FULL-BRIDGE INVERTER TYPE ELECTRONIC BALLAST FOR HIGH INTENSITY DISCHARGE LAMP

摘要

The present invention relates to an electronic ballast stabilizer for a high intensity discharge lamp which solves an unstable lighting problem capable of generating at initial lighting of a discharge lamp while simplifying a circuit by combining step-down buck converter and full-bridge inverter functions together. To this end, two switching elements among four switching elements of the full-bridge inverter have voltage applied to the discharge lamp to have an alternating form of a low frequency while operating at the low frequency. The other two switching elements among the four switching elements control the amount of current applied to the discharge lamp while operating at a high frequency. Also, if an interval which the inductor current is decreased exceeds a predetermined time, inductor current is rapidly reduced by turning off all switching elements in order to solve the problem of turning off the discharge lamp when the discharge lamp voltage is low when using a threshold conducting mode for a zero voltage switching.