WO2018162390A1 - Machine électrique - Google Patents

Machine électrique Download PDF

Info

Publication number
WO2018162390A1
WO2018162390A1 PCT/EP2018/055308 EP2018055308W WO2018162390A1 WO 2018162390 A1 WO2018162390 A1 WO 2018162390A1 EP 2018055308 W EP2018055308 W EP 2018055308W WO 2018162390 A1 WO2018162390 A1 WO 2018162390A1
Authority
WO
WIPO (PCT)
Prior art keywords
rotor
stator
load
electrical machine
exciter winding
Prior art date
Application number
PCT/EP2018/055308
Other languages
English (en)
Inventor
Andrew BLOOR
Original Assignee
Safran Electrical & Power
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Safran Electrical & Power filed Critical Safran Electrical & Power
Publication of WO2018162390A1 publication Critical patent/WO2018162390A1/fr

Links

Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/48Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34Testing dynamo-electric machines
    • G01R31/343Testing dynamo-electric machines in operation
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K11/00Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/20Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/14Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
    • H02P9/16Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field due to variation of ohmic resistance in field circuit, using resistances switched in or out of circuit step by step
    • H02P9/18Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field due to variation of ohmic resistance in field circuit, using resistances switched in or out of circuit step by step the switching being caused by a servomotor, measuring instrument, or relay
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/14Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
    • H02P9/26Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices
    • H02P9/30Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices
    • H02P9/302Brushless excitation
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K11/00Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/20Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
    • H02K11/25Devices for sensing temperature, or actuated thereby
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K11/00Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/20Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
    • H02K11/26Devices for sensing voltage, or actuated thereby, e.g. overvoltage protection devices
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02KDYNAMO-ELECTRIC MACHINES
    • H02K11/00Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/20Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for measuring, monitoring, testing, protecting or switching
    • H02K11/27Devices for sensing current, or actuated thereby
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02PCONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2101/00Special adaptation of control arrangements for generators
    • H02P2101/30Special adaptation of control arrangements for generators for aircraft

