阅读说明：本技术 一种新能源汽车用永磁同步电机的电流谐波优化方法 (Current harmonic optimization method of permanent magnet synchronous motor for new energy automobile ) 是由 翟国建 魏勇 王俊 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种新能源汽车用永磁同步电机的电流谐波优化方法,其中控制方法包括：获取永磁同步电机的三相电流,提取定子高次谐波电流；根据得到的定子高次谐波电流构建谐波电流调节器；对谐波电流调节器输出的谐波电压进行变换；将谐波电压信号与基波电压进行叠加,送入SVPWM三相调制参考电压中；该方法能解决现有技术中谐波电流抑制效果差、运算量大的问题。(The invention discloses a current harmonic optimization method of a permanent magnet synchronous motor for a new energy automobile, wherein the control method comprises the following steps: acquiring three-phase current of the permanent magnet synchronous motor, and extracting stator higher harmonic current; constructing a harmonic current regulator according to the obtained stator higher harmonic current; converting the harmonic voltage output by the harmonic current regulator; superposing the harmonic voltage signal and fundamental voltage, and sending the superposed harmonic voltage signal and fundamental voltage into SVPWM three-phase modulation reference voltage; the method can solve the problems of poor harmonic current suppression effect and large calculation amount in the prior art.)

1. A current harmonic optimization method of a permanent magnet synchronous motor for a new energy automobile is characterized by comprising the following steps:

step 1: acquiring three-phase current of the permanent magnet synchronous motor, and extracting stator higher harmonic current;

step 2: constructing a harmonic current regulator according to the obtained stator higher harmonic current;

and step 3: converting the harmonic voltage output by the harmonic current regulator;

and 4, step 4: and superposing the harmonic voltage signal and the fundamental voltage, and sending the superposed harmonic voltage signal and the fundamental voltage into the SVPWM three-phase modulation reference voltage.

2. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 1, wherein the determination method for extracting the stator higher harmonic current in the step 1 is as follows:

will make three-phase current i_abcAnd respectively converting the current to the dq coordinate systems of 5 times and 7 times through coordinate conversion, and extracting the harmonic currents of 5 times and 7 times through low-pass filtering to respectively obtain the current amplitudes of the harmonic currents in the dq coordinate systems.

3. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 2, wherein the three-phase current i is obtained_abcThe calculation method for respectively transforming the coordinate systems to the dq coordinate systems for 5 times and 7 times through coordinate transformation comprises the following steps:

wherein: i.e. i_5th-dq0For transformation to currents in the 5 dq coordinate system, i_7th-dq0For transformation to currents in the 7 dq coordinate system,a transformation matrix for the fundamental dq coordinate system to the 5 th harmonic dq coordinate system,for the fundamental dq coordinate system to the 7 th harmonic dq coordinate system transformation matrix, P is the transformation matrix of the Park transformation, i_abcAnd theta is the relative angle between the d axis in the dq coordinate system and the a axis in the three-phase static coordinate system.

4. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 2, wherein the calculation method for extracting 5 th and 7 th harmonic currents by low-pass filtering comprises the following steps:

i_5th-d＝K_ai_5th-d ^*×(1-K_a)i_5th-d′

i_5th-q＝K_bi_5th-q ^*×(1-K_b)i_5th-q′

i_7th-d＝K_ai_7th-d ^*×(1-K_a)i_7th-d′

i_7th-q＝K_bi_7th-q ^*×(1-K_b)i_7th-q′

wherein i_5th-d、i_5th-q、i_7th-d、i_7th-qRespectively extracting 5 th harmonic d-axis current, 5 th harmonic q-axis current, 7 th harmonic d-axis current and 7 th harmonic q-axis current after low-pass filtering; i.e. i_5th-d ^*、i_5th-q ^*、i_7th-d ^*、i_7th-q ^*Respectively sampling 5-order harmonic d-axis current, 5-order harmonic q-axis current, 7-order harmonic d-axis current and 7-order harmonic q-axis current before low-pass filtering; i.e. i_5th-d′、i_5th-q′、i_7th-d′、i_7th-qThe harmonic current of 5 th order, the harmonic current of q axis of 5 th order, the harmonic current of d axis of 7 th order and the harmonic current of q axis of 7 th order after the last low-pass filtering treatment are respectively carried out; k_aThe filter coefficient of the d-axis current is in a value range of 0.01-0.02; k_bThe filter coefficient of the q-axis current is in a value range of 0.02-0.03.

5. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 1, wherein the specific method for constructing the harmonic current regulator in the step 2 is as follows:

respectively passing the extracted 5 th harmonic current component and 7 th harmonic current component through a PI regulator, performing cross coupling, introducing a steady state voltage equation under a rotating coordinate system for feedforward compensation, and obtaining corresponding harmonic voltage compensation signals;

u_5th-d＝W_pi(i_5th-d)+W_pi(i_5th-q)·f_5th-q(L_d,L_q)+u_5th-d-ss

u_5th-q＝W_pi(i_5th-q)+W_pi(i_5th-d)·f_5th-d(L_d,L_q)+u_5th-q-ss

u_7th-d＝W_pi(i_7th-d)+W_pi(i_7th-q)·f_7th-q(L_d,L_q)+u_7th-d-ss

u_7th-q＝W_pi(i_7th-q)+W_pi(i_7th-d)·f_7th-d(L_d,L_q)+u_7th-q-ss

wherein: u. of_5th-d、u_5th-q、u_7th-d、u_7th-qRespectively regulating 5 th harmonic d-axis voltage, 5 th harmonic q-axis voltage, 7 th harmonic d-axis voltage and 7 th harmonic q-axis voltage in a dq coordinate system by the harmonic current regulator; w_pi(i_5th-d)、W_pi(i_5th-q)、W_pi(i_7th-d)、W_pi(i_7th-q) Converting 5-order harmonic d-axis voltage, converting 5-order harmonic q-axis voltage, converting 7-order harmonic d-axis voltage and converting 7-order harmonic q-axis voltage after 5-order harmonic current and 7-order harmonic current pass through a PI regulator respectively; f. of_5th-d(L_d,L_q)、f_5th-q(L_d,L_q)、f_7th-d(L_d,L_q)、f_7th-q(L_d,L_q) Cross coupling terms of 5-order harmonic d-axis current, 5-order harmonic q-axis current, 7-order harmonic d-axis current and 7-order harmonic q-axis current respectively; u. of_5th-d-ss、u_5th-q-ss、u_7th-d-ss、u_7th-d-ssRespectively 5 th harmonic steady-state d-axis voltage, 5 th harmonic steady-state q-axis voltage, 7 th harmonic steady-state d-axis voltage and 7 th harmonic steady-state q-axis voltage.

6. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 5, wherein the PI regulator is a PI regulator which introduces a rotation speed as a reference of integral anti-saturation, and the calculation method comprises the following steps:

wherein: e is the input of the PI regulator, t is the integration time, K_pProportional amplification factor, K, of a PI regulator_IIs the integral coefficient of the PI regulator, K_LThe integral anti-saturation coefficient is set by the following method:

wherein: omega is angular velocity, omega₀Is the rated angular speed of the permanent magnet synchronous motor.

7. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 5, wherein the calculation method of the harmonic steady-state voltage equation is as follows:

u_5th-d-ss＝R_si_d-5ωL_qi_5th-q

u_5th-q-ss＝R_si_5th-q+5ωL_di_5th-d

u_7th-d-ss＝R_si_d-7ωL_qi_7th-q

u_7th-q-ss＝R_si_7th-q+7ωL_di_7th-d

wherein: r_sIs the phase resistance of the permanent magnet synchronous motor.

8. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 1, wherein the calculation method for converting the harmonic voltage output by the harmonic current regulator in the step 3 is as follows:

wherein:to output harmonic voltages for transformation to the alpha axis in the alpha beta coordinate system,to output harmonic voltages for transformation to the beta axis in the alpha beta coordinate system,a dq coordinate system to α β coordinate system transformation matrix.

9. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 1, wherein the calculation method for superposing the harmonic voltage signal and the fundamental voltage in the step 4 is as follows:

wherein: u. of_αOutputting total harmonic suppression reference voltage u for alpha axis under alpha-beta coordinate system_βTo output a total reference voltage for completely suppressing harmonics for the beta axis in the alpha beta coordinate system,outputs fundamental wave voltage for the alpha axis transformed to alpha beta coordinate system,and outputting fundamental wave voltage for a beta axis transformed to an alpha and beta coordinate system.

10. The current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile according to claim 1, characterized in that the adopted system comprises:

the device comprises a three-phase current acquisition module, a higher harmonic current extraction module, a harmonic current regulation module, a fundamental voltage calculation module, a harmonic voltage calculation module and an SVPWM (space vector pulse width modulation) regulation module;

the three-phase current acquisition module is connected with the higher harmonic current extraction module and is used for extracting current amplitudes of 5-order and 7-order harmonics under a dq coordinate system through three-phase current;

the three-phase current acquisition module is connected with the fundamental voltage calculation module and is used for obtaining fundamental voltage under an alpha beta coordinate system;

the higher harmonic current extraction module is connected with the harmonic current regulation module and is used for obtaining a harmonic voltage compensation signal;

the harmonic current adjusting module is connected with the harmonic voltage calculating module and is used for converting the processed harmonic voltage compensation signal in the dq coordinate system into an alpha beta coordinate system;

and the fundamental wave voltage calculation module and the harmonic wave voltage calculation module are connected with the SVPWM regulation module after being superposed and are used for calculating a total reference voltage signal required by the complete suppression of current harmonic waves.

Technical Field

The invention relates to the technical field of automobile manufacturing, in particular to a current harmonic optimization method of a permanent magnet synchronous motor for a new energy automobile.

Background

The permanent magnet synchronous motor has the advantages of high power density, low rotational inertia, high efficiency and the like, so that the permanent magnet synchronous motor is more applied to the application occasions of high-performance motion control, such as aerospace, precision machine tools, direct drive of robots, the field of electric automobiles which are developed rapidly recently, and the like.

The higher harmonic current components can cause torque ripple, causing a significant reduction in the reliability, stability and efficiency of the overall system. At the same time, additional copper and iron losses may be generated in the stator winding and the iron core of the permanent magnet synchronous motor, causing the temperature of the motor to rise. In addition, higher harmonic currents also increase motor noise. For suppressing harmonic current, experts and scholars at home and abroad do a lot of research work and propose various methods. For example, the repetitive control can suppress current harmonics which are integral multiples of the motor current frequency, thereby improving torque ripple. However, the conventional repetitive control algorithm is complex and occupies a large amount of memory space. Experts and scholars successively put forward some improved repetitive control algorithms, and Fourier analysis and signal reconstruction methods are adopted at specific frequencies, so that the algorithms can be greatly simplified, and redundant storage space is avoided. However, these methods are insufficient in terms of system stability, and do not consider the influence of the switching frequency on repetitive control in the case of high-speed operation of the motor, and their harmonic suppression effect is limited as the motor operation speed increases.

In the current harmonic optimization method of the permanent magnet synchronous motor for the new energy automobile, the integral anti-saturation is performed on the PI regulator in the harmonic current regulator according to the rotating speed, the operation difficulty of a control algorithm is reduced, and the harmonic suppression effect is improved.

Disclosure of Invention

The invention aims to provide a current harmonic optimization method of a permanent magnet synchronous motor for a new energy automobile, which adopts a method of superposing harmonic voltage and fundamental voltage after harmonic current regulation and conversion and integrating and anti-saturating a PI regulator to solve the problems of poor harmonic current suppression effect and large calculation amount in the prior art.

