Reseach On Technology Of Bi-Directional Voltage Mode Inverter

With development of science and technology, the equipment of power supply is becoming smaller and the digital control is becoming more popular.Research on high-performance power supply has been paid more and more attention. Digital technology greatly simplifies the complexity of hardware circuit, overcomes some problems of analog circuit and makes control and debugging more flexibility. Digitalization of power supply is the main direction of technology development nowadays. Inverter is the technology core of photovoltaic energy system, wind power system and uninterrupted power supply system. Therefore, how to realize the inverter power supply for better digital to develop and utilize the new energy better plays a pivotal role. Bi-directional voltage mode inverter is applied to occasions which need energy transmitted in bi-directions. Based on dsPIC that is the core chip, the paper proposed a scheme for bi-directional voltage mode inverter and an experimental prototype is developed.Six topology structures of bi-directional voltage mode inverter were analized in this paper and the principle of inverter introduced detailedly based on uni-polarity phase shifting control strategy. Bi-directional voltage mode inverter mainly includes three sections high frequency link inverter, high frequency transformer and cycloconverter. The power switches of high frequency link inverter realized zero voltage transition, cycloconverter power switches were zero current commutation naturally which resolved voltage overshoot and reduced power loss of switches greatly. The power efficiency of inverter was improved.The mathematical model of inverter was built using state-space method in this paper.PID parameters were tuned by using poles configuration .Closed-loop feedback model of output voltage was established based on mathematic model. Dynamic response of the inverter designed by the method of poles assignment system is faster, the steady performance is better and the distoration of output voltage is much lower.Main circuit and control circuit of bi-directional voltage mode inverter were designed and simulated with MATLAB/Simulink for platform and the parameters of LC filter and the controller were decided preliminary. An output voltage experimental prototype was designed based on the main control chip dsPIC. Simulation results and principle experimental results both indicated that the topology structure and control strategy of the inverter are correct and feasible. The energy of inverter can be transmitted in bi-directions. When cycloconverter switches start to work, the voltage value of switches is zero. Output voltage waveform is smooth and the symmetry of waveform is good. Stability of inverter is good and the inverter has a little noise.