| The variable speed constant frequency(VSCF) technology is characterized by high efficiency and fast dynamic response. With the rapidly grown of the power electronic and control theory, many system projects are presented. And some of them have been used in wind power generation and the power system of airplane.A design project of the low power VSCF generation system is presented in this paper. The system includes motor, permanent magnet synchronous generator and AC-DC-AC convertor. When the speed of the motor is variable, the frequency and amplitude of voltage generated by permanent magnet synchronous generator is variable. This voltage will be converted to constant by the AC-DC-AC convertor.Firstly, the main circuit of AC-DC-AC inverter is designed. According to the basic principle and experience, the parameters of the system are chosen. Treated the load current as a disturbance input, the continuous and discrete mathematical models of the single-phase PWM inverter are established. At the same time, the whole simulation module is made up by simulink blocks in Matlab environment. The causes of the output voltage waveform distortion are analyzed, which include the influence of the dead-time and nonlinear loads.Then the digital control strategies of the PWM inverter are introduced. As any of them is not perfect, a compound control strategy PD and repetitive controller is designed to control the system and the design method of parameters for controller is given. Simulation results show that PD and repetitive control strategy gives excellent dynamic response as well as high quality voltage waveform.Finally, the hardware circuit of the control system is designed on the platform of DSP TMS320F240. The IR2110 chip is used for the driver circuit, and the negative voltage circuit is designed. The flow chart of the software written by basic language is given. The control scheme is applied on the experimental equipment designed by the above researches, and the results are analyzed. |
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