Patent ID: 7474188

Claim:
A step-up or step-down autotransformer, designed to be connected to a supply of three-phase voltage of given amplitude and supplying nine output voltages with phases separated in steps of 40° and of identical amplitudes, higher or lower than the amplitude between neutral and phase of the three-phase supply, the autotransformer comprising: a magnetic core with three branches and on each magnetic branch a main winding having a first and second terminal three main windings being electrically connected together in delta configuration, wherein the autotransformer also comprises, on each magnetic branch, three auxiliary windings, the main winding of a given branch having between its first and its second terminal, a first, a second and a third intermediate tap, the first auxiliary winding of another branch having a first terminal connected, respectively, to a first intermediate tap of the main winding of the given branch and a second input or output terminal having a voltage in phase with the voltage present on the first terminal of this main winding, the second and third auxiliary windings of the given branch each having a first terminal connected to a second or a third intermediate tap of one or the other of the other branches and a second terminal forming a respective output among nine outputs of the autotransformer.