阅读说明：本技术 基于六相静止坐标系的永磁容错电机模型预测电流控制方法 (Permanent magnet fault-tolerant motor model prediction current control method based on six-phase static coordinate system ) 是由 朱景伟 李想 安达 陈思 郑杰阳 于 2021-08-05 设计创作，主要内容包括：本发明公开了一种基于六相静止坐标系的永磁容错电机模型预测电流控制方法,包括：基于六相定子电流的角度关系得到六相定子电流的相应给定值；将六相定子电流增量与反馈六相定子电流相加得到下一时刻六相定子电流值的预测方程；将不同的空间电压矢量带入六相定子电流增量方程和六相定子电流预测方程得到八组相应的下一时刻六相定子电流预测值,并通过六相定子电流预测值与其给定值构成的价值函数来选取使价值函数最小的空间电压矢量,根据该空间电压矢量控制六相独立H桥逆变电路,从而对电机进行实时电流预测控制。该控制方法能够有效提高电机的动态性能,抑制电机在故障态下的转矩脉动,从而提高电机的运行稳定性。(The invention discloses a permanent magnet fault-tolerant motor model prediction current control method based on a six-phase static coordinate system, which comprises the following steps: obtaining a corresponding given value of the six-phase stator current based on the angle relation of the six-phase stator current; adding the six-phase stator current increment and the feedback six-phase stator current to obtain a prediction equation of the six-phase stator current value at the next moment; and substituting different space voltage vectors into a six-phase stator current increment equation and a six-phase stator current prediction equation to obtain eight groups of corresponding six-phase stator current predicted values at the next moment, selecting a space voltage vector which enables the minimum value function through a value function formed by the six-phase stator current predicted values and given values of the six-phase stator current predicted values, and controlling a six-phase independent H-bridge inverter circuit according to the space voltage vector so as to perform real-time current prediction control on the motor. The control method can effectively improve the dynamic performance of the motor, and inhibit the torque pulsation of the motor in a fault state, thereby improving the operation stability of the motor.)

1. A permanent magnet fault-tolerant motor model prediction current control method based on a six-phase static coordinate system is characterized by comprising the following steps:

collecting rotor position information of a permanent magnet fault-tolerant motor, an actual value of six-phase stator current and an actual rotating speed n of the motor, and setting the rotating speed n_refThe difference value of the actual rotating speed n and the actual rotating speed n is processed by a PI regulator to obtain the amplitude of the six-phase stator current of the motor, and the corresponding given value of the six-phase stator current is obtained based on the angle relation of the six-phase stator current;

based on the strong isolation characteristic of the six-phase permanent magnet fault-tolerant motor, neglecting mutual inductance among all phase windings of the motor, establishing a six-phase voltage equation and a six-phase stator current increment equation of a motor stator winding under a six-phase static coordinate system, and adding the six-phase stator current increment equation and feedback six-phase stator current to obtain a prediction equation of the current value of the six-phase stator at the next moment;

selecting different space voltage vector tables according to different running states of the six-phase permanent magnet fault-tolerant motor, selecting a space voltage vector with the amplitude of 4 as an alternative voltage vector combination in a control algorithm when the motor is in a normal running state, and selecting a space voltage vector without an open-circuit phase with the amplitude of 3 as an alternative voltage vector combination when the motor is in a fault state, so that the aim of reducing torque pulsation of the motor in the fault state is fulfilled, and the amplitude of other phase currents is prevented from being too high;

substituting different space voltage vectors into a six-phase stator current increment equation and a six-phase stator current prediction equation to obtain eight groups of corresponding six-phase stator current predicted values at the next moment, and selecting a space voltage vector which enables a value function to be minimum through the value function formed by the six-phase stator current predicted values and the given values of the six-phase stator current predicted values;

and controlling a six-phase independent H-bridge inverter circuit according to the space voltage vector so as to perform real-time current prediction control on the motor.

