Design of Bipolar Interface Converter for Purely DC Microgrid with Minimally Processed Maximum Power Point Operation of Photovoltaics

Bipolar microgrids are important candidates for the design of upcoming purely DC or islanded systems due to the extra resiliency offered by the multi-bus (±190V) system. However, unbalanced loads may be connected to the bipolar buses which makes voltage control for power balance essential for the converter. Dual secondary winding based Dual Active Bridge converter, with output series connection, offers a viable solution due to its inherent galvanic isolation between the source and the loads. To harvest the maximal energy from a series connection of photovoltaics (PV) it is important to continuously operate the system at the maximal power point (MPPT). To ensure low losses and higher energy yield over time, differential power processing based converters can be integrated to the PV modules such that minimum power is processed to achieve MPPT. This work provides a solution for interfacing the unipolar power source to a bipolar load bus, to which loads of two different voltage requirement (±190V or +380V) can be connected by incorporating voltage control in the same converter that interface unipolar voltage bus to bipolar bus.