PV Fed high efficiency, high voltage gain DC-DC converter for micro-inverter applications

Abstract

The PV fed grid connected systems have become highly relevant due to the escalating global power demand and to reduce the greenhouse effect and environmental pollution. It is desirable to use low voltage PV modules as source due to safety aspects (to prevent DC arcing) and for optimal utilization of the PV source (Distributed maximum power point tracking). If a low voltage source is used, however, a high gain, high efficiency power conversion stage is required to feed the dc-ac stage used to interface with the AC grid. Such systems, referred to as micro-inverters or module integrated inverters, have become quite popular in recent times. This paper presents a high voltage gain, high efficiency dc-dc converter suitable for micro-inverter application is proposed in this paper. The proposed converter has reduced reverse recovery and switching losses. A passive clamp circuit is used to recycle energy stored in the leakage inductor and reduce the voltage stress across the main switch. The low voltage rating switch has lower on state resistance, which reduces switch conduction loss. The reduced switching losses help to increase converter efficiency. One coupled inductor and two intermediate capacitors are used to increase the output voltage. All the analytical and simulation results pertaining to the proposed topology are included.