초록 ▼

This application describes a motor designed to operate as a reluctance machine at low speeds and as an induction machine at high speeds. The drive waveform is composed of one or more harmonics to be used to match the reluctance pattern of the stator-rotor, causing the rotor to rotate due to the relu

This application describes a motor designed to operate as a reluctance machine at low speeds and as an induction machine at high speeds. The drive waveform is composed of one or more harmonics to be used to match the reluctance pattern of the stator-rotor, causing the rotor to rotate due to the reluctance effect, and one or more other harmonics to induce current in the rotor, causing the rotor to rotate due to the induction effect and the subsequent interaction of the stator and rotor magnetic fields. The two effects are generally not applied simultaneously.

대표청구항 ▼

The invention claimed is: 1. A polyphase motor comprising: a) a drive unit operable to: i) synthesize N phases of alternating current where N is more than three per 180 degrees; and ii) select between applying a Type A and a Type B harmonic drive waveform for said N phases, wherein said Type A and

The invention claimed is: 1. A polyphase motor comprising: a) a drive unit operable to: i) synthesize N phases of alternating current where N is more than three per 180 degrees; and ii) select between applying a Type A and a Type B harmonic drive waveform for said N phases, wherein said Type A and Type B harmonic drive waveforms each comprise at least one harmonic order that the other does not comprise; and b) a stator and a rotor, comprising: i) N stator winding phases, driven by said drive unit; and ii) profiles of said stator and rotor, suited to produce substantial reluctance based rotor rotation when a Type A harmonic drive waveform is applied; and iii) rotor windings, suited for producing substantial inductance based rotor rotation when a Type B harmonic drive waveform is applied. 2. The polyphase motor of claim 1 wherein a difference between a number of stator teeth and a number of rotor teeth is equal to half of the pole count of the developed magnetic field used to drive the rotor due to reluctance. 3. The motor of claim 1 wherein a number of stator teeth and a number of rotor teeth have different values, each 30 or more. 4. The motor of claim 1 wherein said stator comprises teeth equidistant around the circumference. 5. The motor of claim 1 wherein said rotor comprises teeth equidistant around the circumference. 6. The motor of claim 1 wherein said Type A harmonic drive waveform is associated with low speed operation, and wherein said Type B harmonic drive waveform is associated with high speed operation. 7. The motor of claim 1 wherein said stator windings are arranged to allow second harmonic to drive the machine, and wherein said Type A harmonic drive waveform comprises fundamental and said Type B harmonic comprises second harmonic. 8. The polyphase motor of claim 1 wherein said profiles of said stator and rotor are suited to produce substantially little cogging torque when said Type B harmonic drive waveform is applied. 9. The motor of claim 1 wherein said stator and rotor profiles serve to produce substantial reluctance based rotor rotation in the same direction to the rotating magnetic field developed by said Type A harmonic drive waveform. 10. The motor of claim 1 wherein said stator and rotor profiles serve to produce substantial reluctance based rotor rotation in the reverse direction to the rotating magnetic field developed by said Type A harmonic drive waveform, and wherein said drive unit further operable to apply said Type A harmonic drive waveform to said stator winding phases in reverse phase order to the application of said Type B harmonic to said stator winding phases. 11. The motor of claim 1 wherein profiles of said stator and rotor profile serve to produce substantial reluctance based rotor rotation in the reverse direction to the rotating magnetic field developed by said Type A harmonic drive waveform, and wherein said Type A harmonic has a harmonic order higher than the phase count and produces a reverse direction rotating field to the rotating field produced by said Type B harmonic. 12. The motor of claim 1 wherein each of said stator winding phases is concentrated in one slot per wound pole. 13. The motor of claim 1 wherein each of said stator winding phases is distributed over at least two adjacent slots per wound pole. 14. The motor of claim 1 wherein said stator phase windings are mesh connected. 15. The motor of claim 1 wherein said stator phase windings are wound on said stator in a toroidal fashion. 16. A method for operating a single motor as an induction machine and as a reluctance machine, comprising: a) providing a stator and rotor comprising windings suitable for use as an induction motor, and comprising a reluctance profile, b) supplying more than three different phases of alternating current to said stator, to rotate said rotor, c) providing a selection of the following operational modes: (i) supplying said alternating current to provide a stator magnetic field that matches the reluctance profile, and operable to rotate the rotor due to the reluctance effect, (ii) supplying said alternating current to provide a stator magnetic field that is substantially inoperable to rotate the rotor due to the reluctance effect, yet is operable to rotate the rotor due to the induction effect. 17. The method of claim 16 wherein the reluctance profile of the stator and rotor structure causes the rotor, in operational mode (i), to rotate in the same direction as the rotational direction of the stator magnetic field. 18. The method of claim 16 wherein the reluctance profile of the stator and rotor structure causes the rotor, in operational mode (i), to rotate in the reverse direction from the rotational direction of the stator magnetic field, and wherein operational mode (i) comprise reversing the phase order from operational mode (ii) so that the rotor rotates in the same direction in both modes. 19. The method of claim 16 wherein the reluctance profile of the stator and rotor causes the rotor, in operational mode (i), to rotate in the reverse direction to the rotational direction of the stator magnetic field, and wherein said operational mode (ii) is realized by supplying a harmonic of the type that produces a reverse-direction magnetic field from the magnetic field produced by operational mode (ii), so that the rotor rotates in the same direction in both modes. 20. The method of claim 16 further comprising the step of: starting the motor by using operational mode (i). 21. The method of claim 16 further comprising the step of starting the motor by using operational mode (ii). 22. The method of claim 16 further comprising the step of: selecting operational mode (i) when a low speed rotor output is required, and selecting operational mode (ii) when a high speed rotor output is required. 23. The method of claim 22 further comprising the steps of: a) when operating in operational mode (i) and a speed increase is required, only selecting operational mode (ii) when an upper limit of an overlap speed region is required, and b) when operating in operational mode (ii) and a speed decrease is required, only selecting operational mode (i) when a lower limit of an overlap speed region is required, whereby substantially preventing cycling between operational modes. 24. The method of claim 16 further comprising the step of providing a lower order harmonic in operational mode (i) than in operational mode (ii). 25. The motor of claim 24 wherein said rotor comprises a number of low reluctance regions that is equal to, or a multiple of, the number of magnetic poles in the magnetic field developed by said first of said at least two different harmonics. 26. A motor comprising a) a drive, for providing alternating current of N different phases per pole, where N is more than three, and for providing a selection of at least two different harmonics, b) a stator, comprising N winding phases, and a stator profile, c) a rotor, comprising a profile that, in combination with said stator profile, causes rotor rotation due to reluctance when operated by a first of said at least two different harmonics, and causes substantially low cogging torque when operated by a second of said at least two different harmonics; and further comprising windings that enable rotor rotation due to inductance. 27. The motor of claim 26 wherein said first of said at least two different harmonics comprises an integer value of H for which H=R/(M*k), where H is the harmonic order, R is the number of low reluctance regions, M is the base magnetic field and k is the set of all real positive integers.