DC-link voltage control of a single-phase photovoltaic inverter

This paper investigates DC-link voltage control in a single- phase photovoltaic (PV) inverter. Recent research has shown that a right-half-plane (RHP) zero exists in the output current control dynamics of a voltage source inverter (VSI) and that the sign of current control loop changes when the VSI is fed from a current source, such as PV generator. Accordingly, VSI with a high-bandwidth current control becomes unstable in such a case without input-voltage control. The use of conventional cascaded control scheme transforms the RHP zero into a RHP pole in the input-voltage control dynamics. Based on this observation, design rules can be determined regarding the dc-link voltage control and input capacitor selection.