A protection scheme for a switched-mode power converter

摘要

The collector voltage of the main transistor switch 262 in a resonant discontinuous forward convener is monitored. The conduction period of the switch is ended early if the collector voltage exceeds a limit. The controller also uses the sensed collector voltage to control the degree of saturation of the main transistor switch, thereby reducing turn-off time and switching losses. The protection scheme allows the transistor to be protected, and converter output power to be limited, if the saturation control loop fails to restrain a rise in collector voltage despite increased base or gate drive.