SEPIC Converter for Solar PV Array Fed Battery Charging in DC Homes

This paper presents a solar photovoltaic (PV) array fed single-ended primary inductance converter (SEPIC) for solar PV-battery charging used in DC homes. The SEPIC converter acts as an interfacing stage between the solar panel and a battery. It has mainly two functions, the first one is to optimize the solar power under all insolation levels, and another is regulating the output voltage in both boost and buck modes. The unique features of SEPIC converter like non-inverting output, a wide range of input voltage, continuous input current, and grounded switch drive circuit, make this system reliable and efficient. The photovoltaic array electrolytic capacitor size is also minimized using an input inductor. Besides, the output diode limits the flow of reverse current and the system does not need any diode at the input side. A fine adjustment in step size of the Maximum Power Point Tracking (MPPT) technique avoids any transient and inrush current in the battery. A simple Incremental Conductance (InC) MPPT technique is utilized for maximizing the PV array power. A prototype of 220 W power capacity is developed in which a 48 V Li-ion battery is used. The effectiveness of the present system is through experimental results obtained on a developed prototype.