Discrete Filtering Method and Discrete Filter for PMSM Motor Position Redundancy Processing

Abstract

The present invention discloses a discrete filtering method and a discrete filter for redundant processing of the position of a PMSM motor. The discrete filtering method includes: after reaching the sampling moment, collecting a first sampling angle value of a main position sensor and a second sampling angle value of an auxiliary position sensor, and calculating and inputting the current position deviation value between the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value; calculating the average deviation value of the last count_step position deviation values; calculating the difference between the current position deviation value and the average deviation value; calculating the local deviation value at the current angle point; calculating and outputting the filtered position deviation value. The present invention can effectively eliminate the problem of the expansion of the deviation range caused by the relative deviation between the two sensors, and reduce the misjudgment caused by the mutual verification of position information during mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of motors. Specifically, it relates to a discrete filtering method and a discrete filter for position redundancy processing of a PMSM motor. Background Art

[0002] A high-performance motor drive system requires real-time motor rotor position information for dynamic control. The rotor position information is usually obtained by installing position sensors on the motor. Common position sensors include optical encoders, resolvers, magnetic encoders, etc. On the other hand, although rotor position sensors can provide accurate position information to help improve the performance of the system, sensors as hardware components bring the risk of failure. Especially when the system operates at high vibration or high speed, the failure of the rotor sensor will cause the loss of control of the motor torque control, which will cause harm to the drive system, load, and even surrounding personnel.

[0003] Currently, there are various methods proposed to use another position signal, which may be an auxiliary position sensor or software-estimated position information, as a redundant system to improve reliability. The methods for position redundancy processing mainly include: First, study different methods to obtain position information, including hardware position sensors or software position estimation; Second, study how different position information can be mutually verified to identify position sensor failures; Third, study how to handle it after identifying sensor failures to minimize the impact on the system.

[0004] Regarding the application of the above second method in the actual mass production stage, due to the deviations in the processes of processing, installation, calibration, measurement, etc. of using two position sensors in actual applications, there are still inconsistencies between different position information during normal operation. This inconsistency will have random variations during mass production, and sometimes the amplitude will be relatively large. Therefore, mutual verification of position information often causes misjudgment. Summary of the Invention

[0005] In order to overcome the problem in the prior art that due to the deviations in the processes of processing, installation, calibration, measurement, etc. of using two position sensors in actual applications, there are random variations during mass production, and sometimes the amplitude is relatively large, resulting in frequent misjudgment in mutual verification of position information, the present invention provides a discrete filtering method and a discrete filter for position redundancy processing of a PMSM motor.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a discrete filtering method for position redundancy processing of a PMSM motor, which is characterized by including:

[0008] Step S1: After reaching the sampling moment, collect the first sampling angle value of the main position sensor and the second sampling angle value of the auxiliary position sensor, and calculate and input the current position deviation value between the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value;

[0009] Step S2: Calculate the average deviation value of the last count_step position deviation values, where count_step is the number of valid samples in the 0-360 degree interval of the motor rotation;

[0010] Step S3: Calculate the difference between the current position deviation value and the average deviation value;

[0011] Step S4: Calculate the local deviation value at the current angle point according to the average deviation value, the difference value and the filter coefficient of the filter;

[0012] Step S5: Calculate and output the filtered position deviation value according to the current position deviation value and the local deviation value.

[0013] For the discrete filtering method for PMSM motor position redundancy processing according to the above solution, the calculation formula for the position deviation value is:

[0014] phase_diff = theta_main - theta_check

[0015] where phase_diff is the current position deviation value, theta_main is the current first sampling angle value, and theta_check is the current second sampling angle value.

[0016] For the discrete filtering method for PMSM motor position redundancy processing according to the above solution, Step S1 further includes:

[0017] Define a position deviation array with count_step elements, and store the calculated current position deviation value in the position deviation array, where the position deviation array is used to store the last count_step position deviation values.

[0018] Further, after Step S1, it further includes:

[0019] Step A1: Calculate the upper threshold value and the lower threshold value for the current angle acquisition according to the current sampling moment serial number, where the sampling moment serial number starts from 1 and cycles between 1 and count_step as the motor rotates;

[0020] Step A2: If the current first acquisition angle value is between the upper threshold value and the lower threshold value of the current angle acquisition, store the current position deviation value in the position deviation array.

