2017 Ministry of Science and Technology Research Project (PI)
Topic—Design and Implementation of A 1-MHz High Power Density Power Pulsation Buffer using GaN Devices and A Novel Three-Phase Interleaved Integrated Coupled Inductor
Abstract—A stable AC-to-DC converter requires small output voltage and current ripple. Traditionally, the output voltage and current ripple is reduced by paralleling multiple large electrolytic capacitors in the converter output side. However, these huge electrolytic capacitors will limit the power density of the converter. This project’s goal is to develop a circuit to limit the input double-line frequency ripple from the AC-to-DC converter with high efficiency and high power density, using a 1-MHz three-phase interleaved boost converter. There are three primary methods to reach high efficiency and high power density. First, by using wide-band-gap devices such as gallium nitride (GaN) high-electron-mobility transistors (HEMT) for high switching frequency applications, switching losses can be dramatically reduced. Second, an interleaved technique for reducing the input and output current ripple is adopted to further reduce the input and output capacitors’ ESR power losses. Third, designing a three-phase interleaved integrated coupling inductor reduces the converter volume. The DC flux in the central legs of the coupled inductor can cancel each other, which reduces core losses. This paper presents a triangular current mode (TCM) control to achieve zero voltage switching (ZVS). Also, the controller conducts a phase-management mechanism to raise the light load conversion efficiency. The preliminary planning work will include simulation to evaluate and verify the proposed designs. A magnetic design, control strategy and a loss analysis based on Magnet, PowerSim and SIMPLIS simulations are also included. A 1-kW laboratory prototype with a 380-V input voltage and 400-V output voltage is designed and tested to verify the feasibility. The values of efficiency of the light load (20% of rated power) to full load at 380-V inputs are greater than 97.5 %, and the power density is 70W/in3.