Abstract: A power unit comprises an input mechanism for inputting kinetic energy as a rotary motion, a storing mechanism connected to the input mechanism for storing the kinetic energy as rotary motion, a first speed-regulating mechanism connected to the storing mechanism for increasing the speed of the rotary motion released from the storing mechanism, and a second speed-regulating mechanism connected to the first speed-regulating mechanism for braking the rotary motion to regulate the speed of the rotary motion. A converting mechanism is connected to the first speed-regulating mechanism for converting the rotary motion whose speed has been increased into electricity. A control circuit is connected to the converting mechanism for controlling the generated electricity, and a positive electrode output terminal and a ground electrode terminal are connected to the control circuit.

Abstract: A motor generator system (120) in accordance with the invention includes a prime mover (21) for driving an output shaft (18), a main motor generator (105), having a rotor driven by the output shaft, for producing electrical power on at least one output winding (36a-36c) in response to the prime mover rotating the output shaft and for driving the output shaft in response to operation as a motor; an exciter (102) for applying excitation to a field winding (34) of the main motor generator during operation for producing electrical power on the at least one output winding and for applying current to the field winding of the main motor and generator to produce a magnetic field in the field winding during operation of the main motor generator as a motor; circuitry (122), responsive to current in a field winding (204) of the exciter, for producing an output signal representing a position of the rotor of the main motor generator driven by the output shaft; and a main inverter (114), responsive to the output signal, fo

Abstract: A conventional turbine driven generator is converted to a synchronous condenser. The generator has a generator shaft; the turbine has a turbine shaft axially aligned with the generator shaft. The turbine shaft is disconnected from the generator shaft and an extension shaft is mounted on the generator shaft. The extension shaft has a journal bearing adjacent an axially outer end of the extension shaft, a thrust bearing, and provision for balancing the extension shaft and generator (now synchronous condenser) rotor.

Abstract: A charging system includes a high capacity charging circuit having the original internal engine alternator connected substantially in parallel with an auxiliary alternator by a simple wiring harness arrangement that easily plugs into the existing connectors for the internal engine alternator circuit so that the outputs of the alternators are cumulative. The auxiliary alternator is relatively compact, and the original engine alternator circuit remains substantially unaltered. The regulators for the two alternators include sensory inputs which are connected to each other. The alternators provide redundancy and a fail-safe backup mode so that if one of the systems fails, that system can be quickly disconnected from the remaining system without disabling the entire vehicle.

Abstract: A control for a brushless generator is operable in a starting mode of operation to convert electrical power into motive power for starting a prime mover. The control applies AC power to an exciter field winding at a first frequency at the initiation of a start sequence and thereafter decreases the frequency of the power applied to the exciter field winding during the start sequence.

Abstract: In a generator starting apparatus, in which commercial frequency electric power supplied from an electric power system is converted into variable-voltage variable-frequency electric power to thereby start a gas turbine generator, a harmonic-component removing apparatus is provided which removes harmonic components contained in the converted variable-voltage variable-frequency electric power on the basis of the detected harmonic components. In addition, an apparatus for removing harmonic components generated in an electric power equipment is provided, wherein harmonic components contained in an electric power system are detected so that they may be removed.

Abstract: An electric power starter/generator, for converting electrical energy from a remote dc electrical power source to mechanical energy to start a turbine engine in the start mode, and for converting mechanical energy from the turbine engine to electrical energy to power utilization equipment in the generate mode, comprises a shaft for transferring rotational mechanical energy between the electric power starter/generator and the turbine engine, a permanent magnet synchronous machine having a rotor driveably coupled to the shaft and a stator. The permanent magnet synchronous machine produces polyphase ac electric power when driven as a generator, and rotational mechanical energy when driven as a motor.

Abstract: A detector for detecting rotor position of a brushless generator having a motive power shaft, a permanent magnet generator (PMG) having a set of armature phase windings and a main generator portion having a set of armature phase windings includes a circuit coupled to the armature phase windings of the main generator portion for deriving a number of interval pulses per revolution of the motive power shaft. A circuit measures time periods between adjacent interval pulses and the measured time periods are converted into an indication of the angular position of the motive power shaft in accordance with a parameter of power delivered to the main generator portion armature phase windings.

Abstract: A detector for detecting rotor position of a brushless generator having a motive power shaft, a permanent magnet generator (PMG) having a set of armature phase windings and a main generator portion having a set of armature phase windings includes a circuit coupled to the armature phase windings of the PMG for deriving a number of interval pulses per revolution of the motive power shaft. A circuit measures time periods between adjacent interval pulses and the measured time periods are converted into an indication of the angular position of the motive power shaft in accordance with a parameter of power delivered to one of the main generator portion armature phase windings.

