阅读说明：本技术 基于电压矢量预选的双电机驱动系统预测转矩控制方法 (Voltage vector preselection-based dual-motor drive system predicted torque control method ) 是由 周扬忠 潘斌 屈艾文 钟天云 于 2020-06-04 设计创作，主要内容包括：本发明涉及基于电压矢量预选的双电机驱动系统预测转矩控制方法。根据采样得到的六相电流计算得到两台PMSM的转矩、定子磁链幅值,与给定值进行比较,判断两台PMSM的转矩、定子磁链幅值的增减,根据两台PMSM定子磁链矢量所在扇区,预选出9-11个电压矢量控制两台PMSM；引入零序电流PI调节器,输出值为零序电压给定值,将每个预选出来的电压矢量与逆变器输出的21号矢量或42号矢量合成,合成出零序电压等于零序电压给定值的虚拟电压矢量以抑制系统的零序电流,最后通过预测转矩控制算法选择出最优虚拟电压矢量作用于下一个周期。本发明减少了两台PMSM的转矩和定子磁链幅值的脉动；抑制了系统的零序电流,改善了系统的稳态运行性能；减少了预测转矩控制算法的计算量。(The invention relates to a two-motor drive system predicted torque control method based on voltage vector preselection. Calculating the torque and the stator flux linkage amplitude of the two PMSMs according to the six-phase current obtained by sampling, comparing the torque and the stator flux linkage amplitude of the two PMSMs with a given value, judging the increase and decrease of the torque and the stator flux linkage amplitude of the two PMSMs, and preselecting 9-11 voltage vectors to control the two PMSMs according to the sector where the stator flux linkage vectors of the two PMSMs are located; and introducing a zero sequence current PI regulator, wherein the output value is a zero sequence voltage given value, synthesizing each preselected voltage vector with the No. 21 vector or the No. 42 vector output by the inverter to synthesize a virtual voltage vector with the zero sequence voltage equal to the zero sequence voltage given value so as to inhibit the zero sequence current of the system, and finally selecting an optimal virtual voltage vector to act on the next period through a predictive torque control algorithm. The invention reduces the torque of two PMSMs and the pulsation of the amplitude of the stator flux linkage; the zero sequence current of the system is inhibited, and the steady-state operation performance of the system is improved; the amount of calculation of the predicted torque control algorithm is reduced.)

1. The method is characterized in that a six-phase series three-phase double-PMSM driving system is provided, the torque and the stator flux linkage amplitude of two PMSMs are obtained through calculation according to six-phase currents obtained through sampling, the torque and the stator flux linkage amplitude of the two PMSMs are compared with a given value, the increase and decrease of the torque and the stator flux linkage amplitude of the two PMSMs are judged, and then 9-11 voltage vectors are preselected to control the two PMSMs according to sectors where the stator flux linkage vectors of the two PMSMs are located; and introducing a zero sequence current PI regulator, wherein the output value is a zero sequence voltage given value, synthesizing each preselected voltage vector with a vector No. 21 or a vector No. 42 in 64 basic voltage vectors output by the inverter to synthesize a virtual voltage vector with zero sequence voltage equal to the zero sequence voltage given value so as to inhibit the zero sequence current of the system, and finally selecting an optimal virtual voltage vector to act on the next period through a predictive torque control algorithm.

2. The two-motor drive system predicted torque control method based on voltage vector preselection of claim 1, characterized in that the method is embodied as follows:

step S1, using constant power transformation matrix T₆Sampling six-phase current i of six-phase PMSM_A～i_FConverted into current i on α 1 β 1, α 2 β 2 and o1o2 coordinate systems_α1、i_β1、i_α2、i_β2、i_o1、i_o2：

Wherein i_α1、i_β1、i_α2、i_β2、i_o1、i_o2Current on α 1, β 1, α 2, β 2, o1 and o2 axes respectively, i_o1、i_o2For two zero sequence currents, i is because the neutral point of the three-phase PMSM is not led out_o1Is always 0;

step S2, obtaining stator flux psi of the two PMSMs on the static coordinate system according to the stator flux current model or the stator flux voltage model_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2；ψ_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2Stator flux linkages on α 1, β 1, α 2, β 2 axes, respectively;

1) if a stator flux linkage current model is adopted, the stator flux linkage psi can be obtained_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2Comprises the following steps:

wherein psi_f1、ψ_f2Permanent magnet flux linkage for two PMSM; l is_sσ1Is the self leakage inductance, L, of a six-phase PMSM phase winding_sm1＝(L_dm1+L_qm1)/2，L_rs1＝(L_dm1-L_qm1)/2，L_dm1、L_qm1The permanent magnet synchronous motor is characterized by comprising six-phase PMSM phase windings, a main magnetic flux direct shaft inductor and a quadrature axis inductor respectively; l is_sσ2Is the self leakage inductance, L, of the three-phase PMSM phase winding_sm2＝(L_dm2+L_qm2)/2，L_rs2＝(L_dm2-L_qm2)/2，L_dm2、L_qm2For main flux direct-axis and quadrature-axis inductances, theta, of three-phase PMSM phase windings_r1Is the angle between the d1 axis and the α 1 axis，θ_r2Is the angle between the d2 axis and the α 2 axis;

2) if the stator flux linkage voltage model is adopted, the stator flux linkage psi can be obtained_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2Comprises the following steps:

wherein R is_s1Resistance, R, of each phase winding of a six-phase PMSM_s2The resistance of each phase winding of the three-phase PMSM; u. of_α1、u_β1、u_α2、u_β2Voltages on the α 1, β 1, α 2, β 2 axes, respectively;

step S3, converting the current i on the static coordinate system_α1、i_β1、i_α2、i_β2Conversion into current i on a rotating coordinate system_d1、i_q1、i_d2、i_q2；

Step S4, obtaining stator flux psi of the two PMSMs on the rotating coordinate system according to the formula (8) and the formula (9)_sd1、ψ_sq1、ψ_sd2、ψ_sq2；

Wherein L is_d1＝L_sσ1+3L_sm1+3L_rs1Is a six-phase PMSM planar d-axis inductor, L_q1＝L_sσ1+3L_sm1-3L_rs1A six-phase PMSM plane q-axis inductor; l is_d2＝L_sσ1+2L_sσ2+3L_sm2+3L_rs2Is a three-phase PMSM planar d-axis inductor, L_q2＝L_sσ1+2L_sσ2+3L_sm2-3L_rs2A three-phase PMSM plane q-axis inductor;

step S5, obtaining two PMSM torques T according to the formula (10) and the formula (11)_e1、T_e2；

T_e1＝p₁(ψ_sd1i_q1-ψ_sq1i_d1) (10)

T_e2＝p₂(ψ_sd2i_q2-ψ_sq2i_d2) (11)

Wherein p is₁Is six-phase PMSM pole pair number, p₂The number of pole pairs of the three-phase PMSM is shown; t is_e1For six-phase PMSM torque, T_e2Three-phase PMSM torque;

step S6, obtaining two PMSM stator flux linkage amplitude psi according to the formula (12) and the formula (13)_s1、ψ_s2；

Step S7, obtaining the given torque T of the two PMSMs by the PI regulators controlling the rotation speeds of the two PMSMs according to the formula (14) and the formula (15)^* _e1、T^* _e2(ii) a Given value psi of six-phase PMSM stator flux linkage amplitude^* _s1Is composed ofThree-phase PMSM stator flux linkageGiven value psi of amplitude^* _s2Is composed of

