Regulated self-oscillating resonant converter with current feedback
 Lamp voltage or current obtained from a self-oscillating converter is stabilized by a feedback circuit. Gates of the switching transistors are connected to output windings of a current transformer whose input current winding is in series with the resonant load lamp circuit. The lamp voltage or current is sensed, and the resulting signal is used to control current through an auxiliary control winding on the current transformer. Preferably, two opposite conductivity type control transistors are connected in parallel across the control winding, and low-pass filtered DC signals corresponding to the lamp voltage or current bias the control transistors. 
Philips Electronics North America Corporation
H Y H
H05B Y02B H05B
inventional additional inventional
Chin
Chang