Abstract: An electric power starter/generator system for a turbine engine capable of transforming mechanical power from the turbine engine to electric power during a generate mode of operation and of transforming electric power from a low voltage dc source to mechanical power to drive the turbine engine during a start mode of operation, comprises a synchronous starter/generator having a poly-phase wound stator, and a rotor rotatably positioned therein, the rotor also being drivably coupled to the turbine engine. Further, the system establishes an electric field in the rotor and directly couples the dc source to an inverter for alternately energizing each of the poly-phase stator windings to drive the starter/generator as a motor. This inverter establishes a rotating electric field in the stator whereby a constant torque is produced by the rotor to drive the turbine engine. Preferably, the inverter is a half wave inverter producing a pseudo-square wave current waveform.

Abstract: A control for a brushless generator operable in starting and generating modes supplies combined AC and DC power to an exciter field winding of the brushless generator during operation in the starting mode. The magnitude of a parameter of the AC power is decreased with increasing rotor speed during operation in the starting mode until a particular rotor speed is reached, following which only DC power is supplied to the exciter field winding.

Abstract: A synchronous machine is operable in a starting mode of operation in which a magnitude of a parameter of power applied to a main generator portion armature winding of the synchronous machine is detected relative to a stationary frame of reference and is converted into field and torque producing components relative to a rotating frame of reference. A controllable power source coupled to the main generator portion armature winding is controlled during operation in the starting mode based upon the field and torque producing components.

Abstract: A synchronous generator start converter offers power conversion for performing multiple functions such as starting AC generators as a motor, charging batteries and also providing regulated DC output without degradation of input power quality. The converter utilizes common magnetic components and common semiconductor rectifiers within its three subcircuits. The three subcircuits include flyback converters, a square wave inverter and a field excitation controller.

Abstract: A power converter that can be used either as a start converter or as a variabe speed constant frequency converter is utilized within a stepped waveform VSCF system having engine start capability. Interfacing with the converter are a load bus, a contactor, a field excitation controller and a starter/generator having a main generator, an exciter generator and a permanent magnet generator. Magnetic components and semiconductor components perform multi-functions and minimal degradation of input power quality occurs.

Abstract: A detector for detecting rotor position of a brushless generator having a motive power shaft and a main generator portion having a set of armature phase windings capable of receiving AC power and developing a back EMF voltage during operation in a starting mode, includes a circuit coupled to the set of armature phase windings and capable of responding to the AC power for producing a back EMF estimate signal representing an estimate of the back EMF voltage. The detector also includes a circuit for converting the back EMF estimate signal into an indication of the angular position of the motive power shaft.

Abstract: A synchronous generator usable in both a starting mode of operation and a generating mode of operation includes a permanent magnet generator having a permanent magnet and an armature winding rotatable with respect to the permanent magnet, an exciter portion having an exciter armature winding and an exciter field winding rotatable with respect to the exciter armature winding, and a main generator portion having a main generator armature winding and a main generator field winding rotatable with respect to the main generator armature winding. An inverter is coupled to supply power to the main generator portion armature winding via a DC link during the starting mode of operation, and an inverter controller includes a position sensing circuit that generates a rotor position signal based upon the differential reluctance between pairs of phase windings in the main generator portion armature winding.

Abstract: A multi-step, alternating current power supply that provides for a failed-operation redundancy safety system that compensates for a short-circuited power switch and maintains an AC regulated output voltage without introducing undesirable harmonic components. The firing and logic controller 33 senses a short-circuited power switch 46 within an inverter bridge 32 and disables all complementary power switches 48 within the faulted bridge and enables the remaining power switches 50 in the faulted bridge. The firing sequence is adjusted for the remaining healthy power switches 52 by increasing the phase shift of the individual waveforms 54. The generator voltage is increased as required to maintain the desired AC voltage output level 56.

Abstract: A switched reluctance machine comprising a housing, a stator attached to the housing and a rotor mounted within the housing. The stator including teeth wound with electrical coils which are connected to form phase windings. The rotor comprising a series of laminates including teeth pressed onto a shaft. According to the present invention, at least one set of opposing phase wound stator teeth comprise permanent magnets.

