A method and system for compensating position error of a rotating high frequency injection method

Abstract

The present invention discloses a method and system for compensating the estimated position error of a rotating high-frequency injection method, and belongs to the technical field of motor control. The motor rotor position obtained by the rotating high-frequency injection method is compensated for the phase shift caused by the non-ideal factors of the inverter and the inherent phase shift of the rotating high-frequency injection method algorithm, so as to obtain the rotor position actually input into the motor closed-loop control system. The present invention can conveniently calculate the phase shift of the high-frequency current caused by the non-ideal factors of the inverter by extracting the form of the high-frequency positive sequence component of the current generated by the injected high-frequency voltage in the high-frequency synchronous rotating coordinate system, and compensate for the error of the rotor position obtained by the rotating high-frequency injection method, so that the error approaches zero.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and more specifically, relates to a method and system for compensating an estimated position error of a rotating high-frequency injection method. Background Art

[0002] The rotating high-frequency injection method is a method for realizing position sensorless control of permanent magnet synchronous motors with salient polarity. It is mainly used in situations where the motor speed is low and the back EMF is relatively small. The rotating high-frequency injection method injects a high-frequency rotating voltage into the two-phase stationary coordinate system of the motor, extracts the motor rotor position through the feedback high-frequency current, and realizes position sensorless control of the motor. Compared with position sensorless implementation methods such as back EMF observers, this method has obvious advantages in the low-speed range where the back EMF signal-to-noise ratio is low, and is often used to realize position sensorless control of permanent magnet synchronous motors at low speeds.

[0003] The high-frequency rotating voltage injected by the rotating high-frequency injection method has a duty cycle given by the control algorithm, and the voltage injection is actually completed by hardware circuits such as the inverter. Due to non-ideal factors of the inverter such as the dead zone effect, there is a certain difference between the voltage given by the algorithm and the actual injected voltage, which causes phase shift and distortion in the injected voltage, affecting the generated current phase, causing errors in sampling current and extracting the motor rotor position, affecting the rotor position accuracy obtained without a position sensor, and reducing the motor control efficiency. Therefore, it is necessary to design a method for compensating for the position error of the rotating high-frequency injection method to compensate for the position error caused by non-ideal factors of the inverter. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a method and system for compensating the estimated position error of a rotating high-frequency injection method, aiming to solve the problem that the current rotating high-frequency injection method has an accuracy error in the estimated rotor position of a permanent magnet synchronous motor caused by non-ideal factors of the inverter, thereby reducing the operating efficiency of the motor.

[0005] To achieve the above object, the present invention provides a method for compensating position error by a rotational high frequency injection method, which specifically comprises the following steps:

[0006] Step S1: Inject a rotating high-frequency voltage V into the two-phase stationary coordinate system of the permanent magnet synchronous motor ha 、V hb ;

[0007] Step S2: Sampling to obtain the motor three-phase stator current I A ,I B ,I C ;

[0008] Step S3: Design a bandpass filter with the same center frequency as the injected high-frequency voltage to filter out the three-phase stator current I A ,I B ,IC The high-frequency component I in the three-phase stator current is obtained by removing the low-frequency components such as the fundamental frequency current in AH ,I BH ,I CH ;

[0009] Step S4: The high frequency component I AH ,I BH ,I CH Transformed to a high-frequency synchronous rotating coordinate system with the same frequency as the injected high-frequency voltage, we get I HD ,I HQ ;

[0010] Step S5: Use a first-order low-pass filter to filter out I HD ,I HQ The high-frequency component in the current is obtained by taking the DC component I in the high-frequency synchronous rotating coordinate system, which represents the high-frequency positive sequence component of the current. HDDC ,I HQDC ;

[0011] Step S6: Using the DC component I in the high-frequency synchronous rotating coordinate system HDDC ,I HQDC , calculate the phase shift caused by the non-ideal factors of the inverter θ inv ;

[0012] Step S7: Compensate the phase shift θ caused by the non-ideal factors of the inverter on the motor rotor position obtained by the rotating high-frequency injection method inv The inherent phase shift θ of the rotating high frequency injection method flt , get the actual input motor closed-loop control system rotor position θ e .