Wherein, ω is_r1、ω_r1A given electrical angular velocity and an actual electrical angular velocity for the six-phase PMSM; omega_r2、ω_r2A given electrical angular velocity and an actual electrical angular velocity for the six-phase PMSM; k_p1、K_i1Proportional coefficient and integral coefficient for controlling PI regulator of six-phase PMSM; k_p2、K_i2Proportional coefficients and integral coefficients for controlling a PI regulator of the three-phase PMSM;

step S8, obtaining the torque of the two PMSMs and the condition that the stator flux linkage amplitude needs to be increased or decreased according to the formula (16), the formula (17), the formula (18) and the formula (19);

wherein phi is₁Taking 1 to show that the stator flux linkage amplitude of the six-phase PMSM needs to be increased, and taking-1 to show that the stator flux linkage amplitude of the six-phase PMSM needs to be decreased; tau is₁Get 1 tableThe torque of the six-phase PMSM is required to be increased, and the torque of the six-phase PMSM is required to be reduced by taking-1; in the same way, phi₂Or τ₂Taking 1 or-1 to represent the condition that the three-phase PMSM needs to increase and reduce the amplitude and the torque of the stator flux linkage;

step S9, obtaining the angles of the flux linkage vectors of the two PMSM stators according to the formula (20) and the formula (21);

wherein, theta_s1The angle of the six-phase PMSM stator flux linkage vector is shown; theta_s2The angle of a flux linkage vector of the three-phase PMSM stator is shown;

step S10, according to theta_s1And theta_s2Obtaining sectors where two PMSM stator flux linkage vectors are located, wherein 0-60 degrees are sectors 1, 60-120 degrees are sectors 2, 120-180 degrees are sectors 3, 180-240 degrees are sectors 4, 240-300 degrees are sectors 5, and 300-360 degrees are sectors 6;

step S11 according to psi_s1At the sector and tau₁、φ₁Preselecting 0 vectors and voltage vectors of 5 directions in a six-phase PMSM plane, a total of 25 voltage vectors being preselected, the set of preselected voltage vectors being S1; according to psi_s2At the sector and tau₂、φ₂Preselecting 0 vectors and voltage vectors of 5 directions in the three-phase PMSM plane, a total of 25 voltage vectors being preselected, the set of preselected voltage vectors being S2;

step S12, taking the intersection S3 of the sets S1 and S2, namely the final preselected voltage vector set, wherein the number of the final preselected voltage vectors is 9-11;

step S13, obtaining a zero sequence voltage given value u according to a formula (22)^* _o2；

Wherein, K_p、K_iProportional coefficient and integral coefficient of PI regulator for controlling system zero sequence current;

step S14, according to u^* _o2Determining a virtual voltage vector synthesized by each preselected voltage vector and the vector No. 21 or the vector No. 42;

step S15, obtaining the component of the virtual voltage vector on each axis of the static coordinate system after each preselected voltage vector is synthesized according to the formula (23) and the formula (24);

wherein, u_α1、uˊ_β1、uˊ_α2、uˊ_β2、uˊ_o1、uˊ_o2The voltage of the synthesized virtual voltage vector on each axis of α 1, β 1, α 2, β 2, o1 and o2 axes, u_α1、u_β1、u_α2、u_β2、u_o1、u_o2The components of the basic voltage vector on each axis of the static coordinate system for synthesizing the virtual voltage vector; when the virtual voltage vector is composed of the basic voltage vector and the vector No. 21,when the virtual voltage vector is composed of the basic voltage vector and the vector No. 42,a is a zero sequence voltage value of a basic voltage vector used for synthesizing the virtual voltage vector;

step S16, predicting the stator flux linkage amplitude psi of two PMSMs in the next period when different voltage vectors are applied to the system_s1(k+1)j、ψ_s2(k+1)jAnd torque T_e1(k+1)j、T_e2(k+1)j: the stator flux linkage amplitude and the torque can be predicted on a static coordinate system or a rotating coordinate system;

1) if the prediction is performed on the stationary coordinate system, the calculation process is as follows:

1.1) obtaining the stator flux linkage change rate d psi of the two PMSMs on the static coordinate system in the next period under the action of each virtual voltage vector according to the formula (25) and the formula (26)_sα1(k)j/dt、dψ_sβ1(k)j/dt、dψ_sα2(k)j/dt、dψ_sβ2(k)j/dt；

Wherein d ψ_sα1(k)/dt、dψ_sβ1(k)/dt、dψ_sα2(k)/dt、dψ_sβ2(k)The dt is the stator flux linkage change rate on the α 1, β 1, α 2 and β 2 axes of the cycle, u_α1(k)、u_β1(k)、u_α2(k)、u_β2(k)The voltage vector applied to the system in the period is the voltage on α 1, β 1, α 2 and β 2 axes i_α1(k)、i_β1(k)、i_α2(k)、i_β2(k)Current on the α 1, β 1, α 2, β 2 axes of the present cycle;

1.2) obtaining the stator flux linkage psi of the two PMSMs on the static coordinate system in the next period under the action of each virtual voltage vector according to the formula (29) and the formula (30)_sα1(k+1)j、ψ_sβ1(k+1)j、ψ_sα2(k+1)j、ψ_sβ2(k+1)j；

Wherein psi_sα1(k+1)、ψ_sβ1(k+1)、ψ_sα2(k+1)、ψ_sβ2(k+1)Is the stator flux linkage on the α 1, β 1, α 2, β 2 axis of the next cycle, T_sIs a control period;

1.3) obtaining the stator flux linkage amplitude psi of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula (33) and the formula (34)_s1(k+1)j、ψ_s2(k+1)j；

Wherein psi_s1(k+1)The stator flux linkage amplitude of the six-phase PMSM in the next period; psi_s2(k+1)The stator flux linkage amplitude of the three-phase PMSM in the next period;

1.4) according to equation (37) andequation (38) obtains the current i on the stationary coordinate system in the next period under the action of each virtual voltage vector_α1(k+1)j、i_β1(k+1)j、i_α2(k+1)j、i_β2(k+1)j；

Wherein i_α1(k+1)、i_β1(k+1)、i_α2(k+1)、i_β2(k+1)Current on the α 1, β 1, α 2, β 2 axes for the next cycle;

1.5) obtaining the torque T of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula (41) and the formula (42)_e1(k+1)j、T_e2(k+1)j；

T_e1(k+1)＝p₁(ψ_sα1(k+1)i_β1(k+1)-ψ_sβ1(k+1)i_α1(k+1))(41)

T_e2(k+1)＝p₂(ψ_sα2(k+1)i_β2(k+1)-ψ_sβ2(k+1)i_α2(k+1))(42)

T_e1(k+1)j＝p₁(ψ_sα1(k+1)ji_β1(k+1)j-ψ_sβ1(k+1)ji_α1(k+1)j)(43)

T_e2(k+1)j＝p₂(ψ_sα2(k+1)ji_β2(k+1)j-ψ_sβ2(k+1)ji_α2(k+1)j)(44)

Wherein, T_e1(k+1)The torque of the six-phase PMSM in the next period; t is_e2(k+1)The torque of the three-phase PMSM in the next period;

2) if the prediction is performed on the rotating coordinate system, the calculation process is as follows:

2.1) obtaining each virtual voltage vector u according to the formula (45) and the formula (46)_jVoltage u on a stationary coordinate system_α1j、u_β1j、u_α2j、u_β2jConversion to voltage u on a rotating coordinate system_d1j、u_q1j、u_d2j、u_q2jWherein j is 1-9 or 10 or 11;

equation (45) is a six-phase PMSM plane rotation transformation matrix R (θ R1) that transforms quantities in the α 1 β 1 coordinate system to the d1q1 coordinate system, equation (46) is a three-phase PMSM plane rotation transformation matrix R (θ R2) that transforms quantities in the α 2 β 2 coordinate system to the d2q2 coordinate system;

2.2) obtaining the stator flux linkage change rate d psi of the two PMSMs on the rotating coordinate system in the next period under the action of each virtual voltage vector according to the formula (49) and the formula (50)_sd1(k)j/dt、dψ_sq1(k)j/dt、dψ_sd2(k)j/dt、dψ_sq2(k)j/dt；

Wherein d ψ_sd1(k)/dt、dψ_sq1(k)/dt、dψ_sd2(k)/dt、dψ_sq2(k)The/dt is the change rate of the stator flux linkage on the axes d1, q1, d2 and q2 in the period; u. of_d1(k)、u_q1(k)、u_d2(k)、u_q2(k)Voltages on d1, q1, d2 and q2 axes are applied to a voltage vector of the system in the period; i.e. i_d1(k)、i_q1(k)、i_d2(k)、i_q2(k)Current on axes d1, q1, d2 and q2 in the period; omega_r1(k)Is the electrical angular velocity, omega, of a six-phase PMSM in the present cycle_r2(k)The electrical angular velocity of the three-phase PMSM in the period is shown; psi_sd1(k)、ψ_sq1(k)、ψ_sd2(k)、ψ_sq2(k)The stator flux linkage on the shafts d1, q1, d2 and q2 in the period;

2.3) obtaining the stator flux linkage psi of the two PMSMs on the rotating coordinate system in the next period under the action of each virtual voltage vector according to the formula (53) and the formula (54)_sd1(k+1)j、ψ_sq1(k+1)j、ψ_sd2(k+1)j、ψ_sq2k+1)j；

Wherein psi_sd1(k+1)、ψ_sq1(k+1)、ψ_sd2(k+1)、ψ_sq2(k+1)A stator flux linkage on d1, q1, d2 and q2 axes is the next period;

2.4) obtaining the stator flux linkage amplitude psi of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula (57) and the formula (58)_s1(k+1)j、ψ_s2(k+1)j；

2.5) obtaining the torque T of the two PMSMs in the next period under the action of each virtual voltage vector according to a formula (61) and a formula (62)_e1(k+1)j、T_e2(k+1)j；

Step S17, obtaining the value of the cost function corresponding to each virtual voltage vector according to the formula (65), and taking the virtual voltage vector with the minimum cost function value to act on the system in the next period;

wherein k is₁、k₂、k₃、k₄The weight coefficients are six-phase PMSM torque, three-phase PMSM torque, six-phase PMSM stator flux linkage amplitude and three-phase PMSM stator flux linkage amplitude respectively.

