An Inductance Fourier Decomposition-Based Current Hysteresis Control For Switched Reluctance Motors

As the goverment of China promotes the development of new nenergy vehicles, switched reluctance machines (SRMs) have attracted extensive attentions due to the inherent advantages, including simplicity, low cost, excellent fault-tolerance and wide speed range. Especially during these years, as a brushless machine without permanent magnets, the SRM-based drive systems have accelerated developments due to the supply limitation and price fluctuation of rare-earth materials, which have been successfully employed in the applications of aerospace, traction and industrial systems. Foreseeably, in the near future, SRMs will be widely used because of its advantages. However, one of the bottlenecks limiting the SRMs for further applications is its unique doubly-salient structure and pulse-current-based power supply method, resulting in large torque ripple, serious noise and vibration. In this thesis, based on a comprehensive research on conventional SRMs, a nonlinear model based on inductance Fourier decomposition is constructed, and consequently, a novel current-hysteresis-control strategy based on Fourier inductance model is proposed to reduce the torque ripple.The main research contents of this thesis can be summaried as follows:(1) The research background and significance of the thesis are introduced. Then, the structure characteristics, working principle and mathematical model of SRMs are analyzed systematically.(2) On the basis of comparing the existing nonlinear modeling methods of SRMs, a novel nonlinear inductance model based fourier-decomposition is obtained by using the inductance data from 2-D finite element analysis. Then, the SRM model in MATLAJB/Simulink platform is established.(3) A novel current hysteresis control based on Fourier inductance model is proposed to minimize torque ripple by indirectly controlling torque, and the corresponding simulation model is established in MATLAB/Simulink platform.(4) The hardware circuit of the SRM-based drive system is designed and implemented, which include the DSP-based minimum system board, current sampling circuits, rotor position detection circuits, protection circuits of over-current and temperature, power supply circuits, and driving circuits of power devices.(5) The control strategies of the SRM-based drive system is designed and programmed. Firstly, a completed software program flow is established. Then, based on the main core chip of TMS320F28335, the current hysteresis control algorithm and the novel current hysteresis control based on Fourier inductance model are proposed and programmed. Finally, the software is progrmmed, debugged and co-operated with the hardware.(6) In order to verify the validity of the novel current hysteresis control strategy based on Fourier inductance model, a three-phase SRM is manufactured, and an experimental platform is built. Then, the steady and the dynamic performances are tested and the measured results verify the theoretical and simulated predictions.