Definitions

  • the present disclosure relates to an electrical machine, a rotor for an electrical machine, a monitor module for use with an electrical machine and a method of determining a first machine characteristic of an electrical machine during operation of the electrical machine.
  • Electrical machines are electromechanical energy converters that convert electricity to mechanical power or vice-versa .
  • One example of an electrical machine is an electric motor that converts electricity to mechanical power.
  • Another example of an electrical machine is an electric generator that converts mechanical power to electricity. The construction and operation of the various different typical electrical machines will be well understood by the skilled person.
  • Electrical machines may be used in aviation for a number of different purposes.
  • electric generators may be fitted to aircraft to convert mechanical power from the aircraft engines to electrical power.
  • Electrical machines, particularly electric generators, that are suitable for use in aviation need to be able to operate at speeds relatively high speeds.
  • electrical machines that are suitable for use in aviation current need to operate at speeds of up to 24,000rpm, although there is a general trend for increasing the maximum speed, such that electrical machines suitable for use in aviation may need to be able to operate at speeds of up to around 28,000rpm, or higher, in the future. Therefore, any equipment operating on the rotor of an aviation electrical machine must be capable of withstanding high centrifugal acceleration levels.
  • the equipment operating on the rotor of the aviation electrical machine should also be capable of withstanding wide temperature ranges, high levels of vibration and immersion in turbine oil. Furthermore, the electrical machine as a whole, including any equipment operating on the rotor of the electrical machine, should also be as small and/or as light as possible, and have long service intervals.
  • Those reasons may include one or more of the following : To validate a theoretical model of an electrical machine during development of a new electrical machine, for example by comparing the actual measurements of one or more machine characteristics with values that are predicted by the theoretical model. In this way, the theoretical model may be improved and/or the design of the electrical machine may be improved.
  • the rotor of an electrical machine is a moving part (most commonly rotating about an axis), it can be difficult to reliably communicate signals from the rotor, and therefore to reliably obtain measurements relating to the rotor.
  • Brushed electrical machines comprise brushes and a slip ring on the rotor.
  • the slip ring rotates with the rotor and interfaces with the stationary brushes.
  • Electrical signals may be communicated to and/or from the rotor through the slip ring and brushes.
  • signals (such as measurements taken on the rotor, or rotor currents to be measured) may be communicated from the rotor to some external entity (for example, to a failure diagnostics module).
  • brushed electrical machines tend to have problems with reliability and require regular servicing. Furthermore, they tend to be large, heavy and have a large overhung moment. Therefore, for many applications, particularly where reliability, weight and size are important (such as in aviation), it is preferable to use brushless electrical machines. Brushless electrical machines do not have a slip ring and brushes, therefore signals cannot be communicated from the rotor in this way.
  • US 2007/0014374 Al describes an isolation device comprising a pulse transformer isolation barrier.
  • the device is configured to perform time division multiplexed transmission of power and data from a primary coil of the transformer to a secondary coil of the transformer.
  • power is transmitted from the primary coil to the secondary coil
  • data is transmitted from the primary coil to the secondary coil.
  • Data is transmitted across the transformer digitally during the data frames, for example using Manchester Coded Data.
  • Duplex communication i.e., communication from the primary coil to the secondary coil and communication from the secondary coil to the primary coil
  • the load current on the primary coil of the digital signal to be transmitted from the primary coil to the secondary coil will change.
  • This change in primary load current caused by a change in load on the secondary coil may be detected by isolating the component of primary side current that is caused by load impedance from the component of primary side current that is caused by magnetising inductance.
  • This may be achieved by using a transmit data encoding scheme for the digital communication from primary to secondary that is double DC balanced (i.e., DC balanced in both current and voltage) and then measuring primary side current at the specific times magnetizing inductance current is known to be close to zero, or by generating a compensating current which acts to cancel the magnetizing inductance current.
  • an electrical machine comprising : a rotor comprising one or more rotor exciter windings; a stator exciter winding for receiving a stator current to establish a magnetic field for causing electrical induction in the one or more rotor exciter windings; a first loading module mounted on the rotor and configured to: receive a first input indicative of a first machine characteristic; and apply a first load to a first rotor exciter winding of the one or more rotor exciter windings based at least in part on the received first input; and a monitor module coupled to the exciter stator and configured to: detect an effect of the applied first load on the stator current; and determine the first machine characteristic based at least in part on the detected effect of the applied first load on the stator current.
  • the effect of the applied first load on the stator current may comprise a first pulse in the stator current corresponding to the first rotor exciter winding passing the stator exciter winding.
  • the monitor module may be further configured to: detect a synchronisation pulse in the stator current; and detect the first pulse in the stator current using at least the synchronisation pulse.
  • the synchronisation pulse may be generated by a synchronisation rotor exciter winding of the one or more rotor windings passing the stator exciter winding.
  • the synchronisation pulse may be a pulse in the stator current with a peak value that is outside of an allowable operating range of the first pulse in the stator current.
  • the electrical machine further comprises a power supply module mounted on the rotor, wherein the power supply module is coupled to the first loading module to provide electrical power to the first loading module.
  • the power supply module may be coupled to the synchronisation rotor exciter winding to draw electrical power from the synchronisation rotor exciter winding, or coupled to a rotor generator winding to draw electrical power from the rotor generator winding.
  • the electrical machine may further comprise: a second loading module mounted on the rotor and configured to: receive a second input indicative of a second machine characteristic; and apply a second load to a second rotor exciter winding of the one or more rotor exciter windings based at least in part on the received second input; and wherein the monitor module is further configured to: detect an effect of the applied second load on the stator current; and determine the second machine characteristic based at least in part on the detected effect of the applied second load on the stator current.
  • a second loading module mounted on the rotor and configured to: receive a second input indicative of a second machine characteristic; and apply a second load to a second rotor exciter winding of the one or more rotor exciter windings based at least in part on the received second input
  • the monitor module is further configured to: detect an effect of the applied second load on the stator current; and determine the second machine characteristic based at least in part on the detected effect of the applied second load on the stator current
  • the effect of the applied second load on the stator current may comprise a second pulse in the stator current corresponding to the second rotor exciter winding passing the stator exciter winding.
  • the electrical machine further comprises a first alternating voltage source coupled to the stator exciter winding and configured and to apply a first alternating voltage to the stator exciter winding at a first frequency.
  • a first alternating voltage source coupled to the stator exciter winding and configured and to apply a first alternating voltage to the stator exciter winding at a first frequency.
  • the monitor module is tuneable to the first frequency to detect the effect of the applied first load on the stator current at the first frequency and determine the first machine characteristic based at least in part on the detected effect of the applied first load on the stator current at the first frequency.
  • the first loading module is tuned to the first frequency so that the applied first load is presented to an electrical signal induced in the first rotor exciter winding and alternating at the first frequency.
  • the electrical machine may be further configured to communicate the first machine characteristic and a further machine characteristic from the rotor to the monitor module using frequency division multiplexing.
  • the electrical machine may further comprise: a multiplexing loading module mounted on the rotor, wherein the multiplexing loading module is tuned to a second frequency and is configured to: receive an input indicative of the further machine characteristic; and apply a multiplexing load to any of the one or more rotor exciter windings based at least in part on the received first input so that the applied multiplexing load is presented to an electrical signal induced in the rotor exciter winding and alternating at the second frequency; and the monitor module is further tuneable to the second frequency to detect the effect of the applied multiplexing load on the stator current at the second frequency and determine the further machine characteristic based at least in part on the detected effect of the applied multiplexing load on the stator current at the second frequency.
  • the electrical machine may further comprise a second alternating voltage source coupled to the stator exciter winding and configured to apply a second alternating voltage to the stator exciter winding at the second frequency.
  • the rotor exciter winding to which the multiplexing load is applied may be the first rotor exciter winding.
  • the first machine characteristic may comprise any of: a rotor temperature; an air gap temperature; an electrical machine temperature; a rotor diode current; a rotor diode voltage; a rotor generator winding current; a rotor generator winding voltage; a mechanical strain on the rotor; an oil pressure; an oil flow; or any other measurable feature, characteristic or parameter relating to the electrical machine.
