Angle error compensation method for electric eddy current sensor of permanent magnet synchronous motor

Abstract

The embodiment of the invention provides a permanent magnet synchronous motor electrical eddy current sensor angle error compensation method, and belongs to the technical field of motor driving. The compensation method comprises the following steps: acquiring differential sine and cosine signals output by the eddy current sensor; calculating a direct-current bias error according to the differential sine and cosine signals so as to obtain differential sine and cosine signals after direct-current bias error compensation; calculating an amplitude asymmetric error compensation coefficient according to the extreme values of the differential sine and cosine signals after the DC bias error compensation so as to obtain the differential sine and cosine signals after the amplitude asymmetric error compensation; and calculating the position angle of the motor rotor according to the difference sine and cosine signals after the amplitude asymmetric error compensation, and compensating the position angle by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation. According to the method, only algebraic addition and subtraction and multiplication are used, the execution time of the system is saved, the operation efficiency is improved, and the requirement for obtaining the position angle in real time is met.

Description

Technical Field

[0001] The present invention relates to the technical field of motor drive, and in particular to a method for compensating an angular error of an eddy current sensor of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have the advantages of high efficiency, high power density, and wide speed regulation range. They have received extensive attention and application in aerospace, electric vehicles, robots, and servo systems. High-performance permanent magnet synchronous motor drive control requires accurate motor position information, which is generally measured by position sensors. Commonly used position sensors include resolvers and eddy current sensors. As an earlier position sensor, resolvers have reliable accuracy, but due to their poor platform compatibility and the large impact of size on cost, they are increasingly unable to meet market demand. Eddy current sensors have high electronic integration, and their cost does not increase linearly with size. They can also better adapt to the development trend of high motor speeds, making them more advantageous in the future market.

[0003] The control accuracy of the position signal is crucial to motor control. For eddy current sensors, the errors mainly come from two parts. One is some errors in the chip itself, such as hysteresis error, nonlinear error, offset error, etc. Most of these errors can be eliminated through internal chip signal processing and programming calibration, and have little effect on the final output accuracy of the sensor. The second is the shape and position errors generated during the production and assembly of the sensor, such as the installation gap and deflection angle between the sensor stator and rotor, and the eccentricity between the sensor rotor signal wheel and the motor shaft, which have a relatively large impact on the accuracy. The accuracy impact caused by shape and position errors is mainly manifested in the differential sine and cosine signals output by the sensor as follows:

[0004] 1. Generate a DC bias voltage, causing the output DC bias voltage of the differential sine signal and cosine signal to be inconsistent.

[0005] 2. Causes amplitude asymmetry. After removing the DC bias, the amplitudes of the differential sine signal and cosine signal are not equal.

[0006] 3. The phase is not completely orthogonal. The phase difference between the output differential sine signal and cosine signal is not 90 degrees orthogonal. Summary of the invention

[0007] The purpose of the embodiment of the present invention is to provide a method for compensating the angle error of an eddy current sensor of a permanent magnet synchronous motor, which solves the problem that the shape and position error generated by the eddy current sensor affects the angle calculation accuracy.

[0008] In order to achieve the above object, an embodiment of the present invention provides a method for compensating an angular error of an eddy current sensor of a permanent magnet synchronous motor, the compensation method comprising:

[0009] Obtain differential sine and cosine signals output by the eddy current sensor;

[0010] Calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation;

[0011] Calculating an amplitude asymmetry error compensation coefficient according to the extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation;

[0012] Calculating the position angle of the motor according to the differential sine and cosine signals after the amplitude asymmetry error compensation;

[0013] The position angle is compensated by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation.

[0014] Optionally, obtaining differential sine and cosine signals output by the eddy current sensor;

[0015] Calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation;

[0016] Calculating an amplitude asymmetry error compensation coefficient according to the extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation;

[0017] The position angle of the motor rotor is calculated according to the differential sine and cosine signals after the amplitude asymmetry error compensation, and the position angle is compensated by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation.

[0018] Optionally, calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation includes:

[0019] calculating a sampled DC bias based on the differential sine and cosine signals;

[0020] Calculating a DC bias error based on the sampled DC bias and an ideal DC bias;

[0021] A DC offset error correction of the differential sine and cosine signals is performed based on the DC offset error.

[0022] Optionally, calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation includes:

[0023] According to formulas (1) to (2), the DC offset error of the sine signal and the DC offset error of the cosine signal are obtained.

