Automotive high intensity discharge ballast

Abstract

A new ballast circuit for automotive high intensity discharge (HID) applications is disclosed. The ballast utilizes two DC/DC converters and two low frequency inverter switches. The ballast also includes an integrated high voltage ignition circuit. The positive DC/DC converter builds up a high ignition voltage in addition to raising the DC positive bus. When the lamp breaks down, the DC bus voltage decreases and the ignition circuit falls inactive. The DC/DC stages are then alternately conductive to supply power to the lamp via the low frequency inverter switches. The disclosed ballast reduces the number of switches used to four from a typical six, it utilizes independently controlled voltage sources, and provides a more efficient run-up voltage waveform during pre-steady state running of the lamp.

Dependencies are inferred from the claim text.