[0021] Furthermore, step S2 further includes:

[0022] When the motor rotates forward, if the current sampling time sequence number is equal to count_step, update the average deviation value;

[0023] When the motor rotates backward, if the current sampling time sequence number is equal to 1, update the average deviation value.

[0024] According to the discrete filtering method for PMSM motor position redundancy processing of the above solution, step S4 includes:

[0025] Define a local deviation array with count_step elements, and store the local deviation values at each angle point in the local deviation array.

[0026] According to the discrete filtering method for PMSM motor position redundancy processing of the above solution, the calculation formula for the local deviation value is:

[0027] asym_position(index) = asym_position(index) * α + difference_to_average * (1 - α)

[0028] where asym_position(index) is the local deviation value at the current angle point, index is the current sampling time sequence number, difference_to_average is the difference between the current position deviation value and the average deviation value, and α is the filter coefficient of the filter, and α ranges from 0 to 1.

[0029] According to the discrete filtering method for PMSM motor position redundancy processing of the above solution, after step S4, it further includes:

[0030] Step A3: When the motor rotates forward, the current sampling time sequence number is incremented by 1. If the incremented sampling time sequence number is greater than count_step, set the incremented sampling time sequence number to 1;

[0031] Step A4: When the motor rotates backward, the current sampling time sequence number is decremented by 1. If the decremented sampling time sequence number is less than 1, set the decremented sampling time sequence number to count_step.

[0032] The discrete filtering method for PMSM motor position redundancy processing according to the above solution further includes, after step S5:

[0033] Step S6: Perform redundancy judgment on the position sensor according to the filtered position deviation value.

[0034] In the discrete filtering method for PMSM motor position redundancy processing according to the above solution, count_step is between 6 and 72.

[0035] In a second aspect, the present invention provides a discrete filter for PMSM motor position redundancy processing, including:

[0036] An input module, configured to, after reaching the sampling moment, collect a first sampling angle value of the main position sensor and a second sampling angle value of the auxiliary position sensor, and calculate and input the current position deviation value between the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value;

[0037] A first calculation module, configured to calculate the average deviation value of the last count_step position deviation values, where count_step is the number of effective samples in the 0-360 degree interval of the motor rotation;

[0038] A second calculation module, configured to calculate the difference between the current position deviation value and the average deviation value;

[0039] A third calculation module, configured to calculate the local deviation value at the current angle point according to the average deviation value, the difference, and the filter coefficient of the filter;

[0040] An output module, configured to calculate and output the filtered position deviation value according to the current position deviation value and the local deviation value.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The present invention can effectively obtain the position deviation between two position sensors (both position sensors or position estimation algorithms are applicable) of the PMSM motor, filter out the local position deviation of the position sensor, effectively eliminate the problem of the deviation range expansion caused by the relative deviation between the two sensors, reduce the misjudgment caused by the mutual verification of position information during mass production, and obtain stable reference data under mass production; at the same time, the relative deviation information between the two position sensors can be extracted to analyze and judge the relative deviation information between the two position sensors, which can be used to analyze and judge the states of the two position sensors. Description of the Drawings

[0043] Figure 1 It is a flowchart of the method according to the first embodiment of the present invention;

[0044] Figure 2 This is the waveform diagram of the current position deviation value input in a cycle of the first embodiment of the present invention. The horizontal axis represents the number of sampling points, with every 12 points being one electrical cycle, and the vertical axis represents the angle value in degrees.

[0045] Figure 3 This is the waveform diagram of the filtered position deviation value output in a cycle of the first embodiment of the present invention. The horizontal axis represents the number of sampling points, with every 12 points being one electrical cycle, and the vertical axis represents the angle value in degrees.

[0046] Figure 4 This is the waveform diagram of the deviation values of each angle point of the position sensor extracted from the local deviation array asym_position

[12] in the first embodiment of the present invention. The horizontal axis represents the number of sampling points, with every 12 points being one electrical cycle, and the vertical axis represents the angle value in degrees.

