Due to their lumen per watt efficiency, the HID lamps are wide used especially in the outdoor applications, but also in indoor industrial or commercial ones. The ballasts necessary for their normal operation could be magnetic or electronic and in the last decade we assist to a long debate on which is a better option. The dimming capabilities are one of the most claimed advantages of the electronic ballasts. But, in the last years, several lower cost solutions for getting dimmability with magnetic ballasts have been reconsidered. In this paper, the possibility to dim lamps trough the voltage amplitude modulation by means an autotransformer is explored. This solution can be cheaper, robust and most suited for the low budget Africa's lighting systems. Several experimental tests have been performed on two type of 250W HID lamps, a High Pressure Sodium (HPS) and a Metal Halide (MH), operated by a Very-Low-Loss (VLL) magnetic ballast. The range of the voltage modulation has been from 160V to 250V and the power consumption, the light output and the harmonics content have been recorded. The results confirm once again the validity of this proposed solution. The energy-saving per lamp by dimming to 160V is about 55 % for HPS lamp and 52.72% for MH lamp.

http://ieeexplore.ieee.org/iel7/6963791/6972582/06972670.pdf

HID lamps dimming in the public lighting installations dominated by magnetic ballasts

An electronic ballast with very high frequency can avoid the intrinsic acoustic resonance problem of HID lamps. The ballast consists of a PFC converter circuit and an inverter circuit The inverter circuit includes a half bridge inverter and a T type filter running on very high frequency. Based on the T type filter, wide dimming ability can be achieved within a narrow frequency variation range. At the same time the lamp current is kept a perfect sine wave, which means low lamp current crest factor is achieved. Frequency modulation with power control is implemented to dim the lamp. Its validity is proved by both theoretical analysis and experimental results.

A novel dimmable electronic ballast with very high frequency

The paper proposes and analyzes an individual automatic energy-saving device destined to the produce light dimming in the public lighting network dominated by high intensity discharge (HID) lamps and magnetic ballasts. The device is based on the single-phase voltage angle regulation and designed to switch the lamp's circuit input voltage within three levels 230V, 190V and 170V. The selection of the level is done automatically and depends on the time hour. The dimming device operation was first simulated and then experimental validated using two power levels (of 250 W and 150W) of high pressure sodium (HPS) lamps. This device can be a relative cheap solution for the low budget lighting systems, an opportunity for the city manager of lighting and electricity to get better energy efficiency.

High energy saving for africa street lighting using individual automatic dimming of HID ballasts

A novel dimmable electronic ballast is proposed in this paper The ballast consists of a PFC converter and a quasi half bridge inverter, pulse width modulation control is implemented to dim the lamp Wide dimming range can be achieved with constant frequency and DC link voltage At the same time the lamp current crest factor is limited Its validity is verified by simulation and experimental results

http://ieeexplore.ieee.org/iel5/9025/28650/01283135.pdf

A novel dimmable electronic ballast for HID lamps

This paper introduces a dimmable electronic ballast for HPS lamps which uses a new strategy to implement the variation of the lamp's power, based on the variation of the switches' duty cycle. The complete operating principle, theoretical analysis and relevant equations are presented in this paper. The experimental results of a 70 W electronic ballast operating at 33 kHz switching frequency are also presented.

I. Brbi

Papers

A new dimmable 70 W electronic ballast for high pressure sodium lamps