[0024] S com =(U sin+ +U sin- ) / 2-U o , (1)

[0025] C com =(U cos+ +U cos- ) / 2-U o , (2)

[0026] Among them, U sin+ , U sin- is a differential sinusoidal signal, U sin- , U cos- is the differential cosine signal, U o is an ideal DC bias, S com DC offset error of differential sinusoidal signal, C com DC offset error of the differential cosine signal;

[0027] According to formulas (3) to (6), the differential sine and cosine signals after DC offset error compensation are obtained.

[0028] U′ sin+ =U sin+ -S com , (3)

[0029] U′ sin- =U sin- -S com , (4)

[0030] U′ cos+ =U cos+ -C com , (5)

[0031] U′ cos- =U cos- -C com , (6)

[0032] Among them, U′ sin+ , U′ sin- is the differential sinusoidal signal after DC offset error compensation, U′ cos+ , U′ cos- is the differential cosine signal after DC offset error compensation.

[0033] Optionally, calculating an amplitude asymmetry error compensation coefficient according to extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation includes:

[0034] Calculating the changing direction of the position angle of the motor rotor according to the differential sine and cosine signals output by the eddy current sensor;

[0035] Determining whether the movement direction of the motor is forward rotation according to the change direction of the position angle;

[0036] When it is determined that the motor is rotating forward, determining whether the position angle exceeds a first preset angle;

[0037] When it is determined that the position angle exceeds the first preset angle, performing a marker extreme value extraction;

[0038] In the case where it is determined that the motor is not rotating forward, determining whether the position angle exceeds a second preset angle;

[0039] When it is determined that the position angle exceeds the second preset angle, mark extreme value extraction is performed.

[0040] Optionally, perform labelled extreme value extraction, including:

[0041] Get the current recognition cycle;

[0042] Determining whether the current recognition period exceeds a specified extreme value recognition period;

[0043] In the case where it is determined that the current identification period exceeds the specified extreme value identification period, obtaining the extreme values ​​of the differential sine and cosine signals of the specified extreme value identification period;

[0044] In the case where it is determined that the current identification period does not exceed the specified extreme value identification period, determining whether the current identification period is ended;

[0045] When it is determined that the current identification cycle is over, the current identification cycle is incremented;

[0046] When it is determined that the current identification period has not ended, the extreme values ​​of the differential sine and cosine signals of the current identification period are obtained.

[0047] Optionally, when it is determined that the current identification period exceeds the specified extreme value identification period, obtaining the extreme value of the differential sine and cosine signal of the specified extreme value identification period includes:

[0048] Obtaining the average value of the maximum values ​​of the differential sinusoidal signal in each period within the specified extreme value identification period as the maximum value of the differential sinusoidal signal, and taking the average value of the minimum values ​​of the differential sinusoidal signal in each period as the minimum value of the differential sinusoidal signal;

[0049] The average value of the maximum value of the differential cosine signal in each period within the specified extreme value identification period is obtained as the maximum value of the differential cosine signal, and the average value of the minimum value of the differential cosine signal in each period is obtained as the minimum value of the differential cosine signal.

[0050] Optionally, when it is determined that the current identification period does not exceed the specified extreme value identification period, determining whether the current identification period ends includes:

[0051] Calculating the changing direction of the position angle of the motor rotor according to the differential sine and cosine signals output by the eddy current sensor;

[0052] Determining whether the movement direction of the motor is forward rotation according to the change direction of the position angle;

[0053] When it is determined that the motor is rotating forward, determining whether the position angle exceeds a first preset angle;

[0054] In the case where it is determined that the position angle exceeds the first preset angle, determining that the current recognition cycle is ended;

[0055] In the case where it is determined that the motor is not rotating forward, determining whether the position angle exceeds a second preset angle;

[0056] When it is determined that the position angle exceeds the second preset angle, it is determined that the current recognition cycle ends.

[0057] Optionally, when it is determined that the current identification cycle has not ended, obtaining extreme values ​​of differential sine and cosine signals of the current identification cycle includes:

[0058] Determine whether the maximum value of the differential sine and cosine signals of the current identification period is greater than the maximum value of the differential sine and cosine signals of the corresponding specified extreme value identification period;

[0059] In the case where it is determined that the maximum value of the differential sine and cosine signals of the current identification period is greater than the maximum value of the differential sine and cosine signals of the corresponding specified extreme value identification period, the maximum value of the differential sine and cosine signals of the current identification period is updated to the maximum value of the differential sine and cosine signals of the extreme value identification period;

[0060] Determine whether the minimum value of the differential sine and cosine signals of the current identification period is less than the minimum value of the differential sine and cosine signals of the corresponding specified extreme value identification period;

[0061] When it is determined that the minimum value of the differential sine and cosine signals of the current identification period is smaller than the minimum value of the differential sine and cosine signals of the corresponding specified extreme value identification period, the minimum value of the differential sine and cosine signals of the current identification period is updated to the minimum value of the differential sine and cosine signals of the extreme value identification period.

