A method and system for verifying motor position angle compensation

Abstract

This disclosure provides a method and system for verifying motor position angle compensation, relating to the field of motor control technology. The method includes: compensating for the motor position angle; rotating the compensated motor; providing direct-axis and quadrature-axis currents based on the motor speed; and determining the accuracy of the position angle compensation based on the direct-axis voltage. When the motor speed does not exceed the initial field-weakening speed, both the given direct-axis and quadrature-axis currents are zero. If the direct-axis voltage fluctuates around zero, the compensation is accurate. This disclosure improves the convenience of verifying motor position angle compensation.

Description

Technical Field

[0001] This disclosure relates to the field of motor control technology, specifically to a method and system for verifying motor position angle compensation. Background Technology

[0002] Currently, vector control is widely used in automotive motor control systems. Its basic idea is to mimic the field orientation of a DC motor: using the rotor flux linkage direction as the reference direction of the rotating coordinate system, the stator current is decomposed into a stator current excitation component in the same direction as the rotor flux linkage and a stator current torque component orthogonal to the flux linkage direction. This process is also called Park transform. The stator current torque component and current excitation component are controlled separately by a controller, outputting control voltages. Then, through inverse Park transform and pulse width modulation, the three-phase voltage in the stationary coordinate system is output. In this process, the phase synchronization of the rotating coordinate system and rotor rotation, as well as the synchronization of current sampling and position sampling, are crucial, directly affecting the magnitudes of the stator current torque component and current excitation component. Since motor control generally uses digital microcontroller control, various delays are included in the position and current sampling processes. These delays, as the speed increases, can cause initial position angle shifts. Without compensation, this can lead to inaccurate calculation of the feedback current component in the Park transform, incorrect control voltage in the inverse Park transform, and ultimately, even loss of control. There are many methods for verifying the correctness of the compensation, such as checking whether the back EMF and the fundamental frequency of the three-phase voltage have a fixed phase difference, but these usually require the observation of multiple parameters, which is quite complex. Summary of the Invention

[0003] This disclosure provides a method and system for verifying motor position angle compensation, which improves the convenience of motor position angle compensation verification. Specifically, it includes the following technical solutions:

[0004] A first aspect of this disclosure provides a method for verifying motor position angle compensation, comprising:

[0005] Compensate for the motor position angle;

[0006] The compensated motor is driven to rotate. The direct-axis current and quadrature-axis current are given according to the motor speed. The position angle compensation is judged based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage fluctuates at zero, the compensation is accurate.

[0007] A second aspect of this disclosure provides a motor position angle compensation verification system, comprising:

[0008] The position angle compensation module is configured to compensate for the motor position angle;

[0009] The compensation verification module is configured to drive the compensated motor to rotate, and to give the direct-axis current and quadrature-axis current according to the motor speed. It judges whether the position angle compensation is accurate based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage fluctuates at zero, the compensation is accurate.

[0010] A third aspect of the present disclosure provides a motor position angle compensation calibration device, including a dynamometer stand and a control system;

[0011] The dynamometer stand is connected to the motor and is used to drive the motor to rotate in order to verify the accuracy of the motor position angle compensation.

[0012] The control system is connected to the motor and is used to provide the motor with direct-axis current and quadrature-axis current, and to obtain the direct-axis voltage of the motor. The accuracy of the compensation is determined based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage fluctuates at zero, the compensation is accurate.

[0013] The beneficial effects of the technical solutions provided in this disclosure are:

[0014] In this embodiment, different direct-axis and quadrature-axis currents are given to the motor at different speeds, and the accuracy of the motor's position angle compensation is determined by measuring the direct-axis voltage. Under sinusoidal steady-state conditions, if the compensation or resolver initial angle is incorrect, the direct-axis current will generate components on both the direct and quadrature axes, and the rotor flux will also generate components on both axes. Therefore, when the direct-axis and quadrature-axis currents are given, the direct-axis voltage will change with the speed. If the compensation is accurate, the direct-axis current and rotor flux will not generate additional components, and the direct-axis voltage will not change with the speed. Only the trend of the direct-axis voltage change needs to be observed to quickly and accurately determine whether the position angle compensation is accurate, without the need to observe multiple parameters or undergo complex control or calculation processes, thus improving the convenience of motor position angle compensation verification.

