阅读说明：本技术 基于逆变器单相故障的开绕组永磁同步电机容错控制方法 (Fault-tolerant control method for open-winding permanent magnet synchronous motor based on single-phase fault of inverter ) 是由 於锋 霍闯 胡德林 茅靖峰 于 2020-05-06 设计创作，主要内容包括：本发明公开了一种基于逆变器单相故障的开绕组永磁同步电机容错控制方法,根据i<Sub>d</Sub>＝0的控制方式得到负载角参考值δ<Sup>ref</Sup>,再得到(k+1)时刻定子磁链d轴、q轴和零轴分量幅值参考值ψ<Sub>sd</Sub><Sup>ref</Sup>(k+1)、ψ<Sub>sq</Sub><Sup>ref</Sup>(k+1)、ψ<Sub>0</Sub><Sup>ref</Sup>(k+1)；然后根据逆变器故障类型得到故障后的电压空间矢量状态,根据电流预测模型并结合磁链方程在线预测(k+1)时刻定子磁链的d轴、q轴和零轴分量ψ<Sub>sd</Sub>(k+1)、ψ<Sub>sq</Sub>(k+1)、ψ<Sub>0</Sub>(k+1)；进而利用(k+1)时刻磁链预测值和参考值构建价值函数,并通过最小化价值函数获得逆变器最优开关状态。本发明可在开绕组永磁同步电机逆变器故障状态下获得良好的动稳态性能。(The invention discloses an open winding permanent magnet synchronous motor fault-tolerant control method based on inverter single-phase fault, which is based on i d Obtaining a load angle reference value in a control mode of 0 ref And then obtaining the reference value psi of the amplitudes of the d axis, the q axis and the zero axis component of the stator flux linkage at the moment (k +1) sd ref (k+1)、ψ sq ref (k+1)、ψ 0 ref (k + 1); and then obtaining the voltage space vector state after the fault according to the fault type of the inverter, and predicting the d-axis, q-axis and zero-axis components psi of the stator flux linkage at the (k +1) moment on line according to a current prediction model and by combining a flux linkage equation sd (k+1)、ψ sq (k+1)、ψ 0 (k + 1); and then constructing a cost function by using the predicted value and the reference value of the flux linkage at the (k +1) moment, and obtaining inversion by minimizing the cost functionThe optimal switching state is achieved. The invention can obtain good dynamic and stable performance under the fault state of the open winding permanent magnet synchronous motor inverter.)

1. The open winding permanent magnet synchronous motor fault-tolerant control method based on the single-phase fault of the inverter is characterized by comprising the following steps of: the method comprises the following steps:

step 1: obtaining reference torque T by a rotating speed outer ring PI controller_e ^ref；

Step 2: acquiring an electrical angle theta and an electrical angular velocity omega of the open-winding permanent magnet synchronous motor from a motor encoder, and acquiring a three-phase stator current i at the time k by using a current sensor_a、i_bAnd i_cObtaining d-axis, q-axis and zero-axis components i of the stator current at the moment k after coordinate transformation_d、i_qAnd i₀；

And step 3: combining flux linkage equation and load angleCalculating flux linkage to obtain reference values psi of d axis, q axis and zero axis component of stator flux linkage at (k +1) moment_sd ^ref(k+1)、ψ_sq ^ref(k+1)、ψ₀ ^ref(k+1)；

And 4, step 4: obtaining a voltage space vector state after the fault according to the fault type of the inverter, and predicting a d-axis component psi, a q-axis component psi and a zero-axis component psi of the stator flux linkage at the (k +1) moment on line according to a voltage space vector state current prediction model after the fault and by combining a flux linkage equation_sd(k+1)、ψ_sq(k+1)、ψ₀(k+1)；

And 5: and constructing a cost function by using the predicted value of the flux linkage at the (k +1) moment and the reference value, and obtaining the optimal switching state of the inverter by minimizing the cost function.

2. The open-winding permanent magnet synchronous motor fault-tolerant control method based on the inverter single-phase fault is characterized in that: reference torque T in said step 1_e ^refThe acquisition method comprises the following steps: the difference e between the reference speed and the actual speed_nInputting a rotating speed outer ring PI controller, and obtaining a reference torque T according to a formula (1)_e ^ref；

In the formula, k_pAnd k_iProportional gain and integral gain of the rotating speed outer ring PI controller are respectively shown, and s represents a complex variable.

