An Investigation Of The Digital Control And A Novel Two-Stage Electronic Ballast For High Intensity Discharge Lamps

The High-Intensity-Discharge Lamps (HID), consisting of a broad range of gas discharge lamps, are notable for their high luminous effeciency, good color rendering and long life and hence are regard as the most ideal light source. As a result, the driver circuit of HID lamps, namely ballast, has become an important research point. Compare with tranditional electromagnetic ballast, electronic ballast has the advantage of energy saving, light weight etc. and have attracted more research forcus.With the characteristics of unparalleled flexibility and programmability, digital control shows many merits in various applications. It is drawing close attention due to its flexibility and realization of complex control mode in electronic ballast for HID lamps and has become another hotpoint in this direction.In the first Chapter, categories of HID lamps are given. And electronic characteristics and operation principles of HID lamps as well as several typical electronic ballast is presented. A simple model considering acoustic resonance effect of HID lamps is introduced, which is compatible with common simulation software.Chapter II presents the latest digital development in power electronics field, especially in lighting field, is introduced.In the Chapter III, a HID ballast with a digital controller is developed to demonstrate the feasibility of the digital control along with some key issues in digital controller selection and design. Digital control is implemented to keep the lamp power constant and offer a capability of dimming the lamp. Besides, a more reliable protect circuit is given. It is verified by experimental results.In the Chapter IV, mechanism and characteristics of acoustic resonance are investigated. A novel two-stage and acoustic resonance free electronic ballast providing line frequency lamp current is proposed with detail design procedure. Simulation and experimental results are given to verify its superiority. Key performances are compared between the proposed ballast and existing ballasts through experimental data.