Current measurement gain error correction method for open-winding permanent magnet synchronous motor

Abstract

The invention relates to an open winding permanent magnet synchronous motor current measurement gain error correction method, and belongs to the technical field of motor control. By means of a three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, an equation after high-frequency voltage signals are injected into a motor system is obtained; injecting a sine high-frequency voltage signal, and comparing the sine high-frequency voltage signal with a carrier wave to generate a high-frequency current with a corresponding frequency at three phases; three second-order generalized integrators are connected in parallel, a feed-forward decoupling network is constructed in front of the second-order generalized integrators, high-frequency current in three-phase current is filtered out, and the current amplitude of the high-frequency current is calculated; three second-order generalized integrators are connected in parallel, a feed-forward decoupling network is constructed in front of the second-order generalized integrators, high-frequency current with system gain errors in three-phase current is filtered out under the condition of closed loop, and the current amplitude of the high-frequency current is calculated; through comparison, the high-frequency current with the gain error is corrected. And the current gain is well corrected to be 1, so that the current waveform does not fluctuate basically.

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 have the advantages of small size, high efficiency, high power density, and good dynamic performance. They are widely used in aerospace, electric vehicles and other fields. However, in some applications, such as electric vehicles, the motor output power is required to be large, and the battery supply voltage is limited. Therefore, the current needs to be increased, which affects the motor efficiency and increases the motor volume. Increasing the supply voltage can expand the motor speed range, and the motor output torque is smaller when the output power is the same, which is beneficial to improve the motor efficiency and reduce the volume, and increase the continuous output power in the weak magnetic field area. In order to meet these requirements, scholars proposed to open the star-shaped neutral point of the traditional motor winding in the single inverter power supply motor system, and only connect the inverter in series at both ends of the winding without changing the original motor electromagnetic design and mechanical structure. Form an open-winding permanent magnet synchronous motor.

[0003] Open-winding permanent magnet synchronous motors are divided into isolated DC bus type, common DC bus type and hybrid power type. Among them, common DC bus type open-winding permanent magnet synchronous motors are widely used due to their low cost, small size, high voltage utilization rate and other advantages. However, due to the existence of the bus, a zero-sequence closed loop is formed, which generates zero-sequence current, causes additional torque pulsation, and reduces the operating efficiency of the motor system. The zero-sequence current controller has been proven to be an effective method to suppress zero-sequence current, but due to the existence of current measurement errors, it will directly affect the performance of the system.

[0004] The current measurement path consists of several parts, such as the Hall sensor, matching circuit, noise filtering circuit, analog-to-digital converter, etc. One or more of these components may be affected by various factors, such as device temperature drift, aging, noise, etc., resulting in measurement errors. At the same time, the magnitude of the measurement error will also change over time. Therefore, the measurement error should be compensated or corrected regularly or continuously to keep the system in good operating condition.

[0005] The current measurement error is divided into gain error and offset error. Since the gain error changes with the phase current amplitude, it is more complicated to compensate or correct it. At present, most current measurement gain error compensation or correction methods are aimed at permanent magnet synchronous motors, and do not consider the influence of zero-sequence current in the zero-sequence closed loop.

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

[0007] In order to solve the above problems, a method for correcting the current measurement gain error of an open-winding permanent magnet synchronous motor is provided. A brief overview of the invention is given 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 the key or important parts 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: With the help of the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, the high-frequency voltage signal u injected into the motor system is obtained. H The equations of the three-phase current of the rear system;

[0011] Step 2: Inject a sinusoidal high-frequency voltage signal u into the 0-axis system H The voltage signal is combined with the modulation wave and compared with the carrier wave to generate a high-frequency current i of the corresponding frequency in the three phases. 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 M when there is no gain error in the system;

[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 in front of 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 to be M*.

[0014] Step 5: Design a gain error correction controller to correct the high-frequency current with gain error by comparing the values ​​of M and M*. 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, Δ i d =i d *-i q *, Δ i q =i q *-i q ;

[0016] PI regulation: The reference voltage u is obtained through PI regulation d * and u q *;

[0017] Inverse Park transform: u d *、u q * and the zero-sequence reference voltage u0* undergo an inverse Park transformation from the synchronous rotating coordinate system dq0 axis to the stationary coordinate system αβ0 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 i is detected by the current sensor nm (n=a,b,c), in a three-phase four-wire system, a, b, c are three phases, n is the neutral line, and the three-phase currents at this time all have measurement gain errors;

[0020] Zero-sequence current control: Given a zero-sequence reference current i0*=0, i0* minus the zero-sequence current i0 and the zero-sequence current angular frequency ω0 are taken as input and input into the quasi-proportional resonant controller. The quasi-proportional resonant controller eliminates the main third harmonic in the zero-sequence current and outputs a zero-sequence reference voltage u0*.