[0062] Optionally, calculating an amplitude asymmetry error compensation coefficient according to extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation includes:

[0063] According to formulas (7) to (8), the extreme value difference of the differential sine signal and the extreme value difference of the differential cosine signal are obtained.

[0064]

[0065] Among them, A sin is the extreme value difference of the differential sine signal, A cos is the extreme value difference of the differential cosine signal, is the maximum value of the differential sinusoidal signal, is the minimum value of the differential sinusoidal signal, is the maximum value of the differential cosine signal, is the minimum value of the differential cosine signal;

[0066] According to formula (9), the amplitude asymmetry error compensation coefficient is obtained:

[0067] A com =A sin / A cos , (9)

[0068] Among them, A com is the amplitude asymmetry error compensation coefficient;

[0069] According to formulas (10) to (13), the differential sine and cosine signals after the amplitude asymmetry error compensation are obtained.

[0070] U″ sin+ =U′ sin+ , (10)

[0071] U″ sin- =U′ sin- , (11)

[0072] U″ cos+ =A com *U′ cos+ , (12)

[0073] U″ cos- =A com *U′cos- , (13)

[0074] Among them, U sin+ , U″ sin- is the differential sinusoidal signal after amplitude asymmetry error compensation, U″ cos+ , U″ cos- is the differential cosine signal after amplitude asymmetry error compensation.

[0075] Optionally, using the second harmonic cosine wave component of the position angle to compensate the position angle to obtain the real position angle of the motor rotor after compensation includes:

[0076] The method comprises: calculating the position angle of the motor rotor according to the differential sine and cosine signals after the compensation of the amplitude asymmetry error, and compensating the position angle by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation, including:

[0077] According to formulas (14) to (15), the position angle of the motor rotor is calculated:

[0078]

[0079] in, is the position angle of the motor rotor after removing the DC offset error and amplitude asymmetry error;

[0080] According to formula (16), the second harmonic cosine component of the position angle is obtained:

[0081]

[0082] in, is the second harmonic cosine component;

[0083] According to formula (17), the phase non-orthogonal position angle compensation value is obtained:

[0084]

[0085] Among them, θ err is the phase non-orthogonal position angle compensation value, B is the compensation coefficient, and C is the compensation bias;

[0086] According to formula (18), the actual position angle of the motor rotor after compensation is obtained:

[0087]

[0088] Among them, θ is the actual position angle of the motor rotor after compensation.

[0089] Through the above technical scheme, the present invention provides a method for compensating the angle error of the eddy current sensor of a permanent magnet synchronous motor. Aiming at the problem that the shape and position error generated by the eddy current sensor affects the angle calculation accuracy, the present invention proposes a method for error compensation for different forms of output signals, wherein, for the generated DC bias error, the average value of the algebraic sum of the differential sine signal and the cosine signal in the operation cycle is selected to compensate for the bias error; for the amplitude asymmetry, the amplitude compensation coefficient is obtained by the maximum and minimum extreme points in the operation cycle to compensate for the amplitude asymmetry error; for the angle second harmonic error generated by the incomplete orthogonal phase, the method of estimating the cosine component of the angle second harmonic is adopted to complete the phase incomplete orthogonal error compensation. Compared with the prior art, the existing resolver or eddy current sensor position error compensation technology mostly uses the method of preliminary calculation and error calibration to design the angle error compensation table, which takes a lot of time and system memory, and the present invention does not have these disadvantages. And the compensation method of the present invention only uses algebraic addition and subtraction and multiplication operations, does not include sine, cosine and division operations, can save the execution time of the system, improve the operation efficiency, and meet the requirements of real-time acquisition of position angle. In addition, there are no preset fixed compensation values ​​for DC bias and amplitude asymmetry errors. Dynamic calculation is used to compensate the position angle, which can adaptively compensate for different installation errors and better meet the needs of mass installation.

