Patent Number:
6,429,604
Title:
Power feedback power factor correction scheme for multiple lamp operation
Abstract:
A ballast circuit for a single or multiple lamp parallel operation where at each lamp a condition may be controlled such that the amplitude of a resonant inductor current and an output voltage are almost constant in the steady state. The circuit consists of a half-bridge of a DC storage capacitor, a DC blocking capacitor, power transistors which alternately switch on and off and have a 50% duty ratio, and an LLC resonant converter having a resonant inductor and one or more resonant capacitors. The circuit also includes an output transformer providing galvanic isolation for a double path type power feedback scheme. The output transformer produces magnetizing inductance utilized for power feedback circuit optimization and is connected right after the resonant inductor of the half-bridge circuit.
Inventors:
Chang; Chin (Yorktown Heights, NY)
Assignee:
Koninklijke Philips Electronics N.V.
International Classification:
H05B 41/282 (20060101); H05B 41/28 (20060101); H05B 037/00 ()
Expiration Date:
08/06/2019