초록 ▼

An electrical machine having stator (30) and rotor (31) is disclosed. The motor has field windings (F) and armature windings (A) energized by a suitable power electronic controller (401). A controller (400) sends signals to the power electronic controller (401) to control the armature current to co

An electrical machine having stator (30) and rotor (31) is disclosed. The motor has field windings (F) and armature windings (A) energized by a suitable power electronic controller (401). A controller (400) sends signals to the power electronic controller (401) to control the armature current to control operation of the machine. When the machine is operating as a motor, the armature windings (A) will be supplied with electrical current from the power electronic controller by the application of applied voltage in synchronism with the rotation of the rotor (31). A mutually induced first electrical signal dependent on rotational position of the rotor will be induced within the field windings (F). This will create a superimposed gradient in the field current delivered by the power electronic controller (401). The mutually induced first electrical signal can be extracted from the field current by block (402) which may be a differentiator circuit or may be a coil coupled to the magnetic field around the field current conductor. A signal conditioning circuit (403) is provided which may contain a filter circuit. Block (404) creates a reference voltage for the comparator (405). The reference voltage can be zero such that the comparator (405) determines the polarity of the mutually induced first electrical signal. The output from the comparator is a digital signal indicating if the mutually induced first electrical signal is less than or greater than the threshold applied by block (404). This comparator output, a second electrical signal, represents the rotational position of the rotor relative to the stator and is supplied to the controller (400) to maintain synchronism between the armature excitation and the rotor position.

대표청구항 ▼

The invention claimed is: 1. An electrical machine for converting electrical energy into mechanical energy and/or mechanical energy into electrical energy, the machine comprising: a rotor having a plurality of rotor poles; a stator for rotatably receiving said rotor and having field magnet means fo