Technical Field

The invention relates to a two-motor drive system predicted torque control method based on voltage vector preselection.

Background

A six-phase series three-phase dual Permanent Magnet Synchronous Motor (PMSM) drive system is a commonly used dual PMSM drive system. The six-phase series three-phase double-permanent-magnet synchronous motor driving system respectively connects U, V, W phases of a three-phase PMSM with AD, BE and CF of the six-phase PMSM, and realizes independent decoupling control of two PMSMs by a single inverter by utilizing the redundant freedom degree of the six-phase PMSM. Compared with the traditional single PMSM controlled by a single inverter, the six-phase series three-phase double PMSM driving system has the advantages of small driving system volume, low cost, easiness in realizing feedback braking and the like, and has wide application prospects in the industries of steel smelting, rewinders, electric automobiles, textile manufacturing and the like.

And (2) based on a motor system prediction model, performing traversal calculation on Torque and stator flux linkage amplitude values of the motor in the next Control period after different voltage vectors in the applied alternative voltage vector set act on the system, thereby obtaining different cost function values, and enabling the voltage vector with the minimum cost function to act on the next Control period of the system as an optimal voltage vector. The predicted torque control has the advantages of simple structure, intuitive realization, quick dynamic response, easy inclusion of constraint conditions and the like, and is a novel advanced control technology.

Compared with the traditional direct torque control method based on a switching vector table, the six-phase series three-phase dual PMSM driving system adopting the predicted torque control has more excellent steady-state characteristics and dynamic characteristics. However, the control target of the dual PMSM drive system comprises the torque and the stator flux linkage amplitude of the two PMSMs, and compared with a single PMSM drive system, the calculation amount of a predicted torque control algorithm is doubled; meanwhile, an inverter connected with the dual PMSM driving system can output 64 voltage vectors, and the calculation amount of the predictive torque control algorithm is greatly increased due to the huge number of the voltage vectors.

In a six-phase series three-phase dual PMSM driving system, the system has 5 degrees of freedom, and 4 degrees of freedom are needed for controlling the torque and the stator flux linkage amplitude of two PMSMs. In the system, if the last 1 degree of freedom is not effectively controlled, the zero sequence current of the system is overlarge. The large zero sequence current can cause the problems of phase current distortion, system loss increase and the like.

Aiming at the problems, the invention provides a predictive torque control method based on voltage vector preselection aiming at a six-phase series three-phase double-PMSM driving system, so that the accurate control of two PMSM torques and stator flux linkage and the effective suppression of zero-sequence current are realized, and the calculated amount of a predictive torque control algorithm is greatly reduced.

Disclosure of Invention

The invention aims to provide a voltage vector preselection-based dual-motor drive system predicted torque control method, which comprises the steps of firstly, realizing the accurate control of two PMSM torques and stator flux linkage amplitudes; secondly, effective suppression of zero-sequence current is realized; and thirdly, reducing the calculation amount of the predicted torque control algorithm.

In order to achieve the purpose, the technical scheme of the invention is as follows: the method comprises the steps of providing a six-phase series three-phase dual PMSM driving system, calculating the torque and the stator flux linkage amplitude of two PMSMs according to six-phase currents obtained by sampling, comparing the torque and the stator flux linkage amplitude with a given value, judging the increase and decrease of the torque and the stator flux linkage amplitude of the two PMSMs, and preselecting 9-11 voltage vectors to control the two PMSMs according to sectors where stator flux linkage vectors of the two PMSMs are located; and introducing a zero sequence current PI regulator, wherein the output value is a zero sequence voltage given value, synthesizing each preselected voltage vector with a vector No. 21 or a vector No. 42 in 64 basic voltage vectors output by the inverter to synthesize a virtual voltage vector with zero sequence voltage equal to the zero sequence voltage given value so as to inhibit the zero sequence current of the system, and finally selecting an optimal virtual voltage vector to act on the next period through a predictive torque control algorithm.

In an embodiment of the present invention, the method of the present invention is specifically implemented as follows:

step S1, using constant power transformation matrix T₆Sampling six-phase current i of six-phase PMSM_A～i_FConverted into current i on α 1 β 1, α 2 β 2 and o1o2 coordinate systems_α1、i_β1、i_α2、i_β2、i_o1、i_o2：

Wherein i_α1、i_β1、i_α2、i_β2、i_o1、i_o2Current on α 1, β 1, α 2, β 2, o1 and o2 axes respectively, i_o1、i_o2For two zero sequence currents, i is because the neutral point of the three-phase PMSM is not led out_o1Is always 0;

step S2, obtaining stator flux psi of the two PMSMs on the static coordinate system according to the stator flux current model or the stator flux voltage model_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2；ψ_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2Stator flux linkages on α 1, β 1, α 2, β 2 axes, respectively;

1) if a stator flux linkage current model is adopted, the stator flux linkage psi can be obtained_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2Comprises the following steps:

wherein psi_f1、ψ_f2Permanent magnet flux linkage for two PMSM; l is_sσ1Is the self leakage inductance, L, of a six-phase PMSM phase winding_sm1＝(L_dm1+L_qm1)/2，L_rs1＝(L_dm1-L_qm1)/2，L_dm1、L_qm1The permanent magnet synchronous motor is characterized by comprising six-phase PMSM phase windings, a main magnetic flux direct shaft inductor and a quadrature axis inductor respectively; l is_sσ2Is the self leakage inductance, L, of the three-phase PMSM phase winding_sm2＝(L_dm2+L_qm2)/2，L_rs2＝(L_dm2-L_qm2)/2，L_dm2、L_qm2For main flux direct-axis and quadrature-axis inductances, theta, of three-phase PMSM phase windings_r1Is the angle between the d1 axis and the α 1 axis, theta_r2Is the angle between the d2 axis and the α 2 axis;

2) if the stator flux linkage voltage model is adopted, the stator flux linkage psi can be obtained_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2Comprises the following steps:

wherein R is_s1Resistance, R, of each phase winding of a six-phase PMSM_s2The resistance of each phase winding of the three-phase PMSM; u. of_α1、u_β1、u_α2、u_β2Voltages on the α 1, β 1, α 2, β 2 axes, respectively;

step S3, converting the current i on the static coordinate system_α1、i_β1、i_α2、i_β2Conversion into current i on a rotating coordinate system_d1、i_q1、i_d2、 i_q2；

Step S4, obtaining two according to the formula (8) and the formula (9)Stator flux linkage psi of the PMSM in a rotating coordinate system_sd1、ψ_sq1、ψ_sd2、ψ_sq2；

Wherein L is_d1＝L_sσ1+3L_sm1+3L_rs1Is a six-phase PMSM planar d-axis inductor, L_q1＝L_sσ1+3L_sm1-3L_rs1A six-phase PMSM plane q-axis inductor; l is_d2＝L_sσ1+2L_sσ2+3L_sm2+3L_rs2Is a three-phase PMSM planar d-axis inductor, L_q2＝L_sσ1+2L_sσ2+3L_sm2-3L_rs2A three-phase PMSM plane q-axis inductor;

step S5, obtaining two PMSM torques T according to the formula (10) and the formula (11)_e1、T_e2；

T_e1＝p₁(ψ_sd1i_q1-ψ_sq1i_d1) (10)

T_e2＝p₂(ψ_sd2i_q2-ψ_sq2i_d2) (11)

Wherein p is₁Is six-phase PMSM pole pair number, p₂The number of pole pairs of the three-phase PMSM is shown; t is_e1For six-phase PMSM torque, T_e2Three-phase PMSM torque;

step S6, obtaining two PMSM stator flux linkage amplitude psi according to the formula (12) and the formula (13)_s1、ψ_s2；

Step S7, obtaining the given torque T of the two PMSMs by the PI regulators controlling the rotation speeds of the two PMSMs according to the formula (14) and the formula (15)^* _e1、T^* _e2(ii) a Given value psi of six-phase PMSM stator flux linkage amplitude^* _s1Is composed ofGiven value psi of three-phase PMSM stator flux linkage amplitude^* _s2Is composed of

