A method and system for weak magnetic control of an electric vehicle torque-enhanced permanent magnet motor

Abstract

This invention discloses a field weakening control method and system for a torque-enhanced permanent magnet synchronous motor for electric vehicles, relating to the field of torque-enhanced permanent magnet synchronous motors, including the following steps: Step S1, based on the actual speed of the torque-enhanced permanent magnet synchronous motor... ω m and given speed ω m * Step S2: Determine the current amplitude setpoint; Step S3: Calculate the current trajectory during MTPA control operation based on the inverter's limit voltage. U lim With stator voltage setpoint U s The difference Δ U Step S4: Determine whether field weakening control needs to be activated; Step S5: The field weakening area includes field weakening zone 1 and field weakening zone 2; Step S6: Generate a space vector pulse width modulation signal based on the current given value and the actual current value. This invention adopts the above-mentioned field weakening control method and system for torque-enhanced permanent magnet motors in electric vehicles to realize speed regulation control of torque-enhanced permanent magnet synchronous motors across the entire speed range.

Description

Technical Field

[0001] This invention relates to the field of torque-enhancing permanent magnet synchronous motor technology, and in particular to a field weakening control method and system for a torque-enhancing permanent magnet motor for electric vehicles. Background Technology

[0002] Compared to traditional permanent magnet synchronous motors, torque-enhanced permanent magnet synchronous motors (PMSMs) enable the permanent magnet torque and reluctance torque to reach their maximum values ​​at the same or similar current phase angles, significantly improving the torque density per unit permanent magnet and the field weakening speed-enhancing capability. When applied in electric vehicles, torque-enhanced PMSMs require excellent field weakening control methods to achieve good field weakening speed regulation capabilities.

[0003] This invention proposes a field weakening control method for a torque-enhanced permanent magnet synchronous motor. First, it calculates the current trajectory during operation at the maximum torque-to-current ratio (MTPA) and maximum torque-to-voltage ratio (MTPV) in the dq coordinate system. Then, it obtains the d'q' coordinate system through coordinate rotation and calculates the current trajectory during MTPA and MTPV operation in the d'q' coordinate system to obtain the current command. However, this method involves coordinate rotation in both the first and second field weakening regions, resulting in a large computational load. An improved lead-angle field weakening control method is proposed. When the torque-enhanced permanent magnet synchronous motor operates in the MTPA and first field weakening regions, a lead-angle field weakening control method is used. In the deep field weakening region, i.e., the second field weakening region, the current command for the deep field weakening region is obtained by linearizing the MTPV curve, but the control is still relatively cumbersome. Summary of the Invention

[0004] The purpose of this invention is to provide a field weakening control method and system for torque-enhanced permanent magnet synchronous motors in electric vehicles, enabling MTPV operation of the torque-enhanced permanent magnet synchronous motor, reducing computational load and control complexity, and achieving speed regulation control of the torque-enhanced permanent magnet synchronous motor across its full speed range.