  • the first loading module is configured to apply the first load to at least one further rotor exciter winding of the one or more rotor exciter windings based at least in part on the received first input. In this way, the first loading module may apply the first load to two or more rotor exciter windings (for example, some or all of the rotor exciter windings)
  • a rotor for use in the electrical machine comprising : one or more rotor exciter windings; and a first loading module configured to: receive a first input indicative of a first machine characteristic; and apply a first load to a first rotor exciter winding of the one or more rotor exciter windings based at least in part on the received first input.
  • a monitor module for coupling to the stator exciter winding of the electrical machine provided above, the monitor module being configured to: detect an effect on the stator current caused by a first load applied to a first rotor winding of the rotor of the electrical machine, wherein the first load is applied by a first loading module based at least in part on a first input that is indicative of a first machine characteristic; and determine the first machine characteristic based at least in part on the detected effect of the applied first load on the stator current.
  • a method of determining a first machine characteristic of an electrical machine during operation of the electrical machine comprising : applying a voltage across a stator exciter winding of the electrical machine; applying a first load to a first rotor exciter winding of the rotor based at least in part on a signal indicative of the first machine characteristic; detecting an effect of the applied first load on a stator current through the stator exciter winding; and determining the first machine characteristic based at least in part on the detected effect of the applied first load on the stator current.
  • a rotor for use in the electrical machine provided above, the rotor comprising : one or more rotor exciter windings; one or more loads; and a first loading module configured to: receive a first input indicative of a first machine characteristic; and apply a first load of the one or more loads to a first rotor exciter winding of the one or more rotor exciter windings based at least in part on the received first input.
  • Figure 1 shows an example prior art three-phase brushless electrical machine
  • Figure 2 shows an electrical machine in accordance with an aspect of the present disclosure
  • Figure 3 shows an example waveform representing changes in the stator exciter winding alternating current of the electrical machine of Figure 2;
  • Figure 4 shows an electrical machine in accordance with a further aspect of the present disclosure
  • Figure 5 shows an example waveform representing changes in the stator exciter winding alternating current of the electrical machine of Figure 5;
  • Figure 6 shows a further example waveform representing a stator exciter winding alternating current of the electrical machine of Figure 5;
  • Figure 7 shows an example configuration of some of the modules of the electrical machines represented in Figure 2 and 4. Detailed description
  • the present disclosure relates to an electrical machine that is configured to communicate at least one machine characteristic from a rotor of the electrical machine to an off-rotor monitor module whilst the electrical machine is operating.
  • the characteristic is communicated by applying a load to at least one of the rotor exciter windings based at least in part on the machine characteristic and the monitor module detecting the effect that causes on the stator exciter winding current.
  • FIG. 1 of the drawings shows an example prior art, three-phase brushless electrical machine 100.
  • the operation of the brushless electrical machine 100 will be well understood by the person skilled in the art. Nevertheless, a brief description of the brushless electrical machine 100 operating as an electrical generator is given below.
  • the electrical machine 100 comprises a stator 120 and a rotor 130.
  • the stator 120 comprises a stator exciter winding 122 and a main exciter DC drive 110 is configured to apply a DC voltage across the stator exciter winding 122. This causes the stator exciter winding 122 to establish a magnetic field.
  • the rotor 130 comprises three rotor exciter windings 132-1, 132-2, 132-3 that are configured for three-phase electrical generation.
  • the rotor 130 is configured to rotate about its axis, such that as the rotor 130 rotates, each of the three rotor exciter windings 132-1, 132-2, 132-3 pass in turn through the magnetic field established by the stator exciter winding 122.
  • the first rotor exciter winding 132-1 may pass through the magnetic field established by the stator exciter winding 122 as the rotor 130 rotates, thereby causing a peak in electrical induction in the first rotor exciter winding 132-1.
  • the second rotor exciter winding 132-2 may pass through the magnetic field established by the stator exciter winding 122, thereby causing a peak in electrical induction in the second rotor exciter winding 132-2.
  • the third rotor exciter winding 132-3 may pass through the magnetic field established by the stator exciter winding 122, thereby causing a peak in electrical induction in the third rotor exciter winding 132-3.
  • the first rotor exciter winding 132-1 may again pass through the magnetic field established by the stator exciter winding 122, thereby again causing a peak in electrical induction in the first rotor exciter winding 132-1, and so on.
  • the rotor diodes 134 are configured as a three-phase bridge rectifier to rectify the induced 3-phase, AC voltage generated by the rotor exciter windings 132-1, 132- 2, 132-3.
  • the rectified voltage is applied across the rotor generator winding 136 to establish a magnetic field.
  • the stator 120 further comprises three stator generator windings 124-1, 124-2, 124-3, that are configured for three-phase electrical generation.
  • the stator generator windings 124-1, 124-2, 124-3 are arranged such that as the rotor 130 rotates, the magnetic field established by the rotor generator winding 136 passes through each of the three stator generator windings 132-1, 132-2, 132-3 in turn.
  • the magnetic field established by the rotor generator winding 136 may pass through the first stator generator winding 124-1, thereby causing a peak in electrical induction in the first stator generator winding 124-1.
  • the magnetic field established by the rotor generator winding 136 may pass through the second stator generator winding 124-2, thereby causing a peak in electrical induction in the second stator generator winding 124-2.
  • the magnetic field established by the rotor generator winding 136 may pass through the third stator generator winding 124-3, thereby causing a peak in electrical induction in the third stator generator winding 124-3.
  • the magnetic field established by the rotor generator winding 136 may again pass through the first stator generator winding 124-1, thereby causing a peak in electrical induction in the first stator generator winding 124-1, and so on.
  • the electrical machine 100 generates a three- phase AC voltage at the generator output terminals 126.
  • RF radiofrequency
  • the radiofrequency used must be one that is allocated by the relevant authorities (for example, governmental agencies, such as Ofcom in the UK, or the FCC in the US) for use for this purpose (i.e., the radiofrequency used should be within a part of the frequency spectrum that is allocated for such purposes). Because different countries allocate the parts of their radiofrequency spectrum differently, the radiofrequency to be used may be different depending on the country in which the electrical machine is operating.
  • FIG. 2 show an example representation of an electrical machine 200 in accordance with an aspect of the present disclosure.
  • the electrical machine 200 is similar to that described in respect of Figure 1 and the process of generating a three-phase AC voltage at the output terminals 126 is the same as that described in respect of Figure 1.
  • the electrical machine 200 represented in Figure 2 also includes some additional components to enable measurements, or other signals or values indicative of a characteristic of the electrical machine 200, to be communicated from the rotor 130 to a monitor module 240 that is off the rotor 130.
  • the electrical machine 200 comprises a first alternating voltage source 210, which is coupled to the stator exciter winding 122 in order to apply a first alternating voltage to the stator exciter winding 122.
  • the first alternating voltage source 210 is coupled to the stator exciter winding 122 using a voltage transformer 212, although it will be appreciated that they may be coupled in any other suitable way. Consequently, an alternating current is superimposed on the direct current of the main exciter DC drive 110.
  • the first alternating voltage may alternate at any suitable frequency and at any suitable voltage level.
  • it may be at any frequency between about 100Hz to 10kHz, such as 800Hz, or 4kHz, or 9kHz, or at a frequency between about 500Hz to 5kHz, such as 1.2kHz, or 3.5kHz, or at a frequency between about 1kHz to 2kHz, such as 1.1kHz, or 1.87kHz, etc.
  • the voltage level may be any suitable voltage which may, for example, be chosen in consideration of the voltage level of the DC exciter drive 110.
  • it may have a peak-to- peak voltage of between 0.2V to 100V, such as 0.6V, or 35V, or 90V, or a peak- to-peak voltage of between about 0.5V to 40V, such as 4V, or 26V, or a peak-to- peak voltage of between about IV to 3V, such as 1.5V, or 2.45V, etc.
  • the alternating current superimposed on the direct current supplied to the stator exciter winding 122 causes an alternating magnetic field to be established by the stator exciter winding 122 at the frequency of the alternating voltage supplied by the first alternating voltage source 210.
  • This will induce an alternating current in each of the rotor exciter windings 132-1, 132-2, 132-3 as they each pass the stator exciter winding 122 as the rotor 130 rotates.
  • the frequency of the induced current will alternate with a frequency that is the same as, or similar to, the frequency of the alternating voltage supplied by the first alternating voltage source 210.
  • a first loading module 230 is mounted on the rotor 130 at any convenient location.
  • the first loading module 230 is coupled across a resistor 235 that is in series with the rotor generator winding 136.
  • the first loading module 230 receives an input signal that is indicative of the current through the rotor generator winding 136 (i.e., the rotor generator winding current).
  • the first loading module 230 can measure the rotor generator winding current.