Wherein, ω is_r1、ω_r1A given electrical angular velocity and an actual electrical angular velocity for the six-phase PMSM; omega_r2、ω_r2A given electrical angular velocity and an actual electrical angular velocity for the six-phase PMSM; k_p1、K_i1Proportional coefficient and integral coefficient for controlling PI regulator of six-phase PMSM; k_p2、K_i2Proportional coefficients and integral coefficients for controlling a PI regulator of the three-phase PMSM;

step S8, obtaining the torque of the two PMSMs and the condition that the stator flux linkage amplitude needs to be increased or decreased according to the formula (16), the formula (17), the formula (18) and the formula (19);

wherein phi is₁Taking 1 to show that the stator flux linkage amplitude of the six-phase PMSM needs to be increased, and taking-1 to show that the stator flux linkage amplitude of the six-phase PMSM needs to be decreased; tau is₁Taking 1 to represent that the torque of the six-phase PMSM needs to be increased, and taking-1 to represent that the torque of the six-phase PMSM needs to be decreased; in the same way, phi₂Or τ₂Taking 1 or-1 to represent the condition that the three-phase PMSM needs to increase and reduce the amplitude and the torque of the stator flux linkage;

step S9, obtaining the angles of the flux linkage vectors of the two PMSM stators according to the formula (20) and the formula (21);

wherein, theta_s1The angle of the six-phase PMSM stator flux linkage vector is shown; theta_s2The angle of a flux linkage vector of the three-phase PMSM stator is shown;

step S10, according to theta_s1And theta_s2Obtaining sectors where two PMSM stator flux linkage vectors are located, wherein 0-60 degrees are sectors 1, 60-120 degrees are sectors 2, 120-180 degrees are sectors 3, 180-240 degrees are sectors 4, 240-300 degrees are sectors 5, and 300-360 degrees are sectors 6;

step S11 according to psi_s1At the sector and tau₁、φ₁Preselecting 0 vectors and voltage vectors of 5 directions in a six-phase PMSM plane, a total of 25 voltage vectors being preselected, the set of preselected voltage vectors being S1; according to psi_s2At the sector and tau₂、φ₂Preselecting 0 vectors and voltage vectors of 5 directions in the three-phase PMSM plane, a total of 25 voltage vectors being preselected, the set of preselected voltage vectors being S2;

step S12, taking the intersection S3 of the sets S1 and S2, namely the final preselected voltage vector set, wherein the number of the final preselected voltage vectors is 9-11;

step S13, obtaining a zero sequence voltage given value u according to a formula (22)^* _o2；

Wherein, K_p、K_iProportional coefficient and integral coefficient of PI regulator for controlling system zero sequence current;

step S14, according to u^* _o2Determining a virtual voltage vector synthesized by each preselected voltage vector and the vector No. 21 or the vector No. 42;

step S15, obtaining the component of the virtual voltage vector on each axis of the static coordinate system after each preselected voltage vector is synthesized according to the formula (23) and the formula (24);

wherein, u_α1、uˊ_β1、uˊ_α2、uˊ_β2、uˊ_o1、uˊ_o2The voltage of the synthesized virtual voltage vector on each axis of α 1, β 1, α 2, β 2, o1 and o2 axes, u_α1、u_β1、u_α2、u_β2、u_o1、u_o2The components of the basic voltage vector on each axis of the static coordinate system for synthesizing the virtual voltage vector; when the virtual voltage vector is composed of the basic voltage vector and the vector No. 21,when the virtual voltage vector is composed of the basic voltage vector and the vector No. 42,a is a base for synthesizing the virtual voltage vectorZero sequence voltage value of the present voltage vector;

step S16, predicting the stator flux linkage amplitude psi of two PMSMs in the next period when different voltage vectors are applied to the system_s1(k+1)j、ψ_s2(k+1)jAnd torque T_e1(k+1)j、T_e2(k+1)j: the stator flux linkage amplitude and the torque can be predicted on a static coordinate system or a rotating coordinate system;

1) if the prediction is performed on the stationary coordinate system, the calculation process is as follows:

1.1) obtaining the stator flux linkage change rate d psi of the two PMSMs on the static coordinate system in the next period under the action of each virtual voltage vector according to the formula (25) and the formula (26)_sα1(k)j/dt、dψ_sβ1(k)j/dt、dψ_sα2(k)j/dt、dψ_sβ2(k)j/dt；

Wherein d ψ_sα1(k)/dt、dψ_sβ1(k)/dt、dψ_sα2(k)/dt、dψ_sβ2(k)The dt is the stator flux linkage change rate on the α 1, β 1, α 2 and β 2 axes of the cycle, u_α1(k)、u_β1(k)、u_α2(k)、u_β2(k)The voltage vector applied to the system in the period is the voltage on α 1, β 1, α 2 and β 2 axes i_α1(k)、i_β1(k)、i_α2(k)、i_β2(k)Current on the α 1, β 1, α 2, β 2 axes of the present cycle;

1.2) obtaining each virtual voltage vector asUsing stator flux psi of two PMSM on static coordinate system in next period_sα1(k+1)j、ψ_sβ1(k+1)j、ψ_sα2(k+1)j、ψ_sβ2(k+1)j；

Wherein psi_sα1(k+1)、ψ_sβ1(k+1)、ψ_sα2(k+1)、ψ_sβ2(k+1)Is the stator flux linkage on the α 1, β 1, α 2, β 2 axis of the next cycle, T_sIs a control period;

1.3) obtaining the stator flux linkage amplitude psi of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula (33) and the formula (34)_s1(k+1)j、ψ_s2(k+1)j；

Wherein psi_s1(k+1)Stator magnet for next cycle six-phase PMSMA chain amplitude; psi_s2(k+1)The stator flux linkage amplitude of the three-phase PMSM in the next period;

1.4) obtaining the current i on the stationary coordinate system of the next period under the action of each virtual voltage vector according to the formula (37) and the formula (38)_α1(k+1)j、i_β1(k+1)j、i_α2(k+1)j、i_β2(k+1)j；

Wherein i_α1(k+1)、i_β1(k+1)、i_α2(k+1)、i_β2(k+1)Current on the α 1, β 1, α 2, β 2 axes for the next cycle;

1.5) obtaining the torque T of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula (41) and the formula (42)_e1(k+1)j、T_e2(k+1)j；

T_e1(k+1)＝p₁(ψ_sα1(k+1)i_β1(k+1)-ψ_sβ1(k+1)i_α1(k+1)) (41)

T_e2(k+1)＝p₂(ψ_sα2(k+1)i_β2(k+1)-ψ_sβ2(k+1)i_α2(k+1)) (42)

T_e1(k+1)j＝p₁(ψ_sα1(k+1)ji_β1(k+1)j-ψ_sβ1(k+1)ji_α1(k+1)j) (43)

T_e2(k+1)j＝p₂(ψ_sα2(k+1)ji_β2(k+1)j-ψ_sβ2(k+1)ji_α2(k+1)j) (44)

Wherein，T_e1(k+1)The torque of the six-phase PMSM in the next period; t is_e2(k+1)The torque of the three-phase PMSM in the next period;

2) if the prediction is performed on the rotating coordinate system, the calculation process is as follows:

2.1) obtaining each virtual voltage vector u according to the formula (45) and the formula (46)_jVoltage u on a stationary coordinate system_α1j、 u_β1j、u_α2j、u_β2jConversion to voltage u on a rotating coordinate system_d1j、u_q1j、u_d2j、u_q2jWherein j is 1-9 or 10 or 11;

equation (45) is a six-phase PMSM plane rotation transformation matrix R (θ R1) that transforms quantities in the α 1 β 1 coordinate system into the d1q1 coordinate system, equation (46) is a three-phase PMSM plane rotation transformation matrix R (θ R2) that transforms quantities in the α 2 β 2 coordinate system into the d2q2 coordinate system;

2.2) obtaining the stator flux linkage change rate d psi of the two PMSMs on the rotating coordinate system in the next period under the action of each virtual voltage vector according to the formula (49) and the formula (50)_sd1(k)j/dt、dψ_sq1(k)j/dt、dψ_sd2(k)j/dt、dψ_sq2(k)j/dt；

Wherein d ψ_sd1(k)/dt、dψ_sq1(k)/dt、dψ_sd2(k)/dt、dψ_sq2(k)The/dt is the change rate of the stator flux linkage on the axes d1, q1, d2 and q2 in the period; u. of_d1(k)、u_q1(k)、u_d2(k)、u_q2(k)Voltages on d1, q1, d2 and q2 axes are applied to a voltage vector of the system in the period; i.e. i_d1(k)、i_q1(k)、i_d2(k)、i_q2(k)Current on axes d1, q1, d2 and q2 in the period; omega_r1(k)Is the electrical angular velocity, omega, of a six-phase PMSM in the present cycle_r2(k)The electrical angular velocity of the three-phase PMSM in the period is shown; psi_sd1(k)、ψ_sq1(k)、ψ_sd2(k)、ψ_sq2(k)The stator flux linkage on the shafts d1, q1, d2 and q2 in the period;

