Design And Research Of DC Power Supply Based On Technique Of Soft Switching And Parallel Balanced Current

Technique of soft switching and parallel balanced current is important research branch of power electronics technique nowadays, and research on soft switching technique is core to realize high power density and high efficiency, it is the main way to realize big power in switch power supply for some switch power supply modules paralleled neatly to expand to big power system, therefore, research and design of DC power supply based on technique of soft switching and parallel balanced current is significant.The paper adopts ZVZCS converter with two diodes in series with lagging-leg switches by comparing and analyzing the different big power topology. The converter realizes ZCS of lagging-leg switches by two diodes in stead of two saturable inductors in series with lagging-leg switches, therefore, the problem of heat dissipation of saturable inductors and the problem of system stability caused by the decentrality of magnetic core are solved. The condition of realizing ZVS of leading-leg switches and ZCS of lagging-leg switches is derived, and also parameters related with resonance are designed. According to the specification of ripple, output filter sector is designed, and the course of designing the inductance is given out.Automatic master-slave current-share is selected by analyzing common current-share methods and modeling of the two automatic master current-share methods. Adopting the current-share method realizes current balancing of power supply modules and improves the response rate of current sharing loop, and also realizes redundancy of the power supply modules system in parallel. The control circuit based on automatic master-slave current-share is designed, and the peripheral circuit of control circuit based on UC3879 is given out.The small-signal model of main circuit and feedback circuit of the FB-ZVZCS converter and open loop transfer function of the system are derived with State-Space Average Method in order to improve the control accuracy and dynamic response rate of the converter. Based on the converter, pole-zero compensator is designed, and also the principle of designing the compensator is proposed. The open-loop system is simulated with Matlab, and the simulation result shows the dynamic response rate of the system is improved and the stable error is reduced to zero with compensating.In order to guarantee the exactness of the design philosophy, the circuit is simulated with Pspice, based on the simulation, and the two power supply modules 5kW(60V/83A) are designed and debugged. The simulation result and experiment result show output of each module meets the specification, and also current-share accuracy meets the specification with modules in parallel.