[0005] To achieve the above objectives, the present invention provides a field weakening control method and system for a torque-enhanced permanent magnet synchronous motor for electric vehicles, comprising the following steps: Step S1, based on the actual speed of the torque-enhanced permanent magnet synchronous motor... ω m and given speed ω m * Determine the current amplitude setpoint ; Step S2: Based on the stator voltage equation, electromagnetic torque equation, and current constraint conditions of the torque-enhanced permanent magnet synchronous motor, calculate the current trajectory during maximum torque-current ratio (MTPA) control operation; determine the current phase angle setpoint during maximum torque-current ratio (MTPA) control operation. γ0. Based on the voltage limit equation and electromagnetic torque equation without considering resistance voltage drop, calculate the current trajectory during MTPV control operation at the maximum torque-voltage ratio, and determine the maximum operating value of the current phase angle. dq Current plane rotation angle ζ ; Step S3: Based on the inverter's limiting voltage U lim With stator voltage setpoint U s The difference Δ U The system determines whether field weakening control needs to be activated. When field weakening control is activated, the current phase angle compensation amount Δγ is output through the current phase angle compensation PI controller. The sum of the current phase angle setpoint and the current phase angle compensation amount during maximum torque current ratio (MTPA) control operation is the current phase angle of the field weakening zone 1, and its upper limit is not greater than the maximum operating value of the current phase angle. The field weakening zone of the torque-enhanced permanent magnet synchronous motor is determined based on the difference between the sum of the current phase angle setpoint and the current phase angle compensation amount during maximum torque current ratio (MTPA) control operation and the maximum operating value of the current phase angle. When field weakening control is not activated, the maximum torque current ratio (MTPA) control operation is performed, and the current setpoint is given by the current amplitude setpoint and the current phase angle setpoint during maximum torque current ratio (MTPA) control operation. Step S4: The magnetic weakening region includes magnetic weakening region one and magnetic weakening region two; When operating in the first field weakening zone, the current setpoint is given by the current amplitude setpoint and the current phase angle in the first field weakening zone. Operating in the weak magnetic field zone II, dq Rotating the current plane by a certain angle yields d 1 q 1. The current plane and the direct-axis current value and quadrature-axis current value are output through the PI controller to compensate for the quadrature-axis current. d 1 q 1. The direct-axis current setpoint in the current plane is the direct-axis current value, and the quadrature-axis current setpoint is the difference between the quadrature-axis current value and the quadrature-axis current compensation. Through coordinate system rotation transformation, the current... d 1 q 1. Rotating the current plane by the corresponding angle yields the original value. dq The current plane is used to obtain the current setpoint during operation in the second weak magnetic region. Step S5: Generate a space vector pulse width modulation signal based on the given current value and the actual current value.

[0006] Preferably, in step S1, the rotor mechanical position angle of the torque-enhanced permanent magnet synchronous motor is measured by an optical encoder mounted on the rotor shaft of the motor. θ mThe data is then sent to the angular velocity processing module, which processes the rotor position angle measured by the photoelectric encoder. θ m The rotational speed is obtained through differential calculation. ω r The speed PI controller calculates the speed based on the angular velocity processing module. ω m and the given target speed ω m * The given value of the current amplitude is calculated. .

[0007] Preferably, in step S2, the stator voltage equation of the torque-enhanced permanent magnet synchronous motor is as follows: ; in, R Phase resistance; , They are respectively dq shaft current; L d , L q They are respectively dq Shaft inductance; ω e The rotor's electric angular velocity; It is a permanent magnet flux linkage; θ s This is the magnetic flux offset angle; The electromagnetic torque equation for a torque-enhanced permanent magnet synchronous motor is shown below: ; in, p It is the extreme logarithm; ψ d , ψ q They are respectively dq Axial magnetic flux; The current constraint condition for a torque-enhanced permanent magnet synchronous motor is shown in the following equation: ; in, I max The maximum allowable current; The current trajectory equation for a torque-enhanced permanent magnet synchronous motor under maximum torque-current ratio (MTPA) control is shown in the following equation: ; In the MPTA module, the current phase angle setpoint for MTPA control is determined based on the current constraints and the current trajectory during MTPA control operation. ; Based on the voltage limit equation and electromagnetic torque equation of the torque-enhanced permanent magnet synchronous motor without considering resistance voltage drop, calculate the current trajectory and the coordinates of the center point C of the voltage limit circle when operating under MTPV control at the maximum torque-voltage ratio. The voltage limit equation, neglecting the voltage drop across the resistor, is as follows: ; in, U lim This is the inverter's maximum output voltage; U dc Limitation of DC bus voltage; The coordinates of the center point C of the voltage limiting circle are shown in the following formula: ; Calculate the current trajectory during MTPV control operation at maximum torque-voltage ratio; The current trajectory under MTPV control at maximum torque-voltage ratio can be obtained using Lagrange's extremum theorem, as shown in the following equation: ; In the MPTV module, based on the current constraints and the current trajectory during MTPV control operation, the intersection point A of the current limit circle and the MTPV current trajectory is calculated. Connecting the intersection point A of the current limit circle and the current trajectory during MTPV control operation to the origin O of the current plane, the maximum operating value of the current phase angle is determined. When the current limiting circle and the maximum torque-voltage ratio (MTPV) control are running, the intersection point A of the current trajectory and the center point C of the voltage limiting circle are used to determine... dq Current plane rotation angle ζ.

