Research On Automotive HID Electronic Ballast Based On Digital Platform

High-intensity discharge (HID) lamps are used more and more widely in the automotive headlight system. Compared with conventional halogen lamps, HID lamps have superior features as low power consumption, high luminous efficacy, good color rendering and long lamp life, which is more energy-efficient and environment-friendly. However, the characteristics of automotive HID lamps are very complex, each start-up stage has different V-I characteristics and different control requirements. Moreover, the characteristics are different between lamps and vary with the lamp aging. So, it is difficulty to design electronic ballast for automotive HID lamps.Chapterl introduces the system of automotive HID lamps in the first. And then reviews the development of light sources for automotive application, a brief comparison between halogen lamps and HID lamps are given in the review. In the last. it talks about some research directions about the electronic ballast for automotive HID lamps.Chapter2 is focus on the control strategy for automotive HID lamps, the start-up characters of automotive HID lamps is analyzed in the first. Include some issues about ignition successful rate, smooth transition and warm-up current. And then, it proposed two adaptive control strategies, multi-mode control strategy and single current control strategy.Chapter3 discusses the stability of automotive HID electronic ballast with digital platform. Modeling the small-signal model for the HID lamps and ballast in the first. and then the PI controller is designed.Chapter4 gives the design process for 35W automotive HID electronic ballast based on the control strategy and stability analysis. The design of hardware is focus on the main power stages, at the same time it analyzes the influence from output capacitance and ignition transformer inductor. The design of digital controller includes control flowchart, timing control and software. Experimental results have been carried out to verify all the functions of the design.Chapter5 discusses some new research directions about automotive headlamp system. The first direction is about the new application about automotive headlamp system on the electric vehicles. And the second direction is about the application of GaN power devices on the automotive HID electronic ballast.