An apparatus for increasing efficiency and reducing heat dissipation in power converters is disclosed. Zero-voltage-switching (ZVS) can reduce switching loss of power converters but it often results in a very complicated design and only works well under constant output current. In order to allow the ZVS to work over a wide loading range, the transformer secondary current is blocked when the primary starts to resonate. Hence, the resonant voltage waveform across the switch will not change even when the loading current is changing. Such a resonant voltage waveform is obtained with the aid of the transformer primary inductance and capacitor(s). Also provided is a novel driving circuit which controls the switching. Alternatives and variations of this apparatus can be made to satisfy different applications such as power conversion and power inversion. The subject power converter significantly lowers the heat loss and achieves higher efficiency for very wide loading ranges.
A discontinuous resonant forward power converter including a controller having an output coupled to a controllable switch and which is configured to control the switch such that a voltage waveform on a secondary winding of a transformer of the converter has a first portion during which the switch is on and current flows into an output node of the converter which is coupled to the output rectifier and to a smoothing capacitor, and which has a second substantially resonant portion during which the switch and an output rectifier are both off. Substantially no current flows into the output node during the second portion of said voltage waveform.
An electrical switching device having a plurality of parallel coupled IGBTs is provided. The electrical switching device balances electrical currents in each of the IGBTs that are supplied to a load.
A high efficiency photovoltaic DC-DC converter achieves solar power conversion from high voltage, highly varying photovoltaic power sources to harvest maximum power from a solar source or strings of panels for DC or AC use, perhaps for transfer to a power grid at high power levels with coordinated control possible for various elements. Photovoltaic DC-DC converters can achieve efficiencies in conversion that are extraordinarily high compared to traditional through substantially power isomorphic photovoltaic DC-DC power conversion capability that can achieve 97%, 98%, 99.2% efficiency, or even only wire transmission losses. Switchmode impedance or voltage conversion circuit embodiments may have pairs of photovoltaic power interrupt switch elements and pairs of photovoltaic power shunt switch elements to first increase voltage and then decrease voltage as part of the desired photovoltaic DC-DC power conversion.
