Fast Photovoltaic Array Reconfiguration for Partial Solar Powered Vehicles

This paper demonstrates that a partially solar powered EV can significantly save battery energy during cruising using innovative fast photovoltaic array (PV) reconfiguration. Use of all the vehicle surface areas, such as the hood, rooftop, door panels, quarter panels, etc., makes it possible to install more PV modules, but it also results in severe performance degradation due to inherent partial shading. This paper introduces fast online PV array reconfiguration and customization of the PV array installation according to the driving pattern and overcomes the partial shading phenomenon. We implement a high-speed, high-voltage PV reconfiguration switch network with IGBTs (insulated-gate bipolar transistors) and a controller. We derive the optimal reconfiguration period based on the solar irradiance/driving profiles using adaptive learning method, where the on/off delay of IGBT, CAN (control area network) delay, computation overhead, and energy overhead are taken into account. Experimental results show 25% more power generation from the PV array. This paper also introduces two important design-time optimization problems to achieve trade-off between performance and overhead. We derive the optimal PV reconfiguration granularity and partial PV array mounting by the car owner's driving pattern, which results in more than 20% PV cell cost reduction.