Permanent magnet synchronous motor rotor position filtering and zero calibration method

Abstract

The application discloses a permanent magnet synchronous motor rotor position filtering and zero position calibration method, which comprises rotor position filtering and coordinate transformation vector angle calculation and rotor zero position calibration; wherein: the rotor position filtering and coordinate transformation vector angle calculation is used for filtering the rotor position and completing the coordinate transformation vector angle calculation of the vector control system; the rotor zero position calibration is used for permanent magnet synchronous motor rotor and sensor zero position deviation calibration, and the obtained rotor position is compensated. The application can make the rotor position obtained by the sensor more stable and accurate, so as to ensure the high efficiency, stability and robustness of the electric drive system.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor control, and specifically to a method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor. Background Technology

[0002] As a key component of new energy vehicle drive systems, electric drive systems currently use permanent magnet synchronous motors as the most common drive motors. For the control of permanent magnet synchronous motors, the accuracy of rotor position acquisition and anti-interference ability are particularly important and are key to ensuring the robustness of the electric drive system.

[0003] Currently, when motor controllers cannot obtain the rotor zero position of a permanent magnet synchronous motor, representative methods for obtaining the rotor zero position include high-frequency signal injection and back electromotive force (EMF) methods. The high-frequency signal injection method is dependent on the motor type, showing significant effectiveness for salient-pole motors but less so for non-salient-pole motors. Furthermore, demodulation algorithms for high-frequency current response signals are often computationally intensive, complex, and theoretically demanding, resulting in poor versatility. The back EMF method calculates the rotor position by detecting the voltage or current of the three-phase windings. However, the amplitude of the back EMF is directly proportional to the rotational speed. When the rotor is stationary or at very low speeds, the motor's zero position cannot be detected, and an oscilloscope is required to observe the waveform, increasing hardware requirements and making operation inconvenient. Other literature uses neural networks and model reference adaptation methods to estimate the rotor's initial position, but these methods require extensive computation and complex algorithms. This invention is based on the motor structure and its mathematical model. It does not depend on the motor parameters, does not require the design of complex estimation algorithms or additional hardware equipment, and combines the two modules of detection and verification of zero position. No human intervention is required. The motor controller can obtain the rotor zero position of the permanent magnet synchronous motor by automatically executing the detection and verification process.

[0004] Currently, with the development trend of new energy vehicles towards high voltage and high speed, there are many sources of interference in the system under such complex environment. How to make the rotor position obtained by the sensor more stable and accurate in order to ensure the performance of the electric drive system is a problem we are currently facing. Summary of the Invention

[0005] This invention provides a method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor. This invention can make the rotor position obtained by the sensor more stable and accurate, so as to ensure the high efficiency, robustness and sturdiness of the electric drive system.

[0006] The technical solution to the above problem is as follows:

[0007] A method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor, including rotor position filtering, coordinate transformation vector angle calculation, and rotor zero-position calibration; wherein:

[0008] The rotor position filtering and coordinate transformation vector angle calculation are used to filter the rotor position and complete the coordinate transformation vector angle calculation of the vector control system.

[0009] Rotor zero-position calibration is used to calibrate the zero-position deviation between the rotor of a permanent magnet synchronous motor and the sensor, and to compensate for the acquired rotor position.

[0010] Furthermore, the rotor position filtering and coordinate transformation vector angle calculation include the following steps:

[0011] S1, acquire the motor rotor position sensor signal and convert it into electrical angle;

[0012] S2, calculate the electrical angle difference between the rotor position before and after the two positions;

[0013] S3, within one sampling period, determine whether the difference Δθ between two consecutive electrical angles exceeds the angle corresponding to the current rotational speed;

[0014] S4, when the electrical angle difference Δθ between two consecutive electrical angles exceeds the limit value, calculate the angle error value and set the angle correction flag to 1;

[0015] S5, determine whether the angle correction flag is set;

[0016] S6, if the result of S5 is yes, then determine whether the number of corrections is less than 2;

[0017] S7, when the number of corrections in S6 is less than 2, the current rotor position angle = the previous position angle + the estimated angle change within one cycle based on the current speed is assigned to the current rotor position angle;

[0018] S8, assign the current rotor position angle to the previous electrical angle variable;

[0019] S9, calculate the difference between the two rotor electrical angles and perform sliding average processing;

[0020] S10, calculate the coordinate transformation vector angle, coordinate transformation vector angle = current electrical angle change + previous electrical angle + zero position deviation angle.

[0021] Furthermore, if the judgment result of S5 is negative, then proceed to step S11 to clear the angle correction number variable to zero, and after clearing, proceed to step S8.

[0022] Further, if the judgment result of S6 is negative, proceed to step S12, read the position sensor angle value, convert it into an electrical angle, and complete the zeroing of the angle correction count. After the zeroing is completed, proceed to step S8.

[0023] Furthermore, rotor zero-position calibration includes the following steps:

[0024] S13, with a voltage vector given by an electrical angle gradient of 60°, lock the corresponding rotor position, and calculate the zero position deviation between the position sensor and the d-axis respectively. A total of several electrical cycles of pole pair testing are completed, the zero position deviation is accumulated, the average value is calculated, and the value is assigned to the zero position deviation variable. The d-axis is the excitation axis.