2.3) obtaining the stator flux linkage psi of the two PMSMs on the rotating coordinate system in the next period under the action of each virtual voltage vector according to the formula (53) and the formula (54)_sd1(k+1)j、ψ_sq1(k+1)j、ψ_sd2(k+1)j、ψ_sq2k+1)j；

Wherein psi_sd1(k+1)、ψ_sq1(k+1)、ψ_sd2(k+1)、ψ_sq2(k+1)A stator flux linkage on d1, q1, d2 and q2 axes is the next period;

2.4) obtaining the stator flux linkage amplitude psi of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula (57) and the formula (58)_s1(k+1)j、ψ_s2(k+1)j；

2.5) obtaining the torque T of the two PMSMs in the next period under the action of each virtual voltage vector according to a formula (61) and a formula (62)_e1(k+1)j、T_e2(k+1)j；

Step S17, obtaining the value of the cost function corresponding to each virtual voltage vector according to the formula (65), and taking the virtual voltage vector with the minimum cost function value to act on the system in the next period;

wherein k is₁、k₂、k₃、k₄The weight coefficients are six-phase PMSM torque, three-phase PMSM torque, six-phase PMSM stator flux linkage amplitude and three-phase PMSM stator flux linkage amplitude respectively.

Compared with the prior art, the invention has the following beneficial effects: 1) the cost function is directly constructed on the basis of the torque errors and the stator flux linkage amplitude errors of the two PMSMs, so that the torque and stator flux linkage amplitude ripples of the two PMSMs are reduced; 2) the method of voltage vector synthesis is adopted, the zero sequence current of the system is inhibited, and the steady-state operation performance of the system is improved; 3) the voltage vector preselection method is adopted, so that the number of voltage vectors participating in the predicted torque control algorithm is reduced, and the calculation amount of the predicted torque control algorithm is reduced.

Drawings

FIG. 1 is a block diagram of a control strategy according to the present invention.

FIG. 2 is a hardware configuration example of a driving system according to the present invention.

Fig. 3 shows the winding connection mode of the six-phase series three-phase dual PMSM driving system.

Fig. 4 is a six-phase PMSM plane.

Fig. 5 is a three-phase PMSM plane.

Fig. 6 is a six-phase PMSM plane basic voltage vector diagram.

Fig. 7 is a three-phase PMSM plane basic voltage vector diagram.

Fig. 8 is a zero sequence plane basic voltage vector diagram.

FIG. 9 is a flow chart of a predicted torque control algorithm for prediction on a stationary frame according to the present invention.

FIG. 10 is a flow chart of a predicted torque control algorithm for prediction on a rotating coordinate system in accordance with the present invention.

Detailed Description

The technical scheme of the invention is specifically explained below with reference to the accompanying drawings.

The invention provides a voltage vector preselection-based dual-motor drive system predicted torque control method, which aims to have three aspects: firstly, the accurate control of the torque of two PMSM and the flux linkage amplitude of a stator is realized; secondly, effective suppression of zero-sequence current is realized; and thirdly, reducing the calculation amount of the predicted torque control algorithm. And calculating the torque and the stator flux linkage amplitude of the two PMSMs according to the six-phase current obtained by sampling, comparing the torque and the stator flux linkage amplitude of the two PMSMs with a given value, judging whether the torque and the stator flux linkage amplitude of the two PMSMs need to be increased or decreased, and preselecting 9-11 voltage vectors to control the two PMSMs according to the sector where the stator flux linkage vectors of the two PMSMs are located. The zero sequence voltage of 64 basic voltage vectors output by the inverter is not all 0, and the direct application of the basic voltage vectors to the system is easy to cause high-amplitude zero sequence current. And introducing a zero-sequence current PI regulator, wherein the output value is a zero-sequence voltage given value. And synthesizing each preselected voltage vector with the 21 or 42 vector to synthesize a virtual voltage vector with the zero-sequence voltage equal to a given value so as to inhibit the zero-sequence current of the system. And finally, selecting an optimal virtual voltage vector to act on the next period through a predicted torque control algorithm. The specific explanation is as follows. The structure block diagram of the system and the control strategy provided by the invention is shown in figure 1. Using T in equation 2₆Matrix, six-phase current i obtained by sampling_A～i_FConverted into current i on α 1 β 1, α 2 β 2 and o1o2 coordinate systems_α1i_β1、i_α2i_β2、i_o1i_o2. Obtaining the stator flux linkage psi of the two PMSMs on the static coordinate system according to the stator flux linkage current models of the formula 3 and the formula 4 or the stator flux linkage voltage models of the formula 6 and the formula 7_sα1ψ_sβ1、ψ_sα2ψ_sβ2. Using equations 23 and 24, the current i on the stationary frame is adjusted_α1i_β1、i_α2i_β2Conversion into current i on a rotating coordinate system_d1i_q1、i_d2i_q2. Obtaining stator flux linkage psi of the two PMSMs on the rotating coordinate system according to the formula 25 and the formula 26_sd1ψ_sq1、ψ_sd2ψ_sq2. Obtaining two PMSM torques T according to the formula 29 and the formula 30_e1、T_e2. Obtaining two PMSM stator flux linkage amplitude psi according to formula 31 and formula 32_s1、ψ_s2. According to the formula 43 and the formula 44, the given torques T of the two PMSMs are obtained by the PI regulators for controlling the rotating speeds of the two PMSMs^* _e1、T^* _e2. Given value psi of six-phase PMSM stator flux linkage amplitude^* _s1Is composed ofGiven value psi of three-phase PMSM stator flux linkage amplitude^* _s2Is composed ofAnd obtaining the conditions that the torque and the stator flux linkage amplitude of the two PMSMs need to be increased or decreased according to the formulas 45 to 48. And obtaining the angles of the flux linkage vectors of the two PMSM stators according to the formula 49 and the formula 50. According to theta_s1And theta_s2And obtaining the sectors where the flux linkage vectors of the two PMSM stators are located. According to psi_s1At the sector and tau₁、φ₁Preselecting 0 vectors and voltage vectors in 5 directions in the six-phase PMSM plane, a total of 25 voltage vectors are preselected, the set of preselected voltage vectors being S1. According to psi_s2At the sector and tau₂、φ₂Preselecting 0 vectors and voltage vectors in 5 directions in the three-phase PMSM plane, a total of 25 voltage vectors are preselected, the set of preselected voltage vectors being S2. The intersection S3 of the sets S1 and S2 is taken as the final set of preselected voltage vectors. Obtaining a zero sequence voltage given value u according to the formula 51^* _o2. According to u^* _o2And determining a virtual voltage vector synthesized by each of the preselected voltage vectors and the 21 or 42 vectors. The components of the virtual voltage vector on the axes of the stationary coordinate system after the synthesis of each of the preselected voltage vectors are obtained according to equations 52 and 53. Predicting the stator flux linkage amplitude psi of two PMSM in next period when different voltage vectors are applied to the system_s1(k+1)j、ψ_s2(k+1)jAnd torque T_e1(k+1)j、T_e2(k+1)j. If the prediction is performed on the stationary coordinate system, the calculation process is as follows: according to the formula 13 and the formula 14, the stator flux linkage change rate d psi of the two PMSMs on the static coordinate system in the next period under the action of each virtual voltage vector is obtained_sα1(k)j/dt、dψ_sβ1(k)j/dt、dψ_sα2(k)j/dt、dψ_sβ2(k)j(dt); according to the formula 15 and the formula 16, the stator flux psi of the two PMSMs on the static coordinate system in the next period under the action of each virtual voltage vector is obtained_sα1(k+1)j、ψ_sβ1(k+1)j、ψ_sα2(k+1)j、ψ_sβ2(k+1)j(ii) a Obtaining the stator flux linkage amplitude psi of two PMSMs in the next period under the action of each virtual voltage vector according to the formula 17 and the formula 18_s1(k+1)j、ψ_s2(k+1)j(ii) a According to the formula 19 and the formula 20, the current i on the stationary coordinate system in the next period under the action of each virtual voltage vector is obtained_α1(k+1)j、i_β1(k+1)j、i_α2(k+1)j、 i_β2(k+1)j(ii) a Obtaining the torque T of two PMSMs in the next period under the action of each virtual voltage vector according to the formula 21 and the formula 22_e1(k+1)j、 T_e2(k+1)j. If the prediction is performed on the rotating coordinate system, the calculation process is as follows: using equations 23 and 24, each virtual voltage vector u is divided into_jVoltage u on a stationary coordinate system_α1j、u_β1j、u_α2j、u_β2jConversion to voltage u on a rotating coordinate system_d1j、u_q1j、u_d2j、 u_q2j(ii) a According to the formula 33 and the formula 34, the stator flux linkage change rate d psi of the two PMSMs on the rotating coordinate system in the next period under the action of each virtual voltage vector is obtained_sd1(k)j/dt、dψ_sq1(k)j/dt、dψ_sd2(k)j/dt、dψ_sq2(k)j(dt); according to the formula 35 and the formula 36, the stator flux psi of the two PMSMs on the rotating coordinate system in the next period under the action of each virtual voltage vector is obtained_sd1(k+1)j、ψ_sq1(k+1)j、ψ_sd2(k+1)j、ψ_sq2k+1)j(ii) a Obtaining the stator flux linkage amplitude psi of the two PMSMs in the next period under the action of each virtual voltage vector according to the formula 37 and the formula 38_s1(k+1)j、ψ_s2(k+1)j(ii) a According to the formula39 and a formula 40, and obtaining the torque T of two PMSMs in the next period under the action of each virtual voltage vector_e1(k+1)j、T_e2(k+1)j. According to the formula 54, the value of the cost function corresponding to each virtual voltage vector is obtained, and the virtual voltage vector with the minimum cost function value is selected to act on the system in the next period.

