Ripple-port module-integrated inverter for grid-connected PV applications

The single-phase inverter has inherent double-frequency power ripple, which if not mitigated internally appears at the input port and deteriorates the MPPT 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 cancelation 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 cancelation purposes. Hence, a very small capacitance is needed, and, as a result, high reliability film capacitor can be used instead of the bulky, low reliability electrolytic ones.