[0015] Advantages of this disclosure in additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a flowchart of a motor position angle compensation verification method provided in an embodiment of this disclosure;

[0018] Figure 2 This is a flowchart of the compensation verification process in a motor position angle compensation verification method provided in this embodiment of the disclosure;

[0019] Figure 3 This is a timing diagram of the sampling execution of motor position angle compensation in a motor position angle compensation verification method provided in this embodiment of the present disclosure;

[0020] Figure 4 This is a schematic diagram of a motor position angle compensation verification system provided in an embodiment of this disclosure;

[0021] Figure 5 This is a schematic diagram of a motor position angle compensation and verification device provided in an embodiment of this disclosure. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0023] Figure 1 This is a flowchart of a motor position angle compensation verification method provided in an embodiment of this disclosure. Figure 2 This is a flowchart of the compensation verification process in a motor position angle compensation verification method provided in this disclosure embodiment. See also... Figure 1 The method includes:

[0024] Step 101: Compensate for the motor position angle;

[0025] Step 102: Drag the compensated motor to rotate, and give the direct-axis current and quadrature-axis current according to the motor speed. Determine whether the position angle compensation is accurate based on the direct-axis voltage.

[0026] In step 101, it is considered that if the angle used in the Park transformation and inverse Park transformation is incorrect, it will lead to a lack of current loop control accuracy, unstable torque output, and even loss of control. Therefore, this embodiment first compensates for the angle used in the coordinate transformation.

[0027] The calibrated initial position angle of the motor resolver used in this disclosure is calibrated by detecting the zero-crossing point of the UV back electromotive force under three-phase open-circuit conditions at a fixed speed. Resolver decoding is performed using a hardware chip, and the decoded position information is transmitted to the main control chip via the SPI communication protocol. Single position information sampling and three-phase motor current sampling use the same trigger source, which employs a 50% duty cycle falling edge trigger. The sampling period is synchronized with the six-channel PWM output cycle. The main control interrupt handler uses the current sampling result to complete the interrupt, and the interrupt service routine execution time exceeds half a sampling period. Figure 1 As shown.

[0028] The position angle compensation disclosed herein is applied in an electric vehicle hub motor controller platform. This platform uses the Infineon TC275 series main control chip and the AD2S1210 resolver decoding chip. Position angle compensation is performed after the resolver's initial position angle has been accurately calibrated. The initial position angle is calibrated by detecting the zero-crossing point of the UV back electromotive force of the three-phase open-circuit drive motor. The vector control program, which involves a series of current loop control procedures from three-phase current sampling through Clarke transformation, Park transformation, PID regulation, inverse Park transformation, and PWM generation, is executed within the three-phase current sampling result interrupt program. The interrupt service routine execution time exceeds the current sampling cycle and is completed before the next sampling result interrupt is generated; the entire execution time does not exceed the PWM cycle. The PWM cycle of the interrupt trigger source is synchronized with the six-channel PWM of the power control device, with the same cycle size and phase. The interrupt trigger source uses a falling edge with a 50% duty cycle as the trigger signal to excite the three-phase ADC sampling and resolver decoding chip sampling.

[0029] Existing technologies for compensation delay analysis typically only consider the current sampling delay, neglecting the impact of the angle sampling delay. This embodiment, however, combines a comprehensive analysis of both angle and current sampling delays to ensure the synchronization of angle and current sampling, thereby achieving accurate compensation.

[0030] Angle compensation in Park transform primarily compensates for the angle difference caused by the time difference between position sampling and phase current sampling, which varies with rotational speed. The key to compensation is considering the components of the time difference. To ensure that position sampling and current sampling are simultaneous, compensation must be made for position offset. The specific calculation method is as follows:

[0031] Δθ Park =ΔT park *ω

[0032] Where, Δθ Park ΔT represents the position angle compensation amount in the Park transform. park ω represents the total delay of the Park transform, and ω represents the electrical angular velocity at the sampling time.

[0033] The position sampling path delay is the position sampling filter circuit delay t1, so the total position sampling path delay T = t1.

