Abstract: A brushless welding generator with a homopolar machine which supplies welding current, and has winding-free rotors with several pole rings. Each of these form an air gap of varying size around its periphery with the stator. The homopolar machine is divided into two electromagnetic parts, each having an exciting winding. The exciting field is controlled in one of the two electromagnetic parts in opposition to the welding current. One electromagnetic part, furthermore, has a further exciting winding fed by the welding current to control its exciting field. This further exciting winding produces an exciting field directed opposite to the exciting field of the first-mentioned exciting winding. A regulator controls the welding current of one exciting winding, and a signal derived from the welding current is applied to the regulator for representing an actual value.