A method for correcting current measurement gain errors in open-winding permanent magnet synchronous motors

Abstract

The present invention relates to a method for correcting the gain error in current measurement of an open-winding permanent magnet synchronous motor, and belongs to the technical field of motor control. Using a three-phase voltage mathematical model of an open-winding permanent magnet synchronous motor, an equation is obtained after injecting a high-frequency voltage signal into the motor system; the sinusoidal high-frequency voltage signal is injected, and by comparing it with the carrier wave, a high-frequency current of the corresponding frequency is generated in the three phases; three second-order generalized integrators are connected in parallel, and a feedforward decoupling network is constructed before the second-order generalized integrators to filter out the high-frequency current in the three-phase current and calculate its current amplitude; three second-order generalized integrators are connected in parallel, and a feedforward decoupling network is constructed before the second-order generalized integrators to filter out the high-frequency current with system gain error in the three-phase current in a closed-loop state and calculate its current amplitude; through comparison, the high-frequency current with gain error is corrected. The current gain is well corrected to 1, so that the current waveform has almost no fluctuation.

Description

Technical Field

[0001] The invention relates to a synchronous motor current measurement gain error correction method, belonging to the technical field of motor control. Background Art

[0002] Permanent magnet synchronous motors (PMSMs) have the advantages of small size, high efficiency, high power density, and good dynamic performance, and are widely used in aerospace, electric vehicles, and other fields. However, in some applications, such as electric vehicles, high motor output power is required, while the battery supply voltage is limited. Therefore, the current needs to be increased, which in turn affects motor efficiency and increases the size of the motor. Increasing the supply voltage can expand the motor speed range, achieving a smaller motor output torque for the same output power, which is beneficial for improving motor efficiency and reducing size, and increasing continuous output power in the weak magnetic field region. To meet these requirements, scholars have proposed opening the star-shaped neutral point of the traditional motor winding in a single inverter-powered motor system. Without changing the original motor's electromagnetic design and mechanical structure, an inverter is connected in series at both ends of the winding to form an open-winding permanent magnet synchronous motor.

[0003] Open-winding permanent magnet synchronous motors are categorized into isolated DC bus, shared DC bus, and hybrid power supply types. Common DC bus open-winding permanent magnet synchronous motors are widely used due to their low cost, compact size, and high voltage efficiency. However, the presence of the busbar creates a zero-sequence closed loop, generating zero-sequence currents that cause additional torque ripple and reduce motor system efficiency. Zero-sequence current controllers have been proven to be an effective method for suppressing zero-sequence currents, but current measurement errors can directly impact system performance.

[0004] The current measurement path consists of several components, including the Hall effect sensor, matching circuit, noise filtering circuit, and analog-to-digital converter. One or more of these components may be affected by various factors, such as device temperature drift, aging, and noise, resulting in measurement errors. Furthermore, the magnitude of measurement errors can vary over time. Therefore, measurement errors should be compensated or corrected regularly or continuously to maintain optimal system operation.

[0005] Current measurement errors are divided into gain error and offset error. Because gain error varies with phase current amplitude, compensating or correcting it is more complex. Currently, most current measurement gain error compensation or correction methods are designed for permanent magnet synchronous motors and do not consider the impact of zero-sequence current in the zero-sequence closed-loop circuit.

[0006] Therefore, it is urgent to propose a current measurement gain error correction method for open-winding permanent magnet synchronous motor to solve the above technical problems. Summary of the Invention

[0007] To address the aforementioned issues, a method for correcting current measurement gain errors in an open-winding permanent magnet synchronous motor is provided. A brief overview of the invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive overview of the invention. It is not intended to identify key or important aspects of the invention, nor is it intended to limit the scope of the invention.

[0008] The technical solution of the present invention:

[0009] A method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor comprises the following steps:

[0010] Step 1: Using the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, obtain the high-frequency voltage signal injected into the motor system u H The equations of the three-phase current of the rear system;

[0011] Step 2: Inject a sinusoidal high-frequency voltage signal into the system along the 0-axis u H The voltage signal is combined with the modulation wave and compared with the carrier wave to generate a high-frequency current of the corresponding frequency in the three phases. i H ;

[0012] Step 3: Use three second-order generalized integrators in parallel and build a feedforward decoupling network in front of the second-order generalized integrator to filter out the high-frequency current in the three-phase current and calculate its current amplitude when there is no gain error in the system. M ;

