Abstract: The invention relates to a method for controlling a series resonant converter (110), wherein the series resonant converter (110) comprises a primary circuit (112) and a secondary circuit (114), wherein the primary circuit (112) or the secondary circuit (114) comprises a series resonant oscillating circuit (118), wherein the series resonant oscillating circuit (118) comprises at least one capacitance C1 and at least one inductance Li, wherein a link voltage Udc is applied to the primary circuit (112), and wherein the secondary circuit (114) provides an average output current ?out, wherein the control of the series resonant converter (110) is carried out by adjusting an averaged value of the output current ?out using a transfer function, wherein the transfer function is a function of the link voltage Udc, the output voltage UCout, the inductance Li, a switching period tp and a duty cycle D, wherein at least the switching period tp and/or the duty cycle D are adjusted.

Abstract: A high pressure gas discharge lamp is operated with normal output by at least predominantly low frequency energy supplied from a conventional power supply unit, and is operated at lower than 25 percent of the normal output by at least predominantly high frequency energy supplied from an electronic power supply unit. The electric output fed to the lamp is controlled. At any level of operation, a steady burning of the lamp for saving service life of the lamp is guaranteed. The switching arrangement, in addition to a conventional power supply unit, has an electronic power supply unit. The electronic power supply unit feeds the lamp with energy at a frequency which is higher than that of the energy supplied from the conventional power supply unit.