Research On A Hybrid Control Technology For Single-phase 400Hz Medium Frequency Power Supply

This thesis focuses on the research and analysis of a 400Hz Medium FrequencyPower Supply system. Constant Voltage Constant Frequency (CVCF) SPWM inverteris the core of the whole Medium Frequency Power Supply. To achieve an outputvoltage with low THD, high stability and fast transient response in every loadcondition, many waveform correction technologies have been proposed.Multiple-loop feedback control approach has a good dynamic performance and it iseasy to implement and design. However, it can not thoroughly eliminate thesteady-state error. While repetitive control strategy has a merit in dealing withsteady-state error and only need to measure one variable, but it is hard to design andits transient response is very poor. This thesis presents a theoretical analysis and asystematic research on the multiple-loop feedback control scheme and repetitivecontrol scheme. The parameter design method of the both controllers is introduced.System stability, steady-state error and error convergence of the repetitive controllersystem are specially disused, and a sufficient condition for stability is presented.A novel hybrid control technology based on multiple-loop feedback control andrepetitive control is proposed. Multiple-loop feedback controller, which can improvethe dynamic performance of the system serves as an inner-layer controller, therefore,the design of the outer-layer repetitive controller is simplified. Thus, the two controlstrategies can coordinate with each other so that the Medium Frequency PowerSupply system can produce high quality voltage waveform and has a fast transientresponse. Both the simulation results and the experimental results show that theproposed hybrid control strategy is feasible and effective.