[0013] Furthermore, in step S3, the three-phase stator current I A ,I B ,I C The low-frequency components in the current are filtered out by a bandpass filter whose center frequency is the same as the injected high-frequency voltage.

[0014] Furthermore, after the coordinate transformation in step S4, the positive-sequence high-frequency current is transformed into a DC current in a steady state, and the negative-sequence high-frequency current is transformed into a negative-sequence signal with a higher frequency.

[0015] Furthermore, in step S5, a first-order low-pass filter is used to filter out I HD ,I HQ The high frequency components in .

[0016] Furthermore, in the calibration phase before the motor is put into use in step S7, under any working condition where the motor is controlled without a position sensor using the rotating high-frequency injection method, the system inherent phase shift is calibrated only once using the position sensor, and its expression is:

[0017] θ flt =θ sensor -θ HF +θ inv =θ err +θ inv

[0018] In the formula, θ sensor is the motor electrical angle detected by the position sensor, θ err Position error detected by the position sensor and calculated by the high frequency injection method.

[0019] The actual rotor position θ input into the motor closed-loop control system e :

[0020] θ e =θ HF -θ inv +θ flt

[0021] Among them, θ HF The rotor position estimated by the high frequency injection method before compensation.

[0022] Another aspect of the present invention provides an estimated position error compensation system of a rotation high frequency injection method, comprising: a computer readable storage medium and a processor;

[0023] The computer-readable storage medium is used to store executable instructions;

[0024] The processor is used to read the executable instructions stored in the computer-readable storage medium to execute the estimated position error compensation method of the above-mentioned rotation high-frequency injection method.

[0025] Compared with the prior art, the above technical solution conceived by the present invention can achieve the following beneficial effects:

[0026] 1. By extracting the form of the high-frequency positive sequence component of the current generated by the injected high-frequency voltage in the high-frequency synchronous rotating coordinate system, the high-frequency current phase shift caused by the non-ideal factors of the inverter can be easily calculated, and the error of the rotor position obtained by the rotating high-frequency injection method can be compensated to make the error approach zero;

[0027] 2. Under different inverter dead time and different injected high-frequency voltage amplitude conditions, the compensation method proposed by the present invention can adaptively calculate the rotor position error caused by non-ideal factors of the inverter and has strong robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A flow chart showing the calculation of the phase shift magnitude and position error compensation caused by non-ideal factors of the inverter using the rotating high frequency injection method.

[0029] Figure 2 This is the logic block diagram of the application of rotating high-frequency injection method position compensation calculation in permanent magnet synchronous motor control system.

[0030] Figure 3 This is a comparison chart of the position error changes before and after compensation when changing the inverter dead zone and injecting high-frequency voltage amplitude. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The present invention provides a method for compensating position errors using a rotational high frequency injection method, the flow chart of which is as follows: Figure 1 As shown, the following steps are included.

[0033] Step S1: Inject a rotating high-frequency voltage V into the two-phase stationary coordinate system of the permanent magnet synchronous motor ha 、V hb .

[0034] Specifically, the injected rotating high-frequency voltage V ha 、V hb The expression is:

[0035]

[0036] Among them, U h is the amplitude of the injected rotating high-frequency voltage, ω h is the frequency of the injected rotating high-frequency voltage, and t is the time of signal injection.

[0037] In this embodiment, the inverter switching frequency used is 10 kHz, and the designed injected rotating high-frequency voltage frequency is 500 Hz.

[0038] Step S2: Obtain the three-phase stator current I of the motor by current sampling of the control system A ,I B ,I C .