[0008] Preferably, in step S3, in the current phase angle compensation module, based on the inverter limit voltage... U lim With stator voltage setpoint U s The difference Δ U To determine whether field weakening control needs to be activated, the following formula is used: Δ U=U lim - U s ; When Δ U≤ At 0, the weak magnetic field control mechanism is triggered; In a current phase angle compensation PI controller, the compensation value is generated based on the voltage difference Δ obtained from the current phase angle compensation module. UOutput current phase angle compensation Δγ; When operating at base speed, the torque-enhanced permanent magnet synchronous motor is under MTPA control. dq Shaft current and ， As shown in the following formula: ; In the field weakening zone 1 current phase angle limiting module, the current phase angle setpoint obtained from the MTPA module is... The current phase angle compensation amount Δ obtained from the current phase angle compensation PI controller γ sum Maximum operating value limited by current phase angle γ m The phase angle of the current in the weak magnetic region is obtained within the range. As shown in the following formula: ; in, = + .

[0009] Preferably, in step S4, the quadrature-axis current compensation PI controller dynamically generates... q The 1-axis compensation amount is shown in the following formula: ; in, For the need in the new coordinate system q The amount of current compensated on axis 1; This is the gain direction factor; and These are the proportional and integral coefficients of the field weakening controller, respectively.

[0010] A torque-enhancing permanent magnet motor field weakening control system for electric vehicles includes a torque-enhancing permanent magnet synchronous motor, a DC power supply, an inverter bridge, and an ABC converter. dq converter q Axis current PI controller d Axis current PI controller dq-αβ Converter, SVPWM module, photoelectric encoder, angular velocity processing module, speed PI controller, MTPA module, current phase angle compensation module, current phase angle compensation PI controller, MTPV module, field weakening zone 1 current phase angle limiting module, quadrature axis current compensation PI controller. dq Coordinate system - d 1 q 1. Coordinate system transformer d 1 q 1. Coordinate system - dqCoordinate system transformer.

[0011] Therefore, the purpose of this invention is to provide a field weakening control method and system for torque-enhanced permanent magnet synchronous motors in electric vehicles, enabling MTPV operation of the torque-enhanced permanent magnet synchronous motor, reducing computational load and control complexity, and achieving full-speed range speed control of the torque-enhanced permanent magnet synchronous motor. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall process of the field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle according to the present invention. Figure 2 This is a schematic diagram of the rotor structure of a torque-enhancing permanent magnet synchronous motor, which is part of the field weakening control method for a torque-enhancing permanent magnet motor in electric vehicles according to the present invention. Figure 3 This is a torque characteristic curve of a torque-enhanced permanent magnet synchronous motor for a torque-enhanced permanent magnet motor field weakening control method for electric vehicles according to the present invention. Figure 4 This is a control principle diagram of an electric vehicle according to the present invention; Figure 5 This is a schematic diagram of the MTPA and the current trajectory in the field weakening zone 1 of the field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle according to the present invention. Figure 6 This is a schematic diagram of the field weakening two-zone current trajectory of the field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle according to the present invention. Figure 7 This is a simulation diagram of the current trajectory of a torque-enhancing permanent magnet motor field weakening control method for electric vehicles according to the present invention.

[0013] Figure Labels 1. Torque-enhanced permanent magnet synchronous motor; 2. DC power supply; 3. Inverter bridge; 4. ABC- dq Converter; 5. q 6. Shaft current PI controller; d 7. Shaft current PI controller; dq - αβ 8. Converter; 9. SVPWM module; 10. Photoelectric encoder; 11. Angular velocity processing module; 12. Speed ​​PI controller; 13. MTPA module; 14. Current phase angle compensation module; 15. Current phase angle compensation PI controller; 16. MTPV module; 17. Field weakening zone I current phase angle limiting module; 18. Quadrature axis current compensation PI controller; dq Coordinate system - d 1 q 1. Coordinate system transformer; 19. d 1 q 1. Coordinate system - dqCoordinate system transformer. Detailed Implementation

[0014] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0016] Example 1 like Figures 1 to 7 As shown, the present invention provides a field weakening control method for a torque-enhancing permanent magnet motor in electric vehicles, comprising the following steps: Step S1: Based on the actual speed of the torque-enhanced permanent magnet synchronous motor 1 ω m and given speed ω m * Determine the current amplitude setpoint .

