# US 5,703,423 A · Energy storage flywheel system

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- Number: US 5,703,423 A
- Document ID: US5703423A
- Status: Granted
- Kind: A
- Application number: 08/621,589
- Filed: 1996-03-26
- Granted: 1997-12-30
- Earliest claimed: 1995-03-29
- Assignees: Tadashi Fukao; Akira Chiba; Chikara Michioka; Seiko Seiki Kabushiki Kaisha; Nikkiso Co., Ltd.; Ebara Corporation
- Inventors: Tadashi Fukao; Akira Chiba; Chikara Michioka
- Web page: https://patentgrep.com/patent/US5703423A

## CPC

- F16C 32/0444: {Details of devices to control the actuation of the electromagnets}
- F16C 32/0493: {integrated in an electrodynamic machine, e.g. self-bearing motor}
- F16C 32/0497: {generating torque and radial force}
- F16F 15/035: {by use of eddy or induced-current damping (dynamo-electric brakes of the eddy-current type H02K49/04)}
- F16F 15/3156: {Arrangement of the bearings}
- H02K 7/025: {for power storage}
- F16C 2361/55: Flywheel systems
- F16C 2380/26: Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators
- Y02E 60/16: Mechanical energy storage, e.g. flywheels or pressurised fluids
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A flywheel for storing inertial energy is integral with a rotor which is rotatable around a stator. The stator has main windings that provide a number of poles for rotating the rotor and auxiliary control windings that provide a number of poles different from the number of poles provided by the main windings. When currents are supplied to the main windings, the rotor and hence the flywheel are rotated. When control currents are supplied to the auxiliary control windings, radial forces acting on the rotors are generated thereby to support the rotor out of contact with the stator.

## Claims

### Claim 1

An energy storage flywheel system comprising:
stator means;
a rotor surrounding said stator means and being rotatable with respect thereto;
a flywheel for storing energy integrally attached to said rotor;
said stator means including a pair of axially spaced actuators each having a stator portion containing a first set of windings comprising main windings that provide a number of poles for rotating said rotor and a second set of windings comprising auxiliary windings that provide a number of poles different from the number of poles provided by said first set of windings;
power supply means for supplying voltages or currents to said first set of windings and to said second set of windings; and
control means for supplying voltages or currents to said first set of windings to rotate said rotor, and to said second set of windings to produce radial forces acting on said rotor to support said rotor out of contact with said stator.

### Claim 2 (depends on 1)

An energy storage flywheel system according to claim 1, wherein said control means comprises means for supplying said control voltages or currents to said second set of windings to produce radial forces acting on said rotor to effect active damping on said flywheel or eliminate disturbances thereon.

### Claim 3 (depends on 1)

An energy storage flywheel system according to claim 1, wherein said main windings have coil ends positioned only on outer axial ends of said actuators and extend through inner confronting axial ends of said actuators for commonly rotating said rotor.

### Claim 4 (depends on 3)

An energy storage flywheel system according to claim 3, wherein said power supply means comprises a first power converter and a pair of second power converters, said main windings being connected to said first power converter, and said auxiliary control windings being connected respectively to said pair of second power converters.

### Claim 5 (depends on 1)

An energy storage flywheel system according to claim 1, wherein the number of poles of the first set of windings is two or four and the second set of windings contains four or two poles, respectively, to complement the number of poles of said first set of windings.

### Claim 6 (depends on 1)

An energy storage flywheel system according to claim 1, wherein the number of poles of the first set of windings is eight and the number of poles of the second set of windings is two.

### Claim 7

An energy storage flywheel system comprising:
a pair of stators;
a pair of axially adjacent rotors, each of which rotors is rotatable with respect to a separate stator, each of said rotors surrounding its associated stator and concentrically mounting a flywheel for storing energy;
each of said stators having main windings that provide a number of poles for rotating the rotor and auxiliary control windings that provide a number of poles different from the number of poles provided by said main windings, said main windings of the stators comprising three-phase windings connected in different phase sequences;
a single power converter for supplying currents to said main windings to rotate said rotors in opposite directions for thereby canceling out gyro moment vectors produced on said flywheels; and
four power converters for supplying control currents to said auxiliary control windings to produce radial forces acting on said rotors to support said rotors out of contact with said stators.

### Claim 8

An energy storage flywheel system comprising:
a pair of stators;
a pair of axially adjacent rotors, each of which rotors is rotatable with respect to a separate stator, each of said rotors concentrically mounting a flywheel for storing energy;
each of said stators having main windings that provide a number of poles for rotating the rotor and auxiliary control windings that provide a number of poles different from the number of poles provided by said main windings;
a pair of power converters for supplying currents to said main windings to rotate each of said rotors in opposite directions for thereby canceling out gyro moment vectors produced on said flywheels; and
four power converters for supplying control currents to said auxiliary control windings to produce radial forces acting on said rotors to support said rotors out of contact with said stators.