The invention provides a current harmonic optimization method of a permanent magnet synchronous motor for a new energy automobile, which comprises the following steps:

step 1: acquiring three-phase current of the permanent magnet synchronous motor, and extracting stator higher harmonic current;

step 2: constructing a harmonic current regulator according to the obtained stator higher harmonic current;

and step 3: converting the harmonic voltage output by the harmonic current regulator;

and 4, step 4: and superposing the harmonic voltage signal and the fundamental voltage, and sending the superposed harmonic voltage signal and the fundamental voltage into the SVPWM three-phase modulation reference voltage.

Optionally, the specific determination method for extracting the stator higher harmonic current in step 1 is as follows:

will make three-phase current i_abcAnd respectively converting the current to the dq coordinate systems of 5 times and 7 times through coordinate conversion, and extracting the harmonic currents of 5 times and 7 times through low-pass filtering to respectively obtain the current amplitudes of the harmonic currents in the dq coordinate systems.

Optionally, the three-phase current i_abcThe specific calculation method for respectively transforming to the dq coordinate systems for 5 times and 7 times through coordinate transformation comprises the following steps:

wherein: i.e. i_5th-dq0For transformation to currents in the 5 dq coordinate system, i_7th-dq0For transformation to currents in the 7 dq coordinate system,a transformation matrix for the fundamental dq coordinate system to the 5 th harmonic dq coordinate system,for the fundamental dq coordinate system to the 7 th harmonic dq coordinate system transformation matrix, P is the transformation matrix of the Park transformation, i_abcAnd theta is the relative angle between the d axis in the dq coordinate system and the a axis in the three-phase static coordinate system.

Optionally, the specific calculation method for extracting the 5 th harmonic current and the 7 th harmonic current through low-pass filtering is as follows:

i_5th-d＝K_ai_5th-d ^*×(1-K_a)i_5th-d′

i_5th-q＝K_bi_5th-q ^*×(1-K_b)i_5th-q′

i_7th-d＝K_ai_7th-d ^*×(1-K_a)i_7th-d′

i_7th-q＝K_bi_7th-q ^*×(1-K_b)i_7th-q′

wherein i_5th-d、i_5th-q、i_7th-d、i_7th-qRespectively extracting 5 th harmonic d-axis current, 5 th harmonic q-axis current, 7 th harmonic d-axis current and 7 th harmonic q-axis current after low-pass filtering; i.e. i_5th-d ^*、i_5th-q ^*、i_7th-d ^*、i_7th-q ^*Respectively sampling 5-order harmonic d-axis current, 5-order harmonic q-axis current, 7-order harmonic d-axis current and 7-order harmonic q-axis current before low-pass filtering; i.e. i_5th-d′、i_5th-q′、i_7th-d′、i_7th-qThe harmonic current of 5 th order, the harmonic current of q axis of 5 th order, the harmonic current of d axis of 7 th order and the harmonic current of q axis of 7 th order after the last low-pass filtering treatment are respectively carried out; k_aThe filter coefficient of the d-axis current is in a value range of 0.01-0.02; k_bThe filter coefficient of the q-axis current is in a value range of 0.02-0.03.

Optionally, the specific method for constructing the harmonic current regulator in step 2 includes:

respectively passing the extracted 5 th harmonic current component and 7 th harmonic current component through a PI regulator, performing cross coupling, introducing a steady state voltage equation under a rotating coordinate system for feedforward compensation, and obtaining corresponding harmonic voltage compensation signals;