[0017] In step S1, the rotor mechanical position angle of the torque-enhanced permanent magnet synchronous motor 1 is measured by the photoelectric encoder 9 installed on the rotor shaft of the torque-enhanced permanent magnet synchronous motor 1. θ m The data is then sent to the angular velocity processing module 10, which processes the rotor position angle measured by the photoelectric encoder 9. θ m The rotational speed is obtained through differential calculation. ω r The rotational speed PI controller 11 calculates the rotational speed based on the angular velocity processing module 10. ω m and the given target speed ω m * The given value of the current amplitude is calculated. .

[0018] Step S2: Based on the stator voltage equation, electromagnetic torque equation, and current constraint conditions of the torque-enhanced permanent magnet synchronous motor 1, calculate the current trajectory during maximum torque-to-current ratio (MTPA) control operation. Determine the current phase angle setpoint during maximum torque-to-current ratio (MTPA) control operation. γ 0. Based on the voltage limit equation and electromagnetic torque equation without considering resistance voltage drop, calculate the current trajectory during MTPV control operation at the maximum torque-voltage ratio, and determine the maximum operating value of the current phase angle. dq Current plane rotation angle ζ .

[0019] In step S2, the stator voltage equation of the torque-enhanced permanent magnet synchronous motor 1 is shown below: ; in, R Phase resistance; , They are respectively dq shaft current; L d , L q They are respectively dq Shaft inductance; ω e The rotor's electric angular velocity; It is a permanent magnet flux linkage; θ s This is the magnetic flux offset angle.

[0020] The electromagnetic torque equation of the torque-enhanced permanent magnet synchronous motor 1 is shown in the following equation: ; in, p It is the extreme logarithm; ψ d , ψ q They are respectively dq Axial magnetic flux linkage.

[0021] The current constraint condition for the torque-enhanced permanent magnet synchronous motor 1 is shown in the following equation: ; in, I max The maximum allowable current.

[0022] The current trajectory equation for the torque-enhanced permanent magnet synchronous motor 1 under maximum torque-to-current ratio (MTPA) control is shown in the following equation: ; In the MPTA module, the current phase angle setpoint for MTPA control is determined based on the current constraints and the current trajectory during MTPA control operation. .

[0023] Based on the voltage limit equation and electromagnetic torque equation of the torque-enhanced permanent magnet synchronous motor 1 without considering resistance voltage drop, calculate the current trajectory and the coordinates of the center point C of the voltage limit circle during operation under MTPV control at the maximum torque-voltage ratio.

[0024] The voltage limit equation, neglecting the voltage drop across the resistor, is as follows: ; in,U lim This is the inverter's maximum output voltage; U dc Limitation of DC bus voltage; The coordinates of the center point C of the voltage limiting circle are shown in the following formula: ; Calculate the current trajectory during MTPV control operation at maximum torque-voltage ratio.

[0025] The current trajectory under MTPV control at maximum torque-voltage ratio can be obtained using Lagrange's extremum theorem, as shown in the following equation: ; In MPTV module 15, based on the current constraint conditions and the current trajectory during MTPV control operation, the intersection point A of the current limit circle and the MTPV current trajectory is calculated; by connecting the intersection point A of the current limit circle and the current trajectory during MTPV control operation with the origin O of the current plane, the maximum operating value of the current phase angle is determined. When the current limiting circle and the maximum torque-voltage ratio (MTPV) control are running, the intersection point A of the current trajectory and the center point C of the voltage limiting circle are used to determine... dq Current plane rotation angle ζ.

[0026] Step S3: Based on the inverter's limiting voltage U lim With stator voltage setpoint U s The difference Δ U The system determines whether field weakening control needs to be activated. When field weakening control is activated, the current phase angle compensation amount Δγ is output through the current phase angle compensation PI controller 14. The sum of the current phase angle setpoint and the current phase angle compensation amount during maximum torque current ratio (MTPA) control operation is the current phase angle of the field weakening zone 1, and its upper limit is not greater than the maximum operating value of the current phase angle. Based on the difference between the sum of the current phase angle setpoint and the current phase angle compensation amount during maximum torque current ratio (MTPA) control operation and the maximum operating value of the current phase angle, the field weakening zone of the torque-enhanced permanent magnet synchronous motor 1 is determined. When field weakening control is not activated, the system operates under maximum torque current ratio (MTPA) control, and the current setpoint is given by the current amplitude setpoint and the current phase angle setpoint during maximum torque current ratio (MTPA) control operation.

