Research On High Efficient Bidirectional DC/DC Converter In ZnBr₂Battery Storage System

Energy crisis and environmental pollution poses a serious threat to people’s survival, the newenergy power generation as one of the remedial measures to improve the human living environmenthas been developing rapidly.The new energy power generation’s random generation characteristicsmakes the energy storage system become a focus in the field of new energy application to realize“cut peak and fill valley” on the grid.Energy storage system consists of two indispensable parts theenergy storing device and the power electronic device.This paper looks for bidirectional DC/DC converter suitable for the ZnBr2battery energy storagesystem requirement. This paper chooses LLC+buck/boost bidirectional DC/DC converter and phaseshift+PWM control dual boost half-bridge bidirectional DC/DC converter to compose the ZnBr2battery energy storage system through the analysis. This paper analyzes the working principle ofLLC+buck/boost bidirectional DC/DC converter.This paper points out the existing problems of theconverter, the causes of the problems,reasonable solutions and the detailed design process of theconverter. This paper compares the phase shift+PWM control method with the phase shift controlmethod.The phase shift+PWM control method can reduce the current stress.It can also improve theability of transmission power of the converter and broaden the range of ZVS of the switches. In thispaper, phase shift+PWM control dual boost half-bridge bidirectional DC/DC converter is studied andthe equivalent circuit models as well as the expressions of inductor current and capacitor voltage in avariety of work situations are given. The soft-switching conditions are analyzed to give a method todesign the parameters of the converter.This paper gives the detailed design process of the dual boosthalf-bridge bidirectional DC/DC converter.Finally, the LLC+buck/boost bidirectional DC/DC converter and phase shift+PWM control dualboost half-bridge bidirectional DC/DC converter prototype are finished.The correctness of thetheoretical analyses are verified by experiments.