Research On Passive Lossless Soft-Switching Methods For Bridge-Inverters

The volume of the power converter reduced and the power density increased with the enhancement of the switching frequency, the losses of the converter increased on the contrary. Soft switching technique could improve the circumstance of the power switch, reduce the losses and increase the efficiency of the converter.During the two methods, passive soft switching has received renewed inspection as a better alternative than the active methods. Passive methods do not require an extra switch or additional control circuitry. They are less expensive, have higher reliability, and have been reported to achieve higher performance/cost ratios than active methods. To the soft-single-switched converter, the passive soft switching has radicated mainstream station in the industry application field. But to the inverter, the soft switching is short of well-rounded, academic, applied topology because of especial configuration. Therefore, the research of passive lossless soft switching methods for inverters is very valuable.This article begins with the basic topology of PWM power converter, and makes a summary of commonly principles. Both single-switched and unified passive lossless soft switching cells are synthesized for the research of inverter. Theoretical foundation is constructed in passive lossless soft switching for VSI (Voltage Source Inverter) bridge legs, which located the possible topological position of key components and branches within the extremely simplified main passive lossless soft switching configuration.A novel passive lossless soft-switching topology for bridge-type inverter was proposed based on academic analysis. The topology realizes zero voltage turning on and zero current turning off in phase arm power switch couple. Only few inductors, capacitors and diodes are attached in the power stage with simple configuration and minimized additional parts'number. No extra auxiliary power source, detection, driving is needed while different control mode can be adopted. Analysis on topological nature, operational principle and commutation process are given in detail with effectiveness confirmation of mathematical equations, numerical simulation results and experimental waveforms.