3. The open-winding permanent magnet synchronous motor fault-tolerant control method based on the inverter single-phase fault is characterized in that: the method for acquiring the electrical angular velocity omega in the step 2 comprises the following steps: obtaining the differential of the electric angle theta with respect to time through a formula (2) to obtain an electric angular velocity omega;

4. the open-winding permanent magnet synchronous motor fault-tolerant control method based on the inverter single-phase fault is characterized in that: the step 3 calculates the flux linkage reference value psi at the (k +1) moment_sd ^ref(k+1)、ψ_sq ^ref(k+1)、ψ₀ ^refThe method of (k +1) is: obtaining the load angle and the electromagnetic torque T according to the formula (3)_eRelation, and the load angle is derived according to the formula (4) to obtain the load angle increment delta of the formula (5), and the reference value of the load angle at the moment of (k +1) is obtained according to the formula (6)^refObtaining the reference value psi of the d axis and the q axis of the stator flux linkage at the moment (k +1) according to the formula (7)_sd ^ref(k+1)、ψ_sq ^ref(k +1), and let i₀Then, the reference value ψ of the zero axis component of the stator flux linkage at the time (k +1) is obtained according to equation (8) when it is 0₀ ^ref(k+1)；

^ref＝Δ+ (6)

In the formula, #_sIs psi_sd、ψ_sqSynthetic flux linkage psi_s(k) Amplitude of (phi)^ref _sd、ψ^ref _sqAmplitude reference values of components of a d axis and a q axis of the stator flux linkage are obtained; n is_pL in number of pole pairs_qIs a quadrature axis inductor;ψ_f1is the flux linkage fundamental component of the permanent magnet of the rotor; delta T_eIs the electromagnetic torque increment;is a stator flux linkage amplitude reference value; psi_f3Is 3 harmonic components of the rotor permanent magnet flux linkage; theta^refAnd (k +1) is the reference value of the electrical angle of the motor at the moment (k + 1).

5. The open-winding permanent magnet synchronous motor fault-tolerant control method based on the inverter single-phase fault is characterized in that: the specific method in the step 4 comprises the following steps: d-axis, q-axis and zero-axis currents i of stator current at the moment k_d、i_q、i₀The electric angular velocity omega and the electric angle theta are input into a model prediction flux linkage control module, a prediction current model at the moment (k +1) is obtained according to the formula (9), and then the d-axis, the q-axis and the zero-axis component psi of the stator flux linkage at the moment (k +1) are obtained according to the formula (10)_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) prediction value;

in the formula u_d(k)、u_q(k)、u₀(k) Voltages of the stator voltage on d-axis, q-axis and zero-axis components at the moment k; i.e. i_d(k)、i_q(k)、i₀(k) The stator current at the moment k is the current of the d-axis, the q-axis and the zero-axis components respectively, R is the stator phase resistance L_d、L_qL is direct and alternating axis inductance₀Is a zero sequence inductance; t is_sIs the sampling period of the system; n is_pIs the number of pole pairs; i.e. i_d(k+1)、i_q(k+1)、i₀(k +1) are predicted values of d-axis, q-axis and zero-axis components of the stator current at the moment (k +1) respectively; psi_sd(k+1)、ψ_sq(k+1)、ψ₀When (k +1) is (k +1)Carving the predicted values of the stator flux linkage on the d-axis component, the q-axis component and the zero-axis component; psi_f1Is the flux linkage fundamental component of the permanent magnet of the rotor; psi_f3Is 3 harmonic components of the rotor permanent magnet flux linkage; theta is the k-moment electrical angle of the permanent magnet synchronous motor; and theta (k +1) is the electric angle of the motor at the moment (k + 1).

6. The open-winding permanent magnet synchronous motor fault-tolerant control method based on the inverter single-phase fault is characterized in that: the method for constructing the cost function in the step 5 comprises the following steps: reference value psi of stator flux linkage d axis, q axis and zero axis component at (k +1) moment_sd ^ref(k+1)、ψ_sq ^ref(k+1)、ψ₀ ^refPredicted values psi of d-axis, q-axis and zero-axis components of stator flux linkage at (k +1) and (k +1) time points_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) input to the cost function module, and the cost function g is calculated according to the formula (11)_iSequentially substituting the voltage space vectors after the inverter fails, and obtaining the optimal switching state of the inverter according to the relation between the switching state and the basic voltage vector;

Technical Field

The invention relates to a fault-tolerant control method of an open-winding permanent magnet synchronous motor based on single-phase faults of an inverter, and belongs to the field of motor driving and control.

