A Single-Phase PV Inverter with Swinging Bus Controller to Eliminate Electrolytic Capacitor and Achieve Reactive Power Generation Capability

摘要

This paper proposes a single-phase, single-stage PV inverter topology, which employs three-state switching (TSS) swinging bus operation. The novelty of the proposed inverter lies in the configuration of the inverter as well as the proposed TSS operation and control scheme. This new design and control solve the instantaneous input and output power mismatch problem without using electrolytic capacitors or adding any additional components to the circuit. The core idea of using a small film capacitor to handle power mismatch is to regulate the link capacitor voltage to have a large double-frequency ripple (swinging bus). The large ripple does not affect the input DC or output AC currents/voltages. This large ripple can reduce the required capacitance and, thus, allow using more reliable film capacitors instead of electrolytic capacitors. In addition, the proposed inverter has the ability of injecting reactive power into the utility for grid support, as required by new released grid codes. Simulation results under unity and non-unity power factors are provided to validate the proposed inverter operation.