[0025] S14, in current mode, gives the d-axis current so that the motor runs under no-load;

[0026] S15, determine whether the motor speed during no-load operation reaches the set speed range;

[0027] S16, when the motor's no-load running speed reaches the set speed range, the currents id=0 and iq=0 of the d-axis and q-axis are given to reduce the motor speed. The q-axis is the torque axis.

[0028] S17. When the no-load speed is decreasing, calculate the rotor position alignment angle θ_align=ATAN(Ud,Uq) and record the value of θ_align, where Ud represents the d-axis voltage and Uq represents the q-axis voltage.

[0029] S18, accumulate θ_align values ​​M times and average them;

[0030] S19, determine whether the θ_align value is within ±2°;

[0031] S20: When the θ_align value is within ±2°, the zero deviation locked in S13 is assigned to the corresponding variable and stored in memory to provide the zero deviation value for the calculation of the coordinate transformation vector angle.

[0032] Furthermore, in S15, the set speed range is 1000rpm-2000rpm.

[0033] Furthermore, in S18, M is 100.

[0034] The beneficial effects of this invention are:

[0035] Based on the aforementioned rotor position filtering and zero-position calibration methods, when using position sensors to acquire rotor position in a vector control system, the anti-interference capability of rotor position calculation can be effectively improved, and real-time corrections can be made, thus enhancing the system's robustness. Furthermore, these methods enable rapid and accurate automatic learning and calibration of the motor rotor's zero position, which can be effectively implemented in motor performance testing and mass production stages. In complex environments with high voltage, high speed, and strong coupling, the acquired rotor position becomes more stable and accurate, ensuring the high efficiency and robustness of the permanent magnet synchronous electric drive system. Attached Figure Description

[0036] Figure 1 A block diagram of a rotor position filtering and zero-position calibration method for a permanent magnet synchronous motor;

[0037] Figure 2 A flowchart for rotor position filtering and coordinate transformation vector angle calculation;

[0038] Figure 3 A flowchart for calibrating the rotor's zero position. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0040] like Figures 1 to 3 As shown, the rotor position filtering and zero-position calibration method for permanent magnet synchronous motors of the present invention includes rotor position filtering, coordinate transformation vector angle calculation, and rotor zero-position calibration; wherein:

[0041] The rotor position filtering and coordinate transformation vector angle calculation are used to filter the rotor position and complete the coordinate transformation vector angle calculation of the vector control system.

[0042] Rotor zero-position calibration is used to calibrate the zero-position deviation between the rotor of a permanent magnet synchronous motor and the sensor, and to compensate for the acquired rotor position.

[0043] Rotor position filtering and coordinate transformation vector angle calculation include the following steps:

[0044] S1: Acquire the motor rotor position sensor signal and convert it into an electrical angle.

[0045] S2, calculate the electrical angle difference between the rotor position before and after the two positions.

[0046] S3, within one sampling period, determines whether the difference Δθ between two consecutive electrical angles exceeds the angle corresponding to the current rotational speed. The current rotational speed is 500 rpm.

[0047] S4, when the difference between two consecutive electrical angles Δθ exceeds the limit value, calculate the angle error value and set the angle correction flag to 1.

[0048] S5, determine whether the angle correction flag is set.

[0049] S6. If the result of S5 is yes, then determine whether the number of corrections is less than 2.

[0050] S7, when the number of corrections in S6 is less than 2, the current rotor position angle = the previous position angle + the estimated angle change within one cycle based on the current speed is assigned to the current rotor position angle.

[0051] S8 assigns the current rotor position angle to the previous electrical angle variable.

[0052] S9. Calculate the difference between the two rotor electrical angles and perform a moving average processing. The moving average processing is as follows: take the difference between the two values ​​before and after each time as data, accumulate the difference between the two values ​​before and after to obtain N data, arrange the N data into a queue with a fixed length of N, accumulate new data each time and put it at the end of the queue, discard the data at the beginning of the queue, add the values ​​of the N data in the queue and divide by N.

[0053] S10, calculate the coordinate transformation vector angle, coordinate transformation vector angle = current electrical angle change + previous electrical angle + zero position deviation angle.

[0054] If the result of S5 is negative, proceed to step S11 to clear the angle correction count variable. After clearing, proceed to step S8. If the result of S6 is negative, proceed to step S12, read the position sensor angle value, convert it to electrical angle, and clear the angle correction count. After clearing, proceed to step S8.

[0055] The rotor zero-position calibration includes the following steps:

[0056] S13, with a voltage vector given by an electrical angle gradient of 60°, lock the corresponding rotor position, and calculate the zero position deviation between the position sensor and the d-axis respectively. A total of several electrical cycles of testing of the pole pairs are completed, the zero position deviation is accumulated, the average value is calculated, and the value is assigned to the zero position deviation variable. The d-axis is the excitation axis.

[0057] S14, in current mode, provides the d-axis current to make the motor run under no-load.

[0058] S15 determines whether the motor's no-load running speed reaches the set speed range; in S15, the set speed range is 1000rpm-2000rpm.

