Patent ID: RE44485

Claim:
A device ( 1 ) for feeding electrical energy from an energy source with variable source voltage into an electric power supply network ( 15 ) , said the device ( 1 ) including comprising: a transformer ( 112 ) for galvanic isolation, ; a resonant high frequency inverter ( 11 ) with semi-conductor comprising first switches (a-d; A, B), and one or several resonant capacitors ( 17 ; 18 , 19 ; 20 , 21 ) ; and one a rectifier ( 113 ) , characterized in that wherein the device ( 1 ) does not comprise a boost chopper or a buck chopper, and that wherein the resonant high frequency inverter ( 11 ) is operated configured to operate in a full resonant mode if an operating voltage is in a maximum power operation point (MPP) that exists in normal operation, whereby wherein in the maximum power point (MPP) the a current from the transformer ( 112 ) is a current made from comprises sinusoidal half-waves, and wherein the resonant high frequency inverter ( 11 ) is operated configured to operate in a hard-switching mode if the voltages exceed the maximum operation power point (MPP), so that the current from the transformer ( 112 ) comprises sine-wave portions, whereby wherein the hard-switching mode only occurs in a start-up phase.