Solar photovoltaic array based brushless DC motor for fans in Indian railways using maximum power point tracking algorithm

Nonconventional sources of energy are gaining attention on account of dwindling fossil fuels. Using solar energy in coordination with conventional sources of energy will be more promising. Solar power can be used to supply brushless DC (BLDC) fans in coaches of Indian railways traction system. These solar panels are installed on the rooftop of the coaches. These fans are supplied from 110V DC and their operating voltage is from 90V to 140V. There are 27 BLDC motor fans installed in each coach. To supply this amount of fans in aforementioned voltage range, a system is designed using solar energy and 25kV AC traction supply. From solar energy, this proposed system extracts maximum power possible and supplies fans at 110V under average solar irradiation of 5.21kWh/m2/day. When solar irradiation falls below a limit and surrounding temperature rises above a limit then system starts getting power from 25kV AC traction supply and feeds the fans through voltage source inverter after converting it to 110V DC. As power output from solar panels reach required value in defined voltage range, system switches back to solar energy. An algorithm named select-input is devised in this paper which decides the input of the BLDC fans. To obtain the required voltage and power from solar panels, maximum power point tracking (MPPT) algorithm is used with buck-boost DC-DC converter. Proposed system has two modes of operation. In one case motor is supplied by solar energy and in other one motor is supplied by 25kV AC supply. This method can save average of 7.78kWh of energy everyday from each coach of each train which shows the immense potential of proposed system. The proposed system is simulated in Matlab/Simulink and results are presented.