Research On ZVZCS Half-Bridge Three-Level DC/DC Converter Based On Digital Control

As higher electromagnetic compatibility desire for power converters,power factor correction(PFC) becomes an important part to reduce the pollution of current harmonic.But it results in high voltage stress on the main switches of latter DC converter.The advantage of three-level(TL) converter is that the voltage stress is only the half of input voltage.Associated with soft-switching,it is very suitable for the occasions of high input voltage,middle/large power.When TL DC/DC converter was brought forward,attention has been paid by scholars in the world,and many topologies have been presented in recent years.Based on analysis of the merit and weak point of TL soft-switching converters proposed already,a novel zero-voltage and zero-current(ZVZCS) TL converter with passive snubber is presented in this paper.It can achieve ZCS/ZVS for all of the active switches and diodes,and it has low secondary voltage stress and simple structure.Furthermore,it improves the duty losing problem faced by the conventional ZVZCS TL converters,thus reduces the loss and improves the efficiency.In this dissertation,the operation principle and the tactic for achieving soft-switching are analyzed in detail.Based on the above analysis,the parameter choice of the main components is discussed and optimized design of the parameters is discussed.Pspice simulation analysis of the operation principles of main circuit is carried out.A 35kHz 960W(48V/20A) prototype is implemented in the laboratory based on the proposed topology.In order to improves the control precision and stability of the system,ARM chip LPC2214 is used as the control chip.The driving circuit,sampling circuit and protection circuit are designed in this paper.The experimental result shows that the novel ZVZCS TL converter is feasible in practical application.It testifies the validity of theory analysis.