Research Of Fault Diagnosis Analysis Based On Open-Winding Five-Phase FTFSCW-IPM Driving System

With the rapid growth of new energy automotive industry, the development of the electric vehicles (EVs) will be the important way to realize the auto industry transformation and national sustainable development. Motor and its driving system are the key of the EVs. Because of its advantages, permanent-magnet synchronous motors (PMSMs) become the preferred choice for the new generation of EVs. In which, the fault-tolerant PM motors have advantages of high power density, good output performance and strong fault-tolerance for motor itself and controller under open-circuit, short-circuit fault. So it has been paid much attention in EVs' power driving area.Firstly, the background and significance are introduced, and the development status of multi-phase fault-tolerant motor and open-winding system is stated. Based on a new five-phase fault-tolerant fractional-slot concentrated winding interior permanent magnet (FTFSCW-IPM) motor, the structure, principle and characteristics are analyzed. The topology of this open-winding (OW) five-phase FTFSCW-IPM motor driving system is designed, which can realize motor's physical and electrical isolation. The modeling analysis is carried out in detail and the mathematical model is built under the five-phase static coordination.The control strategy for five-phase OW FTFSCW-IPM motor driving system is studied in this thesis, including motor's vector control and common mode voltage (CMV) suppression. Due to the existence of CMV in the single-power dual-inverter system, the basic output voltage vector and the mechanism of CMV are analyzed in this paper. According to the choice of suitable vectors produced by the dual-inverter system, CMV can be suppressed. Through exploring the relationship between the switching sequence produced by these two inverters, a matrix to realize 4?/5 anti-clockwise rotation is introduced, which simplifies the dual-inverter modulation to single-inverter modulation.Some research for fault diagnosis is researched based on the five-phase OW FTFSCW-IPM motor driving system. For the interturn short-circuit fault, the diagnosis mothed based on zero-sequence voltage is put forward. It can determine the occurence of interturn short-circuit fault under a certain operating condition, and the fault severity can be estimated approximately. For the inverter fault, stator current normalization processing is adopted to excluding the influence of operating condition. And the fault location can be realized through two diagnostic variables. Additionally, taking all the problems above consideration, the hysteresis fault-tolerance method of phase-loss fault is proposed to integrate the system's control, fault diagnosis and fault-tolerant undisturbed operation.Finally, the system simulation model is established by Matlab/Simulink, and the experimental platform is developed based on controller dSPACE 1104. Both simulation and experimental results verified the feasibility and effectiveness of the proposed control strategies including the dynamic-steady state performance, CMV inhibition, interturn short-circuit fault severity detection, inverter switch and bridge-arm fault detection and motor phase-loss fault-tolerant control strategy.