Battery-supplied transformerless ballast for DC high intensity discharge (HID) lamps

A battery-supplied, DC-HID lamp ballast, inspired on the Loss Free Resistor (LFR) concept is presented here. It consists of two stages. The first one, a boost converter, behaves like a constant power source. The second one, a switched capacitor boost converter is the ignitor circuit. The cascade connection of both converters results in a transformerless ballast able to reach a voltage of 6 kV from 12 V batteries. Among the ballast advantages we find: no light flickering, warm-up time reduction, no aging effects on lamp power, easy dimming control, and absence of acoustic resonance (AR) problems. The proposed system is compared with other existing solutions in the literature. After, the ballast dynamics, at both operation modes, is analyzed and simulated. The results achieved with one DC-HID lamp of 250 W demonstrate experimentally the feasibility of the proposed approach, where extreme voltage gains are achieved without a transformer. Besides of the expected functions of ignition and steady-state operation, the proposed circuit also includes other usual ballast features as diverse protections.