Multi-resonant soft switching snubber network for DC-to-DC converter

Claim 1

A family of switching type DC-to-DC converters for converting voltage from an input DC voltage source to an output DC voltage for delivery electrical energy to an output load, said converters comprising: an input adapted to receive electrical energy from said input DC voltage source; an output adapted to deliver electrical energy to said output load; an energy storage inductor adapted to store energy from said input DC voltage source and deliver said energy to said output load; a controlled power switching means periodically biased conducting for connecting said energy storage inductor to said input DC voltage source; a power rectifier biased conducting for connecting said energy storage inductor to said output load during intervals when said controlled power switching means is biased non-conducting; an output filter capacitor adapted to be connected to said output load to absorb an AC component of the output current; an active snubber network connected across said controlled power switching means; said active snubber network including a first resonant capacitor, a body diode, a resonant inductor; a controlled auxiliary switching means, a first diode, a second resonant capacitor and a second diode; said first resonant capacitor connected across said controlled power switching means; said body diode connected across said controlled power switching means to provide a reverse current path thereacross; said resonant inductor connected in series with said controlled auxiliary switching means and coupled across said first resonant capacitor; said controlled auxiliary switching means biased conducting at zero current to provide resonant discharge of said first resonant capacitor prior to said controlled power switching means being biased conducting, therefore facilitating its zero-voltage turn-on; said first diode connected in series with said second resonant capacitor and coupled across said resonant inductor to clamp the voltage across said controlled auxiliary switching means at zero and facilitate its lossless turn-off; said second resonant capacitor adapted to absorb the resonant energy stored in said resonant inductor; said second diode connected in series with said second resonant capacitor and adapted to limit the voltage across said second resonant capacitor during its resonant charging; said second diode adapted to provide a discharge path for said second resonant capacitor when said controlled power switching means is biased non-conducting and to facilitate its lossless zero-voltage turn-off.

Claim 16

A method of converting a DC input into a DC output voltage in a family of switching type DC-to-DC converters comprising an energy storage inductor; a controlled power switching means for connecting said energy storage inductor to said input DC voltage; a power rectifier for connecting said energy storage inductor to an output load; an output filter capacitor connected to said output load to absorb an AC component of the output current; an active snubber network connected across said controlled power switching means; said active snubber network including a first resonant capacitor, a body diode, a resonant inductor; a controlled auxiliary switching means, a first diode, a second resonant capacitor and a second diode; said first resonant capacitor connected across said controlled power switching means; said body diode connected across said controlled power switching means to provide a reverse current path thereacross; said resonant inductor connected in series with said controlled auxiliary switching means and coupled across said first resonant capacitor; said first diode connected in series with said second resonant capacitor and coupled across said resonant inductor; second diode connected in series with said second resonant capacitor and adapted to limit the voltage across second resonant capacitor during its resonant charging; said second diode adapted to provide a discharge path for said second resonant capacitor; said method comprising the steps of: (a) zero-current switching on said auxiliary switching means while said controlled power switching means is off, thus causing said first resonant capacitor to discharge into said resonant inductor, facilitating soft reverse recovery of said power rectifier and providing zero-voltage condition across said controlled power switching means; (b) zero-voltage switching on said controlled power switching means; (c) zero-voltage switching off said auxiliary switching means, thus causing said resonant inductor to discharge into said second resonant capacitor until said second diode is biased conducting; (d) resetting the current in said resonant inductor to zero; (e) charging said energy storage inductor from said input DC voltage via said controlled power switching means; (f) zero-voltage switching off said controlled power switching means; (g) linear discharging said second resonant capacitor via said second diode and charging said first resonant capacitor; (h) forward biasing said power rectifier for discharging said energy storage inductor into said output load.

