# US 11,909,264 B2 · Rotor configuration for switched reluctance motor with minimized torque ripple

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- Number: US 11,909,264 B2
- Document ID: US11909264B2
- Status: Granted
- Kind: B2
- Application number: 17/305,761
- Filed: 2021-07-14
- Published: 2022-01-20
- Granted: 2024-02-20
- Earliest claimed: 2020-07-14
- Assignees: Board of Regents, The University of Texas System
- Applicants: Board of Regents, The University of Texas System
- Inventors: Babak Fahimi; Seyed Ehsan Movahed Mohammadi; Mehdi Moallem
- Web page: https://patentgrep.com/patent/US11909264B2

## CPC

- H02K 1/246: {Variable reluctance rotors}
- H02K 1/14: Stator cores with salient poles
- H02K 19/10: for multi-phase current
- H02K 29/03: with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
- H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

A hybrid switched reluctance motor is provided that reduces torque ripple. A novel rotor design includes flux barriers. The flux barriers are positioned and shaped to create implicit saliency and reluctance torque for the motor. A gradual change in the motor reluctance results which avoids rapid increases in flux density. The rotor also increases efficiency by reducing acoustical and vibrational responses and associated energy loses.

## Claims

### Claim 1

A switched reluctance motor comprising:
a stator, having a plurality of stator poles;
a rotor, having a plurality of rotor poles and a plurality of interpole segments located between the plurality of rotor poles;
wherein each interpole segment of the plurality of interpole segments further comprises a concave void radially aligned with an arcuate flux barrier;
wherein the arcuate flux barrier comprises an inner arcuate flux barrier and an outer arcuate flux barrier;
wherein the inner arcuate flux barrier further comprises a first inner arcuate surface and a first outer arcuate surface, wherein the outer arcuate flux barrier further comprises a second inner arcuate surface and a second outer arcuate surface and wherein the concave void is bounded by an exterior arcuate surface;
wherein the first inner arcuate surface, the first outer arcuate surface, the second inner arcuate surface, the second outer arcuate surface and the exterior arcuate surface are defined by an equation:
r
⁡
(
θ
)
=
(
D
shaft
2
)
·
C
+
C
2
+
4
·
sin
2
(
p
·
θ
)
2
·
sin
⁡
(
p
·
θ
)
p
where:
p is a machine pole pair number;
Dshaft is a shaft diameter;
r is a radius;
θ is an angle in polar coordinates; and
C is a constant value for a center line of the rotor;
the exterior arcuate surface has a first set of parameter values:
θ1=0.38-1.18 radians; and
C1=9.1975;
the second outer arcuate surface has a second set of parameter values:
θ2=0.37-1.2 radians; and
C2=8.6794;
the second inner arcuate surface has a third set of parameter values:
θ3=0.32-1.25 radians; and
C3=6.5448;
the first outer arcuate surface has a fourth set of parameter values:
θ4=0.29-1.28 radians; and
C4=5.9532; and
the first inner arcuate surface has a fifth set of parameter values:
θ5=0.28-1.3 radians; and
C5=4.7081.

### Claim 2

A switched reluctance motor comprising:
a stator, having a plurality of stator poles;
a rotor, having a plurality of rotor poles and a plurality of interpole segments located between the plurality of rotor poles;
wherein each interpole segment, of the plurality of interpole segments, further comprises a concave void radially aligned with an arcuate flux barrier;
wherein the arcuate flux barrier comprises an inner arcuate flux barrier and an outer arcuate flux barrier;
wherein the inner arcuate flux barrier further comprises a first inner arcuate surface and a first outer arcuate surface, wherein the outer arcuate flux barrier further comprises a second inner arcuate surface and a second outer arcuate surface and wherein the concave void is bounded by an exterior arcuate surface;
wherein the concave void is defined by a first width, the outer arcuate flux barrier is defined by a second width and the inner arcuate flux barrier is defined by a third width; and
wherein the first width is greater than the second width;
wherein the second width is greater than the third width.

### Claim 3 (depends on 2)

The switched reluctance motor of claim 2, wherein each interpole segment of the plurality of interpole segments further comprises a first iron rib adjacent the concave void and the outer arcuate flux barrier and a second iron rib adjacent the outer arcuate flux barrier and the inner arcuate flux barrier.

### Claim 4 (depends on 3)

The switched reluctance motor of claim 3, wherein the first iron rib defines a first width, the second iron rib defines a second width, and the first width is less than the second width.

### Claim 5 (depends on 2)

The switched reluctance motor of claim 2, wherein the rotor further comprises:
a first bridge between the exterior arcuate surface and the outer arcuate flux barrier; and;
a second bridge between the outer arcuate flux barrier and the inner arcuate flux barrier.

### Claim 6 (depends on 5)

The switched reluctance motor of claim 5, wherein the first bridge defines a first width, the second bridge defines a second width, and the first width is less than the second width.

### Claim 7

A switched reluctance motor comprising:
a stator, having a plurality of stator poles;
a rotor, having a plurality of rotor poles and a plurality of interpole segments located between the plurality of rotor poles;
wherein each interpole segment of the plurality of interpole segments further comprises a concave void radially aligned with an arcuate flux barrier;
wherein the arcuate flux barrier comprises an inner arcuate flux barrier and an outer arcuate flux barrier; and
wherein the inner arcuate flux barrier further comprises a first inner arcuate surface and a first outer arcuate surface, wherein the outer arcuate flux barrier further comprises a second inner arcuate surface and a second outer arcuate surface and wherein the concave void is bounded by an exterior arcuate surface;
wherein the inner arcuate flux barrier further comprises a first curved end surface diametrically opposed to a second curved end surface.

### Claim 8 (depends on 7)

The switched reluctance motor of claim 7, wherein the outer arcuate flux barrier further comprises a third curved end surface diametrically opposed to a fourth curved end surface.

### Claim 9 (depends on 8)

The switched reluctance motor of claim 8, wherein the first curved end surface, the second curved end surface, the third curved end surface, and the fourth curved end surface are each defined by an equation:
Yi(x)=ai+bix+cix2+dix3
where:
x is a variable for the equation;
i=1, 2 . . . n−1; and
a, b, c and d are constants.

### Claim 10 (depends on 9)

The switched reluctance motor of claim 9, wherein the first curved end surface is defined by the parameters:
x1 range=33.22-36.35;
i1=1;
a1=−0.0002101e4;
b1=0.0166657e4;
c1=−0.4440131e4; and
d1=3.9378229e4;
the second curved end surface is defined by the parameters:
x2 range=37.1-41.05;
i=2;
a2=−0.0000445e4;
b2=0.0041933e4;
c2=−0.1348427e4; and
d2=1.4225928e4;
the third curved end surface is defined by the parameters:
x3 range=33.22-36.35;
i=3;
a3=0.0002101e4;
b3=−0.0166657e4;
c3=0.4440131e4; and
d3=−3.9378229e4; and
the fourth curved end surface is defined by the parameters:
x4=37.1-41.05;
a4=0.0000445e4;
b4=−0.0041933e4;
c4=0.1348427e4; and
d4=−1.4225928e4.

### Claim 11 (depends on 8)

The switched reluctance motor of claim 8, wherein the first curved end surface and the second curved end surface define a first cut length, and the third curved end surface and the fourth curved end surface define a second cut length.

### Claim 12 (depends on 11)

The switched reluctance motor of claim 11, wherein the first cut length is greater than the second cut length.

### Claim 13 (depends on 1)

The switched reluctance motor of claim 1:
wherein the stator is comprised of M19 steel;
wherein the rotor is comprised of M19 steel.