Design of a High-Efficiency Micro-Inverter with TO-220 Packaged Gallium Nitride - High-Electron-Mobility Transistors

Since solar power panels generate direct current (DC) voltage, inverters are needed to provide DC/alternating current (AC) conversion to obtain suitable AC voltage forms for daily life and grid. Due to the disadvantages of central and string inverter systems, the use of micro-inverter systems is increasing nowadays. In micro-inverters, the use of new-generation gallium nitride-high-electron-mobility transistors (GaN-HEMTs), which has reached commercial maturity, has opened new horizons in solar power plant applications. GaN-HEMTs have low on-state resistance and high breakdown voltage and allow higher switching frequencies. This paper presents a detailed design methodology and analysis of a GaN-HEMT-based 250-W full-bridge micro-inverter. The LCL filter is designed to reduce the harmonic content of the output voltage and current of the inverter. Since more effort is required in layout design to take full advantage of ultra-fast switching GaN devices, layout design has been carefully completed for a better switching efficiency. The performance of the designed prototype was tested with and without the output filter for different power, voltage, and switching frequencies. The efficiencies for the rated operation at 50 kHz and 100 kHz switching frequencies were measured to be 97.5% and 96%, respectively.