Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title Dead Time Compensation of Stand-alone Inverter Under Unbalanced Load
Authors Jinyong Jeong ; Jongmin Jo ; Junwon Lee ; Woo-Kyu Chae ; Hanju Cha
DOI 10.6113/TKPE/2015.20.2.115
Page pp.115-121
ISSN 1229-2214
Keywords Microgrid; Stand-alone inverter; Three phase PWM inverter; Unbalanced load; Dead time; Resonant control; Voltage distortion
Abstract Stand-alone inverter supplies constant voltage to loads. However, when a three-phase stand-alone inverter supplies unbalanced load, the generated output voltages also become unbalanced. The nonlinear characteristics of inverter dead time cause a more serious distortion in the output voltage. With unbalanced load, voltage distortion caused by dead time differs from voltage distortion under balanced load. Phase voltages in the stationary reference frame include unbalanced odd harmonics and then, d-q axis voltages in the synchronous reference frame have even harmonics with different magnitude, which are mitigated by the proposed multiple resonant controller. This study analyzes the voltage distortion caused by unbalanced load and dead time, and proposes a novel dead time compensation method. The proposed control method is tested on a 10-kW stand-alone inverter system, and shows that total harmonic distortion (THD) is reduced to 1.5% from 4.3%.