Battery voltage regulator; Photovoltaic array; Analog positive feedback; Pulse width modulation; Maximum power point tracker; Battery cells; Charge equalisation; Electromotive force
This paper deals with loss of photovoltaic energy due to mismatch between PV array and
battery-bank, and difference in equalisation of charge between cells of battery-bank. These are the two major problems that affect the performance and life of PV system. From I - V characteristics of PV modules and the charging-discharging characteristic of the battery-bank it is shown that in contrary to general assumptions and practices the maximum power point tracker is still relevant, even for a PV system integrated with battery-bank. From charging and discharging cycles of the battery-bank, it was observed that there is a need of charge equalisation among different battery-cells. For overcoming the above limitations a battery voltage regulator (BVR) has been
designed to utilise the maximum available PV energy and also to provide charge equalisation to
different battery cells. This BVR is based on multiple output switch mode design. The control
function is based on analog positive feedback control for pulse width modulation. The BVR has
been fabricated and tested. The increase in utilisation of available solar power lies between 5% to 10%.