Claim 17

A method of converting a DC input into a DC output voltage in a family of switching type DC-to-DC converters comprising an energy storage inductor; a controlled power switching means for connecting said energy storage inductor to said input DC voltage; a power rectifier for connecting said energy storage inductor to an output load; an output filter capacitor connected to said output load to absorb an AC component of the output current; an active snubber network connected across said controlled power switching means; said active snubber network including a first resonant capacitor, a body diode, a resonant inductor; a controlled auxiliary switching means, a first diode, a second resonant capacitor and a second diode; said first resonant capacitor connected across said controlled power switching means; said body diode connected across said controlled power switching means to provide a reverse current path thereacross; said resonant inductor connected in series with said controlled auxiliary switching means and coupled across said first resonant capacitor; said first diode connected in series with said second resonant capacitor and coupled across said resonant inductor; second diode connected in series with said second resonant capacitor and adapted to limit the voltage across second resonant capacitor during its resonant charging; said second diode adapted to provide a discharge path for said second resonant capacitor; said method comprising the steps of: (a) zero-current switching on said auxiliary switching means while said controlled power switching means is off, thus causing said first resonant capacitor to discharge into said resonant inductor, facilitating soft reverse recovery of said power rectifier and providing zero-voltage condition across said controlled power switching means; (b) zero-voltage switching on said controlled power switching means; (c) zero-voltage switching off said auxiliary switching means, thus causing said resonant inductor to discharge into said second resonant capacitor until said second diode is biased conducting; (d) resetting the current in said resonant inductor to zero; (e) charging said energy storage inductor from said input DC voltage via said controlled power switching means; (f) zero-voltage switching off said controlled power switching means; (g) linear discharging said second resonant capacitor via said second diode and charging said first resonant capacitor; (h) forward biasing said power rectifier for discharging said energy storage inductor into said output load.

Claim 21

A method of providing lossless zero voltage switching of a controlled solid-state switching device by utilizing a multi-resonant active snubber network connected across said controlled solid-state switching device; said multi-resonant active snubber network including a first resonant capacitor, a body diode, a resonant inductor; a controlled auxiliary switching means, a first diode, a second resonant capacitor and a second diode; said first resonant capacitor connected across said controlled solid-state switching device; said body diode connected across said controlled solid-state switching device to provide a reverse current path thereacross; said resonant inductor connected in series with said controlled auxiliary switching means and coupled across said first resonant capacitor; said first diode connected in series with said second resonant capacitor and coupled across said resonant inductor; second diode connected in series with said second resonant capacitor and adapted to limit the voltage across second resonant capacitor during its resonant charging; said second diode adapted to provide a discharge path for said second resonant capacitor into an external DC voltage source; said external DC voltage source adapted to be referenced to one of the terminals of said controlled solid-state switching device; said method comprising the steps of: (a) zero-current switching on said auxiliary switching means while said controlled solid-state switching device is off, thus causing said first resonant capacitor to discharge into said resonant inductor providing zero-voltage condition across said controlled solid-state switching device; (b) zero-voltage switching on said controlled solid-state switching device; (c) zero-voltage switching off said auxiliary switching means, thus causing said resonant inductor to discharge into said second resonant capacitor until said second diode is biased conducting; (d) resetting the current in said resonant inductor to zero; (e) zero-voltage switching off said controlled solid-state switching device; (f) linear discharging said second resonant capacitor via said second diode into said external DC voltage source and charging said first resonant capacitor.

Claim 22

A method of providing lossless zero voltage switching of a controlled solid-state switching device by utilizing a multi-resonant active snubber network connected across said controlled solid-state switching device; said multi-resonant active snubber network including a first resonant capacitor, a body diode, a resonant inductor; a controlled auxiliary switching means, a first diode, a second resonant capacitor and a second diode; said first resonant capacitor connected across said controlled solid-state switching device; said body diode connected across said controlled solid-state switching device to provide a reverse current path thereacross; said resonant inductor connected in series with said controlled auxiliary switching means and coupled across said first resonant capacitor; said first diode connected in series with said second resonant capacitor and coupled across said resonant inductor; second diode connected in series with said second resonant capacitor and adapted to limit the voltage across second resonant capacitor during its resonant charging; said second diode adapted to provide a discharge path for said second resonant capacitor into an external DC voltage source; said external DC voltage source adapted to be referenced to one of the terminals of said controlled solid-state switching device; said method comprising the steps of: (a) zero-current switching on said auxiliary switching means while said controlled solid-state switching device is off, thus causing said first resonant capacitor to discharge into said resonant inductor providing zero-voltage condition across said controlled solid-state switching device; (b) zero-voltage switching on said controlled solid-state switching device; (c) zero-voltage switching off said auxiliary switching means, thus causing said resonant inductor to discharge into said second resonant capacitor until said second diode is biased conducting; (d) resetting the current in said resonant inductor to zero; (e) zero-voltage switching off said controlled solid-state switching device; (f) linear discharging said second resonant capacitor via said second diode into said external DC voltage source and charging said first resonant capacitor.