Transverse and/or commutated flux systems having phase offset
Electrical machines, for example transverse flux machines and/or commutated flux machines, may be configured to achieve reduced overall cogging torque via implementation of a sixth-phase offset. Individual cogging torque waveforms in the electrical machine may be evenly distributed across one-sixth of a voltage phase or other suitable spacing, resulting in a reduced magnitude and/or increased sinusoidality of the overall cogging torque waveform for the electrical machine.
1. A stator for a transverse flux machine, the stator comprising:
a first stator portion comprising a first set of stator teeth in number N disposed about the circumference of the first stator portion,
wherein a first stator tooth and an adjacent second stator tooth in the first set of stator teeth are separated, center to center, by an angular distance of about (360/N) degrees plus about (⅙*(360/N)) degrees, and
wherein all other adjacent stator teeth in the first set of stator teeth are separated, center to center, by an angular distance of about (360/N) degrees minus about ((⅙*(360/N))/(N−1)) degrees.
2. The stator of claim 1 , further comprising:
a second stator portion comprising a second set of stator teeth in number M disposed about the circumference of the second stator portion,
wherein a first stator tooth and an adjacent second stator tooth in the second set of stator teeth are separated by an angular distance of about (360/M) degrees plus about (⅙*(360/M)) degrees center to center, and
wherein all other adjacent stator teeth in the second set of stator teeth are each separated by an angular distance of about (360/M) degrees minus about ((⅙*(360/M))/(M−1)) degrees center to center.
3. The stator of claim 2 , wherein the number N is larger than 50.
4. The stator of claim 3 , wherein the stator is configured with an outer diameter of less than six inches.
5. The stator of claim 2 , wherein N is equal to M.
6. The stator of claim 2 , wherein the first stator portion and the second stator portion are coupled such that the first set of stator teeth is interleaved with the second set of stator teeth.
7. The stator of claim 2 , wherein any of the first set of stator teeth provides a flux path to any of the second set of stator teeth, the flux path traversing at least partially around a coil at least partially enclosed by the first stator portion and the second stator portion.
8. The stator of claim 2 , wherein a combined cogging torque waveform associated with operation of the stator approximates an ideal sinusoid.
9. The stator of claim 2 , wherein the stator is configured with at least one of a double sixth-phase offset or a triple sixth-phase offset.
10. The stator of claim 2 , wherein the stator is coupled to a wheel of an electric bicycle.
11. The stator of claim 2 , further comprising a conductive coil which does not traverse completely around a rotational axis of a rotor associated with the stator.
12. The stator of claim 2 , wherein the stator is configured to reduce torque ripple when utilized as part of an electrical machine.
13. The stator of claim 2 , wherein the second harmonic content of a combined cogging torque waveform associated with operation of the stator has a magnitude of less than 5% of the magnitude of the first harmonic content of the combined cogging torque waveform.
14. The stator of claim 1 , wherein the first stator portion comprises at least one of silicon steel, powdered metal, or amorphous metal.
15. A method of making a stator for an electrical machine, the method comprising:
providing a first stator portion comprising a first set of stator teeth in number N disposed about the circumference of the first stator portion,
wherein a first stator tooth and an adjacent second stator tooth in the first set of stator teeth are separated, center to center, by an angular distance of about (360/N) degrees plus about (⅙*(360/N)) degrees, and
wherein all other adjacent stator teeth in the first set of stator teeth are separated, center to center, by an angular distance of about (360/N) degrees minus about ((⅙*(360/N))/(N−1)) degrees.
16. The method of claim 15 , further comprising coupling the first stator portion to a second stator portion comprising a second set of stator teeth in number M disposed about the circumference of the second stator portion,
wherein a first stator tooth and an adjacent second stator tooth in the second set of stator teeth are separated by an angular distance of about (360/M) degrees plus about (⅙*(360/M)) degrees center to center, and
wherein all other adjacent stator teeth in the second set of stator teeth are each separated by an angular distance of about (360/M) degrees minus about ((⅙*(360/M))/(M−1)) degrees center to center.