u_5th-d＝W_pi(i_5th-d)+W_pi(i_5th-q)·f_5th-q(L_d,L_q)+u_5th-d-ss

u_5th-q＝W_pi(i_5th-q)+W_pi(i_5th-d)·f_5th-d(L_d,L_q)+u_5th-q-ss

u_7th-d＝W_pi(i_7th-d)+W_pi(i_7th-q)·f_7th-q(L_d,L_q)+u_7th-d-ss

u_7th-q＝W_pi(i_7th-q)+W_pi(i_7th-d)·f_7th-d(L_d,L_q)+u_7th-q-ss

wherein: u. of_5th-d、u_5th-q、u_7th-d、u_7th-qRespectively regulating 5 th harmonic d-axis voltage, 5 th harmonic q-axis voltage, 7 th harmonic d-axis voltage and 7 th harmonic q-axis voltage in a dq coordinate system by the harmonic current regulator; w_pi(i_5th-d)、W_pi(i_5th-q)、W_pi(i_7th-d)、W_pi(i_7th-q) Converting 5-order harmonic d-axis voltage, converting 5-order harmonic q-axis voltage, converting 7-order harmonic d-axis voltage and converting 7-order harmonic q-axis voltage after 5-order harmonic current and 7-order harmonic current pass through a PI regulator respectively; f. of_5th-d(L_d,L_q)、f_5th-q(L_d,L_q)、f_7th-d(L_d,L_q)、f_7th-q(L_d,L_q) Cross coupling terms of 5-order harmonic d-axis current, 5-order harmonic q-axis current, 7-order harmonic d-axis current and 7-order harmonic q-axis current respectively; u. of_5th-d-ss、u_5th-q-ss、u_7th-d-ss、u_7th-d-ssRespectively 5 th harmonic steady-state d-axis voltage, 5 th harmonic steady-state q-axis voltage, 7 th harmonic steady-state d-axis voltage and 7 th harmonic steady-state q-axis voltage.

Optionally, the PI regulator is specifically a PI regulator that introduces a rotation speed as a reference for integral anti-saturation, and a specific calculation method thereof is as follows:

wherein: e is the input of the PI regulator, t is the integration time, K_pProportional amplification factor, K, of a PI regulator_IIs the integral coefficient of the PI regulator, K_LThe specific setting method of the integral anti-saturation coefficient comprises the following steps:

wherein: omega is angular velocity, omega₀Is the rated angular speed of the permanent magnet synchronous motor.

Optionally, the cross-coupling term function is specifically:

f_5th-q(L_d,L_q)＝-5ωL_d-6ωL_q

f_5th-d(L_d,L_q)＝5ωL_d+6ωL_q

f_7th-q(L_d,L_q)＝-7ωL_d-6ωL_q

f_7th-d(L_d,L_q)＝7ωL_d+6ωL_q

wherein: l is_dD-axis inductance, L, in dq coordinate system_qIs the q-axis inductance in the dq coordinate system.

Optionally, the specific calculation method of the harmonic steady-state voltage equation includes:

u_5th-d-ss＝R_si_d-5ωL_qi_5th-q

u_5th-q-ss＝R_si_5th-q+5ωL_di_5th-d

u_7th-d-ss＝R_si_d-7ωL_qi_7th-q

u_7th-q-ss＝R_si_7th-q+7ωL_di_7th-d

wherein: r_sIs the phase resistance of the permanent magnet synchronous motor.

Optionally, the specific calculation method for converting the harmonic voltage output by the harmonic current regulator in step 3 is as follows:

wherein:to output harmonic voltages for transformation to the alpha axis in the alpha beta coordinate system,to output harmonic voltages for transformation to the beta axis in the alpha beta coordinate system,a dq coordinate system to α β coordinate system transformation matrix.

Optionally, the specific calculation method for superimposing the harmonic voltage signal and the fundamental voltage in step 4 is as follows:

wherein: u. of_αOutputting total harmonic suppression reference voltage u for alpha axis under alpha-beta coordinate system_βTo output a total reference voltage for completely suppressing harmonics for the beta axis in the alpha beta coordinate system,outputs fundamental wave voltage for the alpha axis transformed to alpha beta coordinate system,and outputting fundamental wave voltage for a beta axis transformed to an alpha and beta coordinate system.

