Ripple Current Reduction in DC-Link Capacitor for a Single-Phase Two-Stage Inverter

The single-phase two-stage inverter is a common energy conversion unit for emerging decarbonization applications, such as residential photovoltaics systems. Specifically, a dc–dc converter and an inverter are connected back-to-back with a dc-link capacitor serving as an energy buffer. The reliability of this unit depends on the lifespan of the dc-link capacitor, which decreases significantly with the rms value of the capacitor current. This article proposes a simple but effective method to reduce the switching-frequency capacitor ripple current, which can extend the capacitor lifespan and increase the reliability of the energy conversion unit. The proposed method manipulates the switching pattern of the dc–dc converter by modifying its carrier waveform. Since the duty cycle is unaffected, the method is compatible with any existing carrier-based control scheme. Experimental results are obtained to verify the proposed method.