[0013] Step 4: When there is a gain error in the three-phase current of the system, the high-frequency current generated by the sinusoidal high-frequency voltage signal has a corresponding three-phase current gain error. Three second-order generalized integrators are connected in parallel, and a feedforward decoupling network is constructed before the second-order generalized integrator. In the closed-loop case, the high-frequency current with the system gain error in the three-phase current is filtered out and its current amplitude is calculated as M* ;

[0014] Step 5: Design a gain error correction controller by comparing M and M* The value of is used to correct the high-frequency current with gain error. Since the gain error of the high-frequency current is the gain error of the three-phase current, the three-phase gain error of the open-winding permanent magnet synchronous motor system is corrected.

[0015] Preferred: Error current calculation: Based on the input of the PI regulator, the error is calculated by comparing the reference value and the actual value of the feedback. i d = id *- i q *, i q = i q *- i q ;

[0016] PI regulation: Get the reference voltage through PI regulation u d *and u q *;

[0017] Inverse Park transform: u d *、 u q * and zero sequence reference voltage u 0*Together through the inverse Park transformation, from the synchronous rotating coordinate system dq0 axis to the stationary coordinate system axis;

[0018] SVPWM modulation: Using the SVPWM modulation strategy, the current passes through the open-winding permanent magnet synchronous motor system;

[0019] Current sensor detection: The three-phase measurement current is detected by the current sensor i nm (n=a,b,c), in a three-phase four-wire system, a, b, c are the three phases, and n is the neutral line. In this case, the three-phase currents all have measurement gain errors;

[0020] Zero-sequence current control: given zero-sequence reference current i 0*=0, i 0*minus zero sequence current i 0 and zero sequence current angular frequency The quasi-proportional resonant controller eliminates the main third harmonic in the zero-sequence current and outputs a zero-sequence reference voltage. u 0*.

[0021] Preferably, the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor in step 1 is:

[0022]

[0023] in, u n , i n , L n , e n (n =a, b, c) are the voltage, current, self-inductance and back electromotive force of the three-phase winding respectively. M ab 、 M ac 、 M ba 、 M bc 、 M ca 、 M cb is the mutual inductance of the three-phase winding;

[0024] e n ( n =a, b, c) is as follows:

[0025]

[0026] in, is the electrical angular velocity of the motor rotor, is the motor rotor position, is the permanent magnet flux of the motor rotor, is the tertiary flux linkage of the motor rotor permanent magnet;

[0027] Get a high-frequency voltage signal injected into the motor system u H The equation of the three-phase current of the system is:

[0028]

[0029] in, i nm , K n ( n =a, b, c) are the measured values ​​of the three-phase current and the measurement gain errors of the three-phase current respectively, I is the instantaneous current amplitude, I H is the high-frequency current amplitude, is the high frequency current phase.

[0030] Preferably: in the step 2, the switching frequency of the open-winding permanent magnet synchronous motor used in the present invention is 10kHz, so a sinusoidal signal with a frequency of 1 / 10 of the switching frequency is generated, that is, a sinusoidal high-frequency voltage signal with a frequency of 1kHz. u H Since the frequency of the sinusoidal high-frequency voltage signal is much higher than the operating frequency of the zero-sequence controller, it will not affect the working efficiency of the zero-sequence controller and the operating efficiency of the motor system.

[0031] Preferably: the second-order generalized integrator in step 3 has two transfer functions H 1( s )= C 1( s ) / R ( s )and H 2( s )= C 2( s ) / R ( s ), which respectively function as low-pass filters and band-pass filters;

[0032] The structure of the second-order generalized integrator is as follows Figure 2 shown; is the resonant frequency of the second-order generalized integrator, is the closed-loop coefficient, R ( s ) is the input signal; C 1( s )and C 2( s ) is the output signal; its transfer functions are:

[0033]

[0034]

[0035] The present invention uses only the bandpass filter portion thereof, namely H 1( s );

[0036] Among them, the parameters of the present invention =0.1.

[0037] Preferred: such as Figure 3 As shown, x is the input signal, y 1st is the output fundamental current, y 3rd To output the third harmonic current, y H is the output high frequency current, is the angular velocity of the sinusoidal high-frequency voltage signal injected into the system;

[0038] Taking into account that the main components of the three-phase current include the fundamental current and the third harmonic in addition to the high-frequency current, three second-order generalized integrators in parallel plus a front-stage decoupling network are adopted. The front-stage decoupling network can eliminate the influence of the fundamental current and the third harmonic on the high-frequency component, and the parallel form can also eliminate the subharmonics and interharmonics in the input signal, thereby filtering out the required high-frequency current more accurately.