Background

The common direct current bus type open winding permanent magnet synchronous motor is characterized in that a neutral point of a traditional three-phase permanent magnet synchronous motor is opened to form a winding open type structure with two ports, the constraint relation among motor windings does not exist after the neutral point is opened, the windings are independent, a magnetic circuit and the structure of the motor are not changed, and the reliability of a motor body and the fault-tolerant capability of a motor driving system can be improved to a certain extent. The traditional permanent magnet synchronous motor has 6 switch device structures, and in an open winding permanent magnet synchronous motor system, the double inverters supply power to enable the system to have 12 switch device structures, and the increased switch devices improve the risk of system faults.

The common direct current bus open winding permanent magnet synchronous motor system can generate zero sequence current, and brings additional negative effects of copper consumption, temperature rise, torque fluctuation and the like to the system, so that the suppression of the zero sequence current is an important content in the control of the open winding motor.

Based on the above consideration, in order to ensure that the motor can still work normally under the fault working condition, a simplified PWM method is adopted to calculate the conduction time of each phase of switching tube, and the conduction time is compared with a triangular carrier wave to obtain a switching waveform diagram of the inverter, but the zero-sequence current cannot be well inhibited in fault-tolerant control after the fault. It is also proposed that the open-winding permanent magnet synchronous motor under the fault working condition adopts the SVPWM strategy, and although the zero-sequence current in the fault-tolerant control of the open-winding permanent magnet synchronous motor can be well controlled, the design is complex and the calculated amount is large.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the prior art, the fault-tolerant control method of the open-winding permanent magnet synchronous motor based on the single-phase fault of the inverter is provided, and better dynamic and stable performance can be obtained under the condition of the fault of the inverter.

The technical scheme is as follows: the open winding permanent magnet synchronous motor fault-tolerant control method based on the single-phase fault of the inverter comprises the following steps:

step 1: obtaining reference torque T by a rotating speed outer ring PI controller_e ^ref；

Step 2: acquiring an electrical angle theta and an electrical angular velocity omega of the open-winding permanent magnet synchronous motor from a motor encoder, and acquiring a three-phase stator current i at the time k by using a current sensor_a、i_bAnd i_cObtaining d-axis, q-axis and zero-axis components i of the stator current at the moment k after coordinate transformation_d、i_qAnd i₀；

And step 3: calculating flux linkage by combining a flux linkage equation and a load angle to obtain a reference value psi of the stator flux linkage at the (k +1) moment for d axis, q axis and zero axis components_sd ^ref(k+1)、ψ_sq ^ref(k+1)、ψ₀ ^ref(k+1)；

And 4, step 4: obtaining a voltage space vector state after the fault according to the fault type of the inverter, and predicting a d-axis component psi, a q-axis component psi and a zero-axis component psi of the stator flux linkage at the (k +1) moment on line according to a voltage space vector state current prediction model after the fault and by combining a flux linkage equation_sd(k+1)、ψ_sq(k+1)、ψ₀(k+1)；

And 5: and constructing a cost function by using the predicted value of the flux linkage at the (k +1) moment and the reference value, and obtaining the optimal switching state of the inverter by minimizing the cost function.

Further, the reference torque T in step 1_e ^refThe acquisition method comprises the following steps: the difference e between the reference speed and the actual speed_nInputting a rotating speed outer ring PI controller, and obtaining a reference torque according to a formula (1)

In the formula, k_pAnd k_iProportional gain and integral gain of the rotating speed outer ring PI controller are respectively shown, and s represents a complex variable.

Further, the method for acquiring the electrical angular velocity ω in step 2 includes: obtaining the differential of the electric angle theta with respect to time through a formula (2) to obtain an electric angular velocity omega;

further, the step 3 calculates the flux linkage reference value ψ at the time of (k +1)_sd ^ref(k+1)、ψ_sq ^ref(k+1)、ψ₀ ^refThe method of (k +1) is: obtaining the load angle and the electromagnetic torque T according to the formula (3)_eRelation, and the load angle is derived according to the formula (4) to obtain the load angle increment delta of the formula (5), and the reference value of the load angle at the moment of (k +1) is obtained according to the formula (6)^refObtaining the reference value psi of the d axis and the q axis of the stator flux linkage at the moment (k +1) according to the formula (7)_sd ^ref(k+1)、ψ_sq ^ref(k +1), and let i₀Then, the reference value ψ of the zero axis component of the stator flux linkage at the time (k +1) is obtained according to equation (8) when it is 0₀ ^ref(k+1)；

