Single Ended Primary Inductor Converter reliance of efficiency on switching frequency for use in MPPT application

This paper discusses the dependence of efficiency on the switching frequency of a Single Ended Primary Inductor Converter (SEPIC), for use in photovoltaic (PV) maximum power point tracking (MPPT) applications. An MPPT system comprises of a DC/DC converter and tracking algorithm set to run the PV at its maximum power point. The SEPIC is a non-inverting DC/DC converter able to output a voltage greater or less than the input voltage. In this paper we analyse the theoretical losses of the SEPIC and compare them with the practical losses measured at various switching frequency. The results show that the switching frequency of the device determines its physical size, cost and efficiency. The frequencies tested in this paper were 50Khz, 200kHz and 400kHz, with a 7% drop in efficiency between each frequency. As the switching frequency increases, the units become physically smaller and so cheaper. This however is at the cost of efficiency.