[0039] Preferably, the operations in step 3 are all performed under the condition that there is no current measurement gain error in the system.

[0040] Preferably, the operations in step 4 are all performed when there is a current measurement gain error in the system.

[0041] Preferably: the gain error correction controller in step 5 has a structure as follows: Figure 5 As shown, it contains a PI controller and a parallel second-order generalized integrator;

[0042] The reference value given by the PI controller is the high-frequency current amplitude calculated in step 3 when there is no current measurement gain error in the system. M , by calculating the high-frequency current amplitude calculated in step 4 M* and M Comparison is made to form a negative feedback closed loop, which is input to the PI controller, and then adjusted by the PI controller to output the current measurement gain error required for correction. K a *, K a *and i am Multiplying them together gives i a ;until M* = M , the whole system is stable, the gain error of the high-frequency current is corrected to 1, and the measurement gain error of the three-phase current is corrected to 1.

[0043] Preferably, the method further includes step 6: building a corresponding system simulation model in a multi-domain simulation and model design software (Matlab / Simulink) environment to verify its effectiveness.

[0044] The present invention has the following beneficial effects:

[0045] The present invention effectively corrects the current gain to 1, so that the current waveform has substantially no fluctuation.

[0046] After the present invention introduces gain error correction, the gain errors of the three phases are corrected to about 1.

[0047] When the motor speed changes, the present invention can quickly stabilize the flow waveform after it fluctuates, and correct the gain error to about 1 in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The present invention is a control block diagram of a current measurement gain error correction method for an open-winding permanent magnet synchronous motor;

[0049] Figure 2 The structure diagram of a second-order generalized integrator selected for the gain error correction method of current measurement in an open-winding permanent magnet synchronous motor is shown;

[0050] Figure 3 The structure diagram of a parallel second-order generalized integrator for a current measurement gain error correction method for an open-winding permanent magnet synchronous motor is shown;

[0051] Figure 4 The present invention is a method for correcting the current measurement gain error of an open-winding permanent magnet synchronous motor, and a structure diagram of filtering high-frequency current using a parallel second-order generalized integrator without the current measurement gain error.

[0052] Figure 5 The present invention is a gain error correction controller structure diagram of a current measurement gain error correction method for an open-winding permanent magnet synchronous motor;

[0053] Figure 6 The present invention is a graph showing the result of three-phase current when a gain error correction controller is in effect in a current measurement gain error correction method for an open-winding permanent magnet synchronous motor.

[0054] Figure 7 The present invention is a method for correcting the current measurement gain error of an open-winding permanent magnet synchronous motor, and a graph showing the correction results of the three-phase current measurement gain error by a gain error correction controller;

[0055] Figure 8 The present invention is a method for correcting the current measurement gain error of an open-winding permanent magnet synchronous motor, and a correction result diagram of a gain error correction controller when the three-phase current measurement gain error changes;

[0056] Figure 9 The present invention is a graph showing the results of a gain error correction controller of a current measurement gain error correction method for an open-winding permanent magnet synchronous motor and the three-phase current when the motor speed changes;

[0057] Figure 10 The present invention is a method for correcting the current measurement gain error of an open-winding permanent magnet synchronous motor, and shows the correction result of the three-phase current measurement gain error by the gain error correction controller when the motor speed changes. DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0059] Specific implementation method: Figure 1-10This embodiment describes a method for correcting a current measurement gain error in an open-winding permanent magnet synchronous motor, including the following steps:

[0060] Step 1: Using the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, obtain the high-frequency voltage signal injected into the motor system u H The equations of the three-phase current of the rear system;

[0061] Step 2: Inject a sinusoidal high-frequency voltage signal into the system along the 0-axis u H The voltage signal is combined with the modulation wave and compared with the carrier wave to generate a high-frequency current of the corresponding frequency in the three phases. i H ;

[0062] Step 3: Use three second-order generalized integrators in parallel and build a feedforward decoupling network in front of the second-order generalized integrator to filter out the high-frequency current in the three-phase current and calculate its current amplitude when there is no gain error in the system. M ;

[0063] Step 4: When there is a gain error in the three-phase current of the system, the high-frequency current generated by the sinusoidal high-frequency voltage signal has a corresponding three-phase current gain error. Three second-order generalized integrators are connected in parallel, and a feedforward decoupling network is constructed before the second-order generalized integrator. In the closed-loop case, the high-frequency current with the system gain error in the three-phase current is filtered out and its current amplitude is calculated as M* ;

[0064] Step 5: Design a gain error correction controller by comparing M and M* The value of is used to correct the high-frequency current with gain error. Since the gain error of the high-frequency current is the gain error of the three-phase current, the three-phase gain error of the open-winding permanent magnet synchronous motor system is corrected.

