Low-noise, high rotor pole switched reluctance motor
The present embodiment is a high rotor pole switched reluctance machine (HRSRM) which provides a plurality of combinations of the number of rotor poles R n and number of stator poles S n utilizing a numerical relationship defined by a mathematical formula, R n =2S n −F p , when S n =m×F p , wherein F p is the maximum number of independent flux paths in the stator when stator and rotor poles are fully aligned, and m is the number of phases. The mathematical formulation provides an improved noise performance and design flexibility to the machine. The mathematical formulation further provides a specific number of stator and rotor poles for a chosen m and Fp. The HRSRM can be designed with varying number of phases. The HRSRM provides a smoother torque profile due to a high number of strokes per revolution.
1. A high rotor pole switched reluctance machine comprising:
a stator including a plurality of stator poles; and
a rotor including a plurality of rotor poles;
wherein the plurality of rotor poles is in a numerical relationship with the plurality of stator poles and provides a plurality of combinations of the stator poles and rotor poles utilizing the numerical relationship defined by a mathematical formula:
R n =2 S n −F p ;
such that S n =m×F p , F p >2, m>1 wherein, R n is the number of rotor poles, S n is the number of stator poles, F p is the maximum number of independent flux paths when stator and rotor poles are fully aligned, and m is the number of machine (motor/generator) phases.
2. The electrical machine according to claim 1 wherein the rotor is external to the stator.
3. The electrical machine according to claim 1 wherein each rotor pole constitutes a plurality of flux guides which serve to bend the flux in the stator pole around a periphery of the rotor pole.
4. The electrical machine of claim 1 wherein the machine is a linear generator.
5. The electrical machine of claim 1 wherein the machine is a linear motor.
6. The electrical machine of claim 1 wherein the machine is a rotary generator.
7. The electrical machine of claim 1 wherein the machine is a rotary motor.
8. A high pole switched reluctance machine (HRSRM) comprising a stator including a plurality of salient stator poles and a rotor including a plurality of salient rotor poles, the HRSRM providing a plurality of combinations of the rotor poles and stator poles utilizing a numerical relationship defined by a mathematical formula:
R n =2 S n −F p ;
such that S n =m×F p , F p >2, m>1 wherein R n is the number of rotor poles, S n is the number of stator poles, F p is the maximum number of independent flux paths in the stator when stator and rotor poles are fully aligned, and m is the number of machine (motor/generator) phases.
9. The electrical machine according to claim 8 further providing a high rate of change of inductance with respect to rotor position, which improves torque quality of the machine.
10. The electrical machine according to claim 8 wherein the rotor is external to the stator.
11. The electrical machine according to claim 8 wherein each rotor pole constitutes a plurality of flux guides which serve to bend the flux in the stator pole around a periphery of the rotor pole.
12. The electrical machine of claim 8 wherein the machine is a linear generator.
13. A method for estimating number of rotor poles for a high rotor pole switched reluctance machine (HRSRM) comprising a rotor including a plurality of rotor poles and a stator including a plurality of stator poles each having a plurality of windings, and providing a plurality of combinations of the rotor poles and stator poles, the method comprising the steps of:
(a) energizing at least one stator pole, wherein each of the windings of a remainder of stator poles is in an open circuit state;
(b) applying current to the at least one stator pole;
(c) inducing a magnetic flux, the magnetic flux following a path through the plurality of stator poles, wherein a maximum number of independent flux paths is (F p ) and a number of machine (motor/generator) phases is represented by (m);
(d) determining a number of stator poles (S n ) utilizing a mathematical formula:
S n =m×F p ,
wherein F p >2, m>1; and
(e) estimating the number of rotor poles (R n ) utilizing a mathematical formula:
R n =2 S n −F p .
14. The method of claim 13 providing a high rate of change of inductance with respect to rotor position.
15. The method of claim 13 wherein the switched reluctance machine exhibits a smoothed torque profile due to a high number of strokes per revolution.