Single-phase PWM Soft Switching Rectifier

With the development of miniaturization,light weight,low heat consumption,high conversion efficiency switching power supply and advanced control theory,PWM rectifier has become the key technology of switching power supply.However,the problems of high voltage on-off,high current off,switching loss and electromagnetic interference in commonly used switching devices can not be ignored.Using single-phase PWM soft-switching rectifier as active front-end can reduce input current harmonics,improve power factor and transmission efficiency.Therefore,the study of soft-switching PWM rectifier technology is of great significance.In this paper,the basic principle of single-phase PWM soft-switching rectifier system and the current loop under different switching modes are analyzed,and the mathematical model is obtained.In order to realize the unit power factor control on the network side,the double closed-loop voltage and current control method on the PWM rectifier side is studied.Because the traditional single-phase phase-locked loop(SPLL)has a delay link,which makes the two sets of data asynchronized and reduces the real-time performance of the control system,the method based on second-order generalized integrator phase-locked loop(SOGI-SPLL)is mainly studied.The method of generating the driving waveform of single-phase PWM soft-switching rectifier is studied.In view of the fluctuation of the network-side signal,a PWM driving module which can be compensated with the network-side signal is designed.The control method of feedforward voltage compensation is studied to compensate for the influence of voltage fluctuation in input power grid.Through the research and comparison of several control methods of direct current control,a more suitable compound control method is adopted.Based on the above theoretical research,this paper takes PSIM as the simulation platform to simulate the single-phase digital phase-locked loop,PWM soft-switching rectifier and double-closed-loop voltage and current control system,and designs and builds an results are consistent,which further verifies the research.The correctness and feasibility of the design method.