The invention relates to an apparatus for regulating the exciter current for a rotary-current generator. It has a voltage source, a rectifier, three phase windings, an evaluation unit, and a voltage regulator. The evaluation unit has three input terminals, and each of these input terminals is connected to one of the phase windings. The evaluation unit is intended for evaluating the phase voltages derived from the three phase windings, in order to detect error functions of the rectifier and/or of the phase windings. If such unauthorized work states are detected, then via the voltage regulator, the exciter current flowing through the exciter winding is reduced.

Apparatus and methods are provided for controlling a voltage output of an alternator having a regulated voltage control (RVC). The apparatus includes a processor configured to transmit one of at least two control signals and a switch coupled to the processor and configured to select one of the control signals. One of the control signals is an RVC enable signal, and another control signal is a voltage boost signal. The method includes determining whether RVC requires override, selecting an output voltage mode of the alternator, activating a boosted voltage mode of the alternator by disabling RVC when RVC requires override, and activating an RVC mode by enabling RVC when the RVC does not require override or upon an occurrence of a lapse of a pre-determined amount of time.

There are apparatus and methods for generating a plurality of voltage levels. There is a rotor that includes a first and a second portion of rotor windings. The first portion of rotor windings is constructed and arranged to establish a first magnetic field of a first number of poles. The second portion of rotor windings is constructed and arranged to establish a second magnetic field of a second number of poles. A stator is disposed adjacent the rotor. The stator includes a first and a second portion of stator windings. The first portion of stator windings is related to the first number of poles and has a first output port configured for furnishing an electrical output at a first voltage level. The second portion of stator windings is related to the second number of poles and has a second output port configured for furnishing an electrical output at a second voltage level.

Switching devices control the rectification and flow of alternating current power from a source such as an alternator to a load such as a battery in response to both the voltage of the battery and a minimum selected time period that is selected to eliminate or reduce an imbalance between various phases or polarities in possible current carrying paths. The selected time period may be constant or a predetermined function of variables such as the speed of the alternator.

A method and an apparatus are described for monitoring a rotating synchronous electric machine (9), which comprises a rotor having a rotor winding and a stator having a stator winding. The method comprises the steps of determining the stator winding current, determining the stator winding voltage, determining the rotor winding current, and estimating the temperature in at least two positions in the electric machine (9) using a model of the electric machine and the determined current and voltage values. An apparatus according to the invention is provided for carrying out the method.