Abstract: A turbine engine start system accepts either AC or DC and performs power conversion for multiple functions such as starting an AC synchronous generator as a synchronous motor without degradation of input power quality and with minimal generation of EMI. The system utilizes common magnetic components and common semiconductor transistors and rectifiers within its four major subcircuits. The four major subcircuits include a transformer rectifier, a boost converter, a voltage source inverter and a field excitation controller.

Abstract: A starting/generating system operable in a starting mode and in a generating mode utilizes a dual permanent magnet generator (DPMG) having a motive power shaft and an armature winding together with a power converter having an input and an output. Relays are operable in the starting mode to connect the output of the power converter to the DPMG armature winding and are operable in the generating mode to connect the input of the power converter to the DPMG armature winding. The power converter is controlled in the starting mode such that the DPMG is operated as a motor to produce motive power at the motive power shaft and is controlled in the generating mode such that electrical power developed in the DPMG armature winding is converted into output power.

Abstract: This invention relates to a hybrid AC/DC power source for aircraft power generation and aircraft engine starting. The power source employs an induction motor/generator and a converter for converting high frequency AC power into separate DC and low frequency AC power for use by aircraft electrical systems. The subject invention contemplates the provision of a driver for the motor/generator comprising a circuit for providing excitation to the motor/generator when it is operating as a generator, the circuit also converting AC power produced by the generator into the high frequency AC power for use by the converter. The converter comprises a first rectifier which produces the DC power and a second rectifier and an inverter which together produce the low frequency AC power. The generator produces uncontrolled frequency AC power. Bidirectional switches operate within the circuit to invert DC excitation power to produce power for the AC excitation and to rectify output of the generator into DC.

Abstract: An engine-operated generator system utilizes the switching elements of an inverter transformation circuit to accomplish starting. The starter circuit includes a battery, one electrode of which is connected to one terminal of a smoothing capacitor connected between the DC terminals of the inverter transformation circuit in such a manner that the electrode and the terminal are of the same polarity. The other electrode is connected to one of the output terminals of an AC generator system through a switch which is closed to start the engine, and which is connected to a reactor forming an LC circuit. In starting the engine, the rectifier circuit is driven in an inverter transformation mode, one of the switching elements in the inverter transformation circuit which is connected between the reactor and the one terminal of the smoothing capacitor being driven in a chopper mode. The inverter transformation circuit is formed by bridge-connecting switching elements each having a flywheel diode.

Abstract: An engine starter and electric generator system transmits rotative power to a crankshaft to start an engine and generates electric power based on rotative power from the crankshaft after the engine has started. The engine starter and electric generator system includes a starter/generator operable selectively as a starter motor to produce the rotative power and a generator for generating the electric power, and an electric power supply device for supplying electric power to the starter motor. A power transmitting mechanism operatively interconnects the crankshaft and the starter/generator, for bidirectionally transmitting the rotative power between the crankshaft and the starter/generator. A transmission mechanism is disposed in the power transmitting mechanism, for changing the speed of rotation transmitted between the crankshaft and the starter/generator.

Abstract: The problem of providing field power to a stationary main generator field winding (22) is addressed such that it can be used as a motor. A dynamoelectric machine (12) is operated as both a generator and a motor. An AC-AC exciter (14) is controlled by an exciter inverter (42) to operate as an exciter generator in a generate mode, and as a rotary transformer in a start mode. The exciter inverter (42) supplies low frequency power to an exciter field winding (28) in a generate mode of operation, and supplies high frequency AC power to the generator field winding (28) in the start mode of operation.

Abstract: When a motor/generator is changed over from a motor mode to a generator mode, field current is minimized. In the generator mode, idling is performed until the engine temperature attains a set temperature, after which the field current is supplied. As a result, load upon an engine is lightened immediately after the engine is started and the risk of the engine stalling is eliminated.

Abstract: An excitation system for a brushless generator having a main generator portion including a field winding disposed on a rotor and an armature winding disposed in a stator includes an exciter portion having a set of polyphase exciter field windings disposed in the stator and an armature winding disposed on the rotor and coupled to the main generator portion field winding. A first power converter is coupled to the main generator armature winding and a second power converter is coupled to the set of polyphase exciter field windings. Contactors are operable in a starting mode of operation to couple a source of electrical power to the first and second power converters and are operable in a generating mode to disconnect the source of electrical power from the first and second power converters.