The invention provides a current harmonic optimization system of a permanent magnet synchronous motor for a new energy automobile, which comprises the following steps: the device comprises a three-phase current acquisition module, a higher harmonic current extraction module, a harmonic current regulation module, a fundamental voltage calculation module, a harmonic voltage calculation module and an SVPWM (space vector pulse width modulation) regulation module;

the three-phase current acquisition module is connected with the higher harmonic current extraction module and is used for extracting current amplitudes of 5-order and 7-order harmonics under a dq coordinate system through three-phase current;

the three-phase current acquisition module is connected with the fundamental voltage calculation module and is used for obtaining fundamental voltage under an alpha beta coordinate system;

the higher harmonic current extraction module is connected with the harmonic current regulation module and is used for obtaining a harmonic voltage compensation signal;

the harmonic current adjusting module is connected with the harmonic voltage calculating module and is used for converting the processed harmonic voltage compensation signal in the dq coordinate system into an alpha beta coordinate system;

and the fundamental wave voltage calculation module and the harmonic wave voltage calculation module are connected with the SVPWM regulation module after being superposed and are used for calculating a total reference voltage signal required by the complete suppression of current harmonic waves.

Optionally, the harmonic current adjusting module includes: the system comprises a steady-state voltage equation module, a PI regulation module and a cross-coupling calculation module;

the PI adjusting module is connected with the cross coupling calculating module and is used for obtaining accurate harmonic voltage compensation quantity;

and the steady-state voltage equation module is connected with the cross-coupling calculation module in an overlapping mode and used for improving the dynamic response and the precision of the controller.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention adopts a method of regulating the converted harmonic voltage and fundamental voltage by harmonic current and superposing the harmonic voltage and the fundamental voltage as SVPWM modulation input, and can solve the problem of more effectively inhibiting the harmonic current.

2. The invention adopts a comprehensive method of PI regulation, integral anti-saturation and voltage reference, and provides the precision of higher harmonic conversion. Integral anti-saturation also reduces computational effort and repetitive control.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

fig. 1 shows a general flowchart of a current harmonic optimization method of a permanent magnet synchronous motor for a new energy vehicle according to the present invention.

Fig. 2 shows a current harmonic optimization system diagram of a permanent magnet synchronous motor for a new energy automobile.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a current harmonic optimization method of a permanent magnet synchronous motor for a new energy automobile, which comprises the following steps as shown in figure 1:

step S1: acquiring three-phase current of the permanent magnet synchronous motor, and extracting stator higher harmonic current;

step S2: constructing a harmonic current regulator according to the obtained stator higher harmonic current;

step S3: converting the harmonic voltage output by the harmonic current regulator;

step S4: and superposing the harmonic voltage signal and the fundamental voltage, and sending the superposed harmonic voltage signal and the fundamental voltage into the SVPWM three-phase modulation reference voltage.

Optionally, the specific determination method for extracting the stator higher harmonic current in step S1 is as follows:

will make three-phase current i_abcRespectively converting the current under the dq coordinate system of 5 times and 7 times through coordinate conversion, extracting 5 times and 7 times harmonic current through low-pass filtering, and respectively obtaining the current of the harmonic under the dq coordinate systemThe amplitude value.

Optionally, applying three-phase current i_abcThe specific calculation method for respectively transforming to the dq coordinate systems for 5 times and 7 times through coordinate transformation comprises the following steps:

wherein: i.e. i_5th-dq0For transformation to currents in the 5 dq coordinate system, i_7th-dq0For transformation to currents in the 7 dq coordinate system,a transformation matrix for the fundamental dq coordinate system to the 5 th harmonic dq coordinate system,for the fundamental dq coordinate system to the 7 th harmonic dq coordinate system transformation matrix, P is the transformation matrix of the Park transformation, i_abcAnd theta is the relative angle between the d axis in the dq coordinate system and the a axis in the three-phase static coordinate system.

