Sliding mode control of a single phase transformer-less PV inverter with active power decoupling

This paper proposes a fixed frequency based sliding mode (SM) controller for transformer-less single phase inverter for photovoltaic (PV) application with active power decoupling minimizing the capacitance requirement. Unlike conventional power decoupling techniques in full bridge converters, the proposed technique incorporates a large sinusoidal swing of the half-bridge capacitor voltages and a limited ripple on the DC-link to address the power decoupling. This invokes coupling and complexity in the system making the control of the converter a challenging task. SM control technique is used to provide a robust and stable controller platform for this converter. Extensive simulation results are provided for verification of the SM controller performance and to support the mathematical formulation of the fixed frequency based non-linear sliding mode control for this converter in standalone operation mode.