An optimization design for 5-kW centralized PV inverter to achieve 99% efficiency

In this paper, a 5-kW photovoltaic (PV) inverter with more than 99% peak efficiency is presented. The inverter utilizes two coupled inductors in one resonant pole to ensure the zero-voltage switching (ZVS) for main switches, and zero-current switching (ZCS) for auxiliary switches. Due to the favorable cooling and ease of fabrication characteristics, PCB planar magnetics are employed as the coupled resonant inductors. In addition, super-junction MosFETs with low on-state resistance is selected in order to reduce the inverter conduction loss. The optimization design of planar resonant inductors is described and verified by finite element analysis (FEA) software. During the experiment on the 5-kW inverter prototype, the temperature rise of planar inductors is below 15°C without fan cooling at full load.