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

[0022]

[0023] Among them, 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, M ab 、M ac 、M ba 、M bc 、M ca 、M cb is the mutual inductance of the three-phase winding;

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

[0025]

[0026] Among them, ω e is the electrical angular velocity of the motor rotor, θ e is the motor rotor position, ψ f is the permanent magnet flux of the motor rotor, ψ f3is the tertiary flux linkage of the permanent magnet of the motor rotor;

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

[0028]

[0029] Among them, i nm , K n (n=a, b, c) are the measured values ​​of the three-phase current and the measurement gain error of the three-phase current, I is the instantaneous current amplitude, I H is the high frequency current amplitude, θ H 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 u with a frequency of 1kHz 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 H1(s)=C1(s) / R(s) and H2(s)=C2(s) / R(s), which respectively function as a low-pass filter and a band-pass filter;

[0032] The structure of the second-order generalized integrator is as follows Figure 2 As shown; where ω is the resonant frequency of the second-order generalized integrator, ε is the closed-loop coefficient, R(s) is the input signal; C1(s) and C2(s) are the output signals; their transfer functions are:

[0033]

[0034] The present invention uses the portion of its bandpass filter, namely H1(s);

[0035] Wherein, the parameter ε of the present invention is 0.1.

[0036] Preferred: Figure 3 As shown, x is the input signal, y 1st is the output fundamental current, y 3rd is the output third harmonic current, y H is the output high frequency current, ω H is the angular velocity of the sinusoidal high-frequency voltage signal injected into the system;

[0037] 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, 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, so as to filter out the required high-frequency current more accurately.

[0038] Preferably, the operations in step three are performed under the condition that there is no current measurement gain error in the system.

[0039] Preferably: the operations in step 4 are all performed when there is a current measurement gain error in the system.

[0040] 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;

[0041] The reference value given by the PI controller is the high-frequency current amplitude M calculated in step 3 when there is no current measurement gain error in the system. By comparing the high-frequency current amplitude M* calculated in step 4 with M, a negative feedback closed loop is formed and input to the PI controller, and then adjusted by the PI controller to output the current measurement gain error K required for correction. a *, K a * with i am Multiplication equals i a ; Until M*=M and 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 accordingly.

[0042] Preferably, the method further comprises step six: building a corresponding system simulation model in a multi-domain simulation and model design software (Matlab / Simulink) environment to verify the effectiveness.

[0043] The present invention has the following beneficial effects:

[0044] The present invention can well correct the current gain to 1, so that the current waveform has substantially no fluctuation.

[0045] After the gain error correction is introduced in the present invention, the gain errors of the three phases are corrected to about 1.

[0046] When the motor speed changes, the present invention can quickly reach stability after the flow waveform fluctuates, and correct the gain error to about 1 in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A control block diagram of a method for correcting a current measurement gain error of an open-winding permanent magnet synchronous motor;

[0048] Figure 2 It is a structural diagram of a second-order generalized integrator selected for a method of correcting a gain error in current measurement of an open-winding permanent magnet synchronous motor;

[0049] Figure 3 The present invention is a parallel second-order generalized integrator structure diagram of a current measurement gain error correction method for an open-winding permanent magnet synchronous motor;

[0050] 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 with a parallel second-order generalized integrator without the current measurement gain error;

[0051] 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;

[0052] Figure 6 The present invention is a result diagram of three-phase current when a gain error correction controller of a current measurement gain error correction method of an open-winding permanent magnet synchronous motor acts;

[0053] Figure 7 The present invention is a graph showing the correction result of the gain error of three-phase current measurement by a gain error correction controller of a current measurement gain error correction method of an open-winding permanent magnet synchronous motor;

[0054] Figure 8 The present invention is a correction result diagram of a gain error correction controller of a current measurement gain error correction method of an open-winding permanent magnet synchronous motor when the three-phase current measurement gain error changes;

[0055] Fig. 9 A gain error correction controller of an open-winding permanent magnet synchronous motor current measurement gain error correction method is a result diagram of three-phase current when the motor speed changes;

