Research On Optimization Of Adjustable Magnetic Strategy Of Hybrid Excitation Flux Switching Motor

Nowadays, the problems of air pollution and CO2 emissions within cities have aroused people’s wide attentions globally. To alleviate the two issues of energy crisis and environmental pollution, new-energy based vehicles can play a huge role. In order to meet the demands of new-energy vehicles, high efficiency, fast torque response and wide speed range, etc. are the key characteristics of the motor drive systems.As a novel type of stator-excited brushless machine, hybrid-excitation flux-switching (HEFS) motors exhibit the features of large torque output capacity, high torque density, and flexible flux-regulation ability, and can be realized as a kind of motors with large torque under low-speed and wide adjustable-speed region by pro-magnetization in low-speed and de-magnetization in high-speed respectively, which is favorable for new-energy based vehicles. This thesis mainly focuses on an optimal flux-regulation strategy based on minimal loss, namely, through the appropriate allocations of armature currents and field currents, to ensure the motor to achive a minimum loss in the whole operation region instead of only rated operation point, so as to improve the efficiency of the drive system. The experimental results verify the effectiveness of the proposed control strategy. The main research contents of this thesis can be summaried as follows:(1) The research background and significance of the project are introduced. The structure characteristics, working principle and mathematical model of the HEFS motor are analyzed systematically. Then, the principle of SVPWM control and close loop control of field-excitation current are stated and analyzed.(2) Through the analysis of the mathematical model and the control principle of HEFS motor, a simulation model of the HEFS motor-based drive system on the MATLAB/Simulink platform is established. Then, the steady and dynamic performances of the HEFS motor drive system are conducted.(3) The hardware circuit of the HEFS motor drive system is designed and implemented, which include the DSP minimum system board, voltage and current sampling circuits, the position detection circuit of the rotor, the protection circuits of over-current and temperature, the power supply circuit and the driving circuit of power devices.(4) The software program of the HEFS motor drive system is designed and implemented. Firstly, the completed software program flow is established. Then, based on the main core chip of TMS320F28335 for the control system, the SVPWM-based control algorithm and the closed loop control algorithm of the field-exciting current are proposed and programmed. Finally, the software is progrmmed, decoded and co-operated with the hardware.(5) In order to verify the validity of the optimal flux-regulation strategy based on minimal loss, a three-phase HEFS motor is manufactured, and an experimental platform of the HEFS motor is built. Then, the static characteristics and the steady performance of the HEFS motor are tested. Finally, a series of experiments are carried out under the proposed optimal current control strategy based on the efficiency optimization control in simulation.