[0065] like Figure 1 As shown, the control strategy for the given task includes error current calculation, PI regulation, inverse Park transformation, SVPWM modulation, current sensor detection and zero-sequence current control;

[0066] Error current calculation: dq axis reference current i d *and i q * Subtract feedback current i d and i q Get the error current i d and i q , (the subscripts correspond to the currents of the d-axis and q-axis) That is, based on the input of the PI regulator, the error is calculated by comparing the reference value and the actual value of the feedback. i d = i d *- i q *, i q = i q *- i q ;

[0067] PI regulation: Get the reference voltage through PI regulation u d *and u q *;

[0068] Inverse Park transform: u d *、 u q * and zero sequence reference voltage u 0*Together through the inverse Park transformation, from the synchronous rotating coordinate system dq0 axis to the stationary coordinate system axis;

[0069] SVPWM modulation: Using the SVPWM modulation strategy, the current passes through the open-winding permanent magnet synchronous motor system;

[0070] Current sensor detection: The three-phase measurement current is detected by the current sensor i nm (n=a,b,c), in a three-phase four-wire system, a, b, c are the three phases, and n is the neutral line. In this case, the three-phase currents all have measurement gain errors;

[0071] Zero-sequence current control: given zero-sequence reference current i 0*=0, i 0*minus zero sequence current i 0 and zero sequence current angular frequency The quasi-proportional resonant controller eliminates the main third harmonic in the zero-sequence current and outputs a zero-sequence reference voltage. u 0*; Improve efficiency, ensure stability and accuracy;

[0072] The three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor in step 1 is:

[0073]

[0074] in, u n , i n , L n , e n ( n =a, b, c) correspond to the voltage, current, self-inductance and back electromotive force of the three-phase winding, respectively. M ab 、 M ac 、 M ba 、 M bc 、 M ca 、 M cb is the mutual inductance of the three-phase winding;

[0075] e n ( n =a, b, c) is as follows:

[0076]

[0077] in, is the electrical angular velocity of the motor rotor, is the motor rotor position, is the permanent magnet flux of the motor rotor, is the tertiary flux linkage of the motor rotor permanent magnet;

[0078] Get a high-frequency voltage signal injected into the motor system u H The equation of the three-phase current of the system is:

[0079]

[0080] in, i nm , K n ( n =a, b, c) correspond to the measured values ​​of the three-phase current and the measurement gain error of the three-phase current, respectively. I is the instantaneous current amplitude, I H is the high-frequency current amplitude, is the high-frequency current phase;

[0081] In the step 2, the switching frequency of the open-winding permanent magnet synchronous motor used in the present invention is 10kHz, so a sinusoidal signal with a frequency of 1 / 10 of the switching frequency is generated, that is, a sinusoidal high-frequency voltage signal with a frequency of 1kHz. u H Since the frequency of the sinusoidal high-frequency voltage signal is much higher than the operating frequency of the zero-sequence controller, it will not affect the working efficiency of the zero-sequence controller and the operating efficiency of the motor system;

[0082] The second-order generalized integrator in step 3 has two transfer functions H 1( s )= C 1( s ) / R ( s )and H 2( s )= C 2( s ) / R ( s ), which respectively function as low-pass filters and band-pass filters;

[0083] The structure of the second-order generalized integrator is as follows Figure 2 shown; is the resonant frequency of the second-order generalized integrator, is the closed-loop coefficient, R ( s ) is the input signal; C 1( s )and C 2( s ) is the output signal; its transfer functions are:

[0084]

[0085]

[0086] The present invention uses only the bandpass filter portion thereof, namely H 1( s );

[0087] Among them, the parameters of the present invention =0.1, s is a complex variable;