[0047] Figure 5 This is the structural framework diagram of the second embodiment of the present invention. Detailed implementation manners

[0048] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear and understandable, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0049] It should be noted that the terms "including" and "having" in the description and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products or devices.

[0050] Embodiment 1

[0051] Please refer to Figure 1 , the embodiment of the present invention provides a discrete filtering method for PMSM motor position redundancy processing, including the following steps:

[0052] Step S1: After reaching the sampling moment, collect the first sampling angle value of the main position sensor and the second sampling angle value of the auxiliary position sensor, and calculate and input the current position deviation value of the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value.

[0053] Specifically, both the main position sensor and the auxiliary position sensor of the PMSM motor provide continuous position angle information. A continuous position can be obtained by using a switched Hall sensor and the method of phase-locked loop (PLL) interpolation, or by using a position estimation method, or even by directly using a continuous position sensor.

[0054] In the above steps, define the current position deviation value between the main position sensor and the auxiliary position sensor as phase_diff. The position deviation value phase_diff reflects the deviations that occur during the processes of machining, installation, calibration, measurement, etc. of the main position sensor and the auxiliary position sensor in practical applications, and also includes the incorrect position information during a position fault. It is the input of the discrete filter. Define the first sampled angle value of the main position sensor as theta_main, and define the second sampled angle value of the auxiliary position sensor as theta_check. Define an array of position deviations for the count_step element

[0055] last_phase_diffs[count_step] is used to store the last count_step position deviation values of phase_diff.

[0056] The mathematical calculation description of step S1 is as follows:

[0057] phase_diff = theta_main - theta_check

[0058] Step S2: Calculate the upper threshold value and the lower threshold value for the current angle acquisition according to the current sampling time sequence number.

[0059] Specifically, define the sampling time sequence number as index, which starts from 1 and cycles between 1 and count_step as the motor rotates. count_step is the number of valid samples in the 0 - 360 degree interval of the motor rotation. count_step is related to the maximum speed of the motor. The higher the speed, the smaller the value. The specific calculation method is: within the sampling interval ΔT, at the maximum speed nmax of the motor, the angle rotated by the motor should be less than 360 / count_step, that is, countstep < 60 / (ΔT * nmax * Pn), where ΔT is the sampling interval, nmax represents the maximum speed of the motor, and Pn represents the number of pole pairs of the motor. At the same time, the larger the value of count_step, the more accurate the calculation result and the better the effect of eliminating the deviation. However, a larger value will increase the calculation amount. Therefore, count_step is usually between 6 and 72.

[0060] Define the upper threshold value for current angle acquisition as theta_upper, and the lower threshold value as theta_lower. The upper threshold value theta_upper and the lower threshold value theta_lower are respectively the upper and lower boundaries of each angle interval of 360 / countstep.

[0061] The mathematical calculation description of step S2 is as follows:

[0062] theta_upper = index * 360 / count_step

[0063] theta_lower = (index - 1) * 360 / count_step

[0064] Step S3: If the current first acquisition angle value is between the upper threshold value and the lower threshold value of the current angle acquisition, store the current position deviation value in the position deviation array.

[0065] Since the position deviation array last_phase_diffs[count_step] is used to record the deviations of different position angles, it needs to be stored according to the position interval and cannot record each sampling value. Only one storage can be performed for each interval in each cycle.

[0066] The mathematical calculation description of step S3 is as follows:

[0067] if((theta_main >= theta_lower) && (theta_main <= theta_upper))

[0068] last_phase_diffs(index) = phase_diff

[0069] Step S4: Calculate the average deviation value of the last count_step position deviation values.

[0070] Specifically, define a variable average to store the average deviation value of the main position sensor and the auxiliary position sensor. The average deviation value average corresponds to the average value of the position deviation values collected within a 360-degree cycle. When there is no position fault, this data reflects the average relative deviation information between the main position sensor and the auxiliary position sensor.

[0071] The mathematical calculation description of step S4 is as follows:

[0072]

[0073] In the above steps, when the motor rotates forward, if the current sampling time sequence number is equal to count_step, update the average deviation value. The mathematical calculation description is as follows:

[0074] if(index == count_step)

[0075]

[0076] When the motor rotates backward, if the current sampling time sequence number is equal to 1, update the average deviation value. The mathematical calculation description is as follows:

[0077] if(index == 1)

[0078]

[0079] Step S5: Calculate the difference between the current position deviation value and the average deviation value.

