Integrated Asymmetric Half-Bridge Converter With Boost Operation for Wide Input Voltage Range

Abstract

A conventional asymmetric half-bridge (AHB) conve rter with zero dc offset current of the transformer at any operating points was proposed. It has low-voltage stresses on the two diodes that are clamped to the output voltage. However, for a wide input voltage range, it can have a small nominal duty ratio that causes to large conduction loss at the maximum input voltage. Moreover, it has high-voltage stress on one of the secondary diodes that leads to high power loss. In order to improve these problems, in this article, an AHB converter with an integrated boost converter is proposed. The proposed converter has identical operation to the conventional one as well as boost operation for the wide input voltage range. Thus, it has a large nominal duty ratio and low-voltage stress on the secondary diode at the maximum input voltage. Moreover, it has zero dc offset current of transformer and higher efficiency over the entire input voltage range compared with the conventional converter. The proposed converter has been verified for a laboratory prototype with 200–400 V input and 50 V/300 W output.