[0039] Specifically, the expression of the motor three-phase stator current in the two-phase stationary coordinate system is:

[0040]

[0041] In the formula, i a 、i brepresents the current in the two-phase stationary coordinate system, i aH 、i bH Represents the injected high-frequency current component, i aB 、i bB Represents the low-frequency current component of the motor, L d , L q is the motor d and q axis inductance, ω E is the motor electrical angular frequency.

[0042] There are three main frequency current components in the three-phase stator current, namely, the low-frequency component dominated by the motor electrical frequency, the negative-sequence high-frequency current component affected by the motor speed, and the positive-sequence high-frequency current component with the same frequency as the injection frequency. Among them, the rotating high-frequency injection method uses the negative-sequence high-frequency current component related to the motor speed to extract the motor rotor position, and the present invention uses the positive-sequence high-frequency current component in the subsequent steps to extract the current phase shift caused by the non-ideal factors of the inverter.

[0043] Step S3: The three-phase stator current I A ,I B ,I C The low-frequency component in the current is filtered out by a bandpass filter whose center frequency is the same as the injected high-frequency voltage, and the high-frequency component I in the three-phase stator current is obtained. AH ,I BH ,I CH ;

[0044] Specifically, a bandpass filter whose center frequency is the same as the injected high-frequency voltage is designed. In this embodiment, the bandwidth of the bandpass filter is selected to be 225 Hz, and the transfer function expression of the designed bandpass filter is:

[0045]

[0046] Where, T bp is the transfer function of the designed bandpass filter.

[0047] Step S4: The high frequency component I AH ,I BH ,I CH Transformed to a high-frequency synchronous rotating coordinate system with the same frequency as the injected high-frequency voltage, we get I HD ,I HQ ;

[0048] Specifically, the high-frequency component of the three-phase stator current contains positive and negative sequence components, which have similar frequencies. It is necessary to separate the two signals through coordinate transformation. The matrix expression of coordinate transformation is:

[0049]

[0050] After transformation, we get the high-frequency synchronous rotating coordinate system IHD ,I HQ The current expression is:

[0051]

[0052] In the formula, I HA ,I LA are the amplitudes of the two frequency current components after transformation.

[0053] That is, after the coordinate transformation, the positive-sequence high-frequency current in the steady state is transformed into a DC quantity, and the negative-sequence high-frequency current is transformed into a negative-sequence signal with a higher frequency.

[0054] Step S5: Use a first-order low-pass filter to filter out I HD ,I HQ The high-frequency component in the high-frequency current positive sequence component is obtained, and the DC component I in the high-frequency synchronous rotating coordinate system is obtained. HDDC ,I HQDC ;

[0055] Specifically, in this embodiment, the cutoff frequency of the first-order low-pass filter is designed to be 100 Hz, and its transfer function expression is:

[0056]

[0057] Where, T lp is the transfer function of the designed bandpass filter.

[0058] Step S6: Using the DC component I in the high-frequency synchronous rotating coordinate system HDDC ,I HQDC , calculate the phase shift caused by the non-ideal factors of the inverter θ inv ;

[0059] Specifically, calculate the phase shift θ inv The inverse tangent method and the phase-locked loop method can be selected. In this embodiment, the phase-locked loop method is selected to reduce the jitter of the output angle and ensure the stability of the compensation. The calculation formula of the designed phase-locked loop is:

[0060] ε=-I HDDC sinθ′ inv +I HQDC cosθ′ inv

[0061] θ inv =∫(k p ε+k i ∫εdt)dt

[0062] Where, e is the angle error value of the input phase-locked loop, θ i ' nv k is the phase-locked loop output angle of the previous calculation cycle,p , k i It is the proportional and integral calculation coefficient in the phase-locked loop.

[0063] Step S7: Compensate the phase shift θ caused by the non-ideal factors of the inverter on the motor rotor position obtained by the rotating high-frequency injection method inv The inherent phase shift θ of the rotating high frequency injection method flt , get the actual input motor closed-loop control system rotor position angle θ e .

