Research On High Frequency Structure And Dynamic Characteristics Of Digital-controlled 400Hz Inverter System

Traditional inverter and high-frequency-link inverter are researched based on 400Hz single phase inverter. For traditional inverter, it produces very poor response with sudden load change when repetitive control algorithm is used, so several compounded control methods are employed to improve its dynamic characteristic. For HLF inverter, three control strategy are discussed to realize the CVCF inverter output with the same main circuit topological structure.Based on the state-space averaging and linearization technique ,the continuous and discrete models of single-phase inverter are established with the load current treated as a disturbance. A simulation model is established with MATLAB software and the influence of dead-time, flux imbalance and output impedance in single-phase full-bridge inverters is analyzed.A comprehensive theoretic analyze is carried out on repetitive control system .System stability, error convergence and steady-state error are discussed. Then design method of repetitive control system and example are given out. To improve the dynamics of the inverter, the state feedback pole assignment control is used. The integral control is added in the pole assignment to eliminate the error caused by the sudden change of the load .State observer is used to compensate one-step-delay control .This paper shows the principle and realization of the state observer.In view of HFL inverter, three control strategies are introduced in this paper. Compared with the others, the uni-polarity phase-shifted controlled converters have better performance. It realizes soft commutation of shift-phase bridge and cycloconverter, so it`s a good research direction of HFL inverter .In the end, simulation results prove that the proposed control strategy can realize the good output voltage.