[0088] like Figure 3 As shown, x is the input signal, y 1st is the output fundamental current, y 3rd To output the third harmonic current, y H is the output high frequency current, is the angular velocity of the sinusoidal high-frequency voltage signal injected into the system;

[0089] Considering that the main components of the three-phase current include the fundamental current and the third harmonic in addition to the high-frequency current, the form of three second-order generalized integrators in parallel plus a front-stage decoupling network is adopted. The front-stage decoupling network can eliminate the influence of the fundamental current and the third harmonic on the high-frequency component, and the parallel form can also eliminate the subharmonics and interharmonics in the input signal, and filter out the required high-frequency current more accurately; therefore, it has H 2( s )The role of low-pass filter, H 2( s ) The low-pass filter can be omitted;

[0090] The operations in step 3 are all performed under the condition that there is no current measurement gain error in the system, such as Figure 4 As shown, taking phase a as an example, input phase a to measure current i am , phase current angular velocity and high-frequency current angular velocity To the parallel second-order generalized integrator, the filtered high-frequency current is output i H , calculate the amplitude of high frequency current M ;

[0091] The operations in step 4 are all performed under the condition that the system has a current measurement gain error, such as Figure 5 As shown, taking phase a as an example, input phase a to measure current i am , phase current angular velocity and high-frequency current angular velocity To the parallel second-order generalized integrator, after obtaining the high-frequency current, calculate the amplitude of the high-frequency current M* , which is fed as input into the subsequent correction of the current measurement gain error;

[0092] The gain error correction controller in step 5 has a structure as follows: Figure 5 As shown in the figure, it contains a PI controller and a parallel second-order generalized integrator; taking phase a as an example, the gain error correction controller inputs the phase a current with current measurement gain error i am , after parallel connection of second-order generalized integrator and PI controller, the output is the a-phase current without current measurement gain error after correction i a ;

[0093] The operation of the parallel second-order generalized integrator has been described in detail above;

[0094] The reference value given by the PI controller is the high-frequency current amplitude calculated in step 3 when there is no current measurement gain error in the system. M , by calculating the high-frequency current amplitude calculated in step 4 M* and M Comparison is made to form a negative feedback closed loop, which is input to the PI controller, and then adjusted by the PI controller to output the current measurement gain error required for correction. K a *, K a *and i am Multiplying them together gives i a ;until M* = M , the whole system is stable, the gain error of high-frequency current is corrected to 1, and the measurement gain error of three-phase current is corrected to 1;

[0095] It also includes step 6: building a corresponding system simulation model in a multi-domain simulation and model design software (Matlab / Simulink) environment to verify its effectiveness;

[0096] The motor speed is set to 800 r / min during simulation; the three-phase current waveform is as follows: Figure 6 As shown in the figure, it can be seen that after the gain error is introduced at 0.2s, the current waveform has a large fluctuation; after the correction method of the present invention is introduced at 0.4s, the current waveform is corrected to a normal waveform in a very short time; and after the gain error of the three phases is changed at 0.6s, the method of the present invention can also continue to correct the gain error to about 1, so that the current waveform basically does not fluctuate; Figure 7 The result graph shows that at 0.2s, the three phases introduced current measurement gain errors of 1.2 times, 1.3 times and 0.8 times respectively, and the correction method of the present invention was introduced at 0.4s; it can be seen from the figure that after the introduction of gain error correction, the gain errors of the three phases were corrected to about 1; based on the introduction of the correction method, the gain errors of the abc three phases were changed to 1.3 times, 1.1 times and 0.9 times at 0.6s; Figure 8 It can be seen that after changing the gain error, the method of the present invention can still better correct the gain error to about 1;

[0097] When the motor speed changes, such as Figure 9 、 Figure 10 As shown in the figure, the motor speed changes from 800r / min to 1200r / min at 0.6s; Figure 9It can be seen that after the gain error is introduced at 0.2s, the current waveform has a large fluctuation. After the correction method of the present invention is introduced at 0.4s, the current waveform is corrected to a normal waveform in a very short time. After the motor speed is changed at 0.6s, the current waveform can quickly reach stability after the fluctuation. Figure 10 As can be seen from the result graph, at 0.2s, the three phases introduced current measurement gain errors of 1.2 times, 1.3 times, and 0.8 times, respectively. The correction method of the present invention was introduced at 0.4s. After the gain error correction was introduced, the gain errors of the three phases were all corrected to about 1. After the motor speed was changed at 0.6s, the correction method of the present invention was also able to correct the gain error to about 1 in a short time.