[0090] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0092] Figure 1 is a flow chart of a compensation method according to one embodiment of the present invention;

[0093] Figure 2 is a flow chart of DC offset error compensation according to one embodiment of the present invention;

[0094] Figure 3 is a flow chart of amplitude asymmetry error compensation according to one embodiment of the present invention;

[0095] Figure 4 is a flowchart of extreme value extraction according to one embodiment of the present invention;

[0096] Figure 5 is a flow chart of obtaining extreme values ​​of differential sine and cosine signals of a specified extreme value identification period according to one embodiment of the present invention;

[0097] Figure 6 is a flowchart for determining whether the current identification cycle is finished according to an embodiment of the present invention;

[0098] Figure 7 is a flow chart of obtaining extreme values ​​of differential sine and cosine signals of a current identification period according to one embodiment of the present invention;

[0099] Figure 8 is a flow chart of phase non-orthogonal position angle compensation according to one embodiment of the present invention. DETAILED DESCRIPTION

[0100] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0101] Figure 1 is a flow chart of a compensation method according to an embodiment of the present invention, in which the compensation method comprises:

[0102] In step S1 , differential sine and cosine signals output by the eddy current sensor are obtained.

[0103] In step S2, a DC offset error is calculated according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation.

[0104] In step S3, the amplitude asymmetry error compensation coefficient is calculated according to the extreme values ​​of the differential sine and cosine signals after the DC offset error compensation, so as to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation.

[0105] In step S4, the position angle of the motor rotor is calculated based on the differential sine and cosine signals after the amplitude asymmetry error compensation, and the position angle is compensated by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation.

[0106] In the prior art, during the movement of the motor, the eddy current sensor outputs continuously changing differential sine and cosine signals, which contain DC bias, amplitude and phase errors. The present invention compensates the differential sine and cosine signals by DC bias error compensation and amplitude asymmetry error compensation respectively, and then calculates the position angle of the motor by the differential sine and cosine signals after amplitude asymmetry error compensation, and uses the second harmonic cosine wave component of the position angle to compensate for the position angle, thereby obtaining the true position angle of the motor rotor after compensation, thereby overcoming the problem that the shape and position errors generated by the eddy current sensor affect the angle calculation accuracy.

[0107] In this implementation, the DC bias error needs to be compensated and corrected to provide an ideal sine signal and cosine signal. The specific steps for compensating and correcting the DC bias error may be various steps known to those skilled in the art. In one example of the present invention, specifically, Figure 2 As shown, the DC offset error is calculated according to the differential sine and cosine signals to obtain the differential sine and cosine signals after the DC offset error is compensated, including:

[0108] In step S21, a sampled DC offset is calculated based on the differential sine and cosine signals.

[0109] In step S22, a DC offset error is calculated according to the sampled DC offset and the ideal offset.

[0110] In step S23, the DC offset error correction of the differential sine and cosine signals is completed according to the DC offset error.

[0111] In this implementation, the method for obtaining the differential sine and cosine signals after DC offset error compensation may be various methods known to those skilled in the art. In one example of the present invention, the method may include:

[0112] According to formulas (1) to (2), the DC offset error of the sine signal and the DC offset error of the cosine signal are obtained.

[0113] S com =(U sin+ +U sin- ) / 2-U o , (1)

[0114] C com =(U cos+ +U cos- ) / 2-U o , (2)

[0115] Among them, U sin+ , U sin- is a differential sinusoidal signal, U sin- , U cos- is the differential cosine signal, U o is an ideal DC bias, S com DC offset error of differential sinusoidal signal, C com DC offset error of the differential cosine signal;

[0116] According to formulas (3) to (6), the differential sine and cosine signals after DC offset error compensation are obtained.

[0117] U′ sin+ =U sin+ -S com , (3)

[0118] U′ sin- =U sin- -S com , (4)

[0119] U′ cos+ =U cos+ -C com , (5)

[0120] U′ cos- =U cos- -C com , (6)

[0121] Among them, U′ sin+ , U′ sin- is the differential sinusoidal signal after DC offset error compensation, U′ cos+ , U′ cos- is the differential cosine signal after DC offset error compensation.

[0122] The differential sine and cosine signals after DC offset error compensation may contain amplitude asymmetry errors. Therefore, in this embodiment, the amplitude asymmetry errors need to be compensated to adjust the amplitudes of the differential sine and cosine signals to the same level. At the beginning of the motor start-up, considering that the initial position of the motor rotor may have passed the maximum or minimum point, the extreme value extraction process of the first half of the start-up cycle will be ignored before the extreme value identification cycle calculation. Figure 3 As shown, the following steps may be included:

[0123] In step S31, the changing direction of the position angle of the motor rotor is calculated based on the differential sine and cosine signals output by the eddy current sensor.

