Electrical engineering

Aerospace engineering

Single stage

Solar micro-inverter

Inverter

Engineering

Voltage

Artificial intelligence

Control (management)

Electronic engineering

Single phase

Computer science

Photovoltaic system

Maximum power point tracking

Control theory (sociology)

IEEE Transactions on Power Electronics

Due to the inherent double-frequency (2f0) ripple in single-stage single-phase photovoltaic (PV) grid-connected inverters, the maximum power point tracking (MPPT) will inevitably be affected. To improve the MPPT performances, a passive LC power decoupling circuit with a robust second-order sliding mode control (SOSMC) is thus proposed in this paper. With the passive LC decoupling path, the double-frequency pulsation on the dc-link is effectively cancelled out. Thus, the MPPT accuracy is significantly enhanced and the utilization of a small dc-link capacitor becomes possible. However, resonance between the LC circuit and the main dc-link capacitor may appear, which can be damped through an active damping method. Additionally, the proposed SOSMC ensures good steady-state, dynamic performance (voltage fluctuation and settling time) and the robustness of the dc-link voltage, which is also beneficial to MPPT control in terms of high accuracy and fast dynamics. The systematic design of SOSMC is presented and a detailed parameter optimization design of LC decoupling circuit is discussed. Experimental tests are performed on a 2.5-kW single-stage single-phase grid-connected inverter, and the results validate the effectiveness of the proposed strategy.

Optimization Design and Control of Single-Stage Single-Phase PV Inverters for MPPT Improvement