[0059] S16, when the motor's no-load operating speed reaches the set speed range, the currents id=0 and iq=0 of the d-axis and q-axis are given to reduce the motor speed. The q-axis is the torque axis.

[0060] S17. When the no-load speed is decreasing, calculate the rotor position alignment angle θ_align=ATAN(Ud, Uq) and record the value of θ_align, where Ud represents the d-axis voltage and Uq represents the q-axis voltage; where θ_align is calculated by the arctangent values ​​of Ud and Uq to calculate the rotor position alignment angle θ_align=ATAN(Ud, Uq).

[0061] S18, accumulate θ_align values ​​M times and average them; M is 100.

[0062] S19, determine whether the θ_align value is within ±2°.

[0063] S20: When the θ_align value is within ±2°, the zero deviation locked in S13 is assigned to the corresponding variable and stored in memory to provide the zero deviation value for the calculation of the coordinate transformation vector angle.

[0064] The method proposed in this invention enables anti-interference processing and real-time correction of the rotor position of a permanent magnet synchronous motor, ensuring normal system operation and improving system stability. This invention also allows for self-learning and validity judgment of the motor rotor's zero position deviation, guaranteeing the accuracy of the rotor's zero position deviation. It can be effectively implemented in both motor testing and mass production stages. This invention ensures the accuracy and anti-interference capability of the rotor position acquisition in the vector control system, especially in the context of the high-voltage and high-speed development trend of new energy vehicles. Under such strongly coupled interference environments, it effectively improves the anti-interference capability and robustness of the electric drive system.

[0065] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit them, much less limit the scope of protection of the present invention. Although the invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection of the claims.

Claims

1. A method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor, characterized in that, This includes rotor position filtering, coordinate transformation vector angle calculation, and rotor zero position calibration; among which: The rotor position filtering and coordinate transformation vector angle calculation are used to filter the rotor position and complete the coordinate transformation vector angle calculation of the vector control system. Rotor zero position calibration is used to calibrate the zero position deviation between the rotor of a permanent magnet synchronous motor and the sensor, and to compensate for the acquired rotor position. Rotor position filtering and coordinate transformation vector angle calculation include the following steps: S1, acquire the motor rotor position sensor signal and convert it into electrical angle; S2, calculate the electrical angle difference between the rotor position before and after the two positions; S3, within one sampling period, determine whether the difference Δθ between two consecutive electrical angles exceeds the angle corresponding to the current rotational speed; S4, when the electrical angle difference Δθ between two consecutive electrical angles exceeds the limit value, calculate the angle error value and set the angle correction flag to 1; S5, determine whether the angle correction flag is set; S6, if the result of S5 is yes, then determine whether the number of corrections is less than 2; S7, when the number of corrections in S6 is less than 2, the current rotor position angle = the previous position angle + the estimated angle change within one cycle based on the current speed; S8, assign the current rotor position angle to the previous electrical angle variable; S9: Calculate the difference between the two rotor electrical angles and perform sliding average processing to obtain the current change in electrical angle; S10, calculate the coordinate transformation vector angle, coordinate transformation vector angle = current electrical angle change + previous electrical angle + zero position deviation angle.

2. The method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor according to claim 1, characterized in that, If the result of S5 is negative, proceed to step S11 to clear the angle correction number variable to zero. After clearing, proceed to step S8.

3. The method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor according to claim 1, characterized in that, If the judgment result of S6 is negative, proceed to step S12, read the position sensor angle value, convert it into an electrical angle, and complete the zeroing of the angle correction count. After the zeroing is completed, proceed to step S8.

4. The method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor according to claim 1, characterized in that, Rotor zero-position calibration includes the following steps: S13, with a voltage vector given by an electrical angle gradient of 60°, lock the corresponding rotor position, and calculate the zero position deviation between the position sensor and the d-axis respectively. A total of several electrical cycles of pole pair testing are completed, the zero position deviation is accumulated, the average value is calculated, and the value is assigned to the zero position deviation variable. The d-axis is the excitation axis. S14, in current mode, gives the d-axis current so that the motor runs under no-load; S15, determine whether the motor speed during no-load operation reaches the set speed range; S16, when the motor's no-load running speed reaches the set speed range, the currents id=0 and iq=0 of the d-axis and q-axis are given to reduce the motor speed. The q-axis is the torque axis. S17. When the no-load speed is decreasing, calculate the rotor position alignment angle θ_align=ATAN(Ud,Uq) and record the value of θ_align, where Ud represents the d-axis voltage and Uq represents the q-axis voltage. S18, accumulate θ_align values ​​M times and average them; S19, determine whether the θ_align value is within ±2°; S20: When the θ_align value is within ±2°, the zero deviation locked in S13 is assigned to the corresponding variable and stored in memory to provide the zero deviation value for the calculation of the coordinate transformation vector angle.

5. The method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor according to claim 4, characterized in that, In S15, the set speed range is 1000rpm-2000rpm.

6. The method for rotor position filtering and zero-position calibration of a permanent magnet synchronous motor according to claim 4, characterized in that, In S18, M is 100.

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