SiC-Based Bidirectional Cuk Converter With Differential Power Processing and MPPT for a Solar Powered Aircraft

A silicon-carbide (SiC)-based dc-dc converter is developed for the solarship, a manned solar aircraft for supply delivery in remote locations. The concept of differential power processing (DPP) is utilized to realize a high-efficiency lightweight converter that performs maximum power point tracking (MPPT) to transfer power from the aircraft's wing-mounted solar array to the high-voltage lithium-battery bus. The isolated Cuk topology is augmented with an unfolder to achieve four quadrant operation and minimize the worst-case processed power. A small-signal model is derived for control design, and it is shown that the compensation strategy differs significantly based on the operating mode. The 2.7-kW prototype is verified at a high frequency (200 kHz), high efficiency (> 98%), small mass (0.604 kg), and uses no electrolytic capacitors. MPPT operation is verified on a 376-V commercial solar installation. The DPP Cuk converter is promising for emerging solar aerospace applications.