Single-Switch Integrated DC/DC Converter for Photovoltaic-Battery-Powered Water Pumping System

Abstract

This paper proposes an single-switch DC/DC converter for photovoltaic (PV)-battery-powered water pump system. It is an integration of a classical buck converter and a switched-inductor buck-boost converter to share power switch. Stable operation region of solar cells is also studied when the front-end circuit is controlled with pulse-frequency-modulation (PFM) for battery voltage regulation (BVR). Based on this, the control strategy for the front-end circuit under PFM smoothly switching between maximum power point tracking (MPPT) mode and BVR mode is proposed. Then, inductance design criterion is given to ensure the PV-battery-power pump system work reliably throughout entire operation range. A 24W prototype is implemented to verify theoretical analysis. The investigation shows that the integrated converter has advantages of simple structure, wide voltage output range, high efficiency and reliability.