The Controlling Strategy for Electronic Ballast of HID Lamps

Based on the electric characteristics of HID (high-intensity-discharge) lamps, novel control strategy and implement method for electronic ballasts of HID lamps have been investigated in this paper. The main contributions are as the followings: (1) to ensure to ignite the HID lamps safely, the auto-tracking technique, which can offer proper igniting voltage, has been put forward, (2) to make sure to warm up the HID lamps safely, the start control regulation has been proposed, and the principle of this strategy is that the maximum current must be limited in the start moment, once the lamp starts conducting, the current through lamp should be exponential or approximatively exponential to decrease, and dissipation power should be increased as time is increasing, (3) in steady stage, HID lamps should operate in constant power state. Maintaining the product of the voltage and current of the lamp tracking to equal the rating power, a constant-power-control technique, which takes the current as the main regulation variable, has been proposed in this stage