A high-frequency electronic ballast for HID lamps based on aΛ/4-long distributed constant line

摘要

A novel type of solid-state ballast, which operates in thenmegahertz-range frequency, is presented in this paper. A circuitncomposed of a voltage-source half-bridge inverter, a distributednconstant line and a parallel LC resonant circuit has been developed fornthis purpose. The high-intensity discharge (HID) lamp is connected tonthe output terminal of the inverter through the distributed constantnline. Here, since the length of the line is adjusted to 1/4 of thenpropagation wavelength Λ (Λ/4 condition), the outputnvoltage of the voltage-source inverter can be converted to a currentnsource on the load side. Therefore, the ballast can supply not only highnvoltage to the HID lamp for initiating discharge, but also stablencurrent to it during discharge condition. The modification of thenproposed circuit is also proposed in order to expand the operatingnfrequency without increasing the undesirable harmonic current. Thenexperimental results from a prototype system verify the theoreticalnprocedure