A novel method for collective dimming of high intensity discharge lamps

High intensity discharge (HID) lamps take up a large percentage of the power consumption in the lighting. It is common to operate the HID lamps in 100% lighting state due to the difficulty of dimming control. This paper proposes a simple dimming method for them and manages to dim the lamp group collectively. A frequency control device is inserted between the power supply and the HID magnetic ballast. Because of the use of inductor in the magnetic ballast, its impedance increases with the frequency. Therefore, by changing the output frequency, the current flowing through HID lamps can be decreased/increased with the voltage being kept constant. Also, the generated waveforms of the frequency control device is discussed in this paper. Both simulation and experimental results are given to prove the dimming effect.