[0124] In step S32, the direction of the motor movement is determined to be forward according to the change direction of the position angle. If the motor is determined to be forward, step S33 is executed, and if the motor is determined to be reverse, step S35 is executed.

[0125] In step S33, it is determined whether the position angle exceeds a first preset angle. If it is determined that the position angle exceeds the first preset angle, step S34 is executed. The first preset angle is 360 degrees.

[0126] In step S34, label extreme value extraction is performed.

[0127] In step S35, it is determined whether the position angle exceeds the second preset angle. If it is determined that the position angle exceeds the second preset angle, step S34 is executed. The second preset angle is 0 degrees.

[0128] In the process of extracting the marked extreme value, it is necessary to use the average value of the extreme values ​​of the first few cycles executed by the motor or a plurality of execution cycles within a specified period of time before the operation as the extreme value reference. Therefore, in this embodiment, the specific steps for extracting the marked extreme value can be various ones known to those skilled in the art. In one example of the present invention, Figure 4 As shown, it may include:

[0129] In step S341, the current recognition cycle is obtained.

[0130] In step S342, it is determined whether the current identification period exceeds the specified extreme value identification period. If it is determined that the current identification period exceeds the specified extreme value identification period, step S343 is executed, otherwise, step S344 is executed.

[0131] In step S343, the extreme values ​​of the differential sine and cosine signals of the specified extreme value identification period are obtained.

[0132] In step S344, it is determined whether the current identification cycle is over. If it is determined that the current identification cycle is over, step S345 is executed, otherwise, step S346 is executed.

[0133] In step S345, the current identification period is incremented.

[0134] In step S346, the extreme values ​​of the differential sine and cosine signals of the current identification period are obtained.

[0135] In this implementation, the method for obtaining the extreme value of the differential sine and cosine signals of the specified extreme value identification period can be various methods known to those skilled in the art. In one example of the present invention, for example Figure 5 As shown, it may include:

[0136] In step S3431, the average value of the maximum value of the differential sine signal of each period within the specified extreme value identification period is obtained as the maximum value of the differential sine signal, and the average value of the minimum value of the differential sine signal of each period is obtained as the minimum value of the differential sine signal.

[0137] In step S3432, the average value of the maximum value of the differential sine signal of each period within the specified extreme value identification period is obtained as the maximum value of the differential sine signal, and the average value of the minimum value of the differential sine signal of each period is obtained as the minimum value of the differential sine signal.

[0138] In this implementation, the method for determining whether the current identification cycle is over can be various methods known to those skilled in the art. In one example of the present invention, for example Figure 6 As shown, it may include:

[0139] In step S3441, the changing direction of the position angle of the motor rotor is calculated based on the differential sine and cosine signals output by the eddy current sensor.

[0140] In step S3442, it is determined whether the motor is rotating forward according to the direction of the change of the position angle. If the motor is rotating forward, step S3443 is executed. If the motor is rotating reversely, step S3445 is executed.

[0141] In step S3443, it is determined whether the position angle exceeds the first preset angle. If it is determined that the position angle exceeds the first preset angle, step S3444 is executed. The first preset angle is 360 degrees.

[0142] In step S3444, it is determined that the current recognition cycle ends.

[0143] In step S3445, it is determined whether the position angle exceeds the second preset angle. If it is determined that the position angle exceeds the second preset angle, step S3444 is executed. The second preset angle is 0 degrees.

[0144] In this implementation, when it is determined that the current identification cycle has not ended, the method for obtaining the extreme values ​​of the differential sine and cosine signals of the current identification cycle can be various methods known to those skilled in the art. In one example of the present invention, Figure 7 As shown, it may include:

[0145] In step S3461, it is determined whether the maximum value of the differential sine and cosine signals of the current identification period is greater than the maximum value of the differential sine and cosine signals of the corresponding specified extreme value identification period. If it is determined that the maximum value of the differential sine and cosine signals of the current identification period is greater than the maximum value of the differential sine and cosine signals of the corresponding specified extreme value identification period, step S3462 is executed.

[0146] In step S3462, the maximum value of the differential sine and cosine signals of the current identification period is updated to the maximum value of the differential sine and cosine signals of the extreme value identification period.

[0147] In step S3463, it is determined whether the minimum value of the differential sine and cosine signals of the current identification period is less than the minimum value of the differential sine and cosine signals of the corresponding specified extreme value identification period. If it is determined that the minimum value of the differential sine and cosine signals of the current identification period is less than the minimum value of the differential sine and cosine signals of the corresponding specified extreme value identification period, step S3464 is executed.

