Research On Motoring Characteristics And Control Technology Of Parallel Hybrid Excitation Machine

Parallel hybrid excitation machine(PHEM)is an original axial parallel coupling of permanent magnet synchronous machine(PMSM)part and doubly salient electro-magnet machine(DSEM)part.It combines the merits of high power density,high efficiency,strong ability of flux regulation and high reliability.It has a significant application prospect in the fields of aircraft starter/generator system and electric vehicles.PHEM consists of two types of brushless machine with different operation principles,so the characteristics and control method are different from any one of them.The motoring characteristics and control technology are investigated in this paper.The structure,combination conditions and mathematical model of PHEM are expounded firstly.No-load magnetic field,flux and back EMF are analyzed.The inductance characteristics are studied emphatically.The dq axis reference coordinate of PHEM is established.The field current and d-axis current would mainly affect d-axis inductance,while q-axis current would have more effects on q-axis inductance.The BLAC control method and BLDC control method of PHEM are studied.Torque characteristics are analyzed.The field-circuit coupled co-simulation model of both BLAC and BLDC control method are built.In BLAC control strategy,the third harmonic injection method is used to decrease torque ripple.In BLDC control strategy,the improved bipolar PWM scheme and overlap commutation method are used to improve torque characteristics.The effects of different current components on electromagnetic torque are studied.The electromagnetic torque is decomposed by freezing permeability.The motoring mode of PHEM is analyzed and it mainly depends on the field current of DSEM part.The coordinated control strategy of armature current and field current is studied,when the machine works in flux weakening region.The platform of PHEM prototype is established.Flux regulation experiment,starting experiment and torque experiment are conducted.The experimental results show that the output torque of both control methods is highest at the torque angle of 110°.When the armature current is smaller than rated current,the output torque results of the two control methods are similar.The motoring mode of PHEM is verified preliminarily.