Research On A Three Level Bi-directional DC/DC Converter And Its Soft-switching

With the development of Power Electronics technology, bidirectional DC/DC converters are increasingly used in applications such as DC uninterruptible power supplies, aerospace power systems, electric vehicle, fuel cell system.Three level technology is introduced in bidirectional DC/DC converter. It was shown that this technology can reduces the voltage stress across the main switch to half of the input voltage, decrease the size of passive component, advance dynamic response and reduce the cubage and weight of the converter.Employing soft-switching techniques in bidirectional DC/DC converters reduces switching loss and improves efficiency of the converters. The soft-switching converters can operate in higher frequency. As a result, the converters will have high power density and fast dynamic response.In this dissertation, a novel three level topology bidirectional DC/DC converter is designed, for using in hybrid-energy electric vehicle. The operation principle and process of three-level DC/DC converters are analyzed and discussed with calculation. Then simple passive lossless soft switching cells, which are applicable to our converter, are introduced in this thesis. Their operation process is analyzed in detail with figures and equations.Based on the above analysis, a novel three level topology bidirectional DC/DC converter with passive soft switching is designed in this thesis. The design and consideration of the main circuit, control circuit and protect circuit are presented. First matlab simulation was used. Then prototype aeroplane was excogitated to validate the result. Finally, the experimental waves of the prototype are given to verify the validity of the circuit.