Research On Asymmetric Three Level T-Type Power Converter For Swithed Reluctance Motor

Switched reluctance motor(SRM)has a good application prospect in many fields,especially in the field of electric vehicles because of its simple design,low cost and no permanent magnet.In order to improve the competitive advantage,the drive system needs to have excellent performance in the range of speed regulation,reducing current fluctuation and reliability.Power converter is an important place for energy exchange of drive system,which plays a great role in improving output capacity,optimizing system performance and energy management.Therefore,in order to optimize the control of SRM drive system,this paper takes asymmetric three level T-type power converter as the research object and reasonable control strategy to analyze and study.Firstly,based on the asymmetric half bridge power converter,the topology and working mode of the asymmetric three level T-type power converter are given.Two power switches are added to each phase of the power converter,which can realize the multilevel flexible control of the SRM drive system.In this paper,a new type of switched reluctance motor system with asymmetric three level T-type power converter is proposed.Traditional PWM control only directly adjusts the voltage action time by changing the duty cycle,and the speed current double closed-loop PWM control strategy can also regulate the current.The rationality of the asymmetric three-level Ttype power converter combined with the speed current double closed-loop PWM control strategy is proved by simulation.Secondly,in terms of the reliability of the SRM drive system,a real-time fault diagnosis method of asymmetric three level T-type power converter is presented.The paper analyzes the winding voltage changes under the power switch tube open,short circuit fault state and normal state.It is proposed that the phase voltage difference of two states is the characteristic of fault diagnosis.The fault type and fault location can be comprehensively judged by pulse injection method.The simulation results show that the fault diagnosis method of asymmetric three level T-type power converter can locate the fault quickly and the algorithm is simple.Finally,the experimental platform of SRM drive system based on asymmetric three level T-type power converter is built based on the simulation model.The experimental results not only further verify the feasibility of the above topology and its control strategy,but also verify the fast and accuracy of the fault diagnosis method,and also verify the dynamic performance of the drive system.In this paper,there are 63 pictures,9 tables and 121 references.