[0027] In step S3, in the current phase angle compensation module 13, based on the inverter limit voltage... U lim With stator voltage setpoint U s The difference ΔU To determine whether field weakening control needs to be activated, the following formula is used: Δ U=U lim - U s ; When Δ U≤ At 0, the weak magnetic field control mechanism is triggered; In the current phase angle compensation PI controller 14, the compensation amount is generated based on the voltage difference Δ obtained from the current phase angle compensation module 13. U Output current phase angle compensation amount Δγ.

[0028] When operating at base speed, the torque-enhanced permanent magnet synchronous motor 1 is under MTPA control. dq Shaft current and ， As shown in the following formula: ; In the current phase angle limiting module 16 of the field weakening zone, the current phase angle setpoint obtained from the MTPA module 12 is used. The current phase angle compensation amount Δ obtained from the current phase angle compensation PI controller 14 γ sum Maximum operating value limited by current phase angle γ m The phase angle of the current in the weak magnetic region is obtained within the range. As shown in the following formula: ; in, = + .

[0029] In step S3, based on the current phase angle given value during maximum torque-current ratio control operation... Sum of current phase angle compensation Maximum operating value of phase angle with current The difference is used to determine the weak magnetic field region of the motor operation.

[0030] Step S4: The magnetic weakening region includes magnetic weakening region one and magnetic weakening region two; When operating in the first zone of magnetic field weakening, the current setpoint is given by the current amplitude setpoint and the current phase angle in the first zone of magnetic field weakening.

[0031] Operating in the weak magnetic field zone II, dq Rotating the current plane by a certain angle yields d 1 q1. The current plane and the direct-axis current value and quadrature-axis current value are output through the PI controller to compensate for the quadrature-axis current. d 1 q 1. The direct-axis current setpoint in the current plane is the direct-axis current value, and the quadrature-axis current setpoint is the difference between the quadrature-axis current value and the quadrature-axis current compensation. Through coordinate system rotation transformation, the current... d 1 q 1. Rotating the current plane by the corresponding angle yields the original value. dq The current plane is used to obtain the current setpoint during operation in the weak magnetic field zone II.

[0032] In step S4, when the motor is operating in the field weakening zone, the phase angle is directly compensated. generate dq Axis current.

[0033] ; For the final calculation q shaft current; For the final calculation d Axis current.

[0034] When the current amplitude is saturated, the maximum current output is forced.

[0035] ; for d Shaft current setpoint; for q Shaft current setpoint; This is the maximum allowable current limit of the system.

[0036] After entering the weak magnetic field zone II, dq Current plane rotation ζ Angle obtained d 1 q The current value after rotation in a plane is shown in the following formula: ; In order to be in d 1 q 1 coordinate system d I-axis current setpoint; In order to be in d 1 q 1 coordinate system q 1-axis current setpoint.

[0037] In the quadrature axis current compensation PI controller 17, dynamic generation is performed. q The 1-axis compensation amount is shown in the following formula: ; in, For the need in the new coordinate system q The amount of current compensated on axis 1; This is the gain direction factor; and These are the proportional and integral coefficients of the field weakening controller, respectively.

[0038] Compensation current gain during motor acceleration and deceleration Satisfy the following formula: ; exist dq Coordinate system - d 1 q In coordinate system transformer 18, maintain d The 1-axis current remains unchanged, only updated. q The axial current is shown in the following formula: ; exist d 1 q 1. Coordinate system - dq In coordinate system transformer 19, the optimized d 1 q 1. Current reverse rotation Angle restored to dq The plane generates the final driving instructions, as shown in the following formula.

[0039] .

[0040] Step S5: Based on the current given value and the actual current value obtained, generate a space vector pulse width modulation signal to drive the motor's movement and achieve speed control across the entire speed range.

[0041] ABC - dq The converter utilizes electrical angle θ e The three-phase current value of the motor input obtained from the current transformer is transformed to... dq In coordinate system, we obtain d shaft and q Actual shaft current value and ; q The shaft current PI controller is based on the aforementioned motor q The given value of the shaft current as well as q Actual value of shaft current Calculations yielded q Shaft voltage setpoint u q * . dThe shaft current PI controller is based on the aforementioned motor d The given value of the shaft current as well as d Actual value of shaft current Calculations yielded d Shaft voltage setpoint u d * . dq-αβ The converter utilizes electrical angle θ e Set the voltage value u d * , u q * Depend on d-q Coordinate system transformation to α - β In coordinate system, we obtain u α and u β The SVPWM module is based on voltage reference. u α and u β The three-phase PWM signals are obtained.

