Fault Tolerant Control For A New Synchronous Reluctance Motor Under Single Phase Open-Circuit Fault

In recent years,the synchronous reluctance motor has been widely concerned,especially in some low-cost,high-performance industrial fields.It is much more appropriate for general equipment like fans and pumps to use synchronous reluctance motor as the driving equipment.The reliable performance of SRM drive system is a useful for it is applied into the industrial field safely.Thus,it is of great index to inhence operation performance of synchronous reluctance motor(SRM).Because the existing fault tolerant controls are not suitable for SRM and the effects are not acceptable.Therefore,this paper proposes the fault tolerant control based on 3rd harmonic current injection and multi-objective optimization.On the one hand,based on the ignorance of inductance and cogging torque,the calculation of 3rd harmonic current is realized,which reduces the torque ripples during fault tolerant operation to some extend;on the other hand,the combination of multi-objective optimization and the motor control achieves the optimization of fault tolerant current,which improves the torque performance and fault tolerant operation.The main contents of this paper as follow:(1)Firstly,the topology of the new kind synchronous reluctance motor and the capability of output torque with different kinds of rotors are introduced and the principle of torque ripple reduction is analyzed,which induced that the motor with the new rotor has the minimum torque ripple and the best torque performance.Then,the mechanical structure and working principle of five-phase synchronous reluctance motor are briefly introduced.Afterwards,the mathematical models of the stator flux equation,stator voltage equation and electromagnetic torque of synchronous reluctance motor in three different coordinate systems are derived,respectively.At the same time,the transformation matrix betwwen different coordinate systems is introduced.These works lay the foundation for the research of fault tolerant control strategy.(2)A fault tolerant control of 3rd harmonic current injection for five-phase synchronous reluctance motor is proposed under single phase open fault.Three existing fault tolerant controls are firstly introduced and applied into synchronous reluctance motor,it is found that the control effects are unacceptable and the torque ripples are quite large.Through analysis it is seen that the torque ripples mainly come from cogging torque,therefore,it is proposed to inject 3rd harmonic currents into the motor based on the existing fault tolerant current,and the final fault tolerant currents can be calculated by neglecting the changes of inductance and cooging torque,and the torque ripples can be reduced effectively through the simulation results(3)The idea of multi-objective optimization,which is commonly used in motor design,is applied into the fault tolerant control of motor,so as to further suppress the torque ripples of the motor.Firstly,the flow chart of how to obtain the fault tolerant current through the idea of multi-objective optimization is introduced.Then,the current variables and objective functions are determined.Since there are many current variables and they affect optimiazation with each other,the current variables are divided into two sensitive layers through sensitivity analysis,and the multi-objective optimization is carried out respectively Finally,the optimal value of eight current variables and a new fault tolerant current are obtained.The output torque and torque ripples of synchronous reluctance motor with fault tolerant currents meet the ecpected goal(4)The motor drive experimental platform is built,carried out respectively.The proposed methods are verified of good performance.