[0034] The three-phase current sampling path delay is the current sensor delay t1′, the current sampling filter circuit delay t2′, and the main control chip sampling and holding delay t3′. Therefore, the total delay of the three-phase current sampling path is T′=t1′+t2′+t3′.

[0035] To ensure synchronization of position and angle sampling, see [link / reference]. Figure 3 Total delay ΔT of Park transform park =

[0036] |t1′+t2′-t1|.

[0037] Thus, Δθ is obtained Park = (t1′+t2′-t1)*ω.

[0038] The Park inverse transform accurately applies the calculated PWM duty cycle of the applied voltage to the control loop. Since the duty cycle is synchronously updated at the end of the PWM cycle, when the interrupt service routine for calculating the voltage PWM duty cycle executes within half a PWM cycle, the angle compensation includes not only the delay during sampling but also a 0.5 PWM cycle delay from the trigger source's activation to the update of the calculated voltage PWM duty cycle. When the interrupt service routine for calculating the voltage PWM duty cycle executes beyond half a PWM cycle (i.e., the calculation is completed in the next cycle), the angle compensation includes not only the delay during sampling but also a 1.5 PWM cycle delay from the trigger source's activation to the update of the calculated voltage PWM duty cycle. This delay is significantly greater than the Park transform angle compensation delay. The 0.5 or 1.5 PWM cycle delay includes sampling result conversion delay, program execution delay, and position information reading delay. Considering these delays, the total delay of the Park inverse transform is ΔT. ipark The calculation is as follows:

[0039] ΔT ipark =T + 0.5 (or 1.5) * T pwm

[0040] Among them, T pwm This is the PWM period.

[0041] To synchronize the position and PWM duty cycle, additional compensation is needed at the current resolver sampling angle. The compensation offset is calculated as follows:

[0042] Δθ iPark =ΔTipark *ω=(t1+0.5(or 1.5)*T pwm )*ω

[0043] In summary, the angle θ used in the compensated Park transform can be obtained. Park for:

[0044] θ Park =θ-(t1′+t2′-t1)*ω

[0045] The angle θ used in the inverse Park transform iPark for:

[0046] θ iPark =θ + (t1 + 0.5 (or 1.5) * T pwm )*ω

[0047] Where θ is the sampling angle triggered by the sampling trigger source to the resolver decoding chip. The current sensor delay t1′, according to the sensor datasheet, is <= 6 microseconds; the filter circuit delay t2′, calculated from the hardware circuit, is 10.1 microseconds; the filter circuit delay t1, calculated from the hardware circuit, is 8.8 microseconds; and the PWM period T... pwm Depending on the current rotational speed, it ranges from 50 to 200 microseconds.

[0048] In step 102, the correctness of the compensated angle is verified to confirm the accuracy of the compensation. (See also...) Figure 2 Its main steps include:

[0049] Step 1021: Connect the motor to the dynamometer test bench, complete the relevant preparations, and drive the motor to rotate using the dynamometer. On the dynamometer test bench, set the speed to 0, apply high voltage to the motor controller bus, and provide the direct-axis current I through the calibration software. d and quadrature axis current I q When all values ​​are zero, the power device is turned on, gradually increasing the speed of the dynamometer and driving the motor under test to rotate.

[0050] Step 1022: Determine whether the current rotational speed exceeds the starting rotational speed for field weakening (speed base value ω). rb ).

[0051] If the current rotational speed does not exceed the starting rotational speed for field weakening, then the direct-axis current I is given through the calibration software. d and quadrature axis current I q If all values ​​are zero, proceed to step 1023 to determine the direct-axis current fluctuation state; if the current rotational speed exceeds the starting rotational speed for field weakening, then the region enters the field weakening zone. To avoid runaway, a direct-axis current I is applied. d The quadrature-axis current I is a set value (such that Us is a set value, for example, a per-unit value of 1). qIf the value is zero, proceed to step 1024 to determine the direct-axis current fluctuation status. To ensure the stability of the motor across its entire speed range, the dynamometer speed needs to be gradually increased to ensure correct compensation across the entire speed range.

[0052] Step 1023: Determine the direct-axis current U d If the value fluctuates around zero, the compensation is correct; otherwise, it needs to be recalibrated by modifying the compensation time value or the initial angle of the refractive index.

