Abstract
Partial shading often appears on photovoltaic (PV) strings installed in small space probes, such as moon exploration rovers, due to their body structures, reducing the power yield of PV strings. Such partial shading issues can be precluded by differential power processing (DPP) converters. However, in addition to a main dc-dc converter, a DPP converter is required, increasing the system complexity and cost. In this paper, several kinds of integrated pulse width modulation (PWM) converters that can reduce the system complexity thanks to the integration are reviewed and are quantitatively compared in terms of the switch and magnetic component counts, and voltage conversion ratio. Based on the comparison and consideration from the perspectives of reliability, circuit volume, and voltage conversion requirement, a single-switch single-magnetic integrated PWM converter with a resonant voltage multiplier (RVM) was selected as the best suitable topology for small exploration rovers. Furthermore, the improved version with a non-resonant voltage multiplier (NRVM) was also proposed to achieve further circuit miniaturization and improved reliability. The experimental verification tests using the proposed integrated PWM converter were performed emulating a partial-shading condition. The maximum power yield from the PV modules was improved by 11.1% thanks to the DPP function of the proposed integrated converter.