Abstract: An engine driven generator having an engine, a three-phase synchronous generator to be driven by the engine, a direct current power supply for actuating the engine, a direct current/alternating current power supply converter for converting a direct current power of the direct current power supply to an alternating current power and supplying the alternating current power to the three-phase synchronous generator:(1) characterized in further comprising a full-wave rectifier for rectifying an output of the three-phase generator and supplying the thus rectified output to the direct current/alternating current power converter; a switching unit for switching output terminals of the direct current/alternating current power converter to terminals of an outer device or output terminals of the synchronous generator; a rotor position detector for detecting a position of a rotor of the synchronous generator; and(2) characterized in that during the period when the three-phase synchronous generator performs the power gener

Abstract: In a system for starting an aircraft turbine from a low voltage direct current power supply, the low voltage power supply is coupled by an invertor to the turbine's a.c. generator. The generator operates as a motor during starting. The invertor is initially coupled directly to the generator during starting, and to the generator via a step-up transformer after the speed of the generator increases. In a preferred embodiment of the invention, the transformer is an autotransformer used to step down the output of the generator when operating as a generator after the turbine has been started.

Abstract: A low voltage battery provides the power source for energizing an aircraft generator to operate it as a motor during a starting operation. The battery is coupled to an input to an inverter whose a.c. output is controlled by a pulse width modulator. By controlling the switching points of the output, the generator is so energized that it operates as a brushless d.c. motor. At a point where the available voltage to the generator is insufficient to further accelerate the turbine, even with field weakening and an increased commutation angle, an autotransformer is switched into the system to step up the output voltage from the invertor. Throughout the starting operation the commutation angle is controlled so that current drain on battery is such that the battery terminal voltage at one half its no load terminal voltage, thus providing maximum power transfer from the battery.

Abstract: A power conversion system utilizes a brushless generator driven by a prime mover when operating in a generating mode and drives the prime mover when operating in a starting mode. The system includes first and second bidirectional converter/inverter units, each of the bidirectional units being operable as either an AC to DC converter or a DC to AC inverter. A DC link couples the first and second bidirectional units. A transformer is connected to the second unit and the first unit is further connected to the armature windings, the transformer further being connected to the external power source. A control unit is connected to the first and second bidirectional units and causes the first bidirectional unit to operate as a converter and the second bidirectional unit to operate as an inverter when operating in the generating mode, and for causing the first bidirectional unit to operate as an inverter and the second bidirectional unit to operate as a converter when operating in the starting mode.

Abstract: Prior power conversion system operable in generating and starting modes have utililzed brushless generators which are suitable for only certain applications. In order to overcome this problem, a power conversion system operable in generating and starting modes utilizes a switched reluctance motor/generator which is reliable and inexpensive and which can be used in a variety of environments.

Abstract: A dual purpose alternator starter for an automotive vehicle designed to be positioned between the engine and transmission. In place of the ring gear in a conventional drive train assembly, a pair of off set magnetically permeable discs are bolted to the power shaft. These discs form an annular channel between them. A plurality of rare earth permanent magnets are mounted on the inside face of one of the discs in the channel. On the opposite side of this disc, a set of ring shaped switch contact members are mounted. Positioned stationary to the engine and within the channel is a stationary ironless stator assembly having flat copper windings embedded in an insulation matrix. These windings alternately pass from the perimeter of the disc towards the interior of the disc as each winding forms a single pass around the ring shaped disc.

Abstract: An inverter for use with a brushless generator for operating the generator in generating and starting modes includes an interphase transformer (IPT) having first and second end terminals and a mid-tap, a first subinverter coupled between a rectifier and the first end terminal of the IPT and a second subinverter. Contactors are operable in the generating mode for coupling a main generator portion armature winding to the rectifier and the second subinverter between the rectifier and the second end terminal of the IPT. The contactors are operable in the starting mode for coupling a source of power to the rectifier, the IPT mid-tap to the main generator portion armature winding and the second subinverter between the rectifier and an exciter field winding of the geneator.

Abstract: A power conversion system is operable in a generating mode to convert motive power developed by a prime mover into electrical power and in a starting mode to convert electrical power developed by a source of AC power into motive power for starting the prime mover. The system includes a stepped waveform inverter having a plurality of subinverters that are operable in the generating mode to produce rectangular waveforms wherein the waveforms are summed by a summing transformer to produce a stepped AC output waveform. During operation in the starting mode, the output of a rectifier bridge and an input of one of the subinverters are connected together by an interphase transformer. DC power is developed at a mid-tap of the interphase transformer and is delivered to the remaining subinverters which in turn develop AC power for operating a brushless generator as a motor.

