Frequency Modulation Design For Stage Lighting With High Intensity Discharge Lamps

Because of higher luminous efficacy, better color rendering and longer lifetime, operation ofhigh intensity discharge (HID) lamps at high frequency has been widely used in stage lighting.HID lamps work with ballasts due to the negative impedance characteristic, and electronicballasts of HID lamps have good dimming effects adapting to feature and requirement of stagelighting. However acoustic resonance (AR) occurs in HID lamps with high-frequency powersupply, which influences lighting effects and lamps’ lifetime. Therefore designing gooddimming and reliable suppression circuits is a hot and tough issue at present.Firstly, the operation principle and structure of HID lamps as well as electronic ballastsare introduced in this thesis. Then the control circuit of HID stage lighting is analyzed in detail.Meanwhile EMI filter circuit, rectifier circuit of full bridge, high-frequency inverter circuit,starting circuit, signal control circuit and power supply circuit are designed.Compared with common lighting, stage lighting has special requirements. It not only meetslighting effects, but also needs to change lighting effects based on basic elements such as storyplot, scene, character, and so on, to obtain wonderful visual effects for audiences. Moreover,dimming methods of frequency modulation and duty-cycle for stage lighting with HID lampsare analyzed theoretically and simulated based on dimming principle. And the dimmingcircuits are designed. The experimental results show HID stage lighting can be dimmedflexibly, and different visual effects are obtained.Finally, the AR mechanism is analyzed preliminarily and arc curves are acquired. The arcsare classified according to the degree of AR. The chaotic circuit of AR is designed by injectinglow-frequency signals into control circuit of HID ballast to spread spectrum of driving voltage,thus decreasing AR threshold value. So AR phenomenon is avoided. The AR suppressionexperiment also shows the circuit is simple and convenient, and effects of suppression are fine.