Abstract: Apparatus and method are provided, for connecting prime mover driven alternator to circuit that has an existing alternating current. Alternator is connected to circuit when minimum current flows to or from alternator. The actual current is measured by controller following connection and the value of this current is used to determine the optimal connection conditions when alternator is next connected. Alternator is disconnected by controller by running down prime mover, monitoring the current and stalling prime mover when the current flow is at a minimum.

Abstract: When drive control of a generator is performed, PWM control of a switching circuit comprising an FET and a diode connected to the opposite ends of a winding is performed. In the vicinity of a moment in time Lmax where the winding has a maximum inductance L, an alternating mode for repeating a supply mode and a reflux mode alternately is performed through PWM control. After the alternating mode is performed, the reflux mode is performed temporarily in order to increase the quantity of current, and then a regenerative mode is performed. The regenerative mode is performed by increasing the current level as much as possible when the reflux mode is started while suppressing the brake force of the rotor in the alternating mode. From a position advancing in angle by a time Tah from the moment in time Lmax where the winding has a maximum inductance L, a first alternating mode C1 for repeating the supply mode P and the reflux mode Q alternately is performed.

Abstract: A control apparatus for a vehicular AC generator analyzes, at least, a “HIGH” logic continuation time, a “LOW” logic continuation time and the pulse width duty of an external signal, for the external signal pulse inputted from an external unit. In a case where the “HIGH” logic or “LOW” logic of the external signal pulse has continued for a predetermined time period, the control apparatus controls a generator control voltage as either of adjustment voltages consisting of the two values of an ordinary voltage and a voltage lower than the ordinary voltage. On the other hand, in a case where the “HIGH” logic or “LOW” logic of the external signal pulses are iterated within a predetermined time period, and where the pulse width duty of the external signal falls within a predetermined range, the control apparatus controls the generator control voltage as a multistage or linear adjustment voltage which is the function of the pulse width duty ratio.

Abstract: The stator of the vehicle-mounted alternator includes a stator core formed with a plurality of slots located along a circumferential direction thereof, and first and second multi-phase windings wound in the slots, the first and second multi-phase windings being spaced from each other by a predetermined electrical angle. An output of the first multi-phase winding is rectified by a first rectifier device, and an output of the second multi-phase winding is rectified by a second rectifier device. The second rectifier device is constituted by a plurality of switching devices. The vehicle-mounted alternator includes a control device to perform on/off control on the switching devices such that a phase angle difference between an output of the first rectifier device and an output of the second rectifier device is varied depending on a rotation speed of the stator.

Abstract: An arrangement for electrically powering an aircraft comprises at least one first generator driven by an engine of the aircraft, an electricity network on board the aircraft receiving the voltage produced by the first generator, at least one second generator driven by the motor, and an engine electrical network distinct from the on-board network for powering equipment of the engine of its environment, the engine network comprising: at least one DC electrical voltage distribution bus for the electrical equipment; and a power supply circuit having a first input connected to the on-board network, a second input connected to the second generator to receive the electrical voltage supplied thereby, a voltage converter connected to the second input, and a selector circuit for delivering a voltage on the distribution bus, the voltage being supplied from that received on the first input or from that supplied by the converter depending on the amplitude of the voltage supplied by the second electricity generator.

Abstract: An output voltage regulator for an engine-driven generator that can satisfactory suppress fluctuation in output voltage, even when an output waveform of the generator is distorted. An engine revolution period that represents a period of output voltage is detected by use of an ignition signal. Data that represents an output waveform is obtained by squaring and adding up an instantaneous value of the output voltage for one period of engine revolution. Furthermore, a square root of the data is extracted as an effective value. An operation duty of a transistor Q1 provided in an output circuit of an excitation winding L2 that supplies a field current “if” is determined based on a difference between the effective value and a target voltage. The field current “if” changes according to the difference, and the output voltage is thereby regulated according to a load.

Abstract: In a control system for controlling a power generator based on a command value associated with a control parameter, a receiver receives the command signal, a detector detects the command value included in the received command signal, and a determiner determines whether a duration of the detected command value being invariant within a predetermined range exceeds a predetermined allowed duration. In the control system, a controller controls an output of the power-generator based on a predetermined default value within the predetermined range in place of the command value when it is determined that the duration of the detected command value being invariant within the predetermined range exceeds the predetermined allowed duration.