[0064] Specifically, the inherent phase shift θ of the rotating high-frequency injection method is flt It can be obtained through calibration. In the calibration phase before the motor is put into use, under any working condition where the motor is controlled without a position sensor using the rotating high-frequency injection method, the inherent phase shift of the system is calibrated only once using the position sensor, and its expression is:

[0065] θ flt =θ sensor -θ HF +θ inv =θ err +θ inv

[0066] In the formula, θ sensor is the motor electrical angle detected by the position sensor, θ HF is the rotor position estimated by the high frequency injection method before compensation, θ err Position error detected by the position sensor and calculated by the high frequency injection method.

[0067] For control systems using the same parameter software and hardware, the phase shift is a constant and only needs to be calibrated once in the regular motor calibration process. The calibrated inherent phase shift can be directly applied to other motor position sensorless control.

[0068] The angle compensation value calculated in the above steps is compensated to the motor rotor position estimated by the high-frequency injection method, and the position compensation calculation formula is obtained as follows:

[0069] θ e =θ HF -θ inv +θ flt

[0070] The estimated motor rotor position calculated at this time has a relatively small position error after compensation and is used in the permanent magnet synchronous motor speed and current dual closed-loop control system and coordinate transformation process.

[0071] Based on the rotation high frequency injection method position error compensation method provided by the present invention, the permanent magnet synchronous motor control system block diagram is designed as follows: Figure 2As shown. It mainly includes a coordinate transformation module 1, a speed regulator module 2, a d-axis and q-axis current regulator module 3, an inverse coordinate transformation module 4, a rotating high-frequency voltage injection module 5, an SVPWM modulation module 6, a voltage source type three-phase inverter module 7, a permanent magnet synchronous motor module 8, a bandpass filter module 9, a positive sequence high-frequency synchronous rotating coordinate system transformation module 10, a low-pass filter module 11, a phase-locked loop module 12, and a rotating high-frequency injection method position estimation module 13.

[0072] Specifically, the coordinate transformation module 1 inputs the three-phase stator current of the motor, and outputs the d and q axis feedback current. The speed regulator module 2 inputs the difference between the given motor speed command and the speed output by the phase-locked loop module 12 in the previous calculation cycle, and outputs the q axis current command. The d and q axis current regulator module 3 inputs the difference between the d and q axis current commands and the d and q axis feedback currents, and outputs the d and q axis voltage commands. The inverse coordinate transformation module 4 inputs the d and q axis voltage commands, and outputs the α and β axis voltage commands. The rotating high-frequency voltage injection module 5 injects a rotating high-frequency voltage V on the basis of the α and β axis voltage commands. ha 、V hb , outputs the voltage after injection of α and β axes. The SVPWM modulation module 6 inputs the voltage after injection of α and β axes, and outputs six-way PWM duty cycle instructions. The voltage source three-phase inverter module 7 converts the six-way PWM duty cycle instructions output by the control system software into actual hardware actions and outputs three-phase voltage. The permanent magnet synchronous motor module 8 includes a motor body and a current sampling circuit, with input of three-phase voltage and output of three-phase current sampling value I A ,I B ,I C The input of the bandpass filter module 9 is a three-phase I A ,I B ,I C , the output is the high-frequency component I in the three-phase stator current AH ,I BH ,I CH The positive sequence high frequency synchronous rotating coordinate system transformation module 10 inputs the high frequency component I of the three-phase stator current AH ,I BH ,I CH , the output is the high frequency component of current I HD ,I HQ The input of the low-pass filter module 11 is the high-frequency component of the current I HD ,I HQ , the output is the transformed positive sequence high frequency current component information I HDDC ,I HQDC The input of the phase-locked loop module 12 is the transformed negative sequence high frequency current component information I HDDC ,I HQDC, the output is the phase shift θ caused by the calculated inverter non-ideal factors inv The input of the rotating high frequency injection method position estimation module 13 is the three-phase current sampling value I A ,I B ,I C , the output is the estimated motor speed ω E and the motor rotor angle θ e .

