MHz operation of voltage-fed inverter for HID lamps using distributed constant line

A novel type of solid-state ballast, which operates on the MHz-range frequency, is presented in this paper. A circuit composed of a voltage-fed half-bridge inverter, a distributed constant line, and a parallel LC resonant circuit have been developed for this purpose. The HID (high intensity discharge) lamp is connected to the output terminal of the inverter through the distributed constant line. Here, since the length of the line is adjusted to 1/4 of the propagation wavelength /spl lambda/, the output voltage of the voltage-fed inverter can be converted to a current source in the load side. From experimental results, it was found that the ballast can supply not only high voltage but also constant current for starting the discharge of an HID lamp. Experimental results from a prototype system are used to verify the theoretical procedure.