Abstract: The alternator comprises a wound rotor and a stator with a number of phases connected to a rectifier bridge equipped with switches (7) in the form of MOS type transistors, such as MOSFET type transistors, characterised in that the transistors (7) are voltage-rated to work by avalanche effect or linearly in the case of a load dump.

Abstract: A power generator in which the rotor's mechanical rotation speed and the output frequency can be varied substantially independently of each other through electronic controls, to achieve results such as better match between speed and load regime of the primary mover and the generator's output.

Abstract: An output transistor is serially connected to a field coil in a battery charging AC generator to break and make a field current through it under the control of a control transistor to adjust a rectified voltage from the generator to a predetermined magnitude. Another transistor is connected to the output transistor to respond to a collector-to-emitter voltage of the latter in excess of a predetermined magnitude as sensed by it to turn the output transistor off.

Abstract: For a dynamoelectric machine, excitation power is supplied by a main exciter having two field windings. A first field winding is driven by a pilot exciter which supplies base excitation (small signal) for the main exciter. Forcing excitation (large signal) is supplied by the second field winding which is driven by an external, supplemental power source. The main exciter can thus provide the appropriate excitation for both normal and transient operating conditions. In addition, by switching the controlled rectifier elements associated with the supplemental power source, the second field winding is also capable of providing fast de-excitation for the main exciter.

Abstract: An AC feeding apparatus which comprises a plurality of series solid state switch groups connected in parallel and with each series solid state switch group comprising N solid state switches connected in series. AC windings are provided for n(n.gtoreq.1) phase and m(m.gtoreq.2) independent groups of the windings are respectively connected to corresponding contacts of series connections of the solid state switches of the series switch groups. In the AC feeding apparatus, N solid state switches in each group and m groups of windings have the relation of 2m.gtoreq.N.gtoreq.(m+1) and at least two groups among m groups of the AC windings are excited with each phase difference of .DELTA..theta.(.noteq..pi.) in the turn-on control of the solid state switches. The AC feeding apparatus can be adapted for use in a rotating field generator, a commutator motor or an AC motor apparatus.

Abstract: A field regulating circuit for a brushless alternator or the like in which a field winding is disposed on a rotor and energized from the secondary winding of a rotary transformer which has its primary winding connected to be energized from a circuit controlled by an oscillator and wherein the frequency of the oscillator is varied in response to a voltage sensing circuit providing a potential which varies with the output of the alternator, the output of the oscillator effecting the generation of first and second pulse trains with the trains being 180.degree. out of phase and effecting energization of the primary of the rotary transformer by current pulses of a fixed width with the current pulses caused by the first and second pulse trains flowing in different directions through the primary winding of the brushless transformer, the pulse trains have pulses of fixed duration which is substantially equal to a half period of the oscillation for the frequency of the oscillator for supplying full field current.

Abstract: An automatic voltage regulator for an excited AC generator comprising at least one controlled rectifier for conducting the field current of the generator, a trigger signal supplying means for supplying a trigger signal to the controlled rectifier when the controlled rectifier is forward biased, a voltage detection circuit for detecting the output voltage of the generator, an inhibiting circuit for inhibiting turn-on of the controlled rectifier when the instantaneous value of the voltage detection circuit exceeds a predetermined voltage, characterized in that the voltage detection circuit comprises a phase shifting circuit receiving and shifting the phase of the output voltage of the generator. The amount of phase shift may be selected so that the inhibiting operation terminates and hence the turn-on of the controlled rectifier is effected at any angle within a wide range to adjust to the load being energized.

Abstract: An apparatus for protecting a synchronous machine from a field overvoltage is disclosed. The apparatus comprises a field excitation control circuit which is impressed with the armature voltage of the synchronous machine so as to provide a DC power supply for producing a DC output to excite the field winding of the synchronous machine, a first discharge circuit which is adapted to discharge the stored energy of the field winding when the synchronous machine is to be tripped under predetermined conditions, and a second discharge circuit for reducing the field voltage by allowing a field current to flow therethrough in response to generation of an overvoltage whose absolute value is higher than a predetermined level, across the field winding.

Abstract: An excitation control circuit for a brushless synchronous welding generator, in which the stator-mounted excitation winding is fed from a separate voltage source via two parallel-connected power transistors with independently adjustable base circuits, one transistor controlling the excitation current in the idling mode, the other in the welding mode. A change-over switch, responding to an electromagnet in the welding current circuit, alternatingly energizes one transistor, while blocking the other.

Abstract: An apparatus and a method for controlling the exciter current in a welding generator such that the open circuit voltage of the generator is regulated within suitable limits prior to arc start. A voltage controlled relay is connected to the generator's output and controls the inclusion of a voltage regulated biasing circuit in the base circuit of a transistor connected in series in the exciter circuit to assure that when the voltage exceeds a preset level of the voltage controlled relay, the exciter current will remain substantially constant.

Abstract: A lift truck energized from a battery to supply pressurized fluid to elevate a load-supporting carriage has an energy recovery system for converting kinetic energy of the elevated carriage into battery charging current including a fluid motor through which fluid from the lift ram is exhausted when the carriage is descending, an alternator driven by the fluid motor, a rectifier between alternator and battery, a transistor having its emitter-collector circuit in series with the field winding of the alternator, and a rate-of-descent adjusting potentiometer for selectively varying base drive to the transistor to thereby regulate field excitation of the alternator and the regenerative braking of the fluid motor.