Current sharing for multichannel solar power system with maximum power point tracking

In an effort to maximize its reliability and life expectancy, an output current-sharing scheme is applied to a modular solar-powered DC power system. The proposed scheme fits into the digital controller already in place for use in maximum power point tracking (MPPT), and requires minimal hardware modifications. The digital nature of the scheme provides enough flexibility to accommodate the transition of channels with limited power resources into MPPT mode. A controller area network is setup to form a noise-immune digital current-sharing bus that naturally allows the system to overcome different challenges introduced by the existing analog current-sharing bus schemes. Theoretical analysis predicts the preservation of closed-loop system performance for scalable power systems. A four-channel prototype was constructed and tested to validate the control scheme under different insolation levels and loading conditions.