Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title Reliability Analysis of DC-link Capacitor of Photovoltaic NPC Inverter by Application Angle of Discontinuous PWM
Authors Ga-Hyeon Yeo ; Jae-Heon Choi ; Ui-Min Choi
Page pp.195-201
ISSN 1229-2214
Keywords PV System; NPC(Neutral-point clamped) Inverter; DPWM(Discontinuous pulse width modulation); DC-link Capacitor; Reliability
Abstract The voltage modulation method has a significant effect on the performance of 3-level neutral-point clamped (NPC) inverters such as efficiency and output quality. Discontinuous pulse width modulation (DPWM) has been proposed to improve efficiency by reducing the switching loss of power devices. In previous research, the output quality, power loss, and reliability of the power device were considered when the DPWM method was applied. However, the influence of the DPWM on the reliability of DC-link capacitors, one of the reliability-critical components, has not been investigated. In this paper, the effect of DPWM on the reliability of DC-link capacitors is studied in the NPC inverter. Considering the mission profile of the photovoltaic (PV) system, the accumulated damage of DC-link capacitors is analyzed at the component level first under different applied angles of DPWM. The reliability of DC-link capacitors is then evaluated at the system level by considering all capacitors of the NPC inverter. In addition, the current of the DC-link capacitor is analyzed through the experiment to validate the negative effect of the DPWM on the reliability of the DC-link capacitor.