HYBRID TRANSFORMER ZVS/ZCS DC–DC CONVERTER FOR PHOTOVOLTAIC MODULE APPLICATIONS
The presented converter
utilizes a hybrid transformer to incorporate the resonant operation mode into a
traditional high boost ratio active-clamp coupled-inductor pulse-width-modulation
dc– dc converter, achieving zero-voltage-switching (ZVS) turn-on of active
switches and zero-current-switching turn-off of diodes.
As a result of the
inductive and capacitive energy being transferred simultaneously within the
whole switching period, power device utilization (PDU) is improved and magnetic
utilization (MU) is optimized.
The improved PDU allows reduction of the silicon
area required to realize the power devices of the converter.
The optimized MU
reduces the dc-bias of magnetizing current in the magnetic core, leading to
smaller sized magnetics.
Since the magnetizing current has low dc-bias, the
ripple magnetizing current can be utilized to assist ZVS of main switch, while
maintaining low rootmean- square (RMS) conduction loss.
The voltage stresses on
the active switches and diodes are maintained at a low level and are
independent of the wide changing PV voltages as a result of the resonant
capacitor in series in the energy transfer loop.
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