[0080] Specifically, define a variable difference_to_average as the difference between the current position deviation value phase_diff and the average deviation value average.

[0081] The mathematical calculation description of step S5 is as follows:

[0082] difference_to_average = phase_diff – average

[0083] Step S6: Calculate the local deviation value at the current angle point according to the average deviation value, the difference value and the filter coefficient of the filter.

[0084] Specifically, define a local deviation array asym_position[count_step] of the count_step element to store the local deviation value at each angle point. After calculating the local deviation value at each angle point, store the local deviation value at this angle point in the local deviation array asym_position[count_step]. The local deviation value is the deviation that occurs in the processes of processing, installation, calibration, measurement, etc. of the main position sensor and the auxiliary position sensor in actual applications extracted from the position deviation value. This data extracts the relative deviation information between the main position sensor and the auxiliary position sensor and can be used to analyze and judge the initial state of the position sensor.

[0085] The mathematical calculation description of step S6 is as follows:

[0086] asym_position(index) = asym_position(index) * α + difference_to_average * (1 - α)

[0087] Among them, α is the filter filtering, and α ranges from 0 to 1.

[0088] Of course, in other embodiments, the mathematical calculation description of step S6 can also be:

[0089] asym_position(index) = asym_position(index) * α / K + difference_to_average * (K - α) / K

[0090] Among them, K is greater than α, α ranges from 0 to K, and the above two mathematical calculation descriptions are equivalent.

[0091] In step S6, when the motor rotates forward, the current sampling time serial number increases by 1, and waits to enter the next sampling time; if the increased sampling time serial number is greater than count_step, the increased sampling time serial number is set to 1, and the mathematical calculation description is:

[0092] index = index + 1;

[0093] if (index > count_step)

[0094] index = 1

[0095] In step S7, when the motor rotates backward, the current sampling time serial number decreases by 1, and waits to enter the next sampling time; if the decreased sampling time serial number is less than 1, the decreased sampling time serial number is set to count_step, and the mathematical calculation description is:

[0096] index = index - 1;

[0097] if (index < 1)

[0098] index = count_step

[0099] In step S8, according to the current position deviation value and the local deviation value, calculate and output the filtered position deviation value.

[0100] Specifically, define a variable filtered_phase_diff as the value after filtering the current position deviation value phase_diff, which is also the output of the filter. The filtered deviation value filtered_phase_diff is the deviation after removing the local deviation in the position deviation, reflecting the wrong position information in case of position failure. If there is no position failure, this deviation value is a stable value near 0, so that the normal installation deviation between the main position sensor and the auxiliary position sensor can be effectively reduced, and stable reference data under mass production can be obtained.

[0101] When calculating the filtered position deviation value, first determine the value of the filtered term from the local deviation array asym_position[count_step] according to the current first acquisition angle value theta_main, and then calculate in combination with the current position deviation value.

[0102] The mathematical calculation description of step S8 is as follows:

[0103] i = floor(theta_main * count_step / 360, 0), where floor() is a function for rounding down to an integer, and the output result is an integer.

[0104] filtered_phase_diff = phase_diff - asym_position(i)

[0105] The above discrete filtering method for PMSM motor position redundancy processing can effectively obtain the position deviation of the PMSM motor position sensor (applicable to both position sensors and position estimation algorithms), filter out the local position deviation of the position sensor, effectively reduce the normal deviation between position sensors, and obtain stable reference data under mass production.

[0106] In a preferred embodiment, the above discrete filtering method for PMSM motor position redundancy processing further includes:

[0107] Step S9: Perform redundancy judgment on the position sensor according to the filtered position deviation value.

[0108] Specifically, use the local deviation array asym_position[count_step] to analyze and judge the position sensor status for the extracted position deviation value.

[0109] It should be understood that the actual step sequence of the above discrete filtering method for PMSM motor position redundancy processing can be slightly adjusted within the range allowed by the algorithm, as long as the overall calculation framework is not affected. For example, step S8 can be placed before step S1, or steps S6 and S7 can be placed after step S8, etc.

