Patent ID: 7746671
Filing Date: 2010-06-29
Classification: H02M,Y02B

Abstract:
1. A control circuit for a switch unit of a clocked power supply circuit, the switch unit being designed to effect input-side excitation of a resonant transformer arrangement, the control circuit comprising: an input for receiving an auxiliary signal from the resonant transformer arrangement, the auxiliary signal exhibiting an essentially fixed phase relation to a load alternating current flowing through a resonant circuit of the transformer arrangement; a phase detector designed to detect reference crossing moments when the auxiliary signal crosses a predefined reference value; a driver controllable to switch the switch unit; a synchronizer designed to synchronize a turn-on of the switch unit by the driver with regard to a phase position with the auxiliary signal so as to achieve a turn-on of the switch unit within a predetermined time interval around a zero crossing of a voltage present across the switch unit, or of a current flowing through the switch unit, the synchronizer being designed to receive information about the reference crossing moments from the phase detector, and to provide a turn-on signal to the driver with a fixed phase delay at the reference crossing moments, so as to define turn-on moments at which the driver is to turn on the switch unit; a detector designed to determine an amplitude information which depends on an amplitude or a mean value of the auxiliary signal; and a regulator designed to change an operating frequency in dependence on the amplitude information supplied by the detector, and to determine a period duration between turn-off moments at which the driver is to turn off the switch unit as a reciprocal of the operating frequency.