Research On A Six-phase Fault-tolerant Permanent Magnet Synchronous Motor Used For Electric Vehicle

Fault-tolerant Permanent-magnet Machine (FTPM) is an ideal choice for thedrive motor in Electric Vehicle applications because of its advantages on controlperformance, efficiency, torque density and the capacity of operating under thefailure of windings and converter. This paper researches on the characteristics,design and fault-tolerant control of a6-phase fault-tolerant PM machine used forEV.Firstly, the winding arrangement of the FTPM machine with single-layerfractional-slot concentrated windings is analyzed, and two slot/pole combinations,a24-slot/22-pole one with equal tooth width and a24-slot/14-pole one withunequal tooth width, are proposed. The design principle of the FTPM machine isdetermined in the wake of the analysis on concentrated windings and inductanceequation of the FTPM machine.Secondly, FTPM machines with the two slot/pole combinations are designedand then compared in terms of core loss, eddy current loss and copper loss.Performance of the two motors, pertaining to EV applications, is analyzed; and inthe meantime factors affecting the range of constant output torque and maximumoutput torque are pointed out.Thirdly, the research on open-circuited fault conditions of FTPM ispresented. The performance and features of two fault control strategies areanalyzed and compared under open-circuit condition. It is verified that FTPM cankeep the output capacity whether one phase open or two phases open.Finally，the short-circuit occurs at terminals of winding or within a coil areanalyzed in analytical method. The factors effecting on transient of terminalshort-circuit fault are analyzed. For turn-to-turn fault, an equivalent circuit modelis proposed to analyze the influence of short-turn number, position and the motorspeed on current in short turns and healthy turns. For FTPM machines withdifferent winding configurations, the ability to suppress inter-turn short-circuitcurrent is analyzed.