[0148] In step S3464, the minimum value of the differential sine and cosine signals of the current identification period is updated to the minimum value of the differential sine and cosine signals of the extreme value identification period.

[0149] In this implementation, the amplitude asymmetry error compensation coefficient is calculated according to the extreme values ​​of the differential sine and cosine signals after DC offset error compensation to obtain the differential sine and cosine signals after amplitude asymmetry error compensation, including:

[0150] In step S36, the extreme value difference of the differential sine signal and the extreme value difference of the differential cosine signal are obtained according to formulas (7) to (8),

[0151]

[0152] Among them, A sin is the extreme value difference of the differential sine signal, A cos is the extreme value difference of the differential cosine signal, is the maximum value of the differential sinusoidal signal, is the minimum value of the differential sinusoidal signal, is the maximum value of the differential cosine signal, is the minimum value of the differential cosine signal;

[0153] In step S37, the amplitude asymmetry error compensation coefficient is obtained according to formula (9):

[0154] A com =A sin / A cos , (9)

[0155] Among them, A com is the amplitude asymmetry error compensation coefficient;

[0156] In step S38, the differential sine and cosine signals after amplitude asymmetry error compensation are obtained according to formulas (10) to (13).

[0157] U″ sin+ =U′ sin+ , (10)

[0158] U″ sin- =U′ sin- , (11)

[0159] U″ cos+ =A com *U′ cos+ , (12)

[0160] U″ cos- =A com *U′ cos- , (13)

[0161] Among them, U sin+ , U″ sin-is the differential sinusoidal signal after amplitude asymmetry error compensation, U″ cos+ , U″ cos- is the differential cosine signal after amplitude asymmetry error compensation.

[0162] The compensated differential sine and cosine signals obtained by DC bias and amplitude asymmetry error compensation may contain phase non-orthogonality errors. In this embodiment, the method for correcting the phase non-orthogonality error can be various methods known to those skilled in the art. In one example of the present invention, in order to correct the phase non-orthogonality error, the position angle of the motor rotor can be calculated based on the differential sine and cosine signals after the amplitude asymmetry error compensation, and the position angle is compensated by using the second harmonic cosine wave component of the position angle to obtain the true position angle of the motor rotor after compensation. Specifically, Figure 8 As shown, the following steps are included:

[0163] In step S41, the position angle of the motor rotor is calculated according to formulas (14) to (15),

[0164]

[0165] in, is the position angle of the motor rotor after removing the DC offset error and amplitude asymmetry error;

[0166] In step S42, the second harmonic cosine component of the position angle is obtained according to formula (16):

[0167]

[0168] in, is the second harmonic cosine component;

[0169] In step S43, the phase non-orthogonal position angle compensation value is obtained according to formula (17):

[0170]

[0171] Among them, θ err is the phase non-orthogonal position angle compensation value, B is the compensation coefficient, and C is the compensation bias;

[0172] In step S44, the actual position angle of the motor rotor after compensation is obtained according to formula (18):

[0173]

[0174] Among them, θ is the actual position angle of the motor rotor after compensation.

[0175] In addition, the true angle value during motor movement can be calculated by pre-storing the angle error lookup table method, and the error compensation value can be calculated based on the sensor input signal using some calculation or processing methods to establish an error compensation table between the sensor input signal and the true angle value. The operation is simple and convenient.

[0176] Through the above technical scheme, the present invention provides a method for compensating the angle error of the eddy current sensor of a permanent magnet synchronous motor. Aiming at the problem that the shape and position error generated by the eddy current sensor affects the angle calculation accuracy, the present invention proposes a method for error compensation for different forms of output signals, wherein, for the generated DC bias error, the average value of the algebraic sum of the differential sine signal and the cosine signal in the operation cycle is selected to compensate for the bias error; for the amplitude asymmetry, the amplitude compensation coefficient is obtained by the maximum and minimum extreme points in the operation cycle to compensate for the amplitude asymmetry error; for the angle second harmonic error generated by the incomplete orthogonal phase, the method of estimating the cosine component of the angle second harmonic is adopted to complete the phase incomplete orthogonal error compensation. Compared with the prior art, the existing resolver or eddy current sensor position error compensation technology mostly uses the method of preliminary calculation and error calibration to design the angle error compensation table, which takes a lot of time and system memory, and the present invention does not have these disadvantages. And the compensation method of the present invention only uses algebraic addition and subtraction and multiplication operations, does not include sine, cosine and division operations, can save the execution time of the system, improve the operation efficiency, and meet the requirements of real-time acquisition of position angle. In addition, there are no preset fixed compensation values ​​for DC bias and amplitude asymmetry errors. Dynamic calculation is used to compensate the position angle, which can adaptively compensate for different installation errors and better meet the needs of mass installation.

