Because most of the car DC power supply, while the HID Lamps is needed is alternating current, so the need to provide a HID Ballast transformer action.

There are several components in the HID Ballast to form:
1. DC-AC and the boost converter
2. High-voltage ignition circuit: mainly in the start HID Lamps provide a high pressure
3. DC-AC inverter: The main is to provide the HID Lamp, the lighting after a stable voltage and current
4. To control and drive circuit: The main thing to detect all of the use of HID Lamps, and timely adjustment of voltage and current, so that HID Lamps can maintain a certain degree of efficiency and stability.

The most commonly used two kinds of HID lamps lamp lamp

D2R lamp: this lamp is a reflective design, this design in order not to light exposure to the right on the light bulb has always been cars, the bulb has designed a shade above the board, shading plate can prevent exposure to the right has always been cars, such lamp design and lighting grasped only 40% of the issued bulb light, efficiency be not high.

D2S lamp: this lamp is the projection design, light bulbs there is no shading board design, only in the lamp shade on a board, is mainly upward block off light scattering, and to design a lens shade, so that the lamp can light concentrated in one region and direction of such light bulbs can be grasped, 80% of the light, very efficient, is the number of lamps used in the depot.

Conclusion
  
HID lamps have been widely used in advanced vehicles of the headlights, mainly expensive light bulbs and ballast.
HID light than traditional halogen light with high efficiency, long life and good color rendering, low-power and so on. HID lamp technology has been considered as mature if they can reduce production costs, will be widely used in many ways.