Single-Stage Autotransformer-Based VRM With Input Current Shaper

This paper presents a novel single-stage autotransformer-based voltage regulator module (VRM) with input current shaper. The proposed VRMs with autotransformer achieve possible reductions in switch rms current ratings and filter capacitance. This in turn leads to an increase in power density. The proposed topology can extend the converter duty cycle greater than 50% which the transient performance and overall efficiency may benefit from this. Most of the researched ripple reduction methods cascade a boost-type converter with the VRM system. It is found that the push pull converter, when the duty cycles of the switches are greater than 50%, can simplify the front end of the boost-type converter to a novel single-stage VRM. In order to reduce the VRM size and weight and to achieve near ripple-free input current, coupled inductor techniques are used in the proposed VRM. A prototype is built to illustrate the theoretical prediction.