Abstract: The present invention relates to an apparatus for controlling generation of electric power in a vehicle that is capable of calculating a target state of charge (SOC) of a battery on the basis of a SOC of the battery and an amount of accumulated current according to individual driving modes and performing a feedback control on generation of an alternator to follow the target SOC, thereby maintaining an optimal SOC and improving fuel efficiency.

Abstract: A method and device for optimizing power output of a power generation system having a load engaging system, a load optimizing system, a load selection system, a motive driver and one or more loads or power transfer parameters. The power generation system is configured using an electrical generator to consume system power out. The load engaging system decides when and how the load or power transfer parameters are applied to and removed from the system. The load selection system enables multiple power transfer parameters to be optimized by selecting and isolating one power transfer parameter at a time to be optimized. The load optimizing system optimizes system power output by manipulating the selected power transfer parameter, dynamically in response to change in power output.

Abstract: An automotive rotary electrical apparatus with less than four switching control elements capable of blocking a field current while preventing breakage of the switching control elements in response to a malfunction in a feeder circuit for a field coil is proposed. First and second switching control elements controlled by first and second control signals, and first and second diode elements are used. The field control circuit switches the first control signal to the on-level signal while keeping the second control signal as the on-level signal, then switches the second control signal to the off-level signal while keeping the first control signal as the on-level signal, and further switches the first control signal to the off-level signal while keeping the second control signal to the off-level signal, when a short-to-power malfunction of the positive terminal or a short-circuit malfunction of the first switching control element occurs in the feeder circuit for the field coil.

Abstract: A control system for an electrical power generation system (EPGS) provides overload protection without disconnecting a generator of the EPGS from an excessive electrical load. Available engine power and current levels of the electrical load are continuously measured. A command voltage is calculated that corresponds to a voltage required to sustain with the maximum available power. Output voltage of a generator of the EPGS is controlled at the calculated command voltage so that a power limit of the engine is not exceeded during electrical overload conditions.

Abstract: A failure detection apparatus for an alternator can detect a short circuit failure of a diode in a full-wave rectifier with high precision by use of a simple circuit structure based on the state of a detection terminal when the alternator generates no electricity. The rectifier circuit has a pair of diodes connected to a positive terminal and a negative terminal, respectively, of a battery. A failure detection circuit has the detection terminal connected to a P terminal or a neutral point of an armature coil, and makes a failure determination in the following manner. When in the non-power generation state of the armature coil, the detection terminal is in a floating or high impedance state, the full-wave rectifier circuit is determined to be normal, whereas when otherwise, the full-wave rectifier circuit is determined to be in a failure.

Abstract: A generator control circuit is disclosed. One embodiment provides a first active switching circuit configured to connect a first terminal of an excitation coil either to a first or to a second terminal of a voltage source, a second active switching circuit configured to connect a second terminal of the excitation coil either to the first or to the second terminal of the voltage source, and a generator controller to set the duty cycle of the active switching circuit to rapidly control the current through the excitation coil to an excitation coil current setpoint.

Abstract: A highly reliable control device for an AC generator without using a transistor and diode having high withstand voltage is provided.

Abstract: 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.

Abstract: A coordination control device of a power output apparatus includes a coordination control unit. The coordination control unit calculates an intermediate value between the maximum value and minimum value among voltage controls for a first motor generator, and voltage control from an AC voltage control generation unit to generate an AC voltage across neutral points of first and second motor generators, and outputs a value that is each phase voltage control for the first and second motor generators minus the calculated intermediate value to a signal generation unit as the final voltage control for the first and second motor generators.

Abstract: An electrical power generator includes a controller for making a full power capacity of the generator available for consumption by at least one intelligent load coupled to an output of the generator. The controller obtains data from which both a present output power of the generator and a power capacity of the generator can be determined. The controller then provides the intelligent load with data indicative of both the present output power and the power capacity of the generator for use by the load in controlling its power consumption.

Abstract: A wind turbine control system for twin turbines mounted in common on an accelerator comprising a DC boost converter having pulse width capability, power, speed, current and voltage sensors responsive to an generator driven by one turbine, and a controller.

