Induction machine with integrated magnetic gear and related methods

Patent metadata

Field	Value
Publication number	US-10700583-B2
Application number	US-201715692686-A
Country	US
Kind code	B2
Filing date	Aug 31, 2017
Priority date	Aug 31, 2016
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

An induction machine with integrated magnetic gears is disclosed. The machine comprises two rotors and two stators. An outer stator has ferromagnetic material, producing a rotating magnetic field with a defined number of pole pairs synchronized with a supply frequency. A high speed rotor has ferromagnetic material and a combination of rotor bars and permanent magnet pole pieces selected so that the permanent magnet pole pieces do not interact with the outer stator magnetic field. The high speed rotor rotation is asynchronously coupled to the outer stator magnetic field. An inner stator has ferromagnetic steel segments that modulate the field produced by the high speed rotor permanent magnets. A low speed inner rotor has ferromagnetic material and permanent magnet pole pieces, the low speed inner rotor counter-rotating to the high speed rotor. The low speed inner rotor is synchronously coupled to the high speed rotor using modulation harmonics.

First claim

What is claimed is:

1. An induction machine with integrated magnetic gears, comprising:
i) an outer stator comprising ferromagnetic material and ac winding placed in stator slots, for producing a rotating magnetic field with a defined number of pole pairs that is synchronized with a supply frequency;
ii) a high speed rotor positioned within the outer stator, the high speed rotor comprising ferromagnetic material, rotor bars and permanent magnet pole pieces, wherein a combination of rotor bars, pole pairs and permanent magnet pole pieces is selected so that the permanent magnet pole pieces do not interact with the rotating magnetic field and wherein rotation of the high speed rotor is asynchronously coupled to the rotating magnetic field;
iii) an inner stator with ferromagnetic steel segments that modulate a high speed rotor magnetic field produced by the permanent magnet pole pieces of the high speed rotor; and
iv) a low speed inner rotor comprising ferromagnetic material and permanent magnet pole pieces, the low speed inner rotor counter-rotating to the high speed rotor;
wherein the high speed rotor, low speed inner rotor, outer stator and inner stator are arranged concentrically about a shaft;
wherein the low speed inner rotor is synchronously coupled to the high speed rotor using modulation harmonics; and
wherein a combination of modulating segments and number of permanent magnet pole pieces on the high speed rotor and the low speed inner rotor provide the desired magnetic gearing between the high speed rotor and the low speed inner rotor.

2. The induction machine of claim 1 wherein the combination of rotor bar numbers, pole pairs and permanent magnet pole pieces and the combination of modulating segments and number of permanent magnet pole pieces on the high speed rotor and the low speed inner rotor is selected in accordance with an equation comprising:

τ
=

p
L

⁢
π
⁢

⁢

rlgM
H

⁢

∏
o

⁢

⁢

M
L

⁢

∏
1

4
⁢

⁢

μ
o

⁢
sin
⁢

⁢

p
L

⁢
α

wherein τ is torque, r is the induction machine radius, l is the core length, g is the air gap length; p L is the number of pole pieces of the low speed inner rotor, α is an angle of one of the rotors in a synchronously rotating reference frame, Π 0 is the zeroth coefficient of a Fourier series defining a permeance of the modulating ring, Π 1 is the first coefficient of the Fourier series defining the permeance of the modulating ring, μ 0 is the permeability of vacuum, M H is the magnetomotive force associated to the high speed rotor magnet pieces and M L is the magnetomotive force associated to the low speed inner rotor magnet pieces.

3. A method of determining the number of ring pieces and machine dimensions for an induction machine integrated with magnetic gear, comprising:
a. providing operating conditions of the induction machine, wherein the operating conditions are selected from the required speed and torque,
b. providing the induction machine with internal magnetic gear having two stators and two rotors, wherein the rotors include a high speed rotor and a low speed rotor,
c. determining a combination of rotor bar numbers, pole pairs and permanent magnet pole pieces and a combination of modulating segments and number of permanent magnet pole pieces on the high speed rotor and the low speed rotor are selected in accordance with an equation comprising:

τ
=

p
L

⁢
π
⁢

⁢

rlgM
H

⁢

∏
o

⁢

⁢

M
L

⁢

∏
1

4
⁢

⁢

μ
o

⁢
sin
⁢

⁢

p
L

⁢
α

wherein τ is the torque, r is the induction machine radius, l is the core length, g is the air gap length; p L is the number of pole pieces of the low speed inner rotor, α is an angle of one of the rotors in a synchronously rotating reference frame, Π 0 is the zeroth coefficient of a Fourier series defining a permeance of the modulating ring, Π 1 is the first coefficient of the Fourier series defining the permeance of the modulating ring, μ 0 is the permeability of vacuum, M H is the magnetomotive force associated to the high speed rotor magnet pieces and M L is the magnetomotive force associated to the low speed inner rotor magnet pieces; and

d. incorporating the determined combinations into the two stators and two rotors.

4. A method of integrating an induction machine with a magnetic gear, comprising
a. providing an induction machine with internal magnetic gear having two stators and two rotors, wherein the two rotors comprise a high speed rotor and a low speed rotor,
b. determining a number of ring pieces and induction machine dimensions comprising steps of:
i. providing operating

Assignees

• Uti Lp

Inventors

• Knight Andrew Michael
• ABDELHAMID Dalia Zaky Bassuny

Classifications

• H02K17/16 Primary

  having rotors with internally short-circuited windings, e.g. cage rotors · CPC title

• Y02E10/72

  Wind turbines with rotation axis in wind direction · CPC title

• H02K17/26

  having rotors or stators designed to permit synchronous operation · CPC title

• H02K7/11

  with dynamo-electric clutches · CPC title

• H02K16/02

  Machines with one stator and two {or more} rotors · CPC title