[0110] The simulation verification of the above discrete filtering method for PMSM motor position redundancy processing is specifically as follows:

[0111] For example, for a certain PMSM motor with a sampling rate of 16 kHz, a maximum motor speed of 6000 rpm, and 4 pole pairs, calculate In practice, count_step can be selected as 12.

[0112] Assuming that a PMSM motor is equipped with a main position sensor and an auxiliary position sensor, the angle deviation of the main position sensor and the auxiliary position sensor at each angle point is very small. The filtering effect after using the discrete filtering method for position redundancy processing of the PMSM motor is shown in the following table:

[0113]

[0114]

[0115] Because the sensor deviation is periodic, as the motor rotates one circle, the position deviation value phase_diff is input periodically, such as Figure 2 As shown in the table above, the deviations of the input main position sensor and auxiliary position sensor are both within the range of ±5 degrees, but due to the randomness of the deviation distribution, the deviation range of the main position sensor and auxiliary position sensor is expanded to the range of -10 to 10 degrees.

[0116] After filtering by the discrete filtering method for position redundancy processing of the PMSM motor mentioned above, taking α = 0.875, the filtered data after the simulated motor runs for 25 circles is as follows Figure 3 As shown. Figure 3 It can be seen that as the motor rotates, the filtered data quickly converges to 0.1 degrees, indicating that the average deviation of the two position sensors is very small. And through the discrete filtering method of the above-mentioned PMSM motor position redundancy processing, the periodic deviation can be quickly removed, so that even if it is installed in large quantities, the deviation results obtained have high consistency, eliminating the random fluctuations caused by the deviation of the position sensor itself, and also exceeding the problem of the deviation range expansion caused by the relative deviation between the two position sensors. Because the deviation data after filtering has small volatility, if a position sensor fails at this time, the data will change significantly, so a relatively small threshold parameter can be set to identify sensor failure.

[0117] from Figure 4 It can be seen that the local deviation array asym_position

[12] extracts the deviation information of each angle point of the position sensor.

[0118]

[0119]

[0120] The above table is a precision comparison table of the deviation information of each angular point of the position sensor extracted from the local deviation array asym_position

[12] after the motor runs 25 laps. It can be seen from the above table that the deviation information of each angular point of the position sensor extracted from the local deviation array asym_position

[12] is basically close to the actual deviation of the design. Therefore, the deviation information of each angular point of the position sensor extracted by asym_position

[12] is accurate and effective, and thus can be used to analyze the relative deviation between the two sensors.

[0121] Embodiment 2

[0122] Please refer to Figure 5 , the embodiment of the present invention provides a discrete filter for PMSM motor position redundancy processing, including an input module 1, a first calculation module 2, a second calculation module 3, a third calculation module 4 and an output module 5. Among them,

[0123] The input module 1 is used to collect the first sampling angle value of the main position sensor and the second sampling angle value of the auxiliary position sensor after reaching the sampling moment, and calculate and input the current position deviation value of the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value.

[0124] The first calculation module 2 is used to calculate the average deviation value of the last count_step position deviation values, where count_step is the number of effective samples in the 0-360 degree interval of the motor rotation.

[0125] The second calculation module 3 is used to calculate the difference between the current position deviation value and the average deviation value.

[0126] The third calculation module 4 is used to calculate the local deviation value at the current angular point according to the average deviation value, the difference value and the filter coefficient of the filter.

[0127] The output module 5 is used to calculate and output the filtered position deviation value according to the current position deviation value and the local deviation value.

[0128] The discrete filter for PMSM motor position redundancy processing provided by the embodiment of the present invention can execute the above method embodiment, and its implementation principle and technical effect are similar, and will not be described in detail here.

[0129] In a preferred embodiment, the above discrete filter for PMSM motor position redundancy processing further includes a judgment module 6. The judgment module 6 is used to perform redundancy judgment on the position sensor according to the filtered position deviation value.

[0130] It should be understood that those of ordinary skill in the art can make improvements or transformations based on the above description, and all such improvements and transformations shall fall within the protection scope of the appended claims of the present invention.