An example of a hardware configuration of a drive system embodying the present invention is shown in fig. 2. The method comprises the following steps: the device comprises a voltage regulator, a three-phase uncontrollable rectifying circuit, a large filtering capacitor, a direct current bus voltage detection circuit, a six-phase inverter, an isolation driving circuit, a six-phase winding current detection circuit, a six-phase PMSM, a three-phase PMSM, an encoder, a DSP, a CPLD, a human-computer interaction interface, a fault protection circuit, an AD conditioning circuit and the like. The power tube in the inverter adopts IGBT or MOSFET. The six-phase winding current detection circuit consists of a Hall current sensor and an operational amplifier circuit, and an output signal is input into the DSP through the AD conditioning circuit. The direct current bus voltage detection circuit consists of a Hall voltage sensor and an operational amplifier circuit, and an output signal also needs to be input into the DSP through the AD conditioning circuit. The detection signals of the six-phase winding current and the direct-current bus voltage also need to pass through the fault protection circuit, when the direct-current bus voltage and the winding current are abnormal, the fault protection circuit outputs signals to the CPLD, and the CPLD blocks the PWM output signals to turn off all the switch tubes. The rotor position angles of the two PMSM's are detected by two incremental photoelectric encoders. The six-phase winding current detection signal, the direct current bus voltage detection signal and the rotor position angle signals of the two PMSMs are input into the DSP, the DSP outputs a control signal of the switching tube according to the detected signal and the control strategy of the invention, then the CPLD detects whether the control signal can cause the switching tube to generate direct connection danger or not, and if not, the CPLD outputs the control signal to the isolation driving circuit to control the power switching tube in the inverter to act so as to control the two PMSMs.

The connection mode of the six-phase series three-phase dual-PMSM driving system windings is shown in figure 3, wherein the A-F phases are six-phase PMSM phase windings, the U-W phases are three-phase PMSM phase windings, and the windings of the two PMSM phases are symmetrically distributed in space. The three-phase PMSM adopts a star connection mode. U, V, W phases of the three-phase PMSM are connected to AD, BE, and CF of the six-phase PMSM, respectively. The power current components of the six-phase PMSM are mutually offset due to opposite phases at the connection part of the six-phase PMSM and the three-phase PMSM winding, so that the three-phase PMSM is not influenced; the power current component of the three-phase PMSM equally flows through the two-phase windings with opposite phases of the six-phase PMSM, and has no influence on the six-phase PMSM, so that the decoupling control of the two PMSMs is realized.

FIGS. 4 and 5 are plane definitions of electromechanical energy conversion for six-phase PMSM and three-phase PMSM in FIG. 4, α 1 β 1 and d1q1 coordinate systems are stationary coordinate system and synchronous rotating coordinate system of six-phase PMSM plane, A-F are winding axis of each phase of six-phase PMSM, theta_r1Is the angle between the d1 axis and the α 1 axis,₁is the torque angle, ω_r1、u_s1、i_s1、ψ_s1、ψ_f1The electrical angular velocity, the stator voltage vector, the stator current vector, the stator flux linkage vector and the rotor flux linkage vector of the six-phase PMSM are respectively. The three-phase PMSM plane variable definition in fig. 5 is similar to that of fig. 4. In addition, the system has 1 zero sequence which does not participate in electromechanical energy conversion, and the zero sequence is called a zero sequence plane.

According to the connection mode of the two PMSM windings in fig. 3, the expression of the output voltage of the six-phase inverter can be obtained as follows:

wherein u is_AO～u_FOThe voltages from the A-F output ends of the six-phase inverter, namely the A-F phase winding input ends of the six-phase PMSM, to the neutral point O of the three-phase PMSM are respectively referred to as A-F phase voltages; i.e. i_A～i_FPhase current for a six-phase PMSM; r_s1Resistance, R, of each phase winding of a six-phase PMSM_s2The resistance of each phase winding of the three-phase PMSM; psi_sA～ψ_sFEach phase of stator flux linkage is six-phase PMSM; psi_sU～ψ_sWThe magnetic flux linkage is a stator magnetic flux linkage of each phase of the three-phase PMSM.

Constant power transformation matrix T using equation 2₆And transforming the mathematical model of the dual PMSM drive system from an ABCDEF natural coordinate system to an α 1 β 1 α 2 β 2o1o2 stationary coordinate system.

The flux linkage model under the coordinate systems of alpha 1 beta 1, alpha 2 beta 2 and o1o2 is as follows

Wherein psi_sα1、ψ_sβ1、ψ_sα2、ψ_sβ2、ψ_so1、ψ_so2Is stator flux linkage on α 1, β 1, α 2, β 2, o1 and o2 axes i_α1、i_β1、i_α2、i_β2、i_o1、i_o2Current on α 1, β 1, α 2, β 2, o1 and o2 axes, #_f1、ψ_f2Permanent magnet flux linkage for two PMSM; l is_sσ1Is the self leakage inductance, L, of a six-phase PMSM phase winding_sm1＝(L_dm1+L_qm1)/2，L_rs1＝(L_dm1-L_qm1)/2，L_dm1、L_qm1The permanent magnet synchronous motor is characterized by comprising six-phase PMSM phase windings, a main magnetic flux direct shaft inductor and a quadrature axis inductor respectively; l is_sσ2Is the self leakage inductance, L, of the three-phase PMSM phase winding_sm2＝(L_dm2+L_qm2)/2，L_rs2＝(L_dm2-L_qm2)/2，L_dm2、L_qm2The three-phase PMSM phase winding is provided with a main magnetic flux direct-axis inductor and a quadrature-axis inductor.

The voltage model under the coordinate systems of alpha 1 beta 1, alpha 2 beta 2 and o1o2 is as follows:

wherein u is_α1、u_β1、u_α2、u_β2、u_o1、u_o2Voltages on the α 1, β 1, α 2, β 2, o1, o2 axes.

The torques of the two PMSM are:

T_e1＝p₁(ψ_sα1i_β1-ψ_sβ1i_α1) (formula 9)

T_e2＝p₂(ψ_sα2i_β2-ψ_sβ2i_α2) (formula 10)

Wherein p is₁Is six-phase PMSM pole pair number, p₂The number of pole pairs of the three-phase PMSM is shown; t is_e1For six-phase PMSM torque, T_e2Three-phase PMSM torque.

The stator flux linkage amplitudes of the two PMSMs are respectively as follows:

wherein psi_s1The six-phase PMSM stator flux linkage amplitude value; psi_s2The three-phase PMSM stator flux linkage amplitude.

From the equations 6 and 7, when different voltage vectors are applied to the system, the stator flux linkage variation values in the coordinate systems of α 1 β 1 and α 2 β 2 in the period are:

wherein d ψ_sα1(k)/dt、dψ_sβ1(k)/dt、dψ_sα2(k)/dt、dψ_sβ2(k)The dt is the stator flux linkage change rate on the α 1, β 1, α 2 and β 2 axes of the cycle, u_α1(k)、u_β1(k)、u_α2(k)、u_β2(k)The voltage vector applied to the system in the period is the voltage on α 1, β 1, α 2 and β 2 axes i_α1(k)、i_β1(k)、i_α2(k)、i_β2(k)Current on axis α 1, β 1, α 2, β 2 of this cycle.