Abstract: This invention relates to a bus configuration for a dual channel variable speed constant frequency motor/generator aircraft power system providing for both power generation and engine starting. The subject invention provides for isolation of faults which can occur in long power feeders. Further, the subject invention provides for a novel start mode of operation which allows one channel to provide power to the other channel, thereby avoiding inefficient multiple converter operation and potentially faulty power buses. The bus configuration provides for coupling a first motor/generator to a second motor/generator via a first converter to thereby allow th first motor/generator, operating as a generator, to supply variable frequency power to the first converter, the first converter supplying variable frequency power to the second motor/generator to operate the second motor/generator as a motor.

Abstract: A hybrid electrical generator (20) is disclosed. The hybrid electrical generator has a permanent magnet generator (22) having a permanent magnet rotor (32) mounted on a shaft (26) with the permanent magnet generator providing an output voltage over an operating range which falls in response to an increasing electrical load. The hybrid electrical generator has a variable reluctance generator (24) having a rotor (34) mounted on the shaft with excitation of a stator (30) being provided by the permanent magnet generator. The variable reluctance generator provides an output voltage which varies in response to an increasing load over an operating range. A voltage regulator, responsive to the electrical outputs of the generators, controls the output voltage of the variable reluctance generator to provide a regulated output voltage which is substantially constant independent of electrical load over an operating range.

Abstract: A variable speed, constant frequency starter generator system is provided with a dynamoelectric machine, electrically connected to a multiple-phase bus and pair of multiple-phase rectifiers for producing a DC voltage on a pair of link conductors. An inverter converts the DC voltage to floating AC voltage which is further converted to a ground-referenced AC voltage by a transformer. During generator operation, the output voltage of the machine is rectified by at least one of the rectifiers to produce a DC voltage on the link conductors which is converted to a constant frequency AC voltage by the inverter. During starter operation, an externally supplied AC voltage is applied to the transformer. The transformer converts the externally applied AC voltage to a pair of phase-displaced AC voltages which are rectified by the pair of multiple phase rectifiers to produce twelve-pulse rectified DC voltage on the link conductors. This reduces the harmonic content of the current supplied by the external power source.

Abstract: A power conversion system is operable in a generating mode to convert motive power developed by a prime mover into electrical power and in a starting mode to convert electrical power developed by a source of AC power into motive power for starting the prime mover. The system includes a rectifier having an output coupled to a DC link, first and second inverters, each coupled to the DC link and transformer including first and second sets of primary windings and a set of secondary windings wherein the second set of primary winding is coupled to an output of the second inverter. Contactors are provided for coupling the rectifier to the generator armature windings and the first set of primary windings to an output of the first inverter so that AC power produced by the generator is converted into DC power on the DC link and the DC power is converted into fixed frequency AC power which is developed in the set of secondary windings.

Abstract: A starting system for an aircraft propulsion engine. An electrical motor (62 or 122) is mounted within a case (14) in which first and second hydraulic units (102, 104) are operated as part of a constant speed drive transmission. The electric motor accelerates a motor-generator set (24) to a velocity near the synchronous speed. The motor-generator set is coupled to the drive shaft (20) by operation of the hydraulic units as a variable torque link. The electric motor functions both as a heat source of hydraulic fluid contained within the hydraulic pump and motor case during extreme low temperature conditions at which point the starting torque of the motor is initially insufficient to cause rotation of the output shaft and to further accelerate the motor-generator set up to a rotational velocity at which the motor-generator set may be operated synchronously at which the motor-generator set is coupled to the drive shaft (120) by operation of the hydraulic units as a variable torque link to rotate the engine.

Abstract: A power supply system for developing electrical power from variable-speed motive power produced by a prime mover includes a differential speed summer having a first shaft coupled to the prime mover and further having second and third shafts coupled to first and second generators, respectively, a power conditioner coupled to the second generator for conditioning the power developed thereby and means for regulating the conditioned power developed by the second generator so that the first generator develops constant-frequency AC power.

Abstract: A variable speed, constant frequency electrical generating system has a variable speed, engine driven generator. The system operates in either a generate or an engine start mode. A bidirectional filter connected between the rectifier-converter and the AC bus traps or blocks switching harmonics from the rectifier-converter. Shunt trap circuits are connected either phase-to-phase or phase-to-neutral.

Abstract: An AC exciter and a main AC generator are mounted on a common rotating shaft of an engine, and a power rectifier and a power inverter are connected in series to the output of the main AC generator. In starter mode, an external AC power source is connected by a switch to the input of the power rectifier, and the output of the power inverter is applied to an armature winding of the main AC generator to drive it as a nocommutator motor to start the engine. A permanent magnet AC generator is also mounted on the common shaft of the engine to provide DC excitation to the AC exciter after converting the output of the permanent magnet AC generator into DC current, and the output of the permanent magnet AC generator is further utilized to detect the rotational speed of the engine to control the switch.

