Research on High-efficiency Bidirectional dc-dc Converter for dc Distribution System

点击翻译按钮获取中文摘要

A high-efficiency isolated-type full-bridge bidirectional dc/dc converter, which is employed for energy storage systems such as secondary batteries and electric double layer capacitors (EDLCs), is investigated. This converter consists of a low-voltage-side current-type converter, a high-voltage side voltage-type converter, a high frequency transformer between them, and an active clamp circuit fir suppression of overvoltage due to current commutation and realization of soft switching of switching devices.With a proposed novel control method, soft switching of every switching device of the converter was confirmed in both boost and buck operation modes through numerical simulation. We also carried out experiments using a 1 kW dc-dc converter that is a thousandth scale of an assumed converter in a dc distribution system. The converter employed an Intelligent Power Module of IGBTs as switching devices, and DSP and FPGA as control devices. Soft switching of all the switching devices were dem … More onstrated in both the boost and buck operation through the experiments.The measured conversion efficiencies are 83.3% in the boost operation and 83.1% in the buck operation, respectively. According to the results of loss analysis, the efficiency of the assumed 1 MW converter is estimated to be more than 95% on the assumption of reasonable efficiency of the transformer and reactors.In addition, the EDLC is investigated as an energy storage device. We employed a three-stage ladder type equivalent circuit for the EDLC, and derived its transfer function. To determine the parameters of the equivalent circuit, we conducted constant current charge and discharge, and resistor discharge experiments, and compared the results of experiments and numerical simulations. As a result, we found that the three-stage ladder type equivalent circuit well simulated the actual EDLC in the constant current operation, however the single-stage ladder-type equivalent circuit showed good agreement in the resistor discharge experiment. Less