Optionally, a specific calculation method for extracting 5 th and 7 th harmonic currents by low-pass filtering is as follows:

i_5th-d＝K_ai_5th-d ^*×(1-K_a)i_5th-d′

i_5th-q＝K_bi_5th-q ^*×(1-K_b)i_5th-q′

i_7th-d＝K_ai_7th-d ^*×(1-K_a)i_7th-d′

i_7th-q＝K_bi_7th-q ^*×(1-K_b)i_7th-q′

wherein i_5th-d、i_5th-q、i_7th-d、i_7th-qAre respectively asLow-pass filtering the extracted 5 th harmonic d-axis current, 5 th harmonic q-axis current, 7 th harmonic d-axis current and 7 th harmonic q-axis current; i.e. i_5th-d ^*、i_5th-q ^*、i_7th-d ^*、i_7th-q ^*Respectively sampling 5-order harmonic d-axis current, 5-order harmonic q-axis current, 7-order harmonic d-axis current and 7-order harmonic q-axis current before low-pass filtering; i.e. i_5th-d′、i_5th-q′、i_7th-d′、i_7th-qThe harmonic current of 5 th order, the harmonic current of q axis of 5 th order, the harmonic current of d axis of 7 th order and the harmonic current of q axis of 7 th order after the last low-pass filtering treatment are respectively carried out; k_aThe filter coefficient of the d-axis current is in a value range of 0.01-0.02; k_bThe filter coefficient of the q-axis current is in a value range of 0.02-0.03.

Optionally, the specific method for constructing the harmonic current regulator in step S2 is as follows:

respectively passing the extracted 5 th harmonic current component and 7 th harmonic current component through a PI regulator, performing cross coupling, introducing a steady state voltage equation under a rotating coordinate system for feedforward compensation, and obtaining corresponding harmonic voltage compensation signals;

u_5th-d＝W_pi(i_5th-d)+W_pi(i_5th-q)·f_5th-q(L_d,L_q)+u_5th-d-ss

u_5th-q＝W_pi(i_5th-q)+W_pi(i_5th-d)·f_5th-d(L_d,L_q)+u_5th-q-ss

u_7th-d＝W_pi(i_7th-d)+W_pi(i_7th-q)·f_7th-q(L_d,L_q)+u_7th-d-ss

u_7th-q＝W_pi(i_7th-q)+W_pi(i_7th-d)·f_7th-d(L_d,L_q)+u_7th-q-ss

wherein: u. of_5th-d、u_5th-q、u_7th-d、u_7th-qRespectively 5 th harmonic in dq coordinate system after harmonic current regulator adjustmentd-axis voltage, 5-harmonic q-axis voltage, 7-harmonic d-axis voltage, and 7-harmonic q-axis voltage; w_pi(i_5th-d)、W_pi(i_5th-q)、W_pi(i_7th-d)、W_pi(i_7th-q) Converting 5-order harmonic d-axis voltage, converting 5-order harmonic q-axis voltage, converting 7-order harmonic d-axis voltage and converting 7-order harmonic q-axis voltage after 5-order harmonic current and 7-order harmonic current pass through a PI regulator respectively; f. of_5th-d(L_d,L_q)、f_5th-q(L_d,L_q)、f_7th-d(L_d,L_q)、f_7th-q(L_d,L_q) Cross coupling terms of 5-order harmonic d-axis current, 5-order harmonic q-axis current, 7-order harmonic d-axis current and 7-order harmonic q-axis current respectively; u. of_5th-d-ss、u_5th-q-ss、u_7th-d-ss、u_7th-d-ssRespectively 5 th harmonic steady-state d-axis voltage, 5 th harmonic steady-state q-axis voltage, 7 th harmonic steady-state d-axis voltage and 7 th harmonic steady-state q-axis voltage.