  • a power supply module 220 is also mounted on the rotor 130 at any convenient location.
  • the power supply module 220 is coupled to the rotor generator winding 136 in order to draw power from the rotor generator winding 136 (i.e., it is coupled across the rotor generator winding 136).
  • the power supply module 220 is also coupled to the first loading module 230 in order to provide electrical power to the first loading module 230, so that the first loading module 230 can perform the functionality described below.
  • the power supply module 220 may optionally comprise a smoothing capacitor and regulator to supply consistent DC power to the first loading module 230.
  • the first loading module 230 is coupled to the first rotor exciter winding 132-1 and is configured to apply a load to the first rotor exciter winding 132-1 based at least in part on its received input that is indicative of the rotor generator winding current.
  • the load applied to the first rotor exciter winding 132-1 will affect the electrical induction of the first rotor exciter winding 132-1 as it passes the stator exciter winding 122. For example, depending on the type of load (for example, resistive, reactive, etc) an increase in the load applied may increase the level of electrical induction in the first rotor exciter winding 132-1, and a decrease in the load applied may decrease the level of electrical induction in the first rotor exciter winding 132-1.
  • the load may be an ohmic resistive load, or a reactive load, or an impedance with ohmic resistance and also reactance.
  • the load may comprise at least one of a resistor(s), a capacitor(s), an inductor(s) and/or an active element(s), such as a semiconductor device.
  • the level of electrical induction that takes place in the first rotor exciter winding 132-1 as it passes the stator exciter winding 122 affects the amount of current drawn by the stator exciter winding 122 as the first rotor exciter winding 132-1 passes.
  • the level of electrical induction in the first rotor exciter winding 132-1 increases, the amount of current drawn by the stator exciter winding 122 as the first rotor exciter winding 132-1 passes the stator exciter winding 122 will increase, and if the level of electrical induction in the first rotor exciter winding 132-1 decreases, the amount of current drawn by the stator exciter winding 122 as the first rotor exciter winding 132-1 passes the stator exciter winding 122 will decrease.
  • the monitor module 240 is coupled to the stator exciter winding 122 via a current transformer 242 and is configured to detect an effect of the load applied to the first rotor exciter winding 132-1 on the stator exciter winding alternating current.
  • the monitor module 240 can detect a change (an increase or a decrease) in the level of stator exciter winding alternating current, and optionally a magnitude of that change. It will be appreciated that whilst the monitor module 240 detects changes in the stator exciter winding alternating current with use of a current transformer 242 in this particular example, it may alternatively be coupled to the stator exciter winding 122 and detect changes in the stator exciter winding alternating current by any other suitable means.
  • Figure 3 shows a simplified example waveform representing changes in the level of alternating current in the stator exciter winding (for example, changes in the peak-to-peak current, or changes in the rms current, etc).
  • the x-axis represents time and the y-axis represents the change in current.
  • the monitor module 240 is configured to detect, only the peaks in the alternating current in the stator exciter winding 122 are shown and all noise and other signals are excluded.
  • the first rotor exciter winding 132-1 passes the stator exciter winding 122 and causes a peak of Ii in the alternating current in the stator exciter winding 122. At this point, the rotor 130 may be considered to have rotated by 0°.
  • the second rotor exciter winding 132-2 passes the stator exciter winding 122 and causes a peak of b in the alternating current in the stator exciter winding 122. At this point, the rotor 130 may be considered to have rotated by 120°.
  • the third rotor exciter winding 132-3 passes the stator exciter winding 122 and causes a peak of h in the alternating current in the stator exciter winding 122. At this point, the rotor 130 may be considered to have rotated by 240°.
  • the first rotor exciter winding 132-1 once again passes the stator exciter winding 122 and causes a peak of about Ii in the alternating current in the stator exciter winding 122. At this point, the rotor 130 has made a complete rotation and may therefore be considered to have rotated by 0°.
  • the time T between ti and t 4 represents the time for a complete rotation of the rotor 130, and is therefore the period of rotation of the rotor 130.
  • the load on the second rotor exciter winding 132-2 is not changed, so the peak in the alternating current in the stator exciter winding 122 as the second rotor exciter winding 132-2 passes the stator exciter winding 122 (at times t2, ts, ts and in) stays substantially constant at b (for example, constant within reasonable operating thresholds).
  • the load on the third rotor exciter winding 132-3 is not changed, so the peak in the alternating current in the stator exciter winding 122 as the first rotor exciter winding 132-3 passes the stator exciter winding 122 (at times t3, ⁇ , tg and ti2) stays substantially constant at (for example, constant within reasonable operating thresholds).
  • the load applied to the first rotor exciter winding 132-1 by the first loading module 230 is the same, such that as the first rotor exciter winding 132- 1 passes the stator exciter winding 122, the peak in the alternating current in the stator exciter winding 122 stays substantially consta nt at Ii (for example, constant within reasonable operating thresholds) .
  • the first loading module 230 changes the load applied to the first rotor exciter winding 132- 1 because a change in the rotor generator current has been measured by the first loading module 230.
  • the monitor module 240 is configured not only to detect a change in the alternating current in the stator exciter winding 122, but also to measure the alternating current in the stator exciter winding 122 (for example, measure the peak value in alternating current, or the peak value in the rms of the alternating current), it may be calibrated to determine the load applied by the first loading module 230 based on that measure of alternating current.
  • the first loading module 230 may be configured to apply particular sizes of load (for example, a particular magnitude or value of load) to represent particular values of measured rotor generator current (for example, the a pplied load may change proportiona lly with measured rotor generator current)
  • the machine characteristic may be communicated to the monitor module 240 in an analogue fashion (for example, an analogue measurement or signal may be communicated from the rotor 130 to the monitor module 240 in an analogue way) .
  • the measured value of the rotor generator current may be communicated quickly and straightforwardly to the monitor module 240 by the first loading module 230 applying a load to the first rotor exciter winding 132- 1 that is based at least in part on the measured value of the rotor generator current.
  • the first loading module 230 may receive an input indicative of some other machine characteristic. For example, it may receive an input indicative of a rotor temperature, an airgap temperature or an electrical machine temperature (for example, received from a temperature sensor on the rotor 130) . Alternatively, it may receive an input indicative of a current or voltage for one or more of the rotor diodes 134. Alternatively, it may receive an input indicative of the voltage across the rotor generator winding 136. Alternatively, it may receive an input indicative of mechanical strain somewhere on the rotor 130, or oil pressure within the electrical machine 100, or oil flow within the electrical machine 100.
  • the machine characteristic may simply be whether one or more of the rotor diodes 134 have failed, such that the input is indicative of either 'working' or 'failed'.
  • the machine characteristic may be whether a temperature is above or below a particular threshold temperature, or whether a current is above or below a particular threshold current, or whether a voltage is above or below a particular threshold voltage.
  • the first loading module 230 is configured to apply a load to the first rotor exciter winding 132-1 based on the input and the monitor module 240 is configured to detect an effect on the stator exciter current caused by that applied load and determine the machine characteristic based at least in part on the detected effect.
  • the effect that the monitor module 240 is configured to detect may be that there has been a change in the stator exciter alternating current (for example, an increase or decrease in a peak value of a pulse in the stator exciter alternating current) and/or a measure (for example, a peak value, or peak-to-peak value, or peak rms, etc) of the stator exciter alternating current.
  • a change in the stator exciter alternating current for example, an increase or decrease in a peak value of a pulse in the stator exciter alternating current
  • a measure for example, a peak value, or peak-to-peak value, or peak rms, etc
  • a first machine characteristic may be communicated from the rotor 130 to the monitor module 240 with a minimum of additional components added to the electrical machine, meaning that the electrical machine 200 can still be made lightweight and small. Furthermore, only the first loading module 230 and the power supply 220 are added to the rotor 130, meaning that relatively high operating speeds for the electrical machine can still be achieved. Also, all of the additional the modules are capable of withstanding wide temperature ranges, high levels of vibration and immersion in turbine oil, and do not require any regular servicing so that the electrical machine 200 can have long service intervals. Therefore, the electrical machine 200 is particularly effective for use in aviation.
  • two or more machine characteristics may be communicated from the rotor 130 to the monitor module 240 using frequency division multiplexing.
  • a second alternating voltage source may be coupled to the stator exciter winding 122 (for example, via the voltage transformer 212, or via some other voltage transformer or any other means) and configured to apply a second alternating voltage to the stator exciter winding 122.
  • the second alternating voltage may alternate at any suitable frequency, which is different to the frequency of the first alternating voltage (applied by the first alternating voltage source 210).
  • the frequencies of the first alternating voltage and the second alternating voltage may be chosen so that they are non- harmonically related, optionally including sub-harmonics, so as to reduce or prevent distortion between the voltage signals.