[0053] Step 1024: Determine the direct-axis current U d If the value fluctuates around a fixed value, it indicates that the compensation is correct; otherwise, it needs to be recalibrated by modifying the compensation time value or the initial angle of the refractive index.

[0054] In steps 1023 and 1024, the compensation time value is modified, and the Park transform delay time should be modulated first.

[0055] The theoretical basis for the above steps is as follows.

[0056] The voltage equation for a permanent magnet synchronous motor is as follows:

[0057]

[0058]

[0059] The flux linkage equation is as follows:

[0060] ψ d =L d I d +ψ f

[0061] ψ q =L q I q

[0062] The base velocity values ​​are as follows:

[0063]

[0064] Among them, U d U is the direct-axis voltage of the motor. q U is the quadrature-axis voltage of the motor. s I is the stator voltage of the motor. d I is the direct-axis current of the motor. q L is the quadrature-axis current of the motor, ω is the electric angular velocity of the motor, and L is the electric angular velocity of the motor. d L is the direct-axis inductance of the motor. q R is the quadrature-axis inductance of the motor. s Ψ is the resistance of each phase winding. f For rotor flux linkage, |Us |max represents the maximum value that the stator voltage can reach.

[0065] According to the above formula, under sinusoidal steady state, if the initial angle of the compensation or resolvent is incorrect, then I d Current components I will be generated on the d-axis and q-axis respectively. d 'and I q ',Ψ f Rotor flux linkage components Ψ will be generated on the d-axis and q-axis, respectively. fd and Ψ fq Based on this phenomenon, the following conclusions can be drawn:

[0066] ①When I d and I q When both are zero, if the compensation and the initial angle of the revolving rotation are correct, then U d The value is zero; if the compensation or the initial angle of the resolver is incorrect, then U... d =-ωψ fq U d It is not zero, and it changes with the rotational speed.

[0067] ②When I d For a fixed value, I q When U is zero, if both the compensation and the initial rotation angle are correct, then U d =R s I d It is a fixed value; if the compensation or resolver initial angle is incorrect, then U d =R s I d '-ω(L q I q '+ψ fq ), and it changes with the rotational speed.

[0068] Therefore, according to U d The changing state is used to determine whether the compensation is accurate.

[0069] Figure 4 This is a structural block diagram of a motor position angle compensation and verification system 200 provided in an embodiment of this disclosure, as shown below. Figure 4 As shown, the system includes: a position angle compensation module 201 and a compensation verification module 202.

[0070] Among them, the position angle compensation module 201 is configured to compensate the position angle of the motor.

[0071] The compensation verification module 202 is configured to drive the compensated motor to rotate, and to provide direct-axis current and quadrature-axis current based on the motor speed. It then determines whether the position angle compensation is accurate based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, both the given direct-axis current and quadrature-axis current are zero. If the direct-axis voltage fluctuates around zero, the compensation is accurate. When the motor speed exceeds the starting field weakening speed, the given direct-axis current is a set value, and the quadrature-axis current is zero. If the direct-axis voltage fluctuates around a certain fixed value, the compensation is accurate.

[0072] It should be noted that the motor position angle compensation verification system 200 provided in the above embodiments is only illustrated by the division of the above functional modules when performing motor position angle compensation verification. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the equipment can be divided into different functional modules to complete all or part of the functions described above. In addition, the motor position angle compensation verification system 200 and the motor position angle compensation verification method embodiment provided in the above embodiments belong to the same concept, and the specific implementation process is detailed in the method embodiment, which will not be repeated here.

[0073] Figure 5 This is a structural block diagram of a motor position angle compensation and verification device 300 provided in an embodiment of this disclosure, as shown below. Figure 5 As shown, the device includes a dynamometer stand 301 and a control system 302.

[0074] Among them, the dynamometer stand 301 is connected to the motor and is used to drive the motor to rotate in order to verify the accuracy of the motor position angle compensation.