[0042] A torque-enhancing permanent magnet motor field weakening control system for electric vehicles includes a torque-enhancing permanent magnet synchronous motor 1, a DC power supply 2, an inverter bridge 3, and an ABC-... dq Converter 4 q 5. Shaft current PI controller d 6. Axis current PI controller dq-αβ 7. Converter; 8. SVPWM module; 9. Photoelectric encoder; 10. Angular velocity processing module; 11. Speed ​​PI controller; 12. MTPA module; 13. Current phase angle compensation module; 14. Current phase angle compensation PI controller; 15. MTPV module; 16. Field weakening zone I current phase angle limiting module; 17. Quadrature axis current compensation PI controller. dq Coordinate system - d 1 q 1. Coordinate system transformer 18, d 1 q 1. Coordinate system - dq Coordinate system transformer 19.

[0043] The rotor mechanical position angle of the torque-enhanced permanent magnet synchronous motor 1 is measured by an optical encoder 9 installed on the rotor shaft of the motor 1. θ m The data is then sent to the angular velocity processing module 10; the angular velocity processing module 10 processes the rotor position angle measured by the photoelectric encoder 9. θm The rotational speed is obtained by differential calculation. ω r The rotational speed PI controller 11 calculates the rotational speed based on the angular velocity processing module 10. ω m and the given target rotational speed ω m * The given value of the current amplitude is calculated. 。 MTPA module 12 determines the current phase angle setpoint during MTPA control operation based on the current constraints of the motor and the current trajectory during MTPA control operation, using an auxiliary function. γ 0 。

[0044] Permanent magnet torque in torque characteristic curve T pm and reluctance torque T re The corresponding current phase angles are the same. dq Coordinate system - d 1 q 1. Coordinate system transformer 18 utilizes coordinate system rotation transformation to transform... dq Motor AC and DC axis current values ​​in the non-field weakening zone II under the current plane and Convert to d 1 q 1. Non-field weakening two-zone motor in the current plane d 1. q I-axis current setpoint , 。 Current phase angle compensation module 13 is based on the inverter's limiting voltage. U lim With stator voltage setpoint U s The difference Δ U Determine whether to enable weak magnetic field 。 The current phase angle compensation PI controller 14, based on the Δ obtained from the current phase angle compensation module 13, U The current phase angle compensation amount Δ is calculated. γ. The MTPV module 15 determines the maximum operating value of the current phase angle based on the intersection of the motor's MTPV trajectory and the current limiting circle. γ m and dq Current plane rotation angle ζ.

[0045] The field weakening zone 1 current phase angle limiting module 16 uses the current phase angle setpoint obtained from the MTPA module 12. γThe current phase angle compensation amount Δ obtained from the current phase angle compensation PI controller 14 is 0. γ sum ( γ 0+Δ γ The maximum operating value is limited to the current phase angle. γ m The phase angle of the current in the weak magnetic region is obtained within the range. γ ** ; Quadrature-axis current compensation PI controller 17, field weakening zone 1 current phase angle γ ** and( γ 0+Δ γ The difference between the two values ​​is used to calculate the quadrature axis current compensation amount. ; d 1 q 1. Coordinate system - dq Coordinate system transformer 19 uses coordinate system rotation transformation to transform... d 1 q 1. Quadrature axis current value in the current plane With cross-axis current compensation difference and Convert to dq Quadrature and direct axis current setpoints in the current plane , .

