The Research On Control Strategy Of The Inverter With High Frequency Link

In recent years, with the speedy development of economy, the power electronic technology changed greatly, made the inverter got widespread used, but more strict requirements were put forward on the performance of the inverter, how to improve the conversion device efficiency and power density and performance? High frequency-link inverter with its small volume, light weight, power density, higher efficiency transformation was got attention among the countries’scientists, made high frequency-link inverter gradually became the research focus in the field of inverter. But a single control strategy is difficult to meet the system of high stability, and the system also has a serious defect:can’t take full load inductance load, modulation mode complex, poor overload ability. Therefore, this thesis did depth research on the modulation strategy and closed loop control scheme of the high frequency-link inverter.This thesis first reviewed the history of inverter technology, and then discussed the application prospect of the high frequency-link inverter technology and the main problems of the current modulation.Based on this, the bipolar SPWPM modulation strategy was put forward, and the modulation strategy, the principle of the frequency spectrum analysis and the work mode were discussed in detailed, analysed the SPWPM modulation mode to realize the inverter soft switch technology principle, and discussed mainly the modulation strategy of the inverter power supply system in the steady state characteristics, to the SPWPM modulation of the waveform analysis, the modulation strategy effectively reduced the output voltage harmonic content, and no longer needed the traditional three harmonic injection method to eliminate harmonic, increased the complexity of the control system.Secondly, the design scheme of the inverter control system was discussed. The first, this thesis recommended the calculation to system PI compensation link parameter in the pole assignment method, and then the inductance current instantaneous value feedback and the capacitive current instantaneous value feedback of two kinds of closed-loop control strategies were analysised and contrasted. The inductance current feedback dynamic regulation characteristics were good, system stability was strong; The capacitance current loop feedback had strong ability for load fluctuation, but the system stability was poor. The instantaneous value feedback made the system got fast dynamic performance, guaranteed the output distortion rate was very low, but the output precision was not high, for periodic nonlinear load disturbance can’t be eliminated; Then the thesis put forward the repetitive control scheme, the repetitive control had good inhibition effect for the periodic error disturbance caused by the filter circuit and inverter inherent characteristics, can be very good to improve output voltage waveform quality, at the same time every harmonic amplitude was restrained, this thesis analysised the parameters of the controller design and simulation verification in detailed; Through the use of instantaneous value PI feedback control and repetitive control compound control strategy, it gave full play to the two control strategy of their respective advantages.The system prototype test platform design, the first was the system hardware circuit design, the high frequency transformer AP method parameter design, drive circuit and voltage, current loop sampling circuit design were introduced in this thesis; Then based on ARM controller software design scheme of the discussion, this thesis introduced the SPWPM modulation program generated way, incremental PI program flow chart and repetitive controller program generated flow chart and so on, finally, the experiment waveforms were analyzed in detailed, and verified the feasibility of the design scheme.