[0075] The control system 302, connected to the motor, provides the motor with direct-axis current and quadrature-axis current, and acquires the motor's direct-axis voltage. It determines the accuracy of the compensation based on the direct-axis voltage. When the motor speed does not exceed the starting field-weakening speed, both the given direct-axis current and quadrature-axis current are zero. If the direct-axis voltage fluctuates around zero, the compensation is accurate. When the motor speed exceeds the starting field-weakening speed, the given direct-axis current is a set value, and the quadrature-axis current is zero. If the direct-axis voltage fluctuates around a certain fixed value, the compensation is accurate.

[0076] The motor position angle compensation verification device 300 provided in the above embodiment uses the above-described hardware module division as an example when performing motor position angle compensation verification. In practical applications, the above hardware modules can be replaced with other hardware modules with similar or identical functions as needed, or the function of a certain hardware module can be assigned to different hardware modules. For example, the control system can be further divided into an enabling device, a sensor device, and a calculation module. The enabling device is used to provide direct-axis current and quadrature-axis current to the motor, the sensor device is used to collect the direct-axis voltage of the motor, and the calculation module is used to perform data processing. In addition, the device may further include a display element connected to the control system to display the collected direct-axis voltage of the motor, thereby enabling intuitive observation of the changing trend of the direct-axis voltage.

[0077] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for verifying motor position angle compensation, characterized in that, include: Compensate for the motor position angle; The compensated motor is driven to rotate. The direct-axis current and quadrature-axis current are given according to the motor speed. The position angle compensation is judged based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage fluctuates at zero, the compensation is accurate.

2. The method for verifying motor position angle compensation as described in claim 1, characterized in that, When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage is not zero and changes with the speed, the compensation will be inaccurate.

3. The method for verifying motor position angle compensation as described in claim 1, characterized in that, If the compensation is inaccurate, it also includes the following: when the motor speed exceeds the starting field weakening speed, the given direct-axis current is the set value and the quadrature-axis current is zero. If the direct-axis voltage fluctuates around a certain fixed value, the compensation is accurate.

4. The motor position angle compensation verification method as described in claim 3, characterized in that, When the motor speed exceeds the starting field weakening speed, the given direct-axis current is the set value and the quadrature-axis current is zero. If the direct-axis voltage does not fluctuate around a certain fixed value and changes with the speed, the compensation will be inaccurate.

5. The method for verifying motor position angle compensation as described in claim 1, characterized in that, The compensation for the motor position angle includes compensating for the position angle in the Park transformation and compensating for the position angle in the inverse Park transformation.

6. The method for verifying motor position angle compensation as described in claim 5, characterized in that, The position angle compensation in the Park transform is: Dth Park =(t1′+t2′-t1)*ω Where, Δθ Park t1 represents the position angle compensation amount in the Park transform. ′ For current sensor delay, t2 ′ t1 is the delay of the current sampling filter circuit, t2 is the delay of the position sampling filter circuit, and ω represents the electric angular velocity at the sampling moment.

7. The method for verifying motor position angle compensation as described in claim 6, characterized in that, The position angle compensation in the inverse Park transform is: Δθ iPark =(t1+0.5*Tpwm)*ω or, Δθ iPark =(t1+1.5*Tpwm)*ω Where, Δθ iPark T represents the position angle compensation in the inverse Park transform. pwm This is the PWM period.

8. A motor position angle compensation verification system, characterized in that, include: The position angle compensation module is configured to compensate for the motor position angle; The compensation verification module is configured to drive the compensated motor to rotate, and to give the direct-axis current and quadrature-axis current according to the motor speed. It judges whether the position angle compensation is accurate based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage fluctuates at zero, the compensation is accurate.

9. A motor position angle compensation verification device, characterized in that, Including the dynamometer stand and control system; The dynamometer stand is connected to the motor and is used to drive the motor to rotate in order to verify the accuracy of the motor position angle compensation. The control system is connected to the motor and is used to provide the motor with direct-axis current and quadrature-axis current, and to obtain the direct-axis voltage of the motor. The accuracy of the compensation is determined based on the direct-axis voltage. When the motor speed does not exceed the starting field weakening speed, the given direct-axis current and quadrature-axis current are both zero. If the direct-axis voltage fluctuates at zero, the compensation is accurate.

10. The motor position angle compensation and verification device as described in claim 9, characterized in that, It also includes a display element, which is connected to the control system and is used to display the direct-axis voltage of the motor.

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