Abstract: An engine speed detector detects an engine speed of an engine having a baseline torque versus engine speed curve. A torque sensor detects an engine torque of the engine. A data processor determines if the detected engine speed is within a first speed range and if the detected engine torque is within a first torque range. A motor controller activates an electric motor to rotate substantially synchronously with a corresponding engine speed associated with the detected engine torque in an electric propulsion mode in accordance with a supplemental torque versus engine speed curve if the detected engine speed is within the first speed range and if the detected engine torque is within the first torque range. The supplemental torque versus engine speed curve intercepts the baseline torque versus engine speed curve at a lower speed point and a higher speed point.

Abstract: A method for communicating voltage regulator switching information to a vehicle computer includes generating a first output signal from a voltage regulator, the first output signal configured to regulate a field current of a generating device associated therewith. A second output signal is generated from the voltage regulator, the second output signal communicated to the vehicle computer, the second output signal further indicative of the state of the first output signal. The second output signal represents an average value of the first output signal, having transient values included within the first output signal filtered therefrom.

Abstract: A control system for a vehicle has an engine control unit for an engine and a generator control unit for a power generator driven by the engine. The engine control unit calculates a permissive power generation torque, which is permitted to be used by the power generator, in accordance with a response delay of the engine. The generator control unit calculates a command power to be generated by the power generator so that a battery voltage variation and an engine speed variation are suppressed to be less than respective allowable variation limits, when a power difference is caused between a required power and a permissive power generated by the permissive torque.

Abstract: A control apparatus controls power generation of an electric generator and communicates with an external control apparatus. The control apparatus includes: a control circuit that controls the power generation of the electric generator according to a command signal transmitted from the external control apparatus; means for reseting the control circuit; and means for informing the external control apparatus of a power generation condition of the electric generator by transmitting a condition signal, the condition signal indicating both the power generation condition of the electric generator and information on whether a reset of the control circuit is made by the reseting means. With such a configuration, when the control circuit is reset due to, for example, noises, the control apparatus can reliably inform the external control apparatus of the reset of the control circuit.

Abstract: A feed converter system for small wind energy systems has a compact construction and economically efficient installation and operating costs. The system has a rectifier device and an inverter device disposed in a housing, and a common control device is provided for regulating the system components under different load cases, particularly when the wind energy system starts up, or when it is being operated at an optimal operating point.

Abstract: In a power-generator control apparatus, a control circuit intermittently controls the supply of a field current from a battery to a field winding of a power generator in normal mode so as to adjust power induced in an output winding of the power generator. The control circuit interrupts the supply of the field current from the battery to the field winding in transient mode when a transient voltage occurs. An energy absorbing circuit absorbs magnetic energy stored in the field winding independently of magnetic-energy consumption by a resistance of the field winding itself.

Abstract: A power supply control apparatus for controlling an electric generator of a vehicle limits the rate of change of a power supply voltage to a predetermined variation rate range, when the change is caused by operations to control the charge condition of the vehicle battery, and controls the generated power to match the drive torque applied by the engine to the generator. When the electrical load demand changes, the generated power is controlled to limit a resultant momentary change in the power supply voltage caused by an engine response delay, while minimizing a resultant momentary amount of engine speed variation.

Abstract: In one technique of the present invention, DC electric power from a DC bus is inverted to provide AC electricity to one or more electrical loads, and AC power from a variable speed generator is rectified to provide a first variable amount of electric power to the DC bus. This technique also includes determining power applied to the electrical loads, and dynamically controlling the amount of power supplied from the generator and an electrical energy storage device in response to the power applied to the loads.

Abstract: A vehicle alternator failure monitoring system and related monitoring method are disclosed wherein an ECU executes operations depending on a power generation status of a vehicle alternator and a vehicle alternator control device has a serial communication transmitter circuit operative to transmit a serial communication signal, indicative of the power generation status of the vehicle alternator, to the ECU. The serial communication transmitter circuit has a first power generation status signal transmission mode in which a first power generation status signal, representing the power generation status, is transmitted together with a failure flag representing the presence of or absence of an operational failure, related to the vehicle alternator, and a second power generation status signal transmission mode in which a second power generation status signal, representing the power generation status, is transmitted together with additional data representing an operational state of the vehicle alternator.