2. The method of claim 1, wherein: when the real-time current prediction is carried out on the motor, the six-phase stator current is subjected to prediction control respectively, and an optimal space voltage vector is selected according to the minimum principle of a value function, so that the switching state corresponding to the six-phase H-bridge inverter circuit is obtained, wherein the adopted value function is as follows:

g＝(i_Anext-i_Aref)²+(i_Bnext-i_Bref)²+(i_Cnext-i_Cref)²+(i_Unext-i_Uref)²+(i_Vnext-i_Vref)²+(i_Wnext-i_Wref)²

under the condition of one-phase open circuit fault, the control algorithm adjusts the alternative space voltage vector table on line in real time, and selects the corresponding space voltage vector table with the amplitude of 3 as the alternative voltage vector.

Technical Field

The invention relates to the field of control of permanent magnet fault-tolerant motors, in particular to a permanent magnet fault-tolerant motor model prediction current control method based on a six-phase static coordinate system.

Background

At present, research on a permanent magnet fault-tolerant motor body is gradually perfected, control methods of the permanent magnet fault-tolerant motor are more and more abundant, but most fault-tolerant control algorithms are mainly applied to double-winding and three-phase permanent magnet fault-tolerant motors, space voltage vectors of six-phase symmetrical permanent magnet fault-tolerant motors driven by independent H-bridge inverter circuits are as many as 729, and direct torque control and current hysteresis tracking control are usually adopted for research on the motor control algorithms. When the motor breaks down, although the fault-tolerant control effect can be achieved, the steady-state performance of the motor in normal operation and fault states is slightly poor; the application of model predictive control in the six-phase permanent magnet fault-tolerant motor is less, most motors are controlled under a rotating coordinate system or a static coordinate system, and the problem of large torque pulsation after a fault occurs exists in the aspect of fault-tolerant control performance, so that a large research space exists for the application of a model predictive control algorithm in the six-phase permanent magnet fault-tolerant motor. The motor model prediction current control algorithm based on the six-phase static coordinate system is adopted, the control method is simple, the dynamic performance of motor operation can be improved, and the torque pulsation of motor fault state operation can be inhibited.

Disclosure of Invention

According to the problems in the prior art, the invention discloses a permanent magnet fault-tolerant motor model prediction current control method based on a six-phase static coordinate system, which specifically comprises the following steps:

collecting rotor position information of a permanent magnet fault-tolerant motor, an actual value of six-phase stator current and an actual rotating speed n of the motor, and setting the rotating speed n_refThe difference value of the actual rotating speed n and the actual rotating speed n is processed by a PI regulator to obtain the amplitude of the six-phase stator current of the motor, and the corresponding given value of the six-phase stator current is obtained based on the angle relation of the six-phase stator current;

based on the strong isolation characteristic of the six-phase permanent magnet fault-tolerant motor, neglecting mutual inductance among all phase windings of the motor, establishing a six-phase voltage equation and a six-phase stator current increment equation of a motor stator winding under a six-phase static coordinate system, and adding the six-phase stator current increment equation and feedback six-phase stator current to obtain a prediction equation of the current value of the six-phase stator at the next moment;

selecting different space voltage vector tables according to different running states of the six-phase permanent magnet fault-tolerant motor, selecting a space voltage vector with the amplitude of 4 as an alternative voltage vector combination in a control algorithm when the motor is in a normal running state, and selecting a space voltage vector without an open-circuit phase with the amplitude of 3 as an alternative voltage vector combination when the motor is in a fault state, so that the aim of reducing torque pulsation of the motor in the fault state is fulfilled, and the amplitude of other phase currents is prevented from being too high;

substituting different space voltage vectors into a six-phase stator current increment equation and a six-phase stator current prediction equation to obtain eight groups of six-phase stator current predicted values at the next moment, and selecting a space voltage vector which enables a minimum value function through the value function formed by the six-phase stator current predicted values and the given values of the six-phase stator current predicted values;

and controlling a six-phase independent H-bridge inverter circuit according to the space voltage vector so as to perform real-time current prediction control on the motor.

