A comparison study between series resonant and zero-voltage-resonant-transition DC-DC converters

Modular power conditioning systems, where each PV module has its own power converter, have been proven to yield higher output power due to their superior maximum power point tracking capabilities. In PV strings the typical operating voltages pose reasonable electrical safety problems that can be overcome in conventional modules. For certain cell constructions, such as thin film arrays deposited onto roofing sheets, it is not possible to obtain sufficient galvanic isolation. Some cells, such as the back contact cells, suffer from surface charge accumulation or polarisation effects that require isolation. This paper presents a comparative loss analysis between zero-voltage-resonant-transition half bridge converter and series resonant converter as module isolation converters. Detailed analysis of the operation of these two converters is discussed. Two hardware prototypes of 300W have been made whose efficiency is of 90% for series resonant converter and 88% for zero voltage resonant transition converter.