[0056] Fig.10 The present invention is a gain error correction method for current measurement of an open-winding permanent magnet synchronous motor, and a correction result diagram of the gain error of three-phase current measurement by a gain error correction controller when the motor speed changes. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0058] Specific implementation method: Combination Figure 1-10The present embodiment is described. A method for correcting a current measurement gain error of an open-winding permanent magnet synchronous motor in the present embodiment comprises the following steps:

[0059] Step 1: With the help of the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, the high-frequency voltage signal u injected into the motor system is obtained. H The equations of the three-phase current of the rear system;

[0060] Step 2: Inject a sinusoidal high-frequency voltage signal u into the 0-axis system H The voltage signal is combined with the modulation wave and compared with the carrier wave to generate a high-frequency current i of the corresponding frequency in the three phases. H ;

[0061] 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 M when there is no gain error in the system;

[0062] 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 in front of 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 to be M*.

[0063] Step 5: Design a gain error correction controller to correct the high-frequency current with gain error by comparing the values ​​of M and M*. 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.

[0064] 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;

[0065] Error current calculation: dq axis reference current i d * and i q * Subtract the feedback current i d and i q Get the error current Δ i d and Δ 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. Δ i d =i d *-i q *,Δ i q =i q *-i q ;

[0066] PI regulation: The reference voltage u is obtained through PI regulation d * and u q *;

[0067] Inverse Park transform: u d *、u q * and the zero-sequence reference voltage u0* undergo an inverse Park transformation from the synchronous rotating coordinate system dq0 axis to the stationary coordinate system αβ0 axis;

[0068] SVPWM modulation: Using the SVPWM modulation strategy, the current passes through the open-winding permanent magnet synchronous motor system;

[0069] Current sensor detection: The three-phase measurement current i is detected by the current sensor nm (n=a,b,c), in a three-phase four-wire system, a, b, c are three phases, n is the neutral line, and the three-phase currents at this time all have measurement gain errors;

[0070] Zero-sequence current control: Given a zero-sequence reference current i0*=0, i0* minus the zero-sequence current i0 and the zero-sequence current angular frequency ω0 are used as inputs and input into the quasi-proportional resonant controller. The quasi-proportional resonant controller eliminates the main third harmonic in the zero-sequence current and outputs a zero-sequence reference voltage u0*; improves efficiency and ensures stability and accuracy;

[0071] The three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor in step 1 is:

[0072]

[0073] Among them, u n ,i n , L n , e n (n=a,b,c) respectively correspond to the voltage, current, self-inductance and back electromotive force of the three-phase winding, M ab 、M ac 、M ba 、M bc 、M ca 、M cb is the mutual inductance of the three-phase winding;

[0074] e n The equation for (n=a, b, c) is as follows:

[0075]

[0076] Among them, ωe is the electrical angular velocity of the motor rotor, θ e is the motor rotor position, ψ f is the permanent magnet flux of the motor rotor, ψ f3 is the tertiary flux linkage of the permanent magnet of the motor rotor;

[0077] The high-frequency voltage signal u is injected into the motor system H The equation of the three-phase current of the system is:

[0078]

[0079] Among them, 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, I is the instantaneous current amplitude, I H is the high frequency current amplitude, θ H is the high frequency current phase;

[0080] In 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 u with a frequency of 1kHz 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;

[0081] The second-order generalized integrator in step 3 has two transfer functions H1(s)=C1(s) / R(s) and H2(s)=C2(s) / R(s), which respectively function as a low-pass filter and a band-pass filter;

[0082] The structure of the second-order generalized integrator is as follows Figure 2 As shown; where ω is the resonant frequency of the second-order generalized integrator, ε is the closed-loop coefficient, R(s) is the input signal; C1(s) and C2(s) are the output signals; their transfer functions are:

[0083]

[0084] The present invention uses the portion of its bandpass filter, namely H1(s);

[0085] Wherein, the parameter ε of the present invention is 0.1, and s is a complex variable;

[0086] like Figure 3 As shown, x is the input signal, y 1st is the output fundamental current, y 3rd is the output third harmonic current, y H is the output high frequency current, ω His the angular velocity of the sinusoidal high-frequency voltage signal injected into the system;

[0087] Considering that the main components of the three-phase current include fundamental current and third harmonic in addition to 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 third harmonic on the high-frequency component, and the parallel form can also eliminate the subharmonics and interharmonics in the input signal, so as to filter out the required high-frequency current more accurately.