^ref＝Δ+(6)

In the formula, #_sIs psi_sd、ψ_sqSynthetic flux linkage psi_s(k) Amplitude of (phi)^ref _sd、ψ^ref _sqAmplitude reference values of components of a d axis and a q axis of the stator flux linkage are obtained; n is_pL in number of pole pairs_qIs a crossA shaft inductance; psi_f1Is the flux linkage fundamental component of the permanent magnet of the rotor; delta T_eIs the electromagnetic torque increment;is a stator flux linkage amplitude reference value; psi_f3Is 3 harmonic components of the rotor permanent magnet flux linkage; theta^refAnd (k +1) is the reference value of the electrical angle of the motor at the moment (k + 1).

Further, the specific method in step 4 is as follows: d-axis, q-axis and zero-axis currents i of stator current at the moment k_d、i_q、i₀The electric angular velocity omega and the electric angle theta are input into a model prediction flux linkage control module, a prediction current model at the moment (k +1) is obtained according to the formula (9), and then the d-axis, the q-axis and the zero-axis component psi of the stator flux linkage at the moment (k +1) are obtained according to the formula (10)_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) prediction value;

in the formula u_d(k)、u_q(k)、u₀(k) Voltages of the stator voltage on d-axis, q-axis and zero-axis components at the moment k; i.e. i_d(k)、i_q(k)、i₀(k) The stator current at the moment k is the current of the d-axis, the q-axis and the zero-axis components respectively, R is the stator phase resistance L_d、L_qL is direct and alternating axis inductance₀Is a zero sequence inductance; t is_sIs the sampling period of the system; n is_pIs the number of pole pairs; i.e. i_d(k+1)、i_q(k+1)、i₀(k +1) are predicted values of d-axis, q-axis and zero-axis components of the stator current at the moment (k +1) respectively; psi_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) is a predicted value of the stator flux linkage at the moment (k +1) on the d-axis component, the q-axis component and the zero-axis component; psi_f1Is the flux linkage fundamental component of the permanent magnet of the rotor; psi_f3Is 3 harmonic components of the rotor permanent magnet flux linkage; theta is alwaysThe k-time electrical angle of the magnetic synchronous motor; and theta (k +1) is the electric angle of the motor at the moment (k + 1).

Further, the method for constructing the cost function in step 5 includes: reference value psi of stator flux linkage d axis, q axis and zero axis component at (k +1) moment_sd ^ref(k+1)、ψ_sq ^ref(k+1)、ψ₀ ^refPredicted values psi of d-axis, q-axis and zero-axis components of stator flux linkage at (k +1) and (k +1) time points_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) input to the cost function module, and the cost function g is calculated according to the formula (11)_iSequentially substituting the voltage space vectors after the inverter fails, and obtaining the optimal switching state of the inverter according to the relation between the switching state and the basic voltage vector;

has the advantages that: the invention relates to an open-winding permanent magnet synchronous motor based on a common direct current bus type structure, which achieves the aim of inhibiting zero sequence current by designing a value function containing the zero sequence current, only relates to a direct current power supply and does not need to be isolated, and the zero sequence current is only inhibited by changing a control method without increasing the hardware cost of a system. Compared with the traditional technology, the control method provided by the invention reduces the system calculation amount and complexity, and effectively solves the problems of operation of the open-winding permanent magnet synchronous motor inverter under single-phase fault and zero-sequence current suppression.

Drawings

FIG. 1 is a schematic diagram of a fault-tolerant control method for an open-winding permanent magnet synchronous motor according to the present invention;

FIG. 2 is a voltage space vector diagram of a three-phase four-switch inverter in the open winding permanent magnet synchronous motor fault-tolerant control method provided by the invention; (a) the vector diagram is a voltage space vector diagram generated under different switching states when the a1 bridge arm of the inverter 1 fails; (b) the vector diagram is a voltage space vector diagram generated under different switching states when a b1 bridge arm of the inverter 1 fails; (c) the vector diagram is a voltage space vector diagram generated under different switching states when the c1 bridge arm of the inverter 1 fails;

fig. 3 is a diagram of zero-sequence current suppression comparison and three-phase current simulation comparison under a1 phase fault condition according to the fault-tolerant control method for the open-winding permanent magnet synchronous motor provided by the invention; (a) the zero sequence current waveform diagram is when the zero sequence current is not inhibited; (b) the zero sequence current waveform after the zero sequence current is restrained; (c) is a three-phase current oscillogram when the zero-sequence current is not inhibited; (d) the three-phase current oscillogram after zero-sequence current suppression is shown.