[0177] The optional implementation modes of the examples of the present invention are described in detail above in conjunction with the accompanying drawings; however, the implementation modes of the present invention are not limited to the specific details in the above implementation modes; within the technical concept of the implementation modes of the present invention, a variety of simple modifications can be made to the technical solutions of the implementation modes of the present invention, and these simple modifications all belong to the protection scope of the implementation modes of the present invention.

[0178] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0179] Those skilled in the art can understand that all or part of the steps in the above-mentioned implementation method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions to enable a (which can be a single-chip microcomputer, chip, etc.) or a processor to execute all or part of the steps of the method described in each implementation of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0180] In addition, various different embodiments of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A method for compensating angle error of eddy current sensor of permanent magnet synchronous motor, characterized in that: The compensation method includes: Obtain differential sine and cosine signals output by the eddy current sensor; Calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation; Calculating an amplitude asymmetry error compensation coefficient according to the extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation; The position angle of the motor rotor is calculated according to the differential sine and cosine signals after the amplitude asymmetry error compensation, and the position angle is compensated by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation.

2. The compensation method according to claim 1, characterized in that: Calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation, including: calculating a sampled DC bias based on the differential sine and cosine signals; Calculating a DC bias error based on the sampled DC bias and an ideal DC bias; A DC offset error correction of the differential sine and cosine signals is performed based on the DC offset error.

3. The compensation method according to claim 2, characterized in that: Calculating a DC offset error according to the differential sine and cosine signals to obtain differential sine and cosine signals after DC offset error compensation, including: According to formulas (1) to (2), the DC offset error of the sine signal and the DC offset error of the cosine signal are obtained. WITH com =(U sin+ +U sin- ) / 2-U o , (1) C com =(U cos+ +U cos- ) / 2-U o , (2) Among them, U sin+ , U sin- is a differential sinusoidal signal, U sin- , U cos- is the differential cosine signal, U o is an ideal DC bias, S com DC offset error of differential sinusoidal signal, C com DC offset error of the differential cosine signal; According to formulas (3) to (6), the differential sine and cosine signals after DC offset error compensation are obtained. IN' sin+ =U sin+ -WITH com , (3) IN' sin- =U sin- -WITH com , (4) IN' cos+ =U cos+ -C com , (5) IN' cos- =U cos- -C com , (6) Among them, U′ sin+ , U′ sin- is the differential sinusoidal signal after DC offset error compensation, U′ cos+ , U′ cos- is the differential cosine signal after DC offset error compensation.

4. The compensation method according to claim 3, characterized in that: Calculating an amplitude asymmetry error compensation coefficient according to the extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation, including: Calculating the changing direction of the position angle of the motor rotor according to the differential sine and cosine signals output by the eddy current sensor; Determining whether the movement direction of the motor is forward rotation according to the change direction of the position angle; When it is determined that the motor is rotating forward, determining whether the position angle exceeds a first preset angle; When it is determined that the position angle exceeds the first preset angle, performing a marker extreme value extraction; In the case where it is determined that the motor is not rotating forward, determining whether the position angle exceeds a second preset angle; When it is determined that the position angle exceeds the second preset angle, mark extreme value extraction is performed.

5. The compensation method according to claim 4, characterized in that: Perform labelled extreme value extraction, including: Get the current recognition cycle; Determining whether the current recognition period exceeds a specified extreme value recognition period; In the case where it is determined that the current identification period exceeds the specified extreme value identification period, obtaining the extreme values ​​of the differential sine and cosine signals of the specified extreme value identification period; In the case where it is determined that the current identification period does not exceed the specified extreme value identification period, determining whether the current identification period is ended; When it is determined that the current identification cycle is over, the current identification cycle is incremented; When it is determined that the current identification period has not ended, the extreme values ​​of the differential sine and cosine signals of the current identification period are obtained.

