A DC-AC converter for nonlinear loads

Many industrial printing machines use tubular fluorescent lamps with a power consumption of more than 6 kW. These fluorescent lamps have a highly nonlinear characteristic, especially at powering up time. They are powered in most applications by conventional leak transformers to adapt to their nonlinear characteristics. This conventional make up has several disadvantages, mainly the low efficiency and the large weight in conjunction with the space requirements of the transformer, which make them difficult to handle and their integration into the printing machine time consuming. A further disadvantage is the limited controllability of the luminous flux of the lamp. In this paper a system is presented which eliminates these disadvantages and makes it possible to control the luminous flux of the fluorescent lamp over a wide range. The power supply system requires approximately the same space as a standard PC-switching power supply device of about 300 W. The applied concepts are explained and accompanied by practical results