According to the first-order eulerian method, the stator flux linkage in the coordinate system of α 1 β 1 and α 2 β 2 in the next period is:

wherein psi_sα1(k+1)、ψ_sβ1(k+1)、ψ_sα2(k+1)、ψ_sβ2(k+1)Is the stator flux linkage on the α 1, β 1, α 2, β 2 axis of the next cycle, T_sIs a control cycle.

From equations 11 and 12, the stator flux linkage amplitudes of the two PMSM in the next period are:

wherein psi_s1(k+1)The stator flux linkage amplitude of the six-phase PMSM in the next period; psi_s2(k+1)The stator flux linkage amplitude of the three-phase PMSM in the next period.

From the equations 3 and 4, the current in the coordinate systems of α 1 β 1 and α 2 β 2 in the next period is:

wherein i_α1(k+1)、i_β1(k+1)、i_α2(k+1)、i_β2(k+1)Is the current on the α 1, β 1, α 2, β 2 axis for the next cycle.

From equations 9 and 10, the torques of the two PMSMs in the next cycle are:

T_e1(k+1)＝p₁(ψ_sα1(k+1)i_β1(k+1)-ψ_sβ1(k+1)i_α1(k+1)) (formula 21)

T_e2(k+1)＝p₂(ψ_sα2(k+1)i_β2(k+1)-ψ_sβ2(k+1)i_α2(k+1)) (formula 22)

Wherein, T_e1(k+1)The torque of the six-phase PMSM in the next period; t is_e2(k+1)Is the torque of the three-phase PMSM for the next cycle.

The quantities in the α 1 β 1 coordinate system are transformed to the d1q1 coordinate system using the equation 23 six-phase PMSM plane rotation transformation matrix R (θ R1), and the quantities in the α 2 β 2 coordinate system are transformed to the d2q2 coordinate system using the equation 24 three-phase PMSM plane rotation transformation matrix R (θ R2).

The flux linkage model under the d1q1 and d2q2 coordinate systems is as follows:

wherein psi_sd1、ψ_sq1、ψ_sd2、ψ_sq2Stator flux linkage on d1, q1, d2 and q2 axes；i_d1、i_q1、i_d2、i_q2Currents on d1, q1, d2 and q2 axes; l is_d1＝L_sσ1+3L_sm1+3L_rs1Is a six-phase PMSM planar d-axis inductor, L_q1＝L_sσ1+3L_sm1-3L_rs1A six-phase PMSM plane q-axis inductor; l is_d2＝L_sσ1+2L_sσ2+3L_sm2+3L_rs2Is a three-phase PMSM planar d-axis inductor, L_q2＝L_sσ1+2L_sσ2+3L_sm2-3L_rs2Is a three-phase PMSM plane q-axis inductor.

The voltage model under the d1q1 and d2q2 coordinate systems is as follows:

wherein u is_d1、u_q1、u_d2、u_q2Voltages on d1, q1, d2 and q2 axes.

The torques of the two PMSM are:

T_e1＝p₁(ψ_sd1i_q1-ψ_sq1i_d1) (formula 29)

T_e2＝p₂(ψ_sd2i_q2-ψ_sq2i_d2) (equation 30)

The stator flux linkage amplitudes of the two PMSMs are respectively as follows:

from the equations 27 and 28, when different voltage vectors are applied to the system, the stator flux linkage variation values in the coordinate systems of the periods d1q1 and d2q2 are as follows:

wherein d ψ_sd1(k)/dt、dψ_sq1(k)/dt、dψ_sd2(k)/dt、dψ_sq2(k)The/dt is the change rate of the stator flux linkage on the axes d1, q1, d2 and q2 in the period; u. of_d1(k)、u_q1(k)、u_d2(k)、u_q2(k)Voltages on d1, q1, d2 and q2 axes are applied to a voltage vector of the system in the period; i.e. i_d1(k)、i_q1(k)、i_d2(k)、i_q2(k)Current on axes d1, q1, d2 and q2 in the period; omega_r1(k)Is the electrical angular velocity, omega, of a six-phase PMSM in the present cycle_r2(k)The electrical angular velocity of the three-phase PMSM in the period is shown; psi_sd1(k)、ψ_sq1(k)、ψ_sd2(k)、ψ_sq2(k)The stator flux linkage on the shafts d1, q1, d2 and q2 in the period.

According to a first-order Euler formula, the stator flux linkage in the coordinate system of the next period d1q1 and d2q2 is as follows:

wherein psi_sd1(k+1)、ψ_sq1(k+1)、ψ_sd2(k+1)、ψ_sq2(k+1)The stator flux linkage on the d1, q1, d2 and q2 axes is the next period.

From equations 31 and 32, the stator flux linkage amplitudes of the two PMSM in the next period are:

from equations 25, 26, 29 and 30, the torques of the two PMSMs in the next cycle are:

as can be taken from fig. 3, the six-phase voltages can also be represented as:

wherein, U_DCIs a DC bus voltage u_NORepresenting the voltage from DC bus voltage ground N to neutral O, S_i1(i is a to f) represents that the upper tube of the ith phase bridge arm of the inverter is conducted and the lower tube is turned off; otherwise, S_iAnd 0 represents that the upper tube of the ith phase bridge arm of the inverter is turned off and the lower tube of the ith phase bridge arm of the inverter is turned on.

The six-phase voltage in equation 41 is transformed into the stationary coordinate system α 1 β 1 α 2 β 2o1o2 using the T6 matrix:

basic voltage vector diagrams on the six-phase PMSM plane, the three-phase PMSM plane, and the zero sequence plane can be obtained from formula 42, as shown in fig. 6, 7, and 8. Wherein S_aS_bS_cS_dS_eS_f64 basic voltage vectors are set to 000000 to 111111 (vector numbers: 0 to 63).

According to the formula 43 and the formula 44, the given torques T of the two PMSMs are obtained by the PI regulators for controlling the rotating speeds of the two PMSMs^* _e1、T^* _e2(ii) a Given value psi of six-phase PMSM stator flux linkage amplitude^* _s1Is composed ofGiven value psi of three-phase PMSM stator flux linkage amplitude^* _s2Is composed of

Wherein, ω is_r1、ω_r1A given electrical angular velocity and an actual electrical angular velocity for the six-phase PMSM; omega_r2、ω_r2A given electrical angular velocity and an actual electrical angular velocity of the six-phase PMSM. K_p1、K_i1Proportional coefficient and integral coefficient for controlling PI regulator of six-phase PMSM; k_p2、K_i2To control the proportionality and integral coefficients of a PI regulator of a three-phase PMSM.

The input-output relationship of the comparator is defined as follows:

wherein the content of the first and second substances,respectively six-phase PMSM and three-phase PMSMA given value of amplitude of the sub-flux linkage;the torque set values are six-phase PMSM and three-phase PMSM respectively; phi is a₁Taking 1 to show that the stator flux linkage amplitude of the six-phase PMSM needs to be increased, and taking-1 to show that the stator flux linkage amplitude of the six-phase PMSM needs to be decreased; tau is₁Taking 1 indicates that the torque of the six-phase PMSM needs to be increased, and taking-1 indicates that the torque of the six-phase PMSM needs to be decreased. In the same way, phi₂Or τ₂Indicating that the three-phase PMSM needs to increase and decrease the stator flux linkage amplitude and torque.

The angles of the stator flux linkage vectors of the two PMSM are:

wherein, theta_s1The angle of the six-phase PMSM stator flux linkage vector is shown; theta_s2Is the angle of the flux linkage vector of the three-phase PMSM stator.

The six-phase PMSM plane and the three-phase PMSM plane are sectorized into 6 sectors, wherein 0 ° to 60 ° is sector 1, 60 ° to 120 ° is sector 2, 120 ° to 180 ° is sector 3, 180 ° to 240 ° is sector 4, 240 ° to 300 ° is sector 5, and 300 ° to 360 ° is sector 6.

Dividing the voltage vectors, in a six-phase PMSM plane, recording the voltage vector with an included angle of 0 degrees with an alpha 1 axis as a direction 12 voltage vector, recording the voltage vector with an included angle of 30 degrees as a direction 1 voltage vector, recording the voltage vector with an included angle of 60 degrees as a direction 2 voltage vector, and recording other direction voltage vectors in the same way; 0. the vectors 21, 42 and 63 are represented as zero voltage vectors in a six-phase PMSM plane and a three-phase PMSM plane, namely the four voltage vectors have the same control effect on the two PMSMs, so that the vectors 21, 42 and 63 are not considered when the two PMSMs are controlled, and only the vector 0 is considered; 9. the voltage vectors 18, 27, 36, 45, 54 appear as a zero voltage vector in the six-phase PMSM plane and a maximum magnitude voltage vector in the three-phase PMSM plane, and the group of voltage vectors is denoted as a direction 0 voltage vector, and there are 13 direction voltage vectors and a total of 0 vectors. Similarly in the three-phase PMSM plane, there are 13 directional voltage vectors and a 0 vector, where the directional 0 voltage vector is 7, 14, 28, 35, 49, 56.