Detailed Description

The invention is further explained below with reference to the drawings.

A schematic diagram of a fault-tolerant control method of an open-winding permanent magnet synchronous motor based on single-phase faults of an inverter is shown in figure 1, and the fault-tolerant control method comprises a rotating speed outer ring PI controller 1, a model prediction flux linkage control module 2, a value function module 3, an inverter 4, an inverter 5, a coordinate transformation module 6, an open-winding permanent magnet synchronous motor 7 and an encoder 8. The method comprises the following steps:

step 1: the difference e between the reference speed and the actual speed_nInputting a rotating speed outer ring PI controller, and obtaining a reference torque according to a formula (1)

In the formula, k_pAnd k_iProportional gain and integral gain of the rotating speed outer ring PI controller are respectively shown, and s represents a complex variable.

Step 2: acquiring an electrical angle theta of the open-winding permanent magnet synchronous motor from a motor encoder, then calculating an electrical angular velocity omega according to an equation (2), and acquiring a three-phase stator current i at the time k by using a current sensor_a、i_bAnd i_cObtaining d-axis, q-axis and zero-axis components i of the stator current at the moment k after coordinate transformation_d、i_qAnd i₀。

And step 3: bonding ofFlux linkage calculation is carried out on a flux linkage equation and a load angle to obtain reference values of d-axis, q-axis and zero-axis components of the stator flux linkage at the (k +1) momentThe method specifically comprises the following steps:

obtaining the load angle and the electromagnetic torque T according to the formula (3)_eRelation, and the load angle is derived according to the formula (4) to obtain the load angle increment delta of the formula (5), and the reference value of the load angle at the moment of (k +1) is obtained according to the formula (6)^refObtaining the reference value psi of the d axis and the q axis of the stator flux linkage at the moment (k +1) according to the formula (7)_sd ^ref(k+1)、ψ_sq ^ref(k +1), and let i₀Then, the reference value ψ of the zero axis component of the stator flux linkage at the time (k +1) is obtained according to equation (8) when it is 0₀ ^ref(k+1)；

^ref＝Δ+ (6)

In the formula, #_sIs psi_sd、ψ_sqSynthetic flux linkage psi_s(k) The amplitude of (a) of (b) is,amplitude reference values of components of a d axis and a q axis of the stator flux linkage are obtained; n is_pL in number of pole pairs_qIs a quadrature axis inductor; psi_f1Is the flux linkage fundamental component of the permanent magnet of the rotor; delta T_eIs the electromagnetic torque increment;is a stator flux linkage amplitude reference value; psi_f3Is 3 harmonic components of the rotor permanent magnet flux linkage; theta^refAnd (k +1) is the reference value of the electrical angle of the motor at the moment (k + 1).

(4) And 4, step 4: and obtaining the voltage space vector state after the fault according to the fault type of the inverter. Inverter fault types are shown in table 1:

TABLE 1 inverter Single phase Fault types

When the a1 phase fails, the inverter 1 becomes a three-phase four-switch structure. In a two-phase stationary frame, the combination of switches can generate 4 voltage space vectors, including 4 valid vectors, without a zero vector. Similarly, when the inverter b1 or c1 phase fails, different voltage vectors are generated in different switch states, and the specific voltage vectors are shown in table 2.

TABLE 2 Voltage vector under single-phase fault of inverter

In the table, U_dcIs the inverter dc bus voltage; v. of_αIs the voltage vector α axis component under the two-phase static coordinate system v_βIs the voltage vector β axis component under the two-phase static coordinate system;

if two groups of inverters have a fault of one phase, the two conditions can be considered:

(1) inverter 1, 2 in phase and single phase fault

When a single-phase fault occurs when a of the inverters 1 and 2 are the same, the switching combination state (S) of the two inverters at the time_b1、S_c1)，(S_b2、S_c2) There are 16 differences in totalThe switch states of (1), wherein, 12 effective vectors and 4 zero vectors have 9 different effective vectors and zero vectors after removing the proper redundancy;

(2) the inverter 1, 2 has single-phase fault at the same time with different phases

When the inverters 1 and 2 have single-phase faults at the same time, the switching combination states of the two inverters share 16 different switching states, 16 voltage space vectors can be generated, and zero vectors do not exist.