Abstract: A method of controlling electric power generation during idle charge in a hybrid electric vehicle. The method includes determining whether an idle charge condition is satisfied; if the idle charge condition is satisfied, calculating a first charge power amount based on whether a load is applied, a gear shift position, and a state of charge of a battery; calculating a target charge speed based on the first charge power amount; calculating an altitude correction coefficient based on atmospheric pressure; calculating a second charge power amount based on the altitude correction coefficient and the first charge power amount; and controlling an amount of power generation and an amount of battery charge based on the second charge power amount.

Abstract: A control apparatus for a vehicular AC generator analyzes, at least, a “HIGH” logic continuation time, a “LOW” logic continuation time and the pulse width duty of an external signal, for the external signal pulse inputted from an external unit. In a case where the “HIGH” logic or “LOW” logic of the external signal pulse has continued for a predetermined time period, the control apparatus controls a generator control voltage as either of adjustment voltages consisting of the two values of an ordinary voltage and a voltage lower than the ordinary voltage. On the other hand, in a case where the “HIGH” logic or “LOW” logic of the external signal pulses are iterated within a predetermined time period, and where the pulse width duty of the external signal falls within a predetermined range, the control apparatus controls the generator control voltage as a multistage or linear adjustment voltage which is the function of the pulse width duty ratio.

Abstract: An auxiliary power unit for a motor vehicle includes an auxiliary engine with an output shaft directly connected to a generator. The generator has a field winding and three output windings. A first output winding produces 120 volts AC that is applied to standard electrical outlets in the vehicle. A second output winding produces a low AC voltage that is converted to 12 volts DC and applied to the battery of the truck, thereby charging the battery and powering the vehicle's electrical system when the primary engine of the vehicle is off. An auxiliary winding in which another AC voltage is produced that is used by a controller to excite the field winding. A novel enclosure for the auxiliary power unit also is described.

Abstract: A control device measures a voltage drop across a conductor in a generator to determine and control the total generator output current. A temperature of the conductor is also measured to improve the accuracy. The control device may further improve on the accuracy by compensating for the electrical current through a field coil that may power the generator. The control device may be used in combination with a generator in a vehicle electrical system. Other system parameters may be monitored to improve on the system monitoring, diagnostics, and control. The generator may include a conductor comprising a process-controlled geometric shape.

Abstract: A device for providing a regulated, limited generator excitation current to a generator to acquire a regulated output voltage of the generator, the device including a combiner for weighted combining a first system deviation on the basis of a setpoint voltage and of the regulated output voltage, and a second system deviation on the basis of a predefined current value and of the regulated generator excitation current so as to acquire a combination signal based on the combination of the first system deviation and the second system deviation, a provider for providing a actuating variable on the basis of the combination signal and a regulation specification, and a provider for providing the regulated, limited generator excitation current to the generator on the basis of the actuating variable, so that the regulated output voltage may be provided by the generator.

Abstract: A generation control apparatus for vehicles is provided, in which a drastic change in the drive torque of a generator, which occurs with the cancellation of gradual excitation immediately after starting an internal combustion engine, can be suppressed to prevent stoppage of the internal combustion engine. The generation control apparatus includes an engine-start detection circuit, a gradual excitation circuit, a comparator for gradual-excitation cancellation, and a masking circuit for gradual-excitation cancellation. After detecting an engine start by the engine-start detection circuit, an instruction for gradual-excitation cancellation is released during an initial gradual excitation performed by a gradual excitation circuit, based on an output from the masking circuit for gradual-excitation cancellation. The drastic change in the drive torque occurring with the cancellation of the gradual excitation immediately after the engine start, can thus be suppressed, thereby preventing the engine stop.

Abstract: This invention discloses a vehicle electrical system voltage regulator with improved electrical protection and warning means that discerns and responds to regulator, generator, or vehicle electrical system operation and malfunctions. The regulator includes monitoring, control, and protection circuits with a phase signal monitor, a field switching circuit that operates the field coil in response to electrical power demands, and a field enable switch in series with the field regulating switch. The phase monitor and protection circuit ascertains and transmits generator rotational motion for use by the monitoring and control circuit in discerning the various operating conditions. The monitoring and control circuit operates on the field switching circuit to meet the electrical power demands and provide multi level fault protection to include field switching circuit reconfiguration to continue operating under various fault conditions.