Furthermore, when the real-time current prediction is carried out on the motor, the six-phase stator current is subjected to prediction control respectively, and an optimal space voltage vector is selected according to the minimum principle of a cost function, so that the switching state corresponding to the six-phase H-bridge inverter circuit is obtained, wherein the adopted cost function is as follows:

g＝(i_Anext-i_Aref)²+(i_Bnext-i_Bref)²+(i_Cnext-i_Cref)²+(i_Unext-i_Uref)²+(i_Vnext-i_Vref)²+(i_Wnext-i_Wref)²

under the condition of one-phase open circuit fault, the control algorithm adjusts the alternative space voltage vector table on line in real time, and selects the corresponding space voltage vector table with the amplitude of 3 as the alternative voltage vector.

By adopting the technical scheme, the method for controlling the model prediction current of the permanent magnet fault-tolerant motor based on the six-phase static coordinate system directly discretizes and predictively controls the six-phase stator current under the six-phase static coordinate system, omits complicated control steps of coordinate transformation and inverse transformation, optimizes the combination of alternative voltage vectors of normal operation and fault state of the motor in a plurality of space voltage vectors, improves the steady state and dynamic performance of normal operation of the motor, greatly reduces the torque ripple of the motor under the fault state and can well reduce the amplitude of the six-phase stator current through the model prediction current control.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a topological diagram of an H-bridge inverter circuit of a six-phase permanent magnet fault-tolerant motor in the invention

FIG. 2 is a six-phase static coordinate system of a six-phase permanent magnet fault-tolerant motor according to the present invention

FIG. 3 shows the space voltages with different amplitudes and different directions of 61 six-phase permanent magnet fault-tolerant motors according to the present invention

Vector diagram

FIG. 4 is a block diagram of a system structure of a model predictive current control method for a fault-tolerant permanent magnet motor based on a six-phase stationary coordinate system according to the present invention

FIG. 5 is a rotation speed waveform of a six-phase permanent magnet fault-tolerant motor according to the present invention during normal operation

FIG. 6 is a torque waveform of the six-phase permanent magnet fault-tolerant motor of the present invention during normal operation

FIG. 7 is a torque waveform diagram of the six-phase permanent magnet fault-tolerant motor in the invention when the A-phase open circuit fault occurs

FIG. 8 is a waveform diagram of the stator current when the open-circuit fault of A phase occurs in the six-phase permanent magnet fault-tolerant motor of the present invention

Detailed Description

In order to make the technical solutions and advantages of the present invention clearer, the following describes the technical solutions in the embodiments of the present invention clearly and completely with reference to the drawings in the embodiments of the present invention:

as shown in fig. 1, the topology diagram of the H-bridge inverter circuit of the six-phase permanent magnet fault-tolerant motor adopts six-phase independent control and no neutral point connection, so that electrical isolation can be effectively realized, and the influence of electrical coupling on the fault-tolerant performance of the motor when a fault occurs is avoided; fig. 2 shows a six-phase stationary coordinate system of a six-phase permanent magnet fault-tolerant motor; through analyzing different switch states of six H-bridge inverter circuits, 61 space voltage vectors with different amplitudes and different directions are finally obtained through synthesis, and the space voltage vectors are shown in FIG. 3; fig. 4 is a system structure block diagram of a model predictive current control method for a permanent magnet fault-tolerant motor based on a six-phase stationary coordinate system, which is disclosed by the invention, and the implementation of the control method comprises the following steps:

s1: acquiring feedback information: comprising rotor position theta of permanent-magnet fault-tolerant motor obtained by sensor, actual value (i) of six-phase stator current_A、i_B、i_C、i_U、i_V、i_W) And the motor rotating speed n obtained through processing. By setting a given speed n_refObtaining the amplitude given i of the motor six-phase stator current after the difference value of the actual rotating speed n passes through a PI regulator_mrefAnd respectively obtaining corresponding given values (i) of the six-phase stator currents by calculation according to the angle relation of the six-phase stator currents_Aref、i_Bref、i_Cref、i_Uref、i_Vref、i_Wref)。

