Abstract: A resonant gate drive circuit for a power switching device, having a gate-emitter capacitance, is adapted for use with a high frequency power converter. The resonant gate drive circuit comprises a signal input source, a power supply and a resonant inductor. An electrical isolator is connected between the signal input source and a switching node. The electrical isolator is connected to the power supply. A first bidirectional switch is connected between the resonant inductor and the power switching device and includes a first switch control circuit connected to the node to be controlled by a signal from the signal input source. A second bidirectional switch is connected between the power supply and the power switching device and includes a second switch control circuit connected to the node to be controlled by the signal from the input source.

Abstract: A variable frequency drive comprises a diode rectifier receiving multiphase AC power from a source and converting the AC power to DC power. An inverter receives DC power and converts the DC power to AC power to drive a load. A link circuit is connected between the diode rectifier and the inverter and comprises a DC bus to provide a relatively fixed DC voltage for the inverter. A bus capacitor is across the bus. A soft charge circuit limits inrush current to the bus capacitor. The soft charge circuit comprises an inductor connected between the source and the link circuit and a switch circuit in the link circuit for selectively providing a semiconverter configuration or a full bridge converter configuration to provide two stage charging of the bus capacitor.

Abstract: A resonant gate drive circuit for a power switching device, having a gate-emitter capacitance, is adapted for use with a high frequency power converter. The resonant gate drive circuit comprises a signal input source, a power supply and a resonant inductor. An electrical isolator is connected between the signal input source and a switching node. The electrical isolator is connected to the power supply. A first bidirectional switch is connected between the resonant inductor and the power switching device and includes a first switch control circuit connected to the node to be controlled by a signal from the signal input source. A second bidirectional switch is connected between the power supply and the power switching device and includes a second switch control circuit connected to the node to be controlled by the signal from the input source.

Abstract: A variable frequency drive comprises a diode rectifier receiving multiphase AC power and converting the AC power to DC power. An inverter receives DC power and converts the DC power to AC power to drive a load. A link circuit is connected between the diode rectifier and the inverter and comprises a DC bus to provide a relatively fixed DC voltage for the inverter. A link capacitor is across the bus. A soft charge circuit limits in rush current to the link capacitor. The soft charge circuit comprises an inductor in the bus and a resistor assist circuit across the inductor along with an anti-parallel clamping thyristor reverse connected also across the inductor.

Abstract: A variable frequency drive comprises a diode rectifier receiving multiphase AC power from a source and converting the AC power to DC power. An inverter receives DC power and converts the DC power to AC power to drive a load. A link circuit is connected between the diode rectifier and the inverter and comprises a DC bus to provide a relatively fixed DC voltage for the inverter. A bus capacitor is across the bus. A soft charge circuit limits inrush current to the bus capacitor. The soft charge circuit comprises an inductor connected between the source and the link circuit and a switch circuit in the link circuit for selectively providing a semiconverter configuration or a full bridge converter configuration to provide two stage charging of the bus capacitor.

Abstract: A variable frequency drive comprises a diode rectifier receiving multiphase AC power and converting the AC power to DC power. An inverter receives DC power and converts the DC power to AC power to drive a load. A link circuit is connected between the diode rectifier and the inverter and comprises a DC bus to provide a relatively fixed DC voltage for the inverter. A link capacitor is across the bus. A soft charge circuit limits in rush current to the link capacitor. The soft charge circuit comprises an inductor in the bus and a resistor assist circuit across the inductor along with an anti-parallel clamping thyristor reverse connected also across the inductor.