Research On A Current-fed Control System Of Wound-Field Doubly Salient Motor

Wound-Field Doubly Salient Machines(WFDSM), with the characteristics of simple structure and flexible control, have good prospect in the realm of high speed and high efficiency motor application. This paper mainly researches on the current-fed control system of WFDSM. After analyzing the operating modes of the traditional voltage-fed control system of WFDSM, the contradiction between the speed range and chopping frequency is pointed out. A topology of current-fed control system and the corresponding 12-step control strategy are put forward, which laid the foundation for high speed application of WFDSM.Initially, the working principles of WFDSM are introduced. The armature reaction effects to the motor are analyzed in detail. The simplified mathematical model and circuit model of WFDSM are established. The conventional full bridge voltage-fed control strategy is studied and it is pointed out that this conventional strategy may not only lead to the huge current spike but also make it next to impossible to realize the wide range speed regulation.Then, to tackle those problems under the traditional control strategy, the topology based on current-fed control and the corresponding 12-step control strategy are proposed and analyzed. The rotational speed is controlled through adjusting the bus current, thus widening the speed regulation range. After established the simplified mathematical model for WFDSM current-fed control system with speed and current dual closed loops, the precise model of that current-fed speed regulation system for the 12/8 poles WFDSM is established through finite element simulation softwares Ansoft Maxwell and Simplorer. The steady and dynamic performances of the system are studied via simulation.Finally, on the basis of DSP and CPLD, the WFDSM current-fed control system is established. The speed regulation experiments based on the prototype are accomplished. It is verified that the WFDSM current-fed speed regulation system possess the excellent performance and wide speed regulation range with soft-switching of the inverter bridge IGBTs realized in a certain range. The novel topology and control strategy are suitable for the high-speed and wide-speed range application of WFDSM.