Short-circuit fault-tolerant control method based on deadbeat current tracking for five-phase permanent magnet motor with sinusoidal back-electromotive force or trapezoidal back-electromotive force

Patent metadata

Field	Value
Publication number	US-11611307-B2
Application number	US-202017621256-A
Country	US
Kind code	B2
Filing date	Dec 7, 2020
Priority date	Oct 27, 2020
Publication date	Mar 21, 2023
Grant date	Mar 21, 2023

Abstract

A short-circuit fault-tolerant control method based on deadbeat current tracking for a five-phase permanent magnet motor with a sinusoidal back-electromotive force or a trapezoidal back-electromotive force (EMF) is provided. By fully utilizing a third harmonic space of a five-phase permanent magnet motor in a fault state, the method proposes a fault-tolerant control strategy for a five-phase permanent magnet motor with a sinusoidal back-EMF or a trapezoidal back-EMF in case of a single-phase short-circuit fault. The method enables the five-phase permanent magnet motor to make full use of the third harmonic space during fault-tolerant operation, thereby improving the torque output of the motor in a fault state and improving the fault-tolerant operation efficiency of the motor. The method achieves desirable fault-tolerant performance and dynamic response of the motor, and expands the speed range of the motor during fault-tolerant operation.

First claim

What is claimed is:

1. A short-circuit fault-tolerant control method based on a deadbeat current tracking for a five-phase permanent magnet motor with a sinusoidal back-electromotive force (EMF) or a trapezoidal back EMF, comprising the following steps:
step 1: detecting a speed of the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF as a feedback speed ω m of the five-phase permanent magnet motor; comparing a given speed ω* with the feedback speed ω m to obtain a speed error e r of the five-phase permanent magnet motor; calculating, by a proportional integral (PI) controller, a q-axis current of the five-phase permanent magnet motor according to the speed error e r ; and outputting, by the PI controller, a given q-axis current i q ;
step 2: compensating a short-circuit current, and analyzing and processing a short-circuit fault as an open-circuit fault;
step 3: reconstructing reduced-order matrixes in a fundamental space and a third harmonic space under a single-phase short-circuit fault respectively;
step 4: ignoring a reluctance torque, and obtaining torque expressions of the five-phase permanent magnet motor under the short-circuit fault in the fundamental space and the third harmonic space through the reduced-order matrixes respectively;
step 5: constructing, for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF, an expression of an extra torque ripple generated by an interaction of a short-circuit current and a short-circuit back-EMF;
step 6: generating, through the torque expressions in the fundamental space and the third harmonic space, short-circuit suppression currents i d1s , i q1s , i z1s , i d3s , i q3s and i z3s to offset the extra torque ripple caused by the short-circuit current, wherein i d1s , i q1s and i z1s are short-circuit suppression currents in the fundamental space, and i d3s , i q3s and i z3s are short-circuit suppression currents in the third harmonic space;
step 7: obtaining, for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF, open-circuit fault-tolerant reference currents i d1o , i q1o , i z1o , i d3o , i q3o and i z3o to maintain a smooth output torque, through the given q-axis current i q and the torque expressions in the fundamental space and the third harmonic space under the short-circuit fault, wherein i d1o , i q1o and i z1o are open-circuit fault-tolerant reference currents in the fundamental space, and i d3o , i q3o and i z3o are open-circuit fault-tolerant reference currents in the third harmonic space;
step 8: transforming the open-circuit fault-tolerant reference currents to maintain the smooth output torque and the short-circuit suppression currents on d 1 -q 1 -z 1 axes in the fundamental space and d 3 -q 3 -z 3 axes in the third harmonic space into a natural coordinate system through a coordinate transformation, and superposing the open-circuit fault-tolerant reference currents and the short-circuit suppression currents according to a superposition theorem; and transforming the open-circuit fault-tolerant reference currents and the short-circuit suppression currents integrated in the natural coordinate system to the d 1 -q 1 -z 1 axes through an inverse matrix of a reduced-order transformation matrix in the fundamental space, thereby forming optimal short-circuit fault-tolerant reference currents i dr , i qr and i zr ;
step 9: constructing a discrete model for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF under the short-circuit fault, and obtaining optimal fault-tolerant reference voltages u dr , u qr and u zr under the short-circuit fault through deadbeat model predictive current control; and
step 10: inputting the obtained optimal fault-tolerant reference voltages u dr , u qr and u zr into a carrier-based pulse width modulation (CPWM) module through the coordinate transformation to obtain switching signals of phases; and inputting the obtained switching signals of the phases into an inverter to control the five-phase permanent magnet motor, thereby realizing a short-circuit fault-tolerant control of the five-phase permanent magnet motor.

2. The short-circuit fault-tolerant control method based on the deadbeat current tracking for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF according to claim 1 , wherein in step 2, when the short-circuit fault occurs, an influence of a fault phase on the five-phase permanent magnet motor is divided into two aspects: an influence of a loss of the fault phase on a torque output and an influence of a fault phase short-circuit current on the torque output; and when the influence of the fault phase short-circuit current on the torque output is offset, a short-circuit fault model is equivalent to an open-circuit fault model.

3. The short-circuit fault-tolerant control method based on the deadbeat current tracking for the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF according to claim 1 , wherein step 3 comprises: removing an element corresponding to a fault phase after a single-phase open-circuit fault occurs, and conducting a reconstruction based on a principle that a circular trajectory of a flux linkage and the back-EMF of the five-phase permanent magnet motor remains unchanged in an α-β plane after the single-phase open-circuit fault;
wherein, in case the five-phase permanent magnet motor with the sinusoidal back-EMF or the trapezoidal back-EMF has a phase-A open-circuit fault:
after an element corresponding to a phase A is removed, a matrix is obtained as follows:

T
clarke
A

=

2
5

[

cos
⁢
α

cos
⁢
2
⁢
α

cos
⁢
3
⁢
α

cos
⁢
4
⁢
α

sin
⁢
α

sin
⁢
2
⁢
α

sin
⁢
3
⁢
α

sin
⁢
4
⁢
α

Assignees

• Univ Jiangsu

Inventors

• Chen Qian
• Xia Yuhang
• Gu Licheng
• Zhao Wenxiang
• Liu Guohai

Classifications

• H02P21/00 Primary

  Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation · CPC title

• H02P29/024

  Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load · CPC title

• H02P29/67

  Controlling or determining the motor temperature by back electromotive force [back-EMF] evaluation · CPC title

• H02P25/22

  Multiple windings; Windings for more than three phases · CPC title

• H02P29/028 Primary

  the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault · CPC title