Voltage-fed half-bridge resonant converter for multiple lamp independent operation

In this paper, we explore the voltage-fed half-bridge LLC resonant converter for multiple lamp parallel independent operation (ILO). Based on the observation of almost invariant voltage gain relation with the resonant tank input impedance phase angle for different number of lamps, we propose the so-called phase-shift based control method. With this method, multiple lamp ILO is achieved under voltage-fed half-bridge LLC resonant converter with zero-voltage-switching (ZVS). Experimental results are presented for instant start 4-lamp TL70 F32T8.