Research On A Wound-field Doubly Salient Motor Drive System With Forward Buck Converter

Thanks to the prominent characteristics of simple structure, flexible regulation, and relativelyhigh power density, the Wound-Field Doubly Salient Machine (WFDSM) has a broad applicationprospect in the field of high performance motor. This paper mainly studies the drive system of highspeed WFDSM. Based on the analysis of its working performance in conventional PWM controlmode, especially for the current ripple and torque ripple of the motor, a Buck leading WFDSM drivesystem and its control strategy are proposed. The study lays a foundation for practical application ofWFDSM.Firstly, the operation principle and mathematical model of WFDSM are introduced. And theoperational modes of WFDSM in the non-commutation and commutation regions are analyzedrespectively under conventional PWM control mode. It is pointed out that the current risesexcessively fast in conventional PWM modulation method. There are large current ripple and torqueripple. Therefore, a Buck converter is added lead before the three-phase inverter so that the speed iscontrolled by adjusting the output voltage of the Buck converter, which lead to reduce the currentripple, suppress the torque ripple, and broaden the speed range of the motor.The speed control system of the Buck leading WFDSM is established by co-simulation of AnsoftMaxwell and Simplorer. The drive system of the WFDSM is set up based on DSP and CPLD, and thedesign of software and hardware is presented. The basic experiments of the drive system arecompleted, and the result confirms that the good steady-state and dynamic performance of theproposed drive system is better.According to the electro-mechanical energy conversion process of the Doubly Salient Motor,operational principles of WFDSM, both applied as motor and generator, are illustrated from theperspective of magnetic energy transformation. By means of the finite element simulation software,the different influences on motoring and generating power due to armature reaction are studied in thesame12/8pole WFDSM, the power characteristic curves are acquired under different excitationcurrent. Then, the generating and motoring experiments on the prototype machine are conducted, andthe experimental results verify the analysis above.