Abstract: A method for the operation of a wind energy plant, with a synchronous generator and a superimposition gearbox, which is connected between rotor and generator, and the gear ratio of which is adjusted by a control unit, characterised in that a mode of operation is provided in which the generator is connected to the electric grid, and the generator shaft is uncoupled from the rotor shaft via the superimposition gearbox.

Abstract: A control section 32 supplies a current obtained by rectifying the output of an exciting winding 5 to a field winding 3 responding to variations in the output voltage of the generator to suppress the variations in the output voltage of the generator. The control section 32 drives a transistor 37 at a duty based on a difference between the output voltage of a main winding 4 and a target voltage and controls the gate voltage of an FET 38 to control a field current to a constant value. A flywheel power generation unit including a control power supply winding 14 is provided as a power source of the control section 32 and a power source for passing an initial current through the field winding 3. A current to be supplied to the field winding 3 from the flywheel power generation unit is merged with an exciting current via a diode 31.

Abstract: A method of operating a wind turbine, wherein the wind turbine may include rotor windings of an induction generator, which includes stator coils coupled to a voltage grid, fed with rotor currents by a feed-in unit are driven by a rotor of the wind turbine; wherein the frequencies of the fed-in rotor currents are controlled depending on the rotor rotation frequency and the feed-in unit is electrically decoupled from the rotor windings in the case predetermined variations of the grid voltage amplitude and the rotor current feed-in is resumed after the decoupling caused by the variation of the grid voltage amplitude, when the currents generated in the motor windings by the variation have declined to a predetermined value.

Abstract: The vehicle generator includes a rotor around which a field winding is wound, a stator around which an armature winding is wound, a rectifier rectifying an AC voltage induced in the armature winding to generate a DC output current. The rectifier has a plurality of rectifying elements mounted to a current path section thereof, the DC output current flowing through the current path section to reach an output terminal of the vehicle generator. The vehicle generator further includes a first voltage detector circuit detecting a voltage difference between two points of the current path section located along a direction in which the output current flows, and an output current calculating circuit calculating a value of the output current on the basis of the voltage difference detected by the first voltage detector circuit and a resistance value between the two points of the current path section.

Abstract: A control apparatus controls the generation of a vehicle electric generator having an armature winding, excitation winding and rectifier connected to the armature winding. The apparatus includes a flywheel diode connected to the excitation winding in parallel, a switch element connected to the excitation winding, a control signal setting circuit, and a signal output section. The setting circuit controls a duty ratio of the switch element in correspondence to a first generation status of the generator to control electric current flowing through the excitation winding while varying a switching frequency of the generator depending on a second generation status of the generator. The signal output section is connected to a junction point between the excitation winding and the switch element and outputs a signal, involving a duty ratio associated with the first generation status and a switching frequency associated with the second generation status, to an external device.

Abstract: An electrical control apparatus comprises a current sensor and a current inhibiting circuit that inhibits current flow between first and second terminals of a bicycle dynamo when current sensed by the current sensor is below a selected value.

Abstract: A vehicle alternator and methods for controlling an amount of torque loading of the vehicle alternator on an engine are provided. The vehicle alternator utilizes a voltage regulator with a microprocessor to control an amount of torque loading, based on a rotational speed of a rotor of the alternator, or an amount of current output by the alternator, or both.

Abstract: A generator control circuit is provided that includes a first circuit (44) monitoring a generator voltage change rate and producing a first output when the voltage change rate is above a first level, a second circuit (48) monitoring a generator current change rate and producing a second output when the current change rate is above a second level, and a third circuit (13, 28) operatively connected to the first circuit (44) and the second circuit (48) for decreasing a power level supplied to the generator when a plurality of conditions are satisfied, the plurality of conditions including the voltage change rate being above the first level and the current change rate being above the second level. A method of controlling a generator is also disclosed.

Abstract: An engine speed detector detects an engine speed of an engine having a baseline torque versus engine speed curve. A torque sensor detects an engine torque of the engine. A data processor determines if the detected engine speed is within a first speed range and if the detected engine torque is within a first torque range. A motor controller activates an electric motor to rotate substantially synchronously with a corresponding engine speed associated with the detected engine torque in an electric propulsion mode in accordance with a supplemental torque versus engine speed curve if the detected engine speed is within the first speed range and if the detected engine torque is within the first torque range. The supplemental torque versus engine speed curve intercepts the baseline torque versus engine speed curve at a lower speed point and a higher speed point.

