Differential reactance permanent magnet position transducer
First Claim
1. A differential reactance permanent magnet transducer comprising a stator and an armature, said stator having a first section with at least two pole elements thereon of ferromagnetic material, each stator pole element having an electrically conductive coil wound thereabout, and said armature having a first magnet section with at least one permanent magnet pole element thereon, said pole elements being so disposed as to cause said magnet pole element to register sequentially with said pole elements of said first section of said stator as said armature moves relative to said stator, and being so disposed that the flux density variation produced in one of said stator pole elements by movement of said magnet pole element relative thereto varies in an out-of-phase relationship to the flux density variation produced in the other of said stator pole elements by such magnet pole element movement, said coils being comprised of effectively equal numbers of turns and being connected in series to provide at least one circuit having terminals to enable the application of voltages thereacross and to enable measurement of voltage values at a junction between said coils thereof, each coil comprising a leg of said one circuit, whereby said first stator section, said first magnet section, and said coils provide a first sensor section, and whereby the values of voltages applied across said circuit will be so modulated by such relative movement of said armature as to enable the generation of signals from said first sensor section that vary sinusoidally as a function of armature position and reactance variation in said coils, the electrical and mechanical features of said transducer being such that no net back-EMF value is inductively generated from said coils as a result of such relative movement.
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Accused Products
Abstract
A differential reactance permanent magnet transducer has a stator with at least two pole elements, each having an electrically conductive coil wound thereabout. The reluctances of the stator pole elements are periodically changed, in an electrically out-of-phase relationship to one another, due to the effects of permanent magnet elements moving in proximity thereto. Measurement of the reactance differentials that are thereby produced in coils mounted upon the two stator pole elements is utilized to sense the angular position of the transducer rotor. In addition to a high-resolution sensor zone and a commutation sensor zone, the transducer may include a home sensor zone to indicate a home position upon each revolution of the rotor. All of the coils employed on the stator are so arranged and electrically connected that no net back-EMF value is inductively generated from any coil as a result of movement of the rotor relative to the stator.
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Citations
16 Claims
- 1. A differential reactance permanent magnet transducer comprising a stator and an armature, said stator having a first section with at least two pole elements thereon of ferromagnetic material, each stator pole element having an electrically conductive coil wound thereabout, and said armature having a first magnet section with at least one permanent magnet pole element thereon, said pole elements being so disposed as to cause said magnet pole element to register sequentially with said pole elements of said first section of said stator as said armature moves relative to said stator, and being so disposed that the flux density variation produced in one of said stator pole elements by movement of said magnet pole element relative thereto varies in an out-of-phase relationship to the flux density variation produced in the other of said stator pole elements by such magnet pole element movement, said coils being comprised of effectively equal numbers of turns and being connected in series to provide at least one circuit having terminals to enable the application of voltages thereacross and to enable measurement of voltage values at a junction between said coils thereof, each coil comprising a leg of said one circuit, whereby said first stator section, said first magnet section, and said coils provide a first sensor section, and whereby the values of voltages applied across said circuit will be so modulated by such relative movement of said armature as to enable the generation of signals from said first sensor section that vary sinusoidally as a function of armature position and reactance variation in said coils, the electrical and mechanical features of said transducer being such that no net back-EMF value is inductively generated from said coils as a result of such relative movement.