Abstract: A starting system and method for starting a prime mover connected to a generator by an actuable torque link utilizes a hybrid permanent magnet/induction machine having a rotor coupled to a rotor of the main generator and a stator having windings therein. The method includes the step of applying AC power to the hybrid machine stator windings so that the hybrid machine initially acts as an induction motor to accelerate the hybrid machine rotor, following which the hybrid machine acts as a synchronous motor to rotate the main generator rotor at a particular speed DC power is then applied to a main generator field winding and AC power is supplied to a set of main generator armature windings so that the main generator operates as a synchronous motor to develop motive power the torque link is activated once the main generator is operating as a synchronous motor to bring the prime mover up to self-sustaining speed.

Abstract: A unitary starter motor and generator including a rotor assembly having a plurality of circumferentially disposed rare earth-iron permanent magnets, a stator assembly within which said rotor assembly is rotatable, said stator assembly including a laminated annular stator body formed from a silicon containing iron alloy of high electrical resistivity and low magnetic loss, and a multiphase stator winding secured to the inner periphery of said stator body and lying in the airgap defined between the stator body and the rotor assembly.

Abstract: Engine start capability may be added to an aircraft generating system including a variable speed, constant frequency inverter 34 by placing transistors 48 in shunt relation to diodes 22 forming part of a full wave rectifier for rectifying A.C. power from a brushless generator output winding 10 which is normally supplied to the inverter 34 for conversion to constant frequency A.C. power. A source of D.C. power 60 may be connected to the diodes 22 and transistors 48 and the latter are operated by an inverter controller 52 to convert the D.C. power so provided to alternating current to be fed to the brushless generator output windings 10 and cause the brushless generator to operate as an A.C. motor for the starting of a turbine engine 18 or the like.

Abstract: The output current and drive torque characteristics of a vehicle generator during cold, startup periods are approximated to those of a warmed up generator by sensing the field winding current, and interrupting it for a time period prolonged by a feedback/charging capacitor (904) whenever it exceeds a reference level. The field winding current never exceeds the reference level when the generator is warmed up, whereupon the interrupting circuitry has no effect.

Abstract: A speed control unit for an aircraft generator includes a continuously variable gear ratio drive device through which the generator is driven by a shaft of the engine and which is responsive to an error signal indicative of a difference between desired and sensed generator speeds. A control circuit prevents the error signal from being applied to the drive device until a predetermined speed of the generator is reached and a ramp generating circuit increases the rise time of the error signal after the generator has reached the predetermined speed.

Abstract: An electric braking apparatus for exerting the electric braking action (dynamic braking action) on a generator, further concretely a generator with a brushless exciter which is so constructed that a rectifying circuit for applying field voltage to the brushless exciter as a braking current to be applied to the generator is normally applied with exciting voltage at least during the running of the generator, thereby enabling the electric braking to be applied even on the generator which uses the brushless exciter and which has hitherto never been applicable of the same.

Abstract: A power supply system for supplying electrical energy at an I.S. level to an electrical machine e.g. of a mineral mining machine, comprises two low speed generators A and B mechanically coupled together at coupling 3 and rotatable by means of a drive shaft 2, the mechanical input at the drive shaft 2 producing a separate, isolated electrical output at each of the generators A and B, the output from a first generator A being fed to an I.S. barrier 10, whereby an I.S. power supply is made available to power a first circuit 4, the output from the second generator B being fed to a non-I.S. supply circuit 8, and an I.S. coupling device 7 between the I.S. circuit 4 and the non-I.S. circuit 8, to achieve electrical and physical segregation of the circuits 4 and 8.

Abstract: An electric power supply system for portable miniature size power consuming devices, comprising an AC generator, a rechargeable battery and a charging device to be fed from the AC generator and maintaining the battery charging level, the AC generator comprising a multi-polar rotor wheel having permanently magnetized poles, a stator having one or more windings providing the AC current and an eccentric mass driving the permanently magnetized rotor wheel; the rotor wheel, the stator and the eccentric mass being mounted coaxially, a transmission being arranged between the eccentric mass and the rotor wheel. According to the invention the transmission is a loose coupling means to be tightened by magnetic fields between the poles of the rotor wheel and the respective poles of the stator.