Research On Seven-phase Motor Control Based On DSPACE Semi-physical Simulation Platform

The machine is the core component of the electric vehicle drive system.It needs a large output torque when running at low speed,a wide speed range when operating at constant power area,and a certain fault-tolerant operating capacity when faults occur.Compared with the traditional three-phase machine,the multi-phase permanent magnet machine has the characteristics of high torque density,high power density,strong fault-tolerant ability and more control factors,that is especially suitable for the electric vehicle drive system.Based on the characteristics of multi-phase machines,this paper studies the vector control and fault-tolerant control strategies of seven-phase PMSM.First,this paper based on the theory of winding function,analyzes the space-time distribution characteristics of the stator magnetomotive force,and obtains the correspondence between stator injected harmonic current and the output torque.The mathematical models of seven phase PMSM in different coordinate systems are analyzed and deduced.Based on the vector control principle and mathematical model,the full speed domain vector control design of seven phase PMSM is completed,include MTPA control at low speed and field-weakening control at high speed,and the above analysis is verified by simulation.Secondly,this paper studies the fault-tolerant control strategies of seven phase permanent magnet machine in one phase and two-phase open-circuit fault respectively based on the principle of constant magnetomotive force and the principle of maximum output torque.Among them,seven kinds of fault-tolerant control strategies in the α-βcoordinate system are studied with the goal of keeping the magnetomotive force unchanged before and after the fault occur,and compares various fault-tolerant control strategies in the output torque,torque ripple,Joule loss and so on.When the maximum output torque of the machine is taken as the target,the output voltage limit of the inverter and the thermal limit of the machine winding are taken as the constraints.Through the optimization algorithm,the optimal reference currents of the seven-phase machine in one-phase and two-phase open-circuit faults in the natural coordinate system and the d-q coordinate system are obtained respectively,and the performance of the machine in the two coordinate systems is analyzed and compared.Then,based on dSPACE high performance controller,this paper designs and makes the machine drive circuit and signal conversion circuit,and builds a high-performance semi-physical simulation experiment platform for seven-phase permanent magnet machines,and designed a machine experiment program.Finally,the research content of this paper is summarized,and prospects for further work are put forward.