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12. A differential reactance permanent magnet transducer comprising a stator and an armature, said transducer having a plurality of sensor sections, one of said sensor sections comprising a first stator section, a first magnet section on said armature, and a plurality of electrically conductive first coils, said first stator section having at least two pole elements thereon of ferromagnetic material, each stator pole element having one of said electrically conductive first coils wound thereabout, and said first magnet section of said armature having at least one permanent magnet pole element thereon, said pole elements being so disposed as to cause said magnet pole element to register sequentially with said pole elements of said first section of said stator as said armature moves relative to said stator, and being so disposed that the flux density variation produced in one of said stator pole elements by movement of said magnet pole element relative thereto varies in an out-of-phase relationship to the flux density variation produced in the other of said stator pole elements by such magnet pole element movement, said first coils being comprised of effectively equal numbers of turns and being connected in series to provide at least one circuit having terminals to enable the application of voltages thereacross and to enable measurement of voltage values at a junction between said coils thereof, each coil comprising a leg of said one circuit, whereby the values of voltages applied across said circuit will be so modulated by such relative movement of said armature as to enable the generation of signals from said first sensor section that vary sinusoidally as a function of armature position and reactance variation in said coils;
- another of said sensor sections comprising a second magnet section on said armature with at least one permanent magnet pole element thereon, a second stator section having at least two pole elements thereon of ferromagnetic material, and at least one electrically conductive second coil wound about said pole elements of said second stator section, said second magnet section being so disposed relative to said second stator section as to cause said two pole elements of said second stator section to be subjected simultaneously to a magnetic field of equal strength from said second magnet section, whereby the values of voltages applied across said second coil will be so modulated by relative movement of said armature as to enable the generation of a signal at the start of each cycle of armature movement;
the electrical and mechanical features of said transducer being such that no net back-EMF value is inductively generated from any of said coils as a result of such relative movement. - View Dependent Claims (13, 14, 15)
- another of said sensor sections comprising a second magnet section on said armature with at least one permanent magnet pole element thereon, a second stator section having at least two pole elements thereon of ferromagnetic material, and at least one electrically conductive second coil wound about said pole elements of said second stator section, said second magnet section being so disposed relative to said second stator section as to cause said two pole elements of said second stator section to be subjected simultaneously to a magnetic field of equal strength from said second magnet section, whereby the values of voltages applied across said second coil will be so modulated by relative movement of said armature as to enable the generation of a signal at the start of each cycle of armature movement;
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16. A differential reactance permanent magnet transducer comprised of a stator and a rotor, said transducer having a high-resolution sensor section capable of generating signals with a cycle frequency of 20 to 100 cycles per revolution of said rotor, a commutation sensor section capable of generating signals with an even-number cycle frequency of two to eight cycles per rotor revolution, and a home sensor section for generating a signal with a cycle frequency of one cycle per revolution, each of said high-resolution and commutation sensor sections separately comprising:
- a first stator section, a first magnet section on said armature, and a plurality of electrically conductive first coils, said first stator section having at least two pole elements thereon of ferromagnetic material, each stator pole element having one of said electrically conductive first coils wound thereabout, and said first magnet section of said armature having at least one permanent magnet pole element thereon, said pole elements being so disposed as to cause said magnet pole element to register sequentially with said pole elements of said first section of said stator as said armature moves relative to said stator, and being so disposed that the flux density variation produced in one of said stator pole elements by movement of said magnet pole element relative thereto varies in an out-of-phase relationship to the flux density variation produced in the other of said stator pole elements by such magnet pole element movement, said first coils being comprised of effectively equal numbers of turns and being connected in series to provide at least one circuit having terminals to enable the application of voltages thereacross and to enable measurement of voltage values at a junction between said coils thereof, each coil comprising a leg of said one circuit, whereby the values of voltages applied across said circuit will be so modulated by such relative movement of said armature as to enable the generation of signals from said first sensor section that vary sinusoidally as a function of armature position and reactance variation in said coils;
said home sensor section comprising a second magnet section on said armature with at least one permanent magnet pole element thereon, a second stator section having at least two pole elements thereon of ferromagnetic material, and at least one electrically conductive second coil wound about said pole elements of said second stator section, said second magnet section being so disposed relative to said second stator section as to cause said two pole elements of said second stator section to be subjected simultaneously to a magnetic filed of equal strength from said second magnet section, whereby the values of voltages applied across said second coil will be so modulated by relative movement of said armature as to enable the generation of a signal at the start of each cycle of armature movement;
the electrical and mechanical features of said transducer being such that no net back-EMF value is inductively generated from any of said coils as a result of such relative movement.
- a first stator section, a first magnet section on said armature, and a plurality of electrically conductive first coils, said first stator section having at least two pole elements thereon of ferromagnetic material, each stator pole element having one of said electrically conductive first coils wound thereabout, and said first magnet section of said armature having at least one permanent magnet pole element thereon, said pole elements being so disposed as to cause said magnet pole element to register sequentially with said pole elements of said first section of said stator as said armature moves relative to said stator, and being so disposed that the flux density variation produced in one of said stator pole elements by movement of said magnet pole element relative thereto varies in an out-of-phase relationship to the flux density variation produced in the other of said stator pole elements by such magnet pole element movement, said first coils being comprised of effectively equal numbers of turns and being connected in series to provide at least one circuit having terminals to enable the application of voltages thereacross and to enable measurement of voltage values at a junction between said coils thereof, each coil comprising a leg of said one circuit, whereby the values of voltages applied across said circuit will be so modulated by such relative movement of said armature as to enable the generation of signals from said first sensor section that vary sinusoidally as a function of armature position and reactance variation in said coils;
Specification