Research On The Four Phase SRM Drive System With Split-phase Converter Of No Capacitors

With the rapid economic development, people’s requirements about transportation are changing.Nowadays, energy crisis makes the electric bicycles stand out from different vehicles which are verysuitable for citizens. The low power electric bicycles are convenient, fast, cost effective and becomethe first choice of low speed. So the market will be very broad.The good performance of electric bicycles depends on the performance of the drive motor mostly.It requires high efficiency, high starting torque, small volume and low weight. The switchedreluctance motor meets all these requirements. So the use of switched reluctance motor for electricbicycle drive motor is an ideal viable option.The demands of electric bicycles are rated power of400W; rated speed of550rpm. It suggests afour phase outer rotor SRM. To reduce the volume and improve the ratio of the drive system, the splitphase converter without capacitors is adapted. The paper is to explore the possibility of using splitphase converter without capacitors in the SRM and its characteristics.First, it adapted the four phase24/18structure SRM as the design goal. With the help of finiteelement simulation software Ansoft, it finally obtained the basic size parameters of the motor throughthe comparison of different winding connections, different ratio of rotor pole arc coefficient, andchoosing the number of turns and axial length. Then according to the application, it selected the splitphase converter without midpoint capacitors as converter topology and established mathematicalmodel through finite element simulation. It concluded the basic performance of the machine. In orderto analyze the influence of midpoint voltage ripple, it studied the current, torque ripple and efficiencyof the system and also made a comparison with the asymmetry half bridge circuit. Angle control isoptimized by simulation analysis as well as the whole speed range of control mode.Finally it brieflyintroduced the digital controller using logic devices and dsPIC30f3011and the experimentplatform.Through the contrast experiments of different midpoint capacitors, it verified the analysis ofthe midpoint voltage ripple.Through the load experiment, it shows that the SRM drive system usingthe proposed converter has good speed control performance and it is reliable, high efficiency and costeffective.