Ripple-Port Module-Integrated Inverter for Grid-Connected PV Applications

The single-phase inverter has inherent double-frequency power ripple, which if not internally mitigated, appears at the input port and deteriorates the maximum power point tracker performance. Conventional dc link inverter topologies filter this significant double-frequency ripple by means of the bus capacitance, usually in the form of electrolytic capacitors, which have well known lifetime challenges. This paper presents a double-frequency ripple cancellation concept and experimental proof of concept. The proposed module-integrated inverter is based on the commonly used two-stage inverter. However, a third port is added for ripple cancellation purposes. Hence, a very small capacitance is needed, and, as a result, a high-reliability film capacitor can be used instead of the bulky low-reliability electrolytic ones.