[0088] The operations in step 3 are all performed under the condition that there is no current measurement gain error in the system. Figure 4 As shown, taking phase a as an example, input phase a to measure current i am , phase current angular velocity ω e and the high-frequency current angular velocity ω H To the parallel second-order generalized integrator, the output filtered high-frequency current i H , calculate the amplitude M of the high-frequency current;

[0089] The operations in step 4 are all performed under the condition that there is a current measurement gain error in the system, such as Figure 5 As shown, taking phase a as an example, input phase a to measure current i am , phase current angular velocity ω e and the high-frequency current angular velocity ω H After the high-frequency current is obtained in the parallel second-order generalized integrator, its amplitude M* is calculated for the high-frequency current and is used as input for the subsequent correction of the current measurement gain error;

[0090] 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; taking phase a as an example, the gain error correction controller inputs the phase a current i with current measurement gain error am , after parallel connection of the second-order generalized integrator and the PI controller, the output is the a-phase current i without the current measurement gain error after correction. a ;

[0091] The operation of the parallel second-order generalized integrator has been described in detail above;

[0092] The reference value given by the PI controller is the high-frequency current amplitude M calculated in step 3 when there is no current measurement gain error in the system. By comparing the high-frequency current amplitude M* calculated in step 4 with M, a negative feedback closed loop is formed and input to the PI controller, and then adjusted by the PI controller to output the current measurement gain error K required for correction. a *, K a * with i amMultiplication equals 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;

[0093] It also includes step six: building a corresponding system simulation model in a multi-domain simulation and model design software (Matlab / Simulink) environment to verify the effectiveness;

[0094] The motor speed is set to 800r / 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; on the basis of 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;

[0095] When the motor speed changes, such as Fig. 9 , Fig.10 As shown in the figure, at 0.6s, the motor speed changes from 800r / min to 1200r / min; Fig. 9 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. After the motor speed is changed at 0.6s, the current waveform can quickly reach stability after the fluctuation. Fig.10 It can be seen from the result diagram that 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 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.

[0096] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for correcting current gain error in an open-winding permanent magnet synchronous motor, characterized in that: The following steps are involved: Step 1: With the help of the three-phase voltage mathematical model of the open-winding permanent magnet synchronous motor, the high-frequency voltage signal u injected into the motor system is obtained. H The equations of the three-phase current of the rear system; Step 2: Inject a sinusoidal high-frequency voltage signal u into the 0-axis system H The voltage signal is combined with the modulation wave and compared with the carrier wave to generate a high-frequency current i of the corresponding frequency in the three phases. 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 M when there is no gain error in the system; 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 in front of 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 to be M*. Step 5: Design a gain error correction controller to correct the high-frequency current with gain error by comparing the values ​​of M and M*. 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: Among them, 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, M ab 、M ac 、M ba 、M bc 、M ca 、M cb is the mutual inductance of the three-phase winding; e n The equation for (n=a, b, c) is as follows: Among them, ω e is the electrical angular velocity of the motor rotor, θ e is the motor rotor position, ψ f is the permanent magnet flux of the motor rotor, ψ f3 is the tertiary flux linkage of the permanent magnet of the motor rotor; The high-frequency voltage signal u is injected into the motor system H The equation of the three-phase current of the system is: Among them, i nm , K n (n=a, b, c) are the measured values ​​of the three-phase current and the measurement gain error of the three-phase current, I is the instantaneous current amplitude, I H is the high frequency current amplitude, θ H is the high frequency current phase.

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

4. The method for correcting the current measurement gain error of an open-winding permanent magnet synchronous motor according to claim 3, characterized in that: The second-order generalized integrator in step 3 has two transfer functions H1(s)=C1(s) / R(s) and H2(s)=C2(s) / R(s); their transfer functions are: Where, ω is the resonant frequency of the second-order generalized integrator, ε is the closed-loop coefficient, R(s) is the input signal; C1(s) and C2(s) are the output signals; The part using its bandpass filter, i.e. H1(s); Among them, the parameter ε=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 three 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 M of the high-frequency current is calculated.

6. A 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 M* of the high-frequency current is calculated and input into the gain error correction as input.

7. A 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 five includes a PI controller. The reference value given by the PI controller is the high-frequency current amplitude M calculated in step three when there is no current measurement gain error in the system. By comparing the high-frequency current amplitude M* calculated in step four with M, a negative feedback closed loop is formed, and then the PI controller is used to adjust until M*=M, so that 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.

Images