A New High Efficiency HID Electronic Ballast

Abstract

This paper presents analysis and design of a modified synchronous buck converter used as an intermediate stage of a three-stage high-intensity discharge (HID) electronic ballast. In order to improve the efficiency of the electronic ballast, a synchronous buck converter operating in a new critical continuous conduction mode is proposed. Unlike a standard buck converter which is typically used as an intermediate stage of HID ballasts, in the proposed topology the soft-switching is achieved which significantly improves the efficiency of the three-stage high-intensity discharge electronic ballast. The modified synchronous buck converter and a two-loop controller are analyzed and implemented for a 400W HID lamp. Experimental results of a 400W HID electronic ballast operating in three modes of operation: open circuit (OCM), short circuit (SCM), and power control mode (PCM) is presented.

Keywords:

• HID lamps
• electronic ballast
• modified synchronous buck
• soft switching
• low frequency square wave.