  • the voltage level of the second alternating voltage may be any suitable voltage and may be the same as, or different to, the voltage level of the first alternating voltage.
  • the first loading module 230 may be tuned to the frequency of the first alternating voltage source 210 such that the load applied to the first rotor exciter winding 132-1 is presented to the alternating current induced in the first rotor exciter winding 132- 1 at, or near to, the frequency of the first alternating voltage source.
  • a multiplexing loading module may also be mounted on the rotor 130 and coupled to the first rotor exciter winding 132-1 and powered by the power supply module 220.
  • the multiplexing loading module may be very similar to the first loading module 230, but configured to receive an input of a different machine characteristic and apply a load (referred to from here on as a 'multiplexing load' for the sake of clarity) to the first rotor exciter winding 132-1 based at least in part on the received input. Furthermore, the multiplexing loading module is tuned to the frequency of the second alternating voltage source such that the load it applies to the first rotor exciter winding 132-1 is presented to the alternating current induced in the first rotor exciter winding 132-1 at the frequency of the second alternating voltage source. Techniques for tuning the loading modules to particular frequencies are described in more detail later with reference to Figure 7.
  • the load applied by the first loading module 230 to the first rotor exciter winding 132-1 will affect the level of electrical induction that takes place in the first rotor winding 132-1 at the frequency of the first alternating voltage source 210. This will in turn affect the amount of alternating current drawn by the stator exciter winding 122 at the frequency of the first alternating voltage source 210 as the first rotor exciter winding 132-1 passes.
  • the load applied by the multiplexing loading module to the first rotor exciter winding 132-1 will affect the level of electrical induction that takes place in the first rotor winding 132-1 at the frequency of the second alternating voltage source. This will in turn affect the amount of alternating current drawn by the stator exciter winding 122 at the frequency of the second alternating voltage source as the first rotor exciter winding 132-1 passes.
  • the monitor module 240 may be tuned to the frequency of the first alternating voltage source 210 to detect an effect on the alternating current of the stator exciter winding 122 caused by the load applied to the first rotor exciter winding 132-1 by the first loading module 230.
  • the first loading module 230 can receive a first input indicative of a first machine characteristic and the monitor module 240 can determine the first machine characteristic from the detected effect on the alternating current of the stator exciter winding 122 that is alternating at the frequency of the first alternating voltage source 210.
  • the monitor module 240 may also be tuned to the frequency of the second alternating voltage source (as described in more detail later with reference to Figure 7) to detect an effect on the alternating current of the stator exciter winding 122 caused by the load applied to the first rotor exciter winding 132-1 by the multiplexing loading module.
  • the multiplexing loading module can receive an input indicative of a further machine characteristic and the monitor module 240 can determine the further machine characteristic from the detected effect on the alternating current of the stator exciter winding 122 that is alternating at the frequency of the second alternating voltage source.
  • This frequency division multiplexing technique may be used to communicate more than two different machine characteristic from the rotor 130 to the monitor module 240 by using more than two different frequencies, for example, three, four, five, etc different frequencies. Each different frequency may be used to communicate a different machine characteristic from the rotor 130 to the monitoring module 240. Therefore, a plurality of machine characteristics can be communicated from the rotor 130 to the monitor module 240 with very few additional components.
  • the first alternating voltage source 210 and the second alternating voltage source are described as separate modules, they do not necessarily have to be separate modules.
  • a single module may be configured to generate two different alternating voltage signals with different frequencies by any suitable means, and those signals be superimposed on each other and applied to the stator exciter winding 122.
  • the loading modules are configured to apply a load to the first rotor exciter winding 132-1, they may alternatively apply a load to the second rotor exciter winding 132-2, or the third rotor exciter winding 132-3, or any two or more of the rotor exciter windings 132-1, 132-2, 132-3.
  • FIG 4 shows an example representation of an electrical machine 400 in accordance with a further aspect of the present disclosure.
  • the electrical machine 400 is similar to that described in respect of Figure 2.
  • the power supply module 410 which is mounted on the rotor 130 at any convenient location, is configured to be coupled to the third rotor exciter winding 132-3 in order to draw power from the third rotor exciter winding 132-3 (i.e., it is coupled across the third rotor exciter winding 132-3).
  • the power supply module 410 is coupled to the first loading module 230 and a second loading module 420 in order to provide electrical power to those loading modules.
  • the power supply module 410 may supply AC power to the first and second loading modules, or may supply DC power to the first and second loading modules, in which case the power supply module 410 may comprise a rectifier and optionally also a smoothing capacitor and/or a regulator.
  • the first loading module 230 is configured as described above is respect of Figure 2. It is configured to receive a first input indicative of a first machine characteristic, which in this example is the current in the rotor generator winding 136, as measured across the resistor 235, and apply a first load to the first rotor exciter winding 132-1 based at least in part on the received first input.
  • the second loading module 420 is configured similarly to the first loading module 230, but receives a second input indicative of a second machine characteristic. In this example, the second loading module 420 is coupled across the rotor generator winding 136, such that the second machine characteristic is the rotor generator winding voltage.
  • the second loading module 420 is also configured to apply a second load to the second rotor exciter winding 132-2 based at least in part on the received second input.
  • the size, or magnitude, of the second load applied to the second rotor exciter winding 132-2 will affect the electrical induction of the second rotor exciter winding 132-2 as it passes the stator exciter winding 122. This, in turn, affects the amount of current drawn by the stator exciter winding 122 as the second rotor exciter winding 132-2 passes.
  • the monitor module 240 can detect an effect of the applied second load on the stator exciter winding alternating current and determine the second machine characteristic based on that.
  • the second loading module 420 may receive an input indicative of some other machine characteristic. For example, it may receive an input indicative of a rotor temperature, an airgap temperature or an electrical machine temperature (for example, received from a temperature sensor on the rotor 130). Alternatively, it may receive an input indicative of a current or voltage for one or more of the rotor diodes 134. Alternatively, it may receive an input indicative of mechanical strain somewhere on the rotor 130, or oil pressure within the electrical machine 400, or oil flow within the electrical machine 400. Alternatively, it may receive an input indicative of a measure of any other characteristic.
  • the machine characteristic may receive an input indicative of a machine characteristic that is not a measure of something.
  • the machine characteristic may simply be whether one or more of the rotor diodes 134 have failed, such that the input is indicative of either 'working' or 'failed'.
  • the machine characteristic may be whether a temperature is above or below a particular threshold temperature, or whether a current is above or below a particular threshold current, or whether a voltage is above or below a particular threshold voltage.
  • the second loading module 420 is configured to apply a load to the second rotor exciter winding 132-2 based on the input and the monitor module 240 is configured to detect an effect on the stator exciter current caused by that applied load and determine the machine characteristic based at least in part on the detected effect.
  • Figure 5 shows a simplified example waveform representing changes in the peak value (for example, the peak current, or peak rms current) of alternating current in the stator exciter winding 122 of the electrical machine 400.
  • the waveform of Figure 5 is very similar to that of Figure 3, but between the times t2 and ts, the load on the second rotor exciter winding 132-2 is changed by the second loading module 420 because a change in the rotor generator winding voltage has been measured by the second loading module 420.
  • the monitor module 240 may therefore detect the effect on the stator exciter winding alternating current caused by the applied second load and determine the second machine characteristic based at least in part on that.
  • the monitor module 240 may be configured to identify, in any suitable way, which of the pulses in the level of alternating current represented in Figure 5 corresponds to which of the rotor exciter windings 132-1, 132-2, 132-3 and therefore which machine characteristic corresponds to which current pulse.
  • One particular technique is to detect a synchronisation pulse in the stator exciter winding alternating current.
  • a synchronisation pulse may be a pulse in current level that remains substantially the same over time and/or that is of a significantly different magnitude to the other pulses in the current.
  • the synchronisation pulse may be generated when a synchronisation rotor exciter winding on the rotor 130 passes the stator exciter winding 122.
  • the third rotor exciter winding 132-3 may be the synchronisation rotor exciter winding, because the loading applied to the third rotor exciter winding 132-3 may remain substantially constant.
  • the monitor module 240 may identify that over time, the pulse in alternating current at times t3, ⁇ , tg and ti2 remains at a substantially constant level at and that those pulses in the alternating current must therefore be the synchronisation pulse that corresponds to the third exciter rotor winding 132-3.
