Differential power processing converter design for photovoltaic wearable applications

Traditional photovoltaic (PV) systems are stationary PV systems mounted in one location and, generally, receive consistent and even illumination across the PV panel. However PV cells can also be utilized in wearable applications, in which the PV cells are likely to experience uneven illumination. Under uneven illumination, traditional series-connected PV systems experience severely decreased output power and overall efficiency. The system output power can be increased by improving the power converter connection architecture and control method. To achieve optimal system efficiency, differential power processing (DPP) converters are adapted so that each PV cell can operate at its own maximum power point (MPP) even under uneven illumination. This paper introduces a PV power system with four DPP converters for a wearable application that allows the system to effectively utilize PV energy under even and uneven illumination conditions. The DPP converter design and control method are validated through simulation results, including dynamic illumination changes, and experimental results using a hardware prototype. Results show that each PV cell is controlled independently such that each PV cell operates at its own MPP under uneven illuminations.