The voltage vector preselection is divided into 4 steps, which are as follows:

(1) when the six-phase PMSM stator flux linkage vector is located in sector 1, when τ is₁＝1、φ₁When the voltage vector is 1, only two sets of directions 2 and 3 can simultaneously increase the torque and flux linkage of the six-phase PMSM. However, if only the voltage vectors in both directions are preselected, the voltage vectors preselected by the system depending on the operating situation are severely insufficient. Note that the direction 1 voltage vector may increase the torque and stator flux magnitude of the six-phase PMSM when the stator flux vector is in the first half (i.e., 0 ° to 30 °) of sector 1, and the direction 4 voltage vector may increase the torque and stator flux magnitude of the six-phase PMSM when the stator flux vector is in the second half (i.e., 30 ° to 60 °) of sector 1. The voltage vectors of direction 1 and direction 4 are also preselected. The 0 vector and the direction 0 voltage vector, although not capable of controlling the torque and stator flux amplitude of the motor according to the output of the comparator, can reduce the torque ripple and stator flux amplitude ripple of the six-phase PMSM and are therefore also preselected. Meanwhile, the amplitude of the direction 0 voltage vector on the six-phase PMSM plane is 0, and the amplitude on the three-phase PMSM plane is the largest, so that under a certain condition, the tracking of the torque and the stator flux linkage amplitude of the three-phase PMSM can be well realized while the torque and the stator flux linkage amplitude of the six-phase PMSM are less influenced. In conclusion, when ψ_s1Located in sector 1, τ₁＝1、φ₁When the voltage vector is 1, 25 voltage vectors in total are preselected, namely 0 vector and directions 0, 1, 2, 3 and 4 in the six-phase PMSM plane, and the set S1 of the preselected voltage vectors is {0, 9, 18, 27, 36, 45, 54, 48, 57, 56, 16, 25, 40, 52, 58, 61, 24, 60, 28, 8, 20, 26, 29, 44 and 63 }.

(2) In the same way, when_s2Located in sector 1, τ₂＝1、φ₂When 1, 0 vector, directions 0, 1, 2 in the three-phase PMSM plane,3. A total of 25 voltage vectors of 4 are preselected, the set of preselected voltage vectors S2 being {0, 7, 14, 28, 35, 49, 56, 38, 52, 54, 6, 20, 34, 48, 55, 62, 22, 50, 18, 2, 16, 23, 30, 51, 58 }.

(3) When psi_s1Located in sector 1, τ₁＝1、φ₁While 1, ψ_s2Located in sector 1, τ₂＝1、φ₂1, the intersection S3 of the sets S1 and S2 is S1 ∩ S2 {0, 28, 56, 54, 18, 16, 20, 48, 52, 58, 62} is taken as the final preselected voltage vector.

(4) According to the above principle, psi can be obtained_s1、ψ_s2Table 1 shows the voltage vector preselection tables for each sector 1.

TABLE 1 psi_s1、ψ_s2Table for preselecting voltage vectors all located in sector 1

The zero sequence voltages of the 64 voltage vectors are not all 0. The zero sequence voltage of the 21 vector is6 vectors (denoted T-2)]Group) of zero sequence voltages of15 vectors (noted as T < -1 [)]Group) of zero sequence voltages of20 vectors (denoted as T [0 ]]Group) of 0, 15 vectors (denoted as T1)]Group) of zero sequence voltages ofZero sequence voltage of 6 vectors (denoted as T2]Group) ofA zero sequence voltage of 42 vectors isThe leakage inductance of the six-phase PMSM is very small, very small zero-sequence voltage can generate very small zero-sequence current, the existence of the zero-sequence current can not only influence the THD of the six-phase current, but also cause the system loss to be increased, and the overall efficiency of the double-PMSM driving system is reduced. Because the voltage vector with zero sequence voltage not being 0 may also act on the system, if a certain suppression measure is not adopted for the zero sequence current, the zero sequence current with large amplitude is inevitably caused. In addition, even if the system is controlled by only 20 voltage vectors with zero-sequence voltage of 0, the zero-sequence current of the system will not be 0 constantly due to the non-linear factors such as dead zone, voltage drop of the switch tube, on-off time of the switch tube and the like which are inevitably existed in the system.

Introducing a zero-sequence current PI regulator, setting as 0, feedback value as zero-sequence current value, and outputting as a zero-sequence voltage set value u^* _o2. When the zero sequence voltage output by the inverter is the value, the zero sequence current is controlled to be 0.

Wherein, K_p、K_iProportional coefficient and integral coefficient of PI regulator for controlling system zero sequence current.

And (3) synthesizing the preselected voltage vector with 21 or 42 voltage vectors (the 2 voltage vectors have the same performance as a 0 vector in a six-phase PMSM plane and a three-phase PMSM plane, but have the maximum amplitude of zero-sequence voltage) to synthesize a virtual voltage vector with zero-sequence voltage equal to a given value. Under the given of different zero sequence voltages, the virtual voltage vector synthesis mode is different, and the method specifically comprises the following steps:

①directly selecting 21 voltage vectors to control the system;

② whenEach set of preselected voltage vectors and21, synthesizing voltage vectors;

③ whenT[-2]The preselected voltage vectors of the groups are synthesized with 42 voltage vectors, and the other preselected voltage vectors of each group are synthesized with 21 voltage vectors;

④ whenT[-2]、T[-1]The set of preselected voltage vectors is combined with a 42 voltage vector and the remaining sets of preselected voltage vectors are combined with a 21 voltage vector.

⑤ whenT[-2]、T[-1]The preselected voltage vector of the group is combined with the 42 voltage vector, T1]、T[2]The preselected voltage vector of the set is combined with the 21 voltage vector, T0]The preselected voltage vectors of the group are not combined;

⑥ whenWhen it is in contact with a catalyst, T2]、T[1]The preselected voltage vectors of the groups are synthesized with the 21 voltage vector, and the other preselected voltage vectors of each group are synthesized with the 42 voltage vector;

⑦ whenWhen it is in contact with a catalyst, T2]The preselected voltage vectors of the groups are synthesized with the 21 voltage vector, and the other preselected voltage vectors of each group are synthesized with the 42 voltage vector;

⑧ whenThen, each group of preselected voltage vectors is synthesized with 42 voltage vectors;

⑨the system is controlled by directly selecting 42 the voltage vector.

The components of the virtual voltage vector after the preselected voltage vector is synthesized on each axis are as follows:

wherein the content of the first and second substances,

wherein, u_α1、uˊ_β1、uˊ_α2、uˊ_β2、uˊ_o1、uˊ_o2The voltage of the synthesized virtual voltage vector on each axis of α 1, β 1, α 2, β 2, o1 and o2 axes, u_α1、u_β1、u_α2、u_β2、u_o1、u_o2The components of the basic voltage vector on each axis of the static coordinate system for synthesizing the virtual voltage vector; when the virtual voltage vector is composed of the basic voltage vector and the vector No. 21,when the virtual voltage vector is composed of the basic voltage vector and the vector No. 42,a is a zero sequence voltage value of the basic voltage vector used to synthesize the virtual voltage vector.

In order to select an optimum virtual voltage vector from the preselected virtual voltage vectors combined with the 21 or 42 vectors, a cost function is established such that the virtual voltage vector with the smallest cost function is the optimum virtual voltage vector, which will be applied in the next control cycle.

Wherein k is₁、k₂、k₃、k₄The weight of six-phase PMSM torque, three-phase PMSM torque, six-phase PMSM stator flux linkage amplitude and three-phase PMSM stator flux linkage amplitude respectivelyThe coefficient and the weight coefficient can be adjusted according to actual needs.

When predicting the torque and stator flux linkage magnitude for two PMSM's in the next cycle on the stationary frame, the flow chart of the predicted torque control algorithm is shown in fig. 9.

When predicting the torque and stator flux linkage amplitude of the two PMSM in the next cycle on the rotating coordinate system, the flow chart of the predicted torque control algorithm is shown in fig. 10.

The above are preferred embodiments of the present invention, and all changes made according to the technical scheme of the present invention that produce functional effects do not exceed the scope of the technical scheme of the present invention belong to the protection scope of the present invention.