  • the monitor module 240 may identify that the pulse in alternating current at times t3, ⁇ , tg and ti2 is of a significantly smaller magnitude than the other pulses (the representation in Figure 5 is not drawn to scale for the sake of clarity, so whilst the pulses at t3, t6, tg and ti2 may not appear significantly smaller than the other pulses, in practice they may be) and must therefore be the synchronisation pulse.
  • the electrical machine 400 may be configured such that the synchronisation pulse has a magnitude that is below the minimum magnitude of the other pulses in the alternating current, so that it can always be identified in the alternating current signal.
  • the monitor module 240 may determine that the pulse in the alternating current that follows each synchronisation pulse corresponds to the first rotor exciter winding 132-1 and, as such, the pulses at times t 4 , t7, tio and ti3 may be used to determine the first machine characteristic. Likewise, the monitor module 240 may also determine that the pulses in the alternating current at times ts, ts and in correspond to the second rotor exciter winding 132-2 and, as such, the pulses at ts, ts and tn may be used to determine the second machine characteristic.
  • the electrical machine 400 may be configured to ensure that they are significantly larger than the other pulses, for example by setting the loading applied by the power supply module 410 to be larger (such as 5 times, or 10 times, or 20 times, etc, larger) than the maximum loads that could be applied by the first or second loading modules 230 and 420.
  • the power supply module 410 may be coupled to the rotor generator winding 136 in order to draw power from the rotor generator winding 136, in the same way as power supply module 220 in Figure 3.
  • the third rotor exciter winding 132-3 may act as the synchronisation rotor exciter winding by being unloaded, or loaded with a fixed load, or loaded with a load that is significantly larger than the maximum loads that could be applied by the first or second loading modules 230 and 420, etc.
  • FIG. 6 shows a further example simplified example waveform representing changes in the peak value (for example, the peak current, or peak rms current) of alternating current in the stator exciter winding 122 of the electrical machine 400.
  • This example waveform represents a configuration where the synchronisation pulse is larger than the other pulses in the alternating current in the stator exciter winding 122.
  • the synchronisation pulse has a peak value of Is.
  • a second pulse in the stator exciter winding 122 alternating current At a rotor position of 120°, there is a second pulse in the stator exciter winding 122 alternating current. This second pulse has a peak value of IF.
  • At a rotor position of 240° there is a third pulse in the stator exciter winding 122 alternating current. This second pulse has a peak value of IM.
  • the second pulse relates to a machine characteristic and the third pulse relates to a different machine characteristic.
  • the electrical machine 400 is configured such that peak value Is will always be greater than the peak value of the other pulses in alternating current.
  • IF represents the full scale current that the pulses relating to machine characteristics can reach (i.e., the pulses other than the synchronisation pulse) and IM represents the minimum current that the pulses relating to machine characteristics can reach (i.e., the pulses other than the synchronisation pulse).
  • the peak value of the second pulse and the third pulse may be varied between IF and IM by loading modules on the rotor 130 changing the loading on respective rotor exciter windings 132-1, 132-2, 132-2 in order to communicate machine characteristics off the rotor, but the synchronisation pulse will always be distinguishable as it is greater than IF.
  • the difference between Is and IF may be thought of as a guard band, which ensures that the synchronisation pulse is always distinguishable.
  • the electrical machine 400 may be configured such that the peak value of the synchronisation pulse is less than IM, so that it is always distinguishable in that way. Either way, the electrical machine 400 may be configured such that the peak value Is of the synchronisation pulse is outside (either greater tha n or lesser than) of an allowable operating range (IM to IF) of the other pulses in the stator current.
  • the minimum current IM may be non-zero, to take into account noise levels that may be present in the alternating current in the stator exciter winding 122. Having the minimum current IM as a non-zero value may also provide a degree of fault detection .
  • a synchronisation pulse not only can different pulses within the alternating current in the stator exciter winding 122 be identified in order to determine which machine characteristic they relate to, but it also permits the use of a noise gate to improve signal to noise ratio, measurement dynamic range and accuracy.
  • the electrical machine 400 enables a plurality of machine characteristics to be communicated from the rotor 130 to the monitor module 240 with very few additional components.
  • Figure 7 shows the details of a non-limiting example implementation of the first alternating voltage source 210, the power supply module 410, the first loading module 230 and the monitor module 240.
  • Figure 7 also includes a basic representation of some of the windings of the electrical machine, however, it will be understood that these are significantly simplified compared with Figures 2 and 4 for the sake of clarity. It will be readily apparent to the skilled person that whilst one particular detailed implementation of the modules and components is represented in Figure 7 and described below, there are many other ways in which those modules and components may be configured to achieve the functionality described above, all of which are encompassed by the present disclosure.
  • the first alternating voltage source 210 comprises an oscillator 610 to generate the alternating signal at the desired frequency.
  • the alternating signal is passed through a variable gain levelling amplifier 612 and on to a power amplifier 614 before being applied to the stator exciter winding 122.
  • the applied alternating voltage is also fed-back to a detector 616, which supplies a feedback signal to the variable gain levelling amplifier 612.
  • the variable gain levelling amplifier 612, power amplifier 614 and detector 616 may all work together to maintain the applied alternating voltage at a fixed voltage, such that any detected changes in the stator exciter winding alternating current are caused only by changes in the load(s) applied by the loading module(s).
  • the power supply module 410 represented in Figure 7 is configured to supply DC power to the first loading module 230 and comprises a narrow band filter 620, a rectifier and smoothing capacitor 622 and a regulator 624.
  • the narrow band filter 620 is an optional component and is tuned to the frequency of the alternating voltage supplied by the first alternating voltage source 210.
  • the smoothing capacitor and regulator 624 are also optional for the supply of DC power.
  • the first loading module 230 comprises an input circuit 630 and a gain control 632, wherein the input circuit 630 is configured to supply a control signal to the gain control 632 based on the received first input indicative of a first machine characteristic.
  • the gain control 642 than adjusts the current control 634 (for example, a transistor, or some other suitable variably adjustable component) in order to adjust the amount of the load 636 that is applied to the first rotor exciter winding 132-1.
  • the size or magnitude of the load 636 that is presented to the first rotor exciter winding 132-1 may be adjusted by the input circuit 630, gain control 632 and current control 634 based on the received first input indicative of the first machine characteristic.
  • the second loading module 420 and/or the multiplexing loading module may have the same, or similar, arrangement of components as the first loading module 230.
  • the narrow band filter 638 sits between the current control 634 and the first rotor exciter winding 132-1 to tune the first loading module 230 to a particular range of frequencies.
  • the narrow band filter 638 may be tuned to a narrow band of frequencies that are centred on the frequency of the first alternating voltage source 210.
  • the load 636 would only be presented to alternating current induced in the first rotor exciter winding 132-1 at the tuned frequency. Any other currents induced in the first rotor exciter winding 132-1 at frequencies outside of the tuned narrow band may not be presented with the load 636. This is particularly useful for the frequency division multiplexing aspect described above, where the narrow band filter 638 can be tuned to the frequency of the first alternating voltage source 210.
  • the multiplexing loading module may have the same configuration as the first loading module 230, but be tuned to the frequency of the second alternating voltage source, in order to achieve frequency division multiplexing.
  • the narrow band filter 638 may be an active filter or a passive filter.
  • the first loading module 230 (and likewise, the multiplexing loading module and/or the second loading module 420) may be tuned to particular frequencies in any other suitable way, for example using a high pass, or low pass, filter, or using an L-C tank, or by any other suitable configuration of components. It will also be appreciated that tuning of the loading modules to particular frequencies is optional, particularly for the non-frequency division multiplexing aspects described above.
  • the monitor module 240 in Figure 7 comprises a narrow band filter 640 to tune the monitor module 240 to a particular range of frequencies.
  • the monitor module 240 may be tuned to the same, or very similar, frequencies as the narrow band filter 634 of the first loading module 230, such that the effect on the alternating current of the stator exciter winding 122 caused by the first loading module 230 may be detected by the monitor module 240.
  • the narrow band filter 640 may be an adjustable, or tuneable, narrow band filter 640, such that the monitor module 240 may be tuned to one particular range of frequencies (for example, those of the first loading module 230) to detect changes in stator exciter winding alternating current at those frequencies, and then tuned to a different range of frequencies (for example, those of the multiplexing loading module) to detect changes in the stator exciter winding alternating current at those frequencies.
  • the monitor module 240 may perform the frequency division multiplexing aspects described earlier.
  • the monitor module 240 may comprise one or more duplicates of the circuit comprising components 640-654, wherein the narrow band filter in each duplicate is tuned to a different range of frequencies.
