An electric machine (21) having a stator (20) and having a rotor (29) rotatably mounted to the stator (20) is specified. The stator (20) comprises a stator winding (24), at least three teeth (23), and at least three grooves (22). In each case, one tooth (23) of the stator (20) is arranged between two grooves (22) along a circumference of the stator (20), and the stator winding (24) has at least three coils (25), wherein each of the coils (25) is wound around a tooth (23) of the stator (20), so that the stator winding (24) is a concentrated winding. In addition, the winding direction of all coils (25) is the same, each of the coils (25) is designed to be fed with its own phase current, and the stator (20) is designed to generate at least two rotary fields having different numbers of pole pairs independently of each other, in particular simultaneously. In addition, an activation unit (40) for the electric machine (21) and a method for operating an electric machine (21) are specified.

A field coil type rotating electric machine includes a rotor where both a series resonant circuit including a first winding and a capacitor and a parallel resonant circuit including a second winding and the capacitor are formed. The first winding is radially located closer than the second winding to a stator. The capacitance of the capacitor and the ratio of the number of turns of the second winding to the number of turns of the first winding are set to have the amplitude of a total resultant magnetic flux lower than the amplitude of a field resultant magnetic flux. The total resultant magnetic flux is the resultant of the field resultant magnetic flux and magnetic flux generated by harmonic currents flowing in phase windings of a stator coil. The field resultant magnetic flux is the resultant of magnetic fluxes generated by harmonic currents flowing in the first and second windings.

An excitation system (15) is disclosed for providing excitation to a main rotating electrical machine (2). The excitation system comprises an exciter (50) and an auxiliary generator (52). The exciter and the auxiliary generator have separate stator cores (14, 18) and share a common rotor core (16). The common rotor (16) core may be located between the two stator cores (14, 18). This may help to optimize space, improve material usage and reduce the total rotating mass. A mounting arrangement for the common rotor core is also disclosed.

An excitation system (15) is disclosed for providing excitation to a main rotating electrical machine (2). The excitation system comprises an exciter (50) and an auxiliary generator (52). The exciter and the auxiliary generator have separate stator cores (14, 18) and share a common rotor core (16). The common rotor (16) core may be located between the two stator cores (14, 18). This may help to optimize space, improve material usage and reduce the total rotating mass. A mounting arrangement for the common rotor core is also disclosed.

The present inventions include a rotating electromagnetic machine such as a motor or generator wherein changes of flux direction adjacent the air gap are avoided. The disclosed improvements apply to permanent magnet alternators, induction motors and generators, doubly fed induction generators, and the like. Adaptation of coils to and fixation within the required slot geometries are disclosed. Excitation systems co-located within the primary rotor core and primary stator core are also disclosed. The use of rubber vulcanized to the rotor in conjunction with a stainless steel rotor sleeve is also disclosed.

An alternator includes an exciter field device generating an exciter magnetic field in a first air gap, an exciter armature device configured to rotate with respect to the exciter magnetic field and impart a first voltage in a first set of coils at the first air gap, a main stator device including a second set of coils, and a rotor field device configured to be energized by the first current in the first set of coils and generate a main magnetic field that imparts a second voltage on the main stator device at a second air gap. The main stator device and the exciter field device lie in on a common plane normal to an axis of rotation, and the exciter armature device is inwardly spaced from the exciter field device, main stator device, and the rotor field device.

An alternator includes an exciter field device generating an exciter magnetic field in a first air gap, an exciter armature device configured to rotate with respect to the exciter magnetic field and impart a first voltage in a first set of coils at the first air gap, a main stator device including a second set of coils, and a rotor field device configured to be energized by the first current in the first set of coils and generate a main magnetic field that imparts a second voltage on the main stator device at a second air gap. The main stator device and the exciter field device lie in on a common plane normal to an axis of rotation, and the exciter armature device is inwardly spaced from the exciter field device, main stator device, and the rotor field device.

A field winding type rotary machine includes a stator having a stator core and a stator coil wound on the stator core, a rotor having a rotor core and a rotor field coil wound on the rotor core, and a rectifier element connected between both ends of the rotor field coil. The field winding type rotary machine includes a capacitor having a first terminal connected to an anode terminal of the rectifier element and a second terminal connected to any point of the rotor field coil.

Provided is a driving system and method for a wound rotor synchronous generator. The driving system for a wound rotor synchronous generator according to the present invention includes: a converter controlling the wound rotor synchronous generator and receiving generated power; and a field winding power supply means supplying the power to a field winding of a rotor of the generator. The field winding power supply means is connected to the converter to receive the power from the converter and supply the power to the field winding, the power supplied to the field winding being electrically insulated from the power received from the converter.

Provided is a driving system and method for a wound rotor synchronous generator. The driving system for a wound rotor synchronous generator according to the present invention includes: a converter controlling the wound rotor synchronous generator and receiving generated power; and a field winding power supply means supplying the power to a field winding of a rotor of the generator. The field winding power supply means is connected to the converter to receive the power from the converter and supply the power to the field winding, the power supplied to the field winding being electrically insulated from the power received from the converter.