Optionally, the PI regulator is specifically a PI regulator that introduces a rotation speed as a reference for integral anti-saturation, and a specific calculation method thereof is as follows:

wherein: e is the input of the PI regulator, t is the integration time, K_pProportional amplification factor, K, of a PI regulator_IIs the integral coefficient of the PI regulator, K_LThe specific setting method of the integral anti-saturation coefficient comprises the following steps:

wherein: omega is angular velocity, omega₀Is the rated angular speed of the permanent magnet synchronous motor.

Optionally, the cross-coupling term function is specifically:

f_5th-q(L_d,L_q)＝-5ωL_d-6ωL_q

f_5th-d(L_d,L_q)＝5ωL_d+6ωL_q

f_7th-q(L_d,L_q)＝-7ωL_d-6ωL_q

f_7th-d(L_d,L_q)＝7ωL_d+6ωL_q

wherein: l is_dD-axis inductance, L, in dq coordinate system_qIs the q-axis inductance in the dq coordinate system.

Optionally, the specific calculation method of the harmonic steady-state voltage equation is as follows:

u_5th-d-ss＝R_si_d-5ωL_qi_5th-q

u_5th-q-ss＝R_si_5th-q+5ωL_di_5th-d

u_7th-d-ss＝R_si_d-7ωL_qi_7th-q

u_7th-q-ss＝R_si_7th-q+7ωL_di_7th-d

wherein: r_sIs the phase resistance of the permanent magnet synchronous motor.

Optionally, the specific calculation method for converting the harmonic voltage output by the harmonic current regulator in step S3 is as follows:

wherein:to output harmonic voltages for transformation to the alpha axis in the alpha beta coordinate system,to output harmonic voltages for transformation to the beta axis in the alpha beta coordinate system,as dq coordinate systemTo the alpha beta coordinate system.

Optionally, a specific calculation method for superimposing the harmonic voltage signal and the fundamental voltage in step S4 is as follows:

wherein: u. of_αOutputting total harmonic suppression reference voltage u for alpha axis under alpha-beta coordinate system_βTo output a total reference voltage for completely suppressing harmonics for the beta axis in the alpha beta coordinate system,outputs fundamental wave voltage for the alpha axis transformed to alpha beta coordinate system,and outputting fundamental wave voltage for a beta axis transformed to an alpha and beta coordinate system.

The invention provides a current harmonic optimization system of a permanent magnet synchronous motor for a new energy automobile, which comprises the following steps: a three-phase current acquisition module 51, a higher harmonic current extraction module 52, a harmonic current regulation module 53, a fundamental voltage calculation module 54, a harmonic voltage calculation module 55 and an SVPWM regulation module 56;

the three-phase current acquisition module 51 is connected with the higher harmonic current extraction module 52 and is used for extracting current amplitudes of 5 th and 7 th harmonics in a dq coordinate system through three-phase currents;

the three-phase current obtaining module 51 is connected with the fundamental voltage calculating module 54 and is used for obtaining fundamental voltage under an alpha beta coordinate system;

the higher harmonic current extraction module 52 is connected with the harmonic current regulation module 53 and is used for obtaining a harmonic voltage compensation signal;

the harmonic current adjusting module 53 is connected to the harmonic voltage calculating module 55, and is configured to convert the processed harmonic voltage compensation signal in the dq coordinate system to the α β coordinate system;

the fundamental voltage calculation module 54 is connected to the SVPWM regulation module 56 after being superimposed on the harmonic voltage calculation module 55, and is configured to calculate a total reference voltage signal required for completely suppressing the current harmonic.

Optionally, the harmonic current adjusting module 53 includes: a steady-state voltage equation module 53-1, a PI regulation module 53-2, and a cross-coupling calculation module 53-3;

the PI adjusting module 53-2 is connected with the cross coupling calculating module 53-3 and used for obtaining accurate harmonic voltage compensation quantity;

the steady state voltage equation module 53-1 is connected with the cross coupling calculation module 53-3 in an overlapping mode and used for improving the dynamic response and the accuracy of the controller.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details shown and described herein without departing from the general concept defined by the claims and their equivalents.