  • the monitor module 240 may simultaneously detect changes in the stator exciter winding alternating current at a variety of different frequencies.
  • the narrow band filter 640 may be an active filter or a passive filter. It will be appreciated that the monitor module 240 may be tuned to particular frequencies in any other suitable way, for example using a high pass, or low pass, filter, or using an L-C tank, or by any other suitable configuration of components. It will also be appreciated that tuning the monitor module 240 to particular frequencies is optional, particularly for the non- frequency division multiplexing aspects described above.
  • the monitor module 240 in Figure 7 also comprises a peak detector 642, a pulse shaper & synchroniser 644, a gate 646, a counter 648, a switch 650 (for example, a transistor switch, or any other suitable form of switch), and two peak hold & gain correctors 652 and 654.
  • These components are configured to identify the peak values in the pulses in the stator exciter winding alternating current and to generate output signals at the output 656, using which respective machine characteristics can be determined by subsequent components or blocks of the monitor module 240.
  • the narrow band filter 640 is configured to isolate the alternating current at a particular frequency (for example, the frequency of the first alternating voltage source 210) and reject noise and other frequencies (which is particularly relevant to the frequency division multiplexing aspect described above).
  • the peak detection circuit 642 isolates and identifies the peak of each current pulse and feeds it to the pulse shaper & synchroniser 644.
  • the second output of the peak detection circuit 642 is a facsimile of the output from the narrow band filter 640 and is fed to the gate 646.
  • the pulse shaper in the pulse shaper & synchroniser 644 turns the signal it receives from the peak detector 642 into a square pulse of defined half height duration.
  • the synchroniser in the pulse shaper & synchroniser 644 identifies the synchronisation pulse and each of the machine characteristic pulses and provides this information to the gate 646, counter 648 and switch 650.
  • the square pulse provides the control to open the gate 646 which allows the current pulses through to the switch 650.
  • the counter 648 and switch 650 using the timing information from the pulse shaper & synchroniser 644, routes the correct current pulse to its respective output 656.
  • the peak hold parts of the peak hold & gain correction modules 652 and 654 smooth the output for each channel 656 and the gain correction part of the gain correction modules 652 and 654 provide scaling of the output for each channel 656 to suit the machine characteristic type.
  • a signal on one of the channels of the output 656 may be a facsimile of the signal input to the respective loading module (i.e., the signal on which the measurement was based).
  • the input to the respective loading module on the rotor 130 may be a DC level scaled to represent the parameter being measured and the signal on a channel of the output 656 may be its facsimile.
  • the monitor module 240 may be implemented in any other suitable way that enables it to detect an effect on the stator exciter winding alternating current caused by a load(s) applied to a rotor exciter winding(s) and determine a machine characteristic based in least on part on the detected effect.
  • the functionality of the monitor module 240 may be implemented by software operating on a computing device.
  • the power supply module 220 is coupled to the rotor generator winding 136 in order to draw power from across the rotor generator winding 136.
  • the power supply module 220 may be coupled to, and draw power from, any one or more of the rotor exciter windings 132-1, 132-2, 132-3 (similarly to the power supply module 420 represented in Figure 4).
  • the power supply module 220 may not be coupled to any of the rotor windings and instead may draw power from any other suitable source, for example from a battery mounted on the rotor 130.
  • the power supply module 410 in the aspect represented in Figure 4 may alternatively be coupled to, and draw power from, the rotor generator winding 136 (similarly to the power supply module 220 represented in Figure 2).
  • the power supply module 410 may not be coupled to any of the rotor windings and instead may draw power from any other suitable source, for example from a battery mounted on the rotor 130.
  • the power supply configurations represented in Figure 2 and 4 may be improved in order to minimise additional weight added to the rotor 130 and/or to achieve long service intervals for the electrical machines 200 and 400.
  • All of the electrical machines described above are three-phase, brushless electrical generators. However, the electrical machines may alternatively have any number of phases, for example single phase, two-phase, four phase, etc.
  • the first loading module 230 may still apply the first load to the single rotor exciter winding based at least in part on the first input indicative of the first machine characteristic.
  • further machine characteristics may also be communicated from the rotor 130 to the monitor module 240 using the frequency division multiplexing technique described above.
  • the frequency division multiplexing technique is described with reference to the electrical machine 200 represented in Figure 2.
  • the frequency division multiplexing technique may be used in combination with other arrangements, such as that represented in Figure 4 where the rotor 130 comprises multiple loading modules, each applying a load to a different rotor exciter winding 132-1, 132-2, 132-3.
  • an electrical machine may comprise the first loading module 230 and the second loading module 420, and also a multiplexing loading module coupled to the first rotor exciter winding 132-1 or the second rotor exciter winding 132-2.
  • a plurality of different machine characteristics may be communicated from the rotor 130 to the monitor module 240 by applying loads to a plurality of different rotor exciter windings and/or using frequency division multiplexing.
  • a synchronisation pulse is used, as described above, this may be present in only one of the frequencies used for frequency division multiplexing. The synchronisation provided by the synchronisation pulse may then be applied across all of the frequencies.
  • the electrical machines described above are brushless electric generators, they may alternatively be electric motors, since the operation of electric motors is analogous to that of electric generators. Furthermore, whilst the benefits of the present disclosure may be particularly apparent for brushless electric machines, it can be appreciated that the electrical machine according to the present disclosure may be of any type, for example brushed electric machines.
  • the electrical machines 200 and 400 represented in Figures 2 and 4 include DC blocking capacitors in the couplings between the rotor exciter windings 132-1, 132-2, 132-2, however these capacitors are optional.
  • the main exciter DC drive 110, the first alternating voltage source 210 and the monitor module 240 are all represented as separate entities.
  • a single module may be configured to perform the functionality of any two of the main exciter DC drive 110, the first alternating voltage source 210 and the monitor module 240 (for example, a machine control unit, which may or may not be integrated with the electrical machine).
  • the loading modules and the power supply modules of Figures 2 and 4 are all represented as separate entities.
  • a single module may be configured to perform the functionality of all of the loading module(s) and power supply module.
  • any of the modules represented in Figures 2 and 4 may be implemented by two or more interconnected modules or entities.
  • tuning that single loading module and the monitor module 240 to a particular band of frequencies centred on the frequency of the first alternating voltage source 210 may mean that changes in current causes by a load applied to a rotor exciter winding 132-1, 132-2, 132-3 by a loading module may be more straightforwardly isolated from any other, unrelated changes in the stator exciter winding current (for example, at power generation frequencies and changes in the level of direct current supplied by the main exciter DC driver 110).
  • an improvement in reliability and accuracy of detection of the effect on the stator exciter winding current may be realised.
  • the electrical machines 200 and 400 comprise at least a first alternating voltage 210, and the monitor module 240 is configured to detect an effect on the alternating current in the stator exciter winding 122, these features are not essential.
  • all alternating voltage sources may be omitted and the monitor module 240 configured to detect an effect on the direct current from the main exciter DC drive 110 caused by a load applied to a rotor exciter winding 132-1, 132-2, 132-3 by a loading module (for example, a change in the load applied to a rotor exciter winding 132-1, 132- 2, 132-3 may cause a change in the amount of direct current drawn by the stator exciter winding 122 as the rotor exciter winding passes the stator exciter winding 122) .
  • a loading module may be more straightforwardly isolated from any other, unrelated changes in the stator exciter winding current (for example, at power generation frequencies and changes in the level of direct current supplied by the main exciter DC driver 110).
  • the loading modules 230 and 420 apply a load to a single one of the rotor exciter windings 132-1, 132-2, 132-3.
  • the first loading module 230 and/or second loading module 420 may apply a load to a plurality (two or more) of the rotor exciter windings 132-1, 132-2, 132-3.
  • the first loading module 420 may apply a load to two of the rotor exciter windings 132-1, 132-2, 132-3, or all three of the rotor exciter windings 132-1, 132-2, 132-3.
  • this may also be used in the frequency division multiplexing aspect described above, whereby the first loading module 420 applies the first load to two or more of the rotor exciter windings 132-1, 132-2, 132-3 and the multiplexing loading module applies the multiplexing load to two or more of the rotor exciter windings 132-1, 132-2, 132-3.
  • the speed with which the monitor module 240 determines the machine characteristic(s) is related to the rotational speed of the electrical machine (for example, the more quickly, or more often, the rotor exciter winding to which the loading module has applied the load passes the stator exciter winding 122, the more quickly it can determine the machine characteristic), applying a load to two or more of the rotor exciter windings 132- 1, 132-2, 132-3 should increase the speed with which the monitor module 240 determines the machine characteristic(s). Furthermore, it would not be necessary to use a synchronisation pulse, thereby simplifying the configuration and operation of the electrical machine.

