A compact switched capacitor dc-dc converter based Global Peak Power Point tracker for partially shaded PV arrays of portable equipment

Under uniform insolation there is only one Maximum Power Point (MPP) for the PV array. However, when the array is partially shaded, the power-voltage (P-V) characteristics get more complex, displaying multiple peaks, only one of which called the Global Peak Power Point (GP3) corresponds to the MPP. The rest being local peaks, correspond to lower power. It is very essential, especially in portable systems, to track the MPP and extract maximum power from the array so as to minimize the overall size of the system. Hitherto, conventional dc-dc converters have been used as MPP trackers. This paper proposes a Pulse Width Modulated Switched Capacitor (SC) dc-dc converter based MPP tracker that tracks the peak power point under normal insolation and under partially shaded conditions. There is provision to reconfigure the SC converter configuration to maximize the efficiency even with large input-output voltage differentials. An algorithm is executed to track the GP3 during partial shading. A 10W SC based MPP tracker, weighing less than 50g, for charging a battery is implemented and the details are presented. The size and weight advantages of the SC based MPP tracker makes it ideal for use in portable systems.