A parallel type of HID-lamp electronic ballast

It has been for a long time that in commercial product, only was a series type of HID-lamp ballasts available. Although it has the merit of simple circuit configuration, there still exist limitations, such as high conduction loss on the secondary winding of the igniter transformer or requiring a two-stage ignitor design, high follow-up current flowing through the full-bridge switches, and requiring a sophisticated L-C filter located between the full-bridge inverter and the igniter winding. This paper presents a parallel type of electronic ballast for HID lamps, which can release the aforementioned limitations. Additionally, performance comparison between these two types of ballasts will be also presented. Experimental results measured from a prototype of 35 W Xenon-lamp ballast are used to verify the analysis and discussion.