[0098] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0099] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for correcting current measurement gain error in an open-winding permanent magnet synchronous motor, characterized by: The following steps are involved: Step 1: Using the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, obtain the high-frequency voltage signal injected into the motor system u H The equations of the three-phase current of the rear system; Step 2: Inject a sinusoidal high-frequency voltage signal into the system along the 0-axis u H The voltage signal is combined with the modulation wave and compared with the carrier wave to generate a high-frequency current of the corresponding frequency in the three phases. i H ; Step 3: Use three second-order generalized integrators in parallel and build a feedforward decoupling network in front of the second-order generalized integrator to filter out the high-frequency current in the three-phase current and calculate its current amplitude when there is no gain error in the system. M ; Step 4: When there is a gain error in the three-phase current of the system, the high-frequency current generated by the sinusoidal high-frequency voltage signal has a corresponding three-phase current gain error. Three second-order generalized integrators are connected in parallel, and a feedforward decoupling network is constructed before the second-order generalized integrator. In the closed-loop case, the high-frequency current with the system gain error in the three-phase current is filtered out and its current amplitude is calculated as M* ; Step 5: Design a gain error correction controller by comparing M and M* The value of is used to correct the high-frequency current with gain error. Since the gain error of the high-frequency current is the gain error of the three-phase current, the three-phase gain error of the open-winding permanent magnet synchronous motor system is corrected.

2. The method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 1, characterized in that: The three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor in step 1 is: in, u n , i n , L n , e n , where n=a, b, c are the voltage, current, self-inductance and back electromotive force of the three-phase winding respectively. M ab 、 M ac 、 M ba 、 M bc 、 M ca 、 M cb is the mutual inductance of the three-phase winding; e n ,in, n =a, b, c, the equation is as follows: in, is the electrical angular velocity of the motor rotor, is the motor rotor position, is the permanent magnet flux of the motor rotor, is the tertiary flux linkage of the motor rotor permanent magnet; Get a high-frequency voltage signal injected into the motor system u H The equation of the three-phase current of the system is: in, i nm , K n ,in, n =a, b, c, are the measured values ​​of the three-phase current and the measurement gain error of the three-phase current respectively, I is the instantaneous current amplitude, I H is the high-frequency current amplitude, is the high frequency current phase.

3. The method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 2, wherein: In the step 2, the switching frequency of the open-winding permanent magnet synchronous motor is 10kHz, generating a sinusoidal signal with a frequency of 1 / 10 of the switching frequency and a sinusoidal high-frequency voltage signal with a frequency of 1kHz. u H .

4. The method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 3, wherein: The second-order generalized integrator in step 3 has two transfer functions H 1( s )= C 1( s ) / R ( s )and H 2( s )= C 2( s ) / R ( s ); their transfer functions are: in, is the resonant frequency of the second-order generalized integrator, is the closed-loop coefficient, R ( s ) is the input signal; C 1( s )and C 2( s ) is the output signal; Only the bandpass filter part is used, i.e. H 1( s ); The pre-stage decoupling network can eliminate the influence of the fundamental current and the third harmonic on the high-frequency component, and the parallel connection can also eliminate the subharmonics and interharmonics in the input signal, filtering out the required high-frequency current; Among them, the parameters =0.

1.

5. The method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 4, characterized in that: The operations in step 3 are all performed under the condition that there is no current measurement gain error in the system. After filtering out the high-frequency current, the amplitude of the high-frequency current is calculated. M .

6. The method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 5, characterized in that: The operations in step 4 are all performed under the condition that there is a current measurement gain error in the system. After obtaining the high-frequency current, the amplitude of the high-frequency current is calculated. M* , which is fed as input into the gain error correction.

7. The method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 6, characterized in that: The gain error correction controller in step 5 includes a PI controller, and the reference value given by the PI controller is the high-frequency current amplitude calculated in step 3 when there is no current measurement gain error in the system. M , by calculating the high-frequency current amplitude calculated in step 4 M* and M Compare and form a negative feedback closed loop, and then adjust it through the PI controller until M* = M , the gain error of the high-frequency current is corrected to 1, and the measurement gain error of the three-phase current is corrected to 1.

8. A method for correcting current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 1 or 7, characterized in that: It also includes step six: building a corresponding system simulation model in a multi-domain simulation and model design software environment to verify its effectiveness.

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