If three phases of one inverter are all in fault, the solid-state relays connected with the group of inverters are all conducted, at the moment, the lower winding permanent magnet synchronous motor is controlled by the other group of inverters to be equivalent to a common permanent magnet synchronous motor in Y-shaped connection, and the control technology at the moment is completely consistent with that of the common permanent magnet synchronous motor; if a two-phase bridge arm of a certain inverter fails, the switching states of the inverter at the moment are only two, and the circular flux linkage vector required by the operation of the open-winding permanent magnet synchronous motor cannot be modulated at the moment. Therefore, the fault-tolerant control aims at researching the open-winding permanent magnet synchronous motor under the condition of single-phase fault.

And predicting the d-axis, q-axis and zero-axis components psi of the stator flux linkage at the (k +1) moment on line according to the voltage space vector state current prediction model after the fault and by combining the flux linkage equation_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1), specifically:

d-axis, q-axis and zero-axis currents i of stator current at the moment k_d、i_q、i₀The electric angular velocity omega and the electric angle theta are input into a model prediction flux linkage control module, a prediction current model at the moment (k +1) is obtained according to the formula (9), and then the d-axis, the q-axis and the zero-axis component psi of the stator flux linkage at the moment (k +1) are obtained according to the formula (10)_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) prediction value;

in the formula u_d(k)、u_q(k)、u₀(k) Voltages of the stator voltage on d-axis, q-axis and zero-axis components at the moment k; i.e. i_d(k)、i_q(k)、i₀(k) The stator current at the moment k is the current of the d-axis, the q-axis and the zero-axis components respectively, R is the stator phase resistance L_d、L_qL is direct and alternating axis inductance₀Is a zero sequence inductance; t is_sIs the sampling period of the system; n is_pIs the number of pole pairs; i.e. i_d(k+1)、i_q(k+1)、i₀(k +1) are predicted values of d-axis, q-axis and zero-axis components of the stator current at the moment (k +1) respectively; psi_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) is a predicted value of the stator flux linkage at the moment (k +1) on the d-axis component, the q-axis component and the zero-axis component; psi_f1Is the flux linkage fundamental component of the permanent magnet of the rotor; psi_f3Is 3 harmonic components of the rotor permanent magnet flux linkage; theta is the k-moment electrical angle of the permanent magnet synchronous motor; and theta (k +1) is the electric angle of the motor at the moment (k + 1).

And 5: and constructing a cost function by using the predicted value of the flux linkage at the (k +1) moment and the reference value, and obtaining the optimal switching state of the inverter by minimizing the cost function. The construction method of the cost function comprises the following steps: reference values of d-axis, q-axis and zero-axis components of stator flux linkage at the (k +1) momentAnd (k +1) time stator flux linkage d-axis, q-axis and zero-axis component predicted value psi_sd(k+1)、ψ_sq(k+1)、ψ₀(k +1) input to the cost function module, and the cost function g is calculated according to the formula (11)_iSequentially substituting the voltage space vectors after the inverter fails, and obtaining the optimal switching state of the inverter according to the relation between the switching state and the basic voltage vector;

fig. 2 is a three-phase four-switch inverter voltage space vector diagram. FIG. 2(a) shows the space voltage vector V generated in different switching states when the a1 arm of the inverter 1 fails₁～V₄There are 4 voltage vectors in total at this time, and no zero vector is generated. If the b1 phase or the c1 phase of the converter 1 fails, the two phases are in different switch states (S)_a1、S_c1) Or (S)_a1、S_b1) In combination, a voltage space vector diagram as shown in fig. 2(b) or 2(c) is produced.

Fig. 3 is a comparison graph of zero-sequence current suppression and three-phase current simulation under the condition of a1 phase fault by the open-winding permanent magnet synchronous motor fault-tolerant control method provided by the invention. The simulation working condition is set as follows: the motor is started from a standstill to a given rotational speed of 200r/min, and the torque is 4N m. Fig. 3(a) is a waveform diagram of zero-sequence current when zero-sequence current is not suppressed; fig. 3(b) is a waveform diagram of zero-sequence current after zero-sequence current suppression; FIG. 3(c) is a waveform diagram of three-phase current when zero-sequence current is not suppressed; fig. 3(d) is a waveform diagram of three-phase current after zero-sequence current suppression. When the fault-tolerant method of model predictive control is adopted by the system, the zero-sequence current suppression effect is obvious, and meanwhile, the current tends to be sinusoidal, so that the feasibility and the superiority of the fault-tolerant control method of the open-winding permanent magnet synchronous motor based on the model predictive control are explained.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.