Control Method For Lack Of One Phase In Bearingless Switched Reluctance Motors

The switched reluctance motor (SRM) has caused extensive concern over the recent years due toits simple structure, flexible control method and high fault tolerance. The introduction of bearinglesstechnology could fully take advantage of the high-speed ability of SRM. Meanwhile, bearinglesstechnology can avoid the common mechanical bearing brings vibration, noise and cooling problem,can fully improve SRM speed adaptability.This paper takes the12/8stator pole dual-winding bearingless switched reluctance motor (BSRM)as the object of study, for the problem of lack of one phase in bearingless switched reluctance motor,and researches various control methods from compensation of levitation force and compensation ofelectromagnetic torque, respectively. At last, the open-phase operation of the bearingless switchedreluctance motor is achieved.Firstly, the mathematical models and derivations of bearingless switched reluctance motor areintroducd. Meanwhile, a simple control method is introduced as the basic of control method for lackof one phase.Based on the fault-tolerance ability of SRM, control strategies of levitation-force distribution andtorque compensation were discussed under the open-phase operation of BSRM. The mathematicalmodel of torque and the compensation strategy were introduced. The control method ensured thecontinuity of the levitation force, through the force-compensation for the abnormal phase. In addition,a calculating method of levitation currents was presented, in order to decrease negative torque fromlevitation force compensation. By using finite-element analysis, the algorithm was validated, and theexperiment also showed that the strategy had available control ability under the lack of one phaseoperation.Finallly, the validity of the new method is verified by finite-element analysis. The experiment ispresented and the results verified the available control perfomance of lack of one phase in BSRMs.