[0131] The above has made an exemplary description of the present invention patent in conjunction with the accompanying drawings. Obviously, the implementation of the present invention patent is not limited by the above-mentioned manner. As long as various improvements are made by adopting the method concept and technical solution of the present invention patent, or the concept and technical solution of the present invention patent are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A discrete filtering method for position redundancy processing of a PMSM motor, characterized in that, Including: Step S1: After reaching the sampling moment, collect the first sampling angle value of the main position sensor and the second sampling angle value of the auxiliary position sensor, and calculate and input the current position deviation value of the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value; Step S2: Calculate the average deviation value of the last count_step position deviation values, where count_step is the number of valid sampling in the 0-360 degree interval of the motor rotation; Step S3: Calculate the difference between the current position deviation value and the average deviation value; Step S4: Calculate the local deviation value at the current angle point according to the average deviation value, the difference value and the filter coefficient of the filter; Step S5: Calculate and output the filtered position deviation value according to the current position deviation value and the local deviation value.

2. The discrete filtering method for PMSM motor position redundancy processing according to claim 1, characterized in that, Step S1 further includes: Define a position deviation array of count_step elements, and store the calculated current position deviation value in the position deviation array, where the position deviation array is used to store the last count_step position deviation values.

3. The discrete filtering method for position redundancy processing of the PMSM motor according to claim 2, characterized in that After Step S1, it further includes: Step A1: Calculate the upper threshold value and the lower threshold value of the current angle acquisition according to the current sampling moment serial number, and the sampling moment serial number starts from 1 and circulates between 1 and count_step as the motor rotates; Step A2: If the current first sampling angle value is between the upper threshold value and the lower threshold value of the current angle acquisition, store the current position deviation value in the position deviation array.

4. The discrete filtering method for PMSM motor position redundancy processing according to claim 3, characterized in that Step S2 further includes: When the motor rotates forward, if the current sampling moment serial number is equal to count_step, update the average deviation value; When the motor rotates backward, if the current sampling moment serial number is equal to 1, update the average deviation value.

5. The discrete filtering method for PMSM motor position redundancy processing according to claim 1, characterized in that, Step S4 includes: Define a local deviation array of count_step elements, and store the local deviation value at each angle point in the local deviation array.

6. The discrete filtering method for PMSM motor position redundancy processing according to claim 1, characterized in that, The calculation formula of the local deviation value is: asym_position(index) = asym_position(index) * α + difference_to_average * (1 - α) where asym_position(index) is the local deviation value at the current angle point, index is the current sampling moment serial number, difference_to_average is the difference between the current position deviation value and the average deviation value, and α is the filter coefficient of the filter, and α ranges from 0 to 1.

7. The discrete filtering method for position redundancy processing of a PMSM motor according to claim 1, characterized in that, After Step S4, it further includes: Step A3: When the motor rotates forward, the current sampling moment serial number is incremented by 1. If the incremented sampling moment serial number is greater than count_step, set the incremented sampling moment serial number to 1; Step A4: When the motor rotates in reverse, the current sampling time sequence number is decreased by 1. If the decreased sampling time sequence number is less than 1, the decreased sampling time sequence number is set to count_step.

8. The discrete filtering method for position redundancy processing of the PMSM motor according to claim 1, characterized in that, After step S5, it further includes: Step S6: Perform redundancy judgment on the position sensor according to the filtered position deviation value.

9. The discrete filtering method for position redundancy processing of the PMSM motor according to claim 1, wherein count_step is between 6 and 72.

10. A discrete filter for redundant processing of the position of a PMSM motor, characterized in that, It includes: An input module, configured to, after reaching the sampling time, collect a first sampling angle value of the main position sensor and a second sampling angle value of the auxiliary position sensor, and calculate and input the current position deviation value between the main position sensor and the auxiliary position sensor according to the first sampling angle value and the second sampling angle value; A first calculation module, configured to calculate the average deviation value of the last count_step position deviation values, where count_step is the number of valid samplings in the 0-360 degree interval of the motor rotation; A second calculation module, configured to calculate the difference between the current position deviation value and the average deviation value; A third calculation module, configured to calculate the local deviation value at the current angle point according to the average deviation value, the difference, and the filter coefficient of the filter; An output module, configured to calculate and output the filtered position deviation value according to the current position deviation value and the local deviation value.

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