.70 The W Metal Halide Single-stage Low-frequency Square Wave Electronic Ballasts And Its Stability Study

As development of Green Lighting Project, the high intensity discharge (HID) lamp is drawing close attention due to its energy saving and high lighting efficiency. Therefore the development of the drive circuit of the lamp, namely ballast has become an important research topic. Because of excellence in energy saving, light weight, etc., electronic ballast will gradually take over the traditional electromagnetic (EM) ballast.A series of latest developments of electronic ballast are discussed in the thesis based on the detail design of a novel single-stage low-frequency square-wave electronic ballast for a 70 W HID lamps.At the beginning of the thesis, characteristics of HID lamps, especially of metal halide (MH) lamps, are introduced. The operation principles and developments of electronic ballast are also presented.The low-frequency square-wave solution is considered the most practical and effective to eliminate acoustic resonance, and is accepted widely. Chapter 2 proposed a novel single-stage low-frequency square-wave electronic ballast for low-wattage HID lamps, detailed design are introduced. Some experimental results obtained from a laboratory prototype for a 70W metal halide lamp verifies its feasibility.Due to the negative impedance characteristic of HID lamps, a ballast, which is a device to control or limit the current of the lamp, should be used. In order to understand the lamp's negative incremental impedance of characteristics and analyze the stability of Ballast/Lamp system clearly, the low-frequency square-wave ballast system stability with closed loop are analyzed in detail based on the HID lamp frequency-domain model in Chapter 3.