Abstract

La présente invention concerne une machine électrique, un rotor destiné à être utilisé dans une machine électrique, un module de surveillance destiné à être utilisé avec une machine électrique et un procédé de détermination d'une première caractéristique de machine d'une machine électrique. La machine électrique comprend un rotor comprenant un ou plusieurs enroulements d'excitation de rotor et un enroulement d'excitation de stator pour recevoir un courant de stator afin d'établir un champ magnétique pour provoquer une induction électrique dans le ou les enroulements d'excitation de rotor. La machine électrique comprend également un premier module de chargement monté sur le rotor et configuré pour recevoir une première entrée indicative d'une première caractéristique de machine et appliquer une première charge à un premier enroulement d'excitation de rotor du ou des enroulements d'excitation de rotor sur la base, au moins en partie, de la première entrée reçue. La machine électrique comprend également un module de surveillance couplé au stator d'excitation et configuré pour détecter un effet de la première charge appliquée sur le courant de stator et déterminer la première caractéristique de machine sur la base, au moins en partie, de l'effet détecté de la première charge appliquée sur le courant de stator.
PCT/EP2018/055308 2017-03-06 2018-03-05 Machine électrique WO2018162390A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1703542.9A GB2560314B (en) 2017-03-06 2017-03-06 An electrical machine
GB1703542.9 2017-03-06

Publications (1)

Publication Number Publication Date
WO2018162390A1 true WO2018162390A1 (fr) 2018-09-13

Family

ID=58543800

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2018/055308 WO2018162390A1 (fr) 2017-03-06 2018-03-05 Machine électrique

Country Status (2)

Country Link
GB (1) GB2560314B (fr)
WO (1) WO2018162390A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3916994A1 (fr) * 2020-05-26 2021-12-01 Beckhoff Automation GmbH Système d'entraînement planaire et procédé de fonctionnement d'un système d'entraînement planaire

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5856710A (en) * 1997-08-29 1999-01-05 General Motors Corporation Inductively coupled energy and communication apparatus
WO2000067355A1 (fr) * 1999-04-30 2000-11-09 Abb Ab Convertisseur de puissance dote d'elements de communication/traitement rotatifs/fixes
EP1705604A1 (fr) * 2005-03-21 2006-09-27 Commisariat à l'énergie Atomique Méthode et dispositif de démodulation multiniveaux
US20160149527A1 (en) * 2014-11-26 2016-05-26 Kohler Co. Alternator Rotor Controller

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE7506469U (de) * 1975-01-17 1976-11-25 Bbc Ag Brown, Boveri & Cie, Baden (Schweiz) Messanordnung
US7936830B2 (en) * 2003-05-29 2011-05-03 Maxim Integrated Products, Inc. Active rectifier with load impedance switching
GB201400702D0 (en) * 2014-01-16 2014-03-05 Rolls Royce Plc Rectifier diode fault detection in brushless exciters

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5856710A (en) * 1997-08-29 1999-01-05 General Motors Corporation Inductively coupled energy and communication apparatus
WO2000067355A1 (fr) * 1999-04-30 2000-11-09 Abb Ab Convertisseur de puissance dote d'elements de communication/traitement rotatifs/fixes
EP1705604A1 (fr) * 2005-03-21 2006-09-27 Commisariat à l'énergie Atomique Méthode et dispositif de démodulation multiniveaux
US20160149527A1 (en) * 2014-11-26 2016-05-26 Kohler Co. Alternator Rotor Controller

Also Published As

Publication number Publication date
GB2560314B (en) 2022-03-30
GB2560314A (en) 2018-09-12
GB201703542D0 (en) 2017-04-19

Similar Documents

Publication Publication Date Title
US9459320B2 (en) Fault detection in brushless exciters
US9325225B2 (en) Rotating electrical machine
KR101530731B1 (ko) 브러쉬리스 전기 머신들에서 계자 전류를 결정하기 위한 방법 및 장치
EP3373445B1 (fr) Système de production d'énergie électrique comportant un générateur synchrone et un filtre accordable
CN107889545A (zh) 涉及无励磁器同步电机的系统和方法
US10020763B2 (en) Power generation system
US10877098B2 (en) Method for detecting a fault in an electrical machine
CN109425488B (zh) 确定轴承状态的方法、用于确定轴承状态的模块、轨道车辆和系统
US7050313B2 (en) Aircraft AC-DC converter
US8362730B2 (en) Synchronous machine starting device
EP3373430B1 (fr) Système de génération d'énergie électrique avec un générateur à aimant permanent et combinaison de redresseurs actifs et passifs
CN102761282B (zh) 振荡回路逆变器及其运行方法和相应的电路装置
WO2018162390A1 (fr) Machine électrique
EP3214757B1 (fr) Procédé et appareil de détection de défaillance de composant de machine électrique
CN105871276B (zh) 凸极特性变化的三级式电机转子位置估算方法
JP7238344B2 (ja) 電動機駆動装置
KR102146496B1 (ko) 블루투스 양방향 통신방식의 자기진단 정밀제어 동기발전기
CN104052347B (zh) 用于驱控感应式电机的控制装置和方法
US10461537B2 (en) Method to drive a power control device connected to unbalanced three-phase loads when no neutral reference is available in an alternative electrical network
Wechsler et al. The development of a novel rotor protection for large doubly-fed induction machines
US20220103016A1 (en) Combination of Resolver and Inductive Rotor Supply in One Magnetic Circuit
Alfieri et al. Advanced methods for the assessment of time varying waveform distortions caused by wind turbine systems. Part I: Teoretical aspects
KR101531341B1 (ko) 3상 커패시터 고장 검출기

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18709335

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18709335

Country of ref document: EP

Kind code of ref document: A1