[0046] ABC - dq Converter 4 is used to utilize electrical angle θ e The three-phase current value of the motor input obtained from the current transformer is transformed to... dq In coordinate system, we obtain d shaft and q Actual shaft current value and . q Shaft current PI controller 5, based on the aforementioned motor q The given value of the shaft current as well as q Actual value of shaft current Calculations yielded q Shaft voltage setpoint u q * . d Shaft current PI controller 6, based on the aforementioned motor d The given value of the shaft current as well as d Actual value of shaft current Calculations yielded d Shaft voltage setpoint u d* . dq-αβ Converter 7 utilizes electrical angle θ e Set the voltage value u d * , u q * Depend on d-q Coordinate system transformation to α - β In coordinate system, we obtain u α and u β 。 SVPWM module 8 is based on voltage setpoint u α and u β The three-phase PWM signals are obtained and sent to the inverter bridge module. The inverter bridge module 3 is connected to the DC power supply 2 and the torque-enhanced permanent magnet synchronous motor 1. It generates three-phase voltage values ​​based on the aforementioned three-phase PWM signals to drive the motor.

[0047] The present invention employs the above-mentioned field weakening control method and system for torque-enhanced permanent magnet synchronous motors in electric vehicles to realize MTPV operation of torque-enhanced permanent magnet synchronous motors, reduce the amount of calculation and control complexity, and realize speed regulation control of torque-enhanced permanent magnet synchronous motors across the entire speed range.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle, characterized in that, Includes the following steps: Step S1: Based on the actual speed of the torque-enhanced permanent magnet synchronous motor ω m and given speed ω m * Determine the current amplitude setpoint i s * ; Step S2: Calculate the current trajectory during MTPA control operation based on the stator voltage equation, electromagnetic torque equation, and current constraint conditions of the torque-enhanced permanent magnet synchronous motor. Determine the current phase angle setpoint when operating under MTPA control at maximum torque-to-current ratio. γ 0. Based on the voltage limit equation and electromagnetic torque equation without considering resistance voltage drop, calculate the current trajectory during MTPV control operation at the maximum torque-voltage ratio, and determine the maximum operating value of the current phase angle. dq Current plane rotation angle ζ ; Step S3: Based on the inverter's limiting voltage U lim With stator voltage setpoint U s The difference Δ U The system determines whether field weakening control needs to be activated. When field weakening control is activated, the current phase angle compensation amount Δγ is output through the current phase angle compensation PI controller. The sum of the current phase angle setpoint and the current phase angle compensation amount during maximum torque current ratio (MTPA) control operation is the current phase angle of the field weakening zone 1, and its upper limit is not greater than the maximum operating value of the current phase angle. The field weakening zone of the torque-enhanced permanent magnet synchronous motor is determined based on the difference between the sum of the current phase angle setpoint and the current phase angle compensation amount during maximum torque current ratio (MTPA) control operation and the maximum operating value of the current phase angle. When field weakening control is not activated, the maximum torque current ratio (MTPA) control operation is performed, and the current setpoint is given by the current amplitude setpoint and the current phase angle setpoint during maximum torque current ratio (MTPA) control operation. In step S3, in the current phase angle compensation module, based on the inverter's limiting voltage... U lim With stator voltage setpoint U s The difference Δ U To determine whether field weakening control needs to be activated, the following formula is used: D U=U lim - U s ; When Δ U≤ At 0, the weak magnetic field control mechanism is triggered; In a current phase angle compensation PI controller, the compensation value is generated based on the voltage difference Δ obtained from the current phase angle compensation module. U Output current phase angle compensation Δγ; When operating at base speed, the torque-enhanced permanent magnet synchronous motor is under MTPA control. dq Shaft current and ， As shown in the following formula: ； In the field weakening zone 1 current phase angle limiting module, the current phase angle setpoint obtained from the MTPA module is used. The current phase angle compensation amount Δ obtained from the current phase angle compensation PI controller γ sum Maximum operating value limited by current phase angle γ m The phase angle of the current in the weak magnetic region is obtained within the range. As shown in the following formula: ； in, = + ; Step S4: The magnetic weakening region includes magnetic weakening region one and magnetic weakening region two; When operating in the first field weakening zone, the current setpoint is given by the current amplitude setpoint and the current phase angle in the first field weakening zone. Operating in the weak magnetic field zone II, dq Rotating the current plane by a certain angle yields d 1 q 1. The current plane and the direct-axis current value and quadrature-axis current value are output through the PI controller to compensate for the quadrature-axis current. d 1 q 1. The direct-axis current setpoint in the current plane is the direct-axis current value, and the quadrature-axis current setpoint is the difference between the quadrature-axis current value and the quadrature-axis current compensation. Through coordinate system rotation transformation, the current... d 1 q 1. Rotating the current plane by the corresponding angle yields the original value. dq The current plane is used to obtain the current setpoint during operation in the second weak magnetic region. In step S4, the quadrature-axis current compensation PI controller dynamically generates... q The axial compensation amount is shown in the following formula: ； in, For the need in the new coordinate system q The amount of current compensated on axis 1; This is the gain direction factor; and These are the proportional and integral coefficients of the field weakening controller, respectively. Step S5: Generate a space vector pulse width modulation signal based on the given current value and the actual current value.

