Design and Analysis for Driving Circuit for DC-DC Converter Employing Current Transformer and Auxiliary Switching Transistor

摘要

When bipolar transistors are used in the main circuit for a DC-DC converter, a driving circuit using a current transformer is widely used due to its driving efficiency. However, there are limitations for reducing the turn-on and turn-off times of the bipolar transistors if only the current transformer is used. In the present paper, a bipolar transistor as an auxiliary switch with a high-speed capability and a small capacitance is connected in parallel to the bipolar transistor as the main switch. The auxiliary switch is operated only when a trigger pulse for turn-on is applied. In the newly proposed driving circuit, a high-speed operation is realized by applying the emitter current of the auxiliary switch transistor as the base current of the main switch. An analysis and a design method for the new circuit are presented.