Research On ZVZCS Half-bridge Three-Level Converter With Series Diode

With the continuous development of power electronics technology, three-level converterhas been widely used in various power electronic DC/DC converters because of their ownadvantages. Three-level converter has many advantages, such as the voltage stress oftransistor is low and output filter is small, and so on. So, it is very suitable for the occasionsof high voltageand large power, and it has great value to research the converter and itssoft-switching technology.The basic zero-voltage switching half-bridge three-level converter working principle andthe advantages and disadvantages are analyzed, aiming at the Lagging tube of the converter isdifficult to achieve zero voltage switching when the load is lighter and the loss of duty cyclecaused by resonant inductance, studied the zero-voltage and zero-current switchinghalf-bridge three-level converter with series diode. Analysised the idea of adding the blockingcapacitor and series diode, and the principle of working, and do a thorough analysis of thedesign and choose of blocking capacitor. Based on the above analysis, the parameter choiceof the main components is discussed, and the design and method of winding of thetransformer, especially the design and select of the control circuit and driver circuit isolation.The converter can take advantage of the added devices over a wide load range of thezero-voltage switching of leading switches, and can achieve zero-current switching of laggingswitches in the range of any load and input voltage variations, and there is no primarycirculation, with a higher conversion efficiency.Last，a frequency of100kHz, the power of2kW (200V/10A) the prototype has beencompleted. The experimental results show that the converter is feasible in practicalapplication. It testifies the validity of theory analysis.