A sinusoidal pulse width modulated inverter using three-winding high-frequency flyback transformer for PV power conditioner

This paper presents a novel prototype of the utility-interfacing sinusoidal pulse width modulation (SPWM) inverter using the high-frequency flyback transformer for the small-scale solar photovoltaic power conditioner (1 kW - 4 kW). The proposed SPWM power conditioner circuit with a high-frequency link has a function of electrical isolation, which is vital for PV power conditioner systems with the viewpoint of safety, noise requirement and convenience. The discontinuous conduction mode (DCM) operation of the flyback transformer link pulse modulation is also introduced to establish a simple topology of the inverter circuit and control scheme. The proposed PV power conditioner operates with ZVS when it turns off the primary-side switches by the high-frequency switching. This reduces the power losses of the semi-conductor device switchings and improves the power conversion efficiency of the total system as PV power processor. The operating principle of the proposed circuit is described for the understanding of the circuit parameters establishment. Then, the digital control scheme is demonstrated herein. The proposed power conditioner is verified on the basis of the computer simulations and experiments. The experimented results show the validity of the proposed power conditioner to have high power conversion efficiency and low harmonic distortions.