2. The field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle according to claim 1, characterized in that, In step S1, the rotor mechanical position angle of the torque-enhanced permanent magnet synchronous motor is measured by an optical encoder installed on the rotor shaft of the motor. θ m The data is then sent to the angular velocity processing module, which processes the rotor position angle measured by the photoelectric encoder. θ m The rotational speed is obtained through differential calculation. ω r ; The speed PI controller calculates the speed based on the angular velocity processing module. ω m and the given target speed ω m * The given value of the current amplitude is calculated. i* s .

3. The field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle according to claim 1, characterized in that, In step S2, the stator voltage equation of the torque-enhanced permanent magnet synchronous motor is shown below: ； in, R Phase resistance; i d , i q They are respectively dq shaft current; L d , L q They are respectively dq Shaft inductance; ω e The rotor's electric angular velocity; ψ f It is a permanent magnet flux linkage; θ s This is the magnetic flux offset angle; The electromagnetic torque equation for a torque-enhanced permanent magnet synchronous motor is shown below: ； in, p It is the extreme logarithm; ψ d , ψ q They are respectively dq Axial magnetic flux; The current constraint condition for a torque-enhanced permanent magnet synchronous motor is shown in the following equation: ； in, I max The maximum allowable current; The current trajectory equation for a torque-enhanced permanent magnet synchronous motor under maximum torque-current ratio (MTPA) control is shown in the following equation: ； In the MPTA module, the current phase angle setpoint for MTPA control is determined based on the current constraints and the current trajectory during MTPA control operation. ; Based on the voltage limit equation and electromagnetic torque equation of the torque-enhanced permanent magnet synchronous motor without considering resistance voltage drop, calculate the current trajectory and the coordinates of the center point C of the voltage limit circle when operating under MTPV control at the maximum torque-voltage ratio. The voltage limit equation, neglecting the voltage drop across the resistor, is as follows: ； in, U lim This is the inverter's maximum output voltage. U dc Limitation of DC bus voltage; The coordinates of the center point C of the voltage limiting circle are shown in the following formula: ； Calculate the current trajectory during MTPV control operation at maximum torque-voltage ratio; The current trajectory under MTPV control at maximum torque-voltage ratio can be obtained using Lagrange's extremum theorem, as shown in the following equation: ； In the MPTV module, based on the current constraints and the current trajectory during MTPV control operation, the intersection point A of the current limit circle and the MTPV current trajectory is calculated. Connecting the intersection point A of the current limit circle and the current trajectory during MTPV control operation to the origin O of the current plane, the maximum operating value of the current phase angle is determined. When the current limiting circle and the maximum torque-voltage ratio (MTPV) control are running, the intersection point A of the current trajectory and the center point C of the voltage limiting circle are used to determine... dq Current plane rotation angle ζ.

4. The field weakening control method for a torque-enhancing permanent magnet motor in an electric vehicle according to claim 1, characterized in that, In step S3, based on the current phase angle given value during maximum torque-current ratio control operation... Sum of current phase angle compensation Maximum operating value of phase angle with current The difference is used to determine the weak magnetic field region of the motor operation.

5. A field weakening control system for a torque-enhancing permanent magnet motor in an electric vehicle, applied to the control method described in any one of claims 1-4, characterized in that, Includes torque-enhanced permanent magnet synchronous motors, DC power supplies, inverter bridges, ABC- dq converter q Axis current PI controller d Axis current PI controller dq-αβ Converter, SVPWM module, photoelectric encoder, angular velocity processing module, speed PI controller, MTPA module, current phase angle compensation module, current phase angle compensation PI controller, MTPV module, field weakening zone 1 current phase angle limiting module, quadrature axis current compensation PI controller. dq Coordinate system - d 1 q 1. Coordinate system transformer d 1 q 1. Coordinate system - dq Coordinate system transformer.

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