A New APWM Half-Bridge Converter with Enhanced Zero-Voltage-Switching Range in Wide Input Voltage Range

摘要

In this paper, asymmetrical half-bridge (AHB) converter using a new rectifier with an active-clamp cell is proposed. The AHB converter is one of the popular topologies in low power applications due to small number of components, ZVS capability, and small output filter size. However, when the AHB converter is designed to cover wide input voltage range for hold-up time requirement, it has several problems such as large DC offset current in transformer, poor ZVS condition, and large conduction losses. To solve these problems, the proposed converter uses an active-clamp cell in rectifier. The active-clamp cell not only clamps the voltage stress of a diode, but also makes additional voltage gain for the hold-up time. Therefore, the proposed converter can be designed with narrow input voltage range regardless of hold-up time. In consequence, the proposed converter has a high efficiency in entire load conditions. The effectiveness of the proposed converter is verified with a 280-410V input and 19.5V/200W output prototype.