Abstract: A rotary electric apparatus, such as on-vehicle three-phase AC generator (i.e., alternator) comprises a main rotary unit, a semiconductor power converter, and an air cooling mechanism. The main rotary unit is provided with a rotor and an armature disposed as a stator around the armature. The armature has armature windings wound therearound. The semiconductor power converter is disposed together with the main rotary unit. The air cooling mechanism cools down the semiconductor power converter. This mechanism comprises a fan motor driven in response to an AC (alternating current) excitation by current coming from the armature windings.

Abstract: A driving circuit of a fan includes a magnetic pole sensor for generating a magnetic pole sensing signal, a first waveform generator coupled to the magnetic pole sensor for generating a first waveform according to the magnetic pole sensing signal, a second waveform generator for generating a second waveform, a comparison circuit coupled to the first waveform generator and the second waveform generator for comparing the first waveform and the second waveform for generating a third waveform, a control signal generator coupled to the comparison circuit for generating a control signal according to the third waveform and an external signal, and a current generator coupled to the magnetic pole sensor and the control signal generator for outputting current to a coil of a stator of the fan according to the magnetic pole sensing signal and the control signal.

Abstract: A wind powered turbine with low voltage ride-through capability. An inverter is connected to the output of a turbine generator. The generator output is conditioned by the inverter resulting in an output voltage and current at a frequency and phase angle appropriate for transmission to a three-phase utility grid. A frequency and phase angle sensor is connected to the utility grid operative during a fault on the grid. A control system is connected to the sensor and to the inverter. The control system output is a current command signal enabling the inverter to put out a current waveform, which is of the same phase and frequency as detected by the sensor. The control system synthesizes current waveform templates for all three-phases based on a sensed voltage on one phase and transmits currents to all three-phases of the electrical system based on the synthesized current waveforms.

Abstract: The invention relates to a control and power module for an alternator-starter for a motor vehicle, connected between the alternator-starter (3), an on-board wiring network (Ua) and a ground line (GND) of the vehicle, and comprising: a transistor bridge with several branches (B1–B3), and a control unit for comparing a phase voltage (?) of the machine with a reference voltage (Ua, GND) and for controlling the transistors as a function of the result of the comparison, the control unit comprising: a driver (10, 20, 30) for each branch of the transistor bridge, the driver being connected close to the transistors of the branch, and a control circuit for controlling the drivers.

Abstract: An apparatus for regulating a transient response of an output signal of an electrical generator. The apparatus comprises a tapped output winding means for providing a first AC signal and a second AC signal. The first and second AC signals have respective RMS values. The RMS value of the first AC signal is greater than the RMS value of the second AC signal. An AC switching means for selecting between the first AC signal or the second AC signal, and thereby providing a switched AC signal which has a duty cycle. A rectifier means for rectifying the switched AC signal and providing a rectified DC signal. The rectified DC signal has a DC signal component, a square wave signal component and a ripple signal component. The square wave signal component has a duty cycle. The duty cycle of the square wave signal component is equal to the duty cycle of the switched AC signal. A filter means for filtering the rectified DC signal and for providing the output signal.

Abstract: A generator control circuit is provided that includes a first circuit (44) monitoring a generator voltage change rate and producing a first output when the voltage change rate is above a first level, a second circuit (48) monitoring a generator current change rate and producing a second output when the current change rate is above a second level, and a third circuit (13, 28) operatively connected to the first circuit (44) and the second circuit (48) for decreasing a power level supplied to the generator when a plurality of conditions are satisfied, the plurality of conditions including the voltage change rate being above the first level and the current change rate being above the second level. A method of controlling a generator is also disclosed.

Abstract: A vehicle-mounted electrical generating system has a first voltage system which operates from a high supply voltage and a second voltage system which operates from a low supply voltage that is substantially constant, and an electrical generator for supplying power to operate the first voltage system at a voltage determined by the level of field current of the generator, with the field current being derived from the low supply voltage of the second voltage system. The specifications of the field winding of the electrical generator can thereby be optimally established irrespective of the value of the high supply voltage.