A DC/DC power converter suitable for high power applications has an input converter which converts the DC input voltage to an AC voltage and supplies this voltage to a transformer. The output of the transformer is provided to an output converter which converts the AC to a DC output voltage at a controlled level to a load. Both the input and output converters are composed of active gate controlled switching devices and are switched in a soft-switched manner to minimize switching losses and increase switching frequency. The converters can be implemented in single phase or polyphase configurations and can be controlled to closely maintain the output voltage provided to the load at a desired level.

Power conversion apparatus for DC/DC conversion using dual active bridges

A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times of the controlled rectifiers. The control inputs to the controlled rectifiers are cross-coupled from opposite secondary transformer windings.

High efficiency power converter

A multi-resonant-switching network that operates under switching conditions that are favorable to both the active switch and the diode that constitute the switch. In a zero-current multi-resonant switch, the resonant circuit is formed in a T-network with resonant inductors in series with the switching devices. In a zero-voltage multi-resonant switch, the resonant circuit is formed in a π-network with resonant capacitors connected in parallel with the switch. In this way, the two networks are dual. During operation of a multi-resonant converter, a multi-resonant switches forms three different resonant circuits depending on whether the active switch and diode are open or closed. This results in operation of the converter with three different resonant stages in one cycle of operation. In practicing the present invention, certain rules are applied to derive a ZVS-MRC from a PWM converter. In particular, one resonant capacitor is placed in parallel with the active switch, which may be either uni-directional or bi-directional, another resonant capacitor is placed in parallel with the rectifying diode, and an inductor is inserted in the loop containing the switch and the diode. This loop can also contain voltage sources and filter or blocking capacitors. Improvement in the operation of ZVS-MRCs is obtained with synchronous rectification which is achieved by replacing rectifying diodes in a DC/DC converter with active devices, called synchronous rectifiers.

Zero-voltage-switched multi-resonant converters including the buck and forward type

A full bridge switching power converter employs zero-voltage, resonant-transition (ZVRT) switching techniques which appreciably reduces the switching losses at high switching frequencies, (for example, 1 MHz and above), using constant frequency, pulse-width-modulation techniques. The converter is implemented using a transfer with four switching FET's coupled to the primary of the transformer and four switching FET's coupled to the output of the transformer and a control unit that supplies the constant waveforms necessary to achieve synchronization and timing required to achieve the ZVRT switching.

Full bridge power converter with multiple zero voltage resonant transition switching

A synchronous rectifier is able to operate at higher frequencies and provides an output having lower noise than prior art FET synchronous rectifier system by using field effect switching devices which contain only one conductivity type of semiconductor material and connecting a high speed, low charge storage diode in parallel. Schottky diodes are preferred whereby there is no junction diode in the structure. Conventional FETs may be used when paralleled with a Schottky diode which prevents the FET's parasitic internal diode from becoming conductive.

Low noise, high frequency synchronous rectifier

A power converter which supplies AC or positive or negative DC output voltage with positive or negative current while isolating the output voltage from the input power source This converter includes a pulse width modulator converts power amplitude signals to pulses of proportionate width A power driver circuit applies these pulses to a sychronous demodulator and low pass filter via a pulse transformer A low output impedance is presented to all output disturbances such that the converter can source or sink current in true four quadrant operation, including the passing of power from output to input when a load voltage exceeds the intended supply voltage

James S. Butcher

Papers

Bi-lateral four quadrant power converter