S2: under a six-phase static coordinate system, due to the strong isolation characteristic of the six-phase permanent magnet fault-tolerant motor, an equation of each phase voltage of a motor winding is as follows:

wherein R is_sResistance of each phase of the stator of the motor, L inductance of each phase of the stator, psi_fFor permanent magnet flux linkage of electric machine, omega_eDiscretizing the above formula for the electrical angular velocity of the motor, taking phase a as an example, yields the following formula:

i_Anext＝di_A+i_A (3)

in the formula, di_AFor A-phase stator current increment, i_AnextFor the predicted value of the A-phase stator current at the next moment, the corresponding di can be obtained by a similar equation_B、di_C、di_U、di_V、di_WAnd corresponding current prediction values.

Based on the strong isolation characteristic of the six-phase fault-tolerant motor, the mutual inductance between stator windings of all phases of the motor is ignored, a six-phase voltage equation and a six-phase current increment equation (formula 2) of the motor windings are established under a six-phase static coordinate system, and the six-phase current increment equation and the fed-back six-phase current are added to obtain a prediction equation (formula 3) of the six-phase current value at the next moment.

S3: incremental equation for u in six-phase stator current (equation 2)_A、u_B、u_C、u_U、u_V、u_WThe values of the voltage vectors are related to alternative space voltage vectors, the states of bridge arm switches of the related H-bridge are shown in table 1, when the motor does not have faults in normal operation, the space voltage vectors shown in table 2 are adopted as the alternative voltage vectors, and when the motor is opened in one phaseThe space voltage vector shown in table 3 is used as the candidate voltage vector at the time of the path failure.

TABLE 1H bridge inverter circuit bridge arm switch state table

TABLE 2 Normal state alternative voltage vector table

TABLE 3 Fault State alternative Voltage vector Table

U in table₀₁、u₀₂And u₀₃Are all zero vectors u₀Different combinations of (3).

The predicted values of the corresponding eight groups of six-phase stator currents at the next moment can be obtained by bringing different space voltage vectors into equations (2) and (3), and the space voltage vector which enables the minimum value function is selected through the value function of the following equation:

g＝(i_Anext-i_Aref)²+(i_Bnext-i_Bref)²+(i_Cnext-i_Cref)²+(i_Unext-i_Uref)²+(i_Vnext-i_Vref)²+(i_Wnext-i_Wref)² (4)

s4: after the space voltage vector is selected, trigger pulses are respectively sent to the six-phase independent H-bridge inverter circuit according to the rules of table 1, and the space voltage vector is selected through a value function in different control periods, so that the purpose of performing real-time current prediction control on the motor is achieved.

S5: simulation experiment verification: firstly, carrying out simulation verification on a motor in a normal running state, wherein the given rotating speed of the motor is 600r/min of rated rotating speed, the load torque is 23 N.m of rated torque, a rotating speed waveform of the six-phase permanent magnet fault-tolerant motor in normal running is shown in a figure 5, and a torque waveform of the six-phase permanent magnet fault-tolerant motor in normal running is shown in a figure 6; and then carrying out simulation verification on the motor under the condition of the fault of the motor under the same simulation condition, keeping the given rotating speed and the given torque of the motor unchanged, and adding a fault-tolerant control strategy at 0.15s for comparing the torque pulsation conditions before and after fault-tolerant control when the A phase of the motor has an open-circuit fault at 0.1 s. Fig. 7 is a torque waveform diagram of the six-phase permanent magnet fault-tolerant motor when an a-phase open circuit fault occurs, and fig. 8 is a stator current waveform diagram of the six-phase permanent magnet fault-tolerant motor when an a-phase open circuit fault occurs.

Simulation results show that by adopting the model prediction current control strategy, the permanent magnet fault-tolerant motor has good static and dynamic performance in a normal operation state, and can reduce the torque ripple of the motor in a fault state, inhibit the increase of the amplitude of six-phase stator current and ensure the normal operation of the motor in an open-circuit fault state.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.