The invention claimed is: 1. An electrical machine for converting electrical energy into mechanical energy and/or mechanical energy into electrical energy, the machine comprising: a rotor having a plurality of rotor poles; a stator for rotatably receiving said rotor and having field magnet means for generating a first magnetomotive force between said rotor and said stator, the stator incorporating at least two electrical windings at least one which is an armature winding adapted to carry electrical current varying in synchronism with rotation of said rotor relative to said stator to generate a varying second magnetomotive force having a component transverse to said first magnetomotive force; control means for controlling supply of electrical current to the or each said armature winding; and position sensing means for detecting at least one induced first electrical signal dependent on rotational position of said rotor relative to said stator, the said induced first electrical signal being induced in a respective one of said windings by a voltage across at least one other of said windings, said voltage being a requirement of normal operation of the machine to convert electrical energy into mechanical energy and/or mechanical energy into electrical energy, to thereby supply at least one second electrical signal to said control means representive of the rotational position of said rotor relative to said stator. 2. A machine according to claim 1, wherein said stator has a plurality of stator poles, and at least one said armature winding is wound with a pitch corresponding to a plurality of stator pole pitches. 3. A machine according to claim 1, wherein said field magnet means includes at least one field winding adapted to be connected in series or in parallel with a circuit containing at least one said armature winding. 4. A machine according to claim 3, wherein the position sensing means is adapted to detect said at least one induced first electrical signal in said at least one field winding. 5. A machine according to claim 1, wherein the position sensing means is adapted to detect when at least one said induced first electrical signal passes through at least one threshold value to produce said at least one second electrical signal. 6. A machine according to claim 5, wherein the position sensing means is adapted to detect when at least one said induced first electrical signal passes through at least one respective threshold value when at least one of said windings is energized with substantially uniform voltage and/or when at least one of said windings is not energized, said voltage being a requirement of normal operation of the machine to convert electrical energy into mechanical energy and/or mechanical energy into electrical energy. 7. A machine according to claim 5, wherein the position sensing means is adapted to determine when to begin and/or end energisation of at least one said armature winding by determining relative proportions of time for which at least one said induced first electrical signal is greater than or less than at least one respective threshold value in at least one of said windings during a predetermined period of rotation of said rotor. 8. A machine according to claim 7, wherein the position sensing means is adapted to control timing of energisation of at least one said armature winding to maintain relative proportions of time for which said at least one induced first electrical signal is greater than or less than at least one respective threshold value in at least one of said windings within predetermined limits. 9. A machine according to claim 8, wherein the predetermined limits are adapted to vary in dependence upon output performance of said machine. 10. A machine according to claim 8, wherein the position sensing means is adapted to control timing of said energisation by means of at least one error signal input to said control means. 11. A machine according to claim 8, wherein the position sensing means is adapted to selectively control timing of said energisation in response to failure to detect at least one said induced first electrical signal passing through a threshold value during a predetermined period. 12. A machine according to claim 5, wherein the position sensing means is adapted to detect when at least one said induced first electrical signal passes through at least one respective threshold value to produce at least one said second electrical signal, at least one said threshold value being a function of the corresponding said induced first electrical signal. 13. A machine according to claim 1, wherein the position sensing means is adapted to extract at least one said induced first electrical signal dependent on rotational position of said rotor relative to said stator, from the rate of change of current occurring in an electrical winding of the machine arising as a result of the existence of a voltage across at least one of said windings. 14. A machine according to claim 13, wherein the position sensing means includes at least one respective coil adapted to be magnetically coupled to a magnetic field generated by a conductor carrying current passing through at least one of said windings. 15. A machine according to claim 1, wherein the position sensing means is adapted to obtain data relating to at least one said induced first electrical signal and compare said data with data relating to at least one known rotor position. 16. A machine according to claim 1, wherein the position sensing means is adapted to provide at least one said second electrical signal representative of rotational position of the rotor at standstill by determining at least one said induced first electrical signal in at least one of said windings when at least one other of said windings is energised. 17. A machine according to claim 16, wherein the control means is adapted to cause said rotor to move relative to said stator to a position of stable equilibrium in response to at least one said second electrical signal from said position sensing means generated at standstill of said rotor. 18. A machine according to claim 17, wherein the position sensing means is adapted to indicate the nearest position of stable equilibrium of said rotor relative to said stator by observing the respective said induced first electrical signal in said at least one winding when said at least one other winding is energized. 19. A machine according to claim 1, wherein the position sensing means is adapted to monitor at least one said induced first electrical signal by intermittently sampling said signal. 20. A machine according to claim 1, wherein the position sensing means is adapted to monitor at least one said second electrical signal by intermittently sampling said signal. 21. A machine according to claim 1, wherein the position sensing means is adapted to detect the rate of change of said at least one induced first electrical signal caused by a change in the magnetic flux through said winding. 22. A method of controlling an electrical machine for converting electrical energy into mechanical energy and/or mechanical energy into electrical energy, the machine comprising a rotor having a plurality of rotor poles and a stator for rotatably receiving said rotor and having field magnet means for generating a first magnetomotive force between said rotor and said stator, the stator having at least two electrical windings at least one of which is a respective armature winding adapted to carry electrical current varying in synchronism with rotation of said rotor relative to said stator to generate a varying second magnetomotive force having a component transverse to said first magnetomotive force, the method comprising the steps of: detecting at least one induced first electrical signal dependent on rotational position of said rotor relative to said stator, the or each said first electrical signal being induced in a respective one of said windings by a voltage across at least one other of said windings, said voltage being a requirement of normal operation of the machine to convert electrical energy into mechanical energy and/or mechanical energy into electrical energy; supplying at least one second electrical signal representive of the rotational position of said rotor relative to said stator; and controlling supply of electrical current to the or each said armature winding in response to at least one said second electrical signal. 23. A method according to claim 22, wherein the detection of said at least one induced first electrical signal comprises detecting at least one said induced first electrical signal in at least one field winding of said field magnet means. 24. A method according to claim 22, wherein the detection of said at least one induced first electrical signal comprises detecting when at least one said induced first electrical signal passes through at least one threshold value to produce at least one said second electrical signal. 25. A method according to claim 24, wherein the detection of said at least one induced first electrical signal comprises detecting when at least one induced first electrical signal passes through at least one respective threshold value when at least one of said windings is energized with substantially uniform voltage and/or when at least one of said windings is not energized, said voltage being a requirement of normal operation of the machine to convert electrical energy into mechanical energy and/or mechanical energy into electrical energy. 26. A method according to claim 24, further comprising the step of determining when to begin and/or end energisation of at least one said armature winding by determining relative proportions of time for which at least one said induced first electrical signal is greater than or less than at least one respective threshold value in at least one of said windings during a predetermined period of rotation of said rotor. 27. A method according to claim 26, further comprising the step of controlling timing of energisation of at least one said armature winding to maintain relative proportions of time for which at least one said induced first electrical signal is greater than or less than at least one respective threshold value in at least one of said windings within predetermined limits. 28. A method according to claim 27, further comprising the step of varying said predetermined limits in dependence upon output performance of said machine. 29. A method according to claim 22, further comprising the step of controlling timing of said energisation by means of at least one error signal. 30. A method according to claim 29, further comprising the step of selectively controlling timing of said energisation in response to failure to detect at least one said induced first electrical signal passing through a threshold value during a predetermined period. 31. A method according to claim 22, wherein the detection of said at least one induced first electrical signal comprises detecting when at least one said induced first electrical signal passes through at least one respective threshold value to produce at least one said second electrical signal, at least one said threshold value being a function of an average value of the corresponding said induced first electrical signal. 32. A method according to claim 22, further comprising the step of extracting at least one said induced first electrical signal dependent on rotational position of said rotor relative to said stator, from the rate of change of current occurring in one of said windings arising as a result of the existence of a voltage across one or more other of said windings. 33. A method according to claim 22, further comprising the step of obtaining data relating to at least one said induced first electrical signal and comparing said data with data relating to at least one known rotor position. 34. A method according to claim 22, further comprising the step of providing at least one said second electrical signal representative of rotational position of said rotor at standstill by determining at least one said induced first electrical signal in at least one of said windings when at least one other of said windings is energised. 35. A method according to claim 34, further comprising the step of causing said rotor to move relative to said stator to a position of stable equilibrium in response to at least one said second electrical signal from said position sensing means generated at standstill of said rotor. 36. A method according to claim 35, further comprising the step of indicating the nearest position of stable equilibrium of said rotor relative to said stator by observing the respective said induced first electrical signal in at least one of said windings when at least one other of said windings is energized. 37. A method according to claim 22, further comprising the step of monitoring at least one said induced first electrical signal by intermittently sampling said signal. 38. A method according to claim 22, further comprising the step of monitoring at least one said second electrical signal by intermittently sampling said signal. 39. A method according to claim 22, wherein the detecting of said at least one first electrical signal dependent on rotational position of said rotor comprises detecting the rate of change of said at least one induced first electrical signal caused by a change in the magnetic flux through said winding. 40. A method of determining the rate of change of current in at least one winding of an electrical machine for converting electrical energy into mechanical energy and/or mechanical energy into electrical energy, the method comprising monitoring a voltage induced in at least one respective coil magnetically coupled to a magnetic field generated by a conductor carrying said current.