A Bi-directional Full Bridge DC-DC Converter Based On LLC Resonant Tank

In power electronics industry, with the rapid development of soft-switchingtechnology widely put into use, many systems such as battery chargers, electric vehicles,energy, uninterrupted power supply (UPS) and smart grid systems where soft switchingbidirectional converters are applied to eliminate switching losses and reduceelectromagnetic interference, resulting in efficient high frequency capabilities withoutsacrificing efficiency and power density. For this reason, it will be significant to knowhow to make a bi-directional DC-DC converter with the efficient working capacity ofhigh-frequency under the premise of reducing its volume weight，cost and the energy lossof the equipment and systems as much as possible, and it is an important factor to abi-directional DC-DC converter to know how to improve the conversion efficiency ofenergy.Besides the development of the LLC resonant converter, design requirements andcharacteristics of bi-directional DC-DC converter are analyzed in this paper. Both of themare combined to form a new band resonance LLC bi-directional DC-DC converter. Buckdirections with Type-4resonant tank circuit and the boost direction with Type-11resonanttank circuit can ensure the resonant element is utilized in the process of the both flows ofenergy to reduce the volume of the device. And switch ZVS and rectifier ZCS can beachieved in two operating modes. At the same time the method of using a dedicatedfrequency control chip MC33067is introduced to adjust switch operating frequency.Principle and different working conditions of the LLC circuit are analyzed in this paper,The main parameters of the circuit design and an experimental prototype with an LLCresonant bi-directional DC-DC converter are also produced.Through the simulation of the circuit schematic and debugging the experimentalprototype, the boost and buck converter operating mode experiments and experimentalwaveforms were analyzed and compared in this paper. The experimental results obtainedprove that the LLC resonant tank circuit can achieve soft switching without any additionaldevices, and the output of basic buck-boost can meet the design requirements.