A novel soft-switching two-stage step-up DC/DC converter

In an electric vehicle power system, a step-up converter is required to increase the voltage from 24 V to 270 V. To achieve such a high voltage boost ratio, there are several challenges that must be overcome: tackling the leakage inductance of the isolation transformer; reducing the voltage stress on the power switches; and guaranteeing fast dynamic response and high efficiency Thus, innovative approaches are needed. A novel two-stage step-up DC/DC converter has been developed. This device has the advantages of high power density, easy control, high efficiency, high transformer utilization, and fast dynamic response. The two-stage step-up DC/DC converter is composed of a boost converter cascaded with a push-pull converter. The boost diode and filter capacitor, as found in conventional boost converters, are eliminated. All switches achieve soft-switching by using a simple auxiliary circuit. Therefore, this novel converter is well-suited for applications where the input voltage level is significantly lower than the output voltage, for example, in the areas of electric vehicle power supplies, communication systems, aeronautic power, and power systems. Analysis, prototype development, and experimental tests have been conducted, and the results are presented in this paper. The results confirm the performance and features of the novel converter.