculation function expression is: ， in, is the number of pole pairs of the motor, and They are The stator inductance component in the coordinate system, is the rotor flux, is the stator flux amplitude, is the load angle, and the load angle is the angle between the stator flux and the rotor flux.

4. The direct torque flux control method for a dual three-phase electric drive system for an electric vehicle according to claim 1, characterized in that: The Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and stator flux angle When the torque and flux observer is used to observe the amplitude of the stator flux estimate The function expression is: ， in, and They are The estimated value of stator flux at time , Axis component, and They are The stator flux at the moment , Axis component, is the sampling period, and They are Moment Axis reference voltage , Axis component, is the stator resistance, and They are The stator current at the moment , Axis component.

5. The direct torque flux control method for a dual three-phase electric drive system for an electric vehicle according to claim 1, characterized in that: The Shaft current component and The real-time torque estimate of the motor is obtained by using the torque and flux observer , the magnitude of the estimated stator flux and the estimated stator flux angle When the torque and flux observer is used to observe the estimated value of the stator flux angle The function expression is: ， in, is the reference stator flux angle at time k, for The estimated value of the stator flux angle at time , for Always Observing The estimated value of the stator flux angle at time , for The given torque at the time, for Always Observing The estimated real-time torque of the motor at the moment, for Always Observing Intermediate variables at time The estimated value of for Always Observing The magnitude of the estimated stator flux at time , is the sampling period, for The real-time motor speed at the moment, and the intermediate variable The calculation function expression is: ， in, is the number of pole pairs of the motor, and They are The stator inductance component in the coordinate system, is the rotor flux, is the stator flux amplitude, is the load angle, which is the angle between the stator flux and the rotor flux; the intermediate variable The calculation function expression of the estimated value of is: ， in, for Always Observing The load angle at the moment.

6. The direct torque flux control method for a dual three-phase electric drive system for an electric vehicle according to claim 5, characterized in that: The amplitude of the given stator flux is , Shaft current component and The torque and flux observer observation results are used to calculate the torque and flux errors for direct torque and flux control. The function expression of the shaft reference voltage is: ， in, and They are time Axis reference voltage , Axis component, and They are Reference to stator flux at all times , Axis component, and They are Predicted at all times The estimated value of stator flux at time , Axis component, is the stator resistance, and They are Phase current sampled at every moment through After coordinate transformation, , Axis component.

7. The direct torque flux control method for a dual three-phase electric drive system for an electric vehicle according to claim 6, characterized in that: Said Reference to stator flux at all times , The calculation function expression of the axis component is: ， in, for The given stator flux at time, for The reference stator flux angle at time.

8. A dual three-phase electric drive system direct torque flux control system for an electric vehicle, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the direct torque flux control method for a dual three-phase electric drive system for an electric vehicle as claimed in any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the direct torque flux control method for a dual three-phase electric drive system for an electric vehicle as claimed in any one of claims 1 to 7 through a processor.

10. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the direct torque flux control method for a dual three-phase electric drive system for an electric vehicle as claimed in any one of claims 1 to 7 through a processor.

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