6. The compensation method according to claim 5, characterized in that: In the case where it is determined that the current identification period exceeds the specified extreme value identification period, obtaining the extreme value of the differential sine and cosine signals of the specified extreme value identification period includes: Obtaining the average value of the maximum values ​​of the differential sinusoidal signal in each period within the specified extreme value identification period as the maximum value of the differential sinusoidal signal, and taking the average value of the minimum values ​​of the differential sinusoidal signal in each period as the minimum value of the differential sinusoidal signal; The average value of the maximum value of the differential cosine signal in each period within the specified extreme value identification period is obtained as the maximum value of the differential cosine signal, and the average value of the minimum value of the differential cosine signal in each period is obtained as the minimum value of the differential cosine signal.

7. The compensation method according to claim 6, characterized in that: In the case where it is determined that the current identification period does not exceed the specified extreme value identification period, determining whether the current identification period ends includes: Calculating the changing direction of the position angle of the motor rotor according to the differential sine and cosine signals output by the eddy current sensor; Determining whether the movement direction of the motor is forward rotation according to the change direction of the position angle; When it is determined that the motor is rotating forward, determining whether the position angle exceeds a first preset angle; In the case where it is determined that the position angle exceeds the first preset angle, determining that the current recognition cycle is ended; In the case where it is determined that the motor is not rotating forward, determining whether the position angle exceeds a second preset angle; When it is determined that the position angle exceeds the second preset angle, it is determined that the current recognition cycle ends.

8. The compensation method according to claim 7, characterized in that: In the case where it is determined that the current identification cycle has not ended, obtaining extreme values ​​of differential sine and cosine signals of the current identification cycle includes: Determine whether the maximum value of the differential sine and cosine signals of the current identification period is greater than the maximum value of the differential sine and cosine signals of the corresponding specified extreme value identification period; In the case where it is determined that the maximum value of the differential sine and cosine signals of the current identification period is greater than the maximum value of the differential sine and cosine signals of the corresponding specified extreme value identification period, the maximum value of the differential sine and cosine signals of the current identification period is updated to the maximum value of the differential sine and cosine signals of the extreme value identification period; Determine whether the minimum value of the differential sine and cosine signals of the current identification period is less than the minimum value of the differential sine and cosine signals of the corresponding specified extreme value identification period; When it is determined that the minimum value of the differential sine and cosine signals of the current identification period is smaller than the minimum value of the differential sine and cosine signals of the corresponding specified extreme value identification period, the minimum value of the differential sine and cosine signals of the current identification period is updated to the minimum value of the differential sine and cosine signals of the extreme value identification period.

9. The compensation method according to claim 8, characterized in that: Calculating an amplitude asymmetry error compensation coefficient according to the extreme values ​​of the differential sine and cosine signals after the DC offset error compensation to obtain the differential sine and cosine signals after the amplitude asymmetry error compensation, including: According to formulas (7) to (8), the extreme value difference of the differential sine signal and the extreme value difference of the differential cosine signal are obtained. Among them, A sin is the extreme value difference of the differential sine signal, A cos is the extreme value difference of the differential cosine signal, is the maximum value of the differential sinusoidal signal, is the minimum value of the differential sinusoidal signal, is the maximum value of the differential cosine signal, is the minimum value of the differential cosine signal; According to formula (9), the amplitude asymmetry error compensation coefficient is obtained: A com =A sin / A cos , (9) Among them, A com is the amplitude asymmetry error compensation coefficient; According to formulas (10) to (13), the differential sine and cosine signals after the amplitude asymmetry error compensation are obtained. IN" sin+ =U′ sin+ , (10) IN" sin- =U′ sin- , (11) U″ cos+ =A com *U′ cos+ , (12) U″ cos- =A com *U′ cos- , (13) Among them, U sin+ , U″ sin- is the differential sinusoidal signal after amplitude asymmetry error compensation, U″ cos+ , U″ cos- is the differential cosine signal after amplitude asymmetry error compensation.

10. The compensation method according to claim 9, characterized in that: The method comprises: calculating the position angle of the motor rotor according to the differential sine and cosine signals after the compensation of the amplitude asymmetry error, and compensating the position angle by using the second harmonic cosine wave component of the position angle to obtain the real position angle of the motor rotor after compensation, including: According to formulas (14) to (15), the position angle of the motor rotor is calculated: in, is the position angle of the motor rotor after removing the DC offset error and amplitude asymmetry error; According to formula (16), the second harmonic cosine component of the position angle is obtained: in, is the second harmonic cosine component; According to formula (17), the phase non-orthogonal position angle compensation value is obtained: Among them, θ err is the phase non-orthogonal position angle compensation value, B is the compensation coefficient, and C is the compensation bias; According to formula (18), the actual position angle of the motor rotor after compensation is obtained: Among them, θ is the actual position angle of the motor rotor after compensation.

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