[0073] In order to verify and illustrate the technical effect adopted in this method, this embodiment takes a specific permanent magnet synchronous motor as an example. Figure 2 The control system shown compares the position error of the rotation high-frequency injection method without position sensor control before and after compensation to verify the effectiveness of the method proposed in the present invention.

[0074] This embodiment takes a permanent magnet synchronous motor with a rated power of 1kW, a rated voltage of 200V, a rated speed of 3000RPM, a d-axis inductance of 2.9mH and a q-axis inductance of 4.03mH, a phase resistance of 50mΩ, and a pole pair number of 5 as an example. When the motor speed is 300RPM, the rotor position estimation error of the high-frequency injection method before and after compensation is compared. Figure 3 As shown in the figure, before compensation, the estimated position error varies greatly in the range of -30° to 0° as the inverter dead zone and the injected high-frequency voltage amplitude change. After compensation, the estimated position error fluctuates around 0°, and the estimated position is more accurate.

[0075] In summary, the present invention can compensate the position estimation error under different dead time and injection amplitude to near zero, with obvious compensation effect and strong robustness.

[0076] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for compensating an estimated position error of a rotating high frequency injection method, characterized in that: The following steps are involved: Step S1: Inject a rotating high-frequency voltage V into the two-phase stationary coordinate system of the permanent magnet synchronous motor ha 、V hb ; Step S2: Sampling to obtain the motor three-phase stator current I A ,I B ,I C ; Step S3: Filter out the three-phase stator current I A ,I B ,I C The low-frequency component in the three-phase stator current is obtained by AH ,I BH ,I CH ; Step S4: The high frequency component I AH ,I BH ,I CH Transformed to a high-frequency synchronous rotating coordinate system with the same frequency as the injected high-frequency voltage, we get I HD ,I HQ ; Step S5: Filter out I HD ,I HQ The high-frequency component in the current is obtained by taking the DC component I in the high-frequency synchronous rotating coordinate system, which represents the high-frequency positive sequence component of the current. HDDC ,I HQDC ; Step S6: Using the DC component I in the high-frequency synchronous rotating coordinate system HDDC ,I HQDC , calculate the phase shift caused by the non-ideal factors of the inverter θ inv ; Step S7: Compensate the phase shift θ caused by the non-ideal factors of the inverter on the motor rotor position obtained by the rotating high-frequency injection method inv The inherent phase shift θ of the rotating high frequency injection method flt , get the actual input motor closed-loop control system rotor position θ e ; Under any working condition where the motor is controlled without a position sensor using the rotating high-frequency injection method, the system inherent phase shift is calibrated only once using the position sensor, and its expression is: i flt =θ err +θ inv The actual rotor position θ input into the motor closed-loop control system e : i e =θ HF -θ inv +θ flt In the formula, θ err is the position error detected by the position sensor and calculated by the high-frequency injection method, θ HF The rotor position estimated by the high frequency injection method before compensation.

2. The method according to claim 1, characterized in that In step S3, the three-phase stator current I A ,I B ,I C The low-frequency components in the current are filtered out by a bandpass filter whose center frequency is the same as the injected high-frequency voltage.

3. The method according to claim 1, characterized in that After the coordinate transformation in step S4, the positive-sequence high-frequency current is transformed into a DC current in a steady state, and the negative-sequence high-frequency current is transformed into a negative-sequence signal with a higher frequency.

4. The method according to claim 1, characterized in that In step S5, a first-order low-pass filter is used to filter out I HD ,I HQ The high frequency components in .

5. A system for compensating an estimated position error using a rotating high frequency injection method, characterized in that: include: A computer readable storage medium and a processor; The computer-readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer-readable storage medium to execute the estimated position error compensation method of the rotation high-frequency injection method according to any one of claims 1 to 4.

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