Electronic pole-changing for induction motors

Patent metadata

Field	Value
Publication number	US-2025047226-A1
Application number	US-202418778495-A
Country	US
Kind code	A1
Filing date	Jul 19, 2024
Priority date	Aug 4, 2023
Publication date	Feb 6, 2025
Grant date	—

Abstract

An induction motor includes a plurality of flux linkage configurations that control current to drive relative movement between a rotor and a stator. Each flux configuration powers a different number of poles. A controller is configured to droop switch flux linkage configurations by ramping up torque in a new configuration h 1 at the same rate as torque decay by decaying flux from a previous configuration h 2 . Multiple flux configurations can also be powered during steady state. A method for smoothing torque transitions receives a command to change from one of a plurality of flux configurations to another of the plurality of the flux configurations. Torque is ramped up in the another flux configuration at the same rate as decaying torque in the one of the plurality of flux configurations.

First claim

1 . An induction motor, comprising:
a plurality of flux linkage configurations that control current to drive relative movement between a rotor and a stator, wherein each flux configuration powers a different number of poles; and a controller that is configured to droop switch flux linkage configurations by ramping up torque in a new configuration h 1 at the same rate as torque decay by decaying flux from a previous configuration h 2 .

2 . The induction motor of claim 1 , wherein the controller commands a continuous reconfiguration of superimposed flux states.

3 . The induction motor of claim 2 , wherein the controller maintains linkage to two of the plurality of flux linkage configurations during steady state motor operation.

4 . The induction motor of claim 1 , wherein the controller sets a transition between flux configurations by ramping up torque in the new configuration h 1 at the same rate as torque decay due to deflux h 2 the control beings by setting the torque derivative to zero

dT
e

dt

=
0

where T e is the electrical torque, which leads to the following condition on q-axis current

i

qs
,
2

=

i

qs
,
1

⁢

k
1

⁢

d
⁢

λ

r
⁢
1

dt

k
2

⁢

d
⁢

λ

r
⁢
2

dt

,

where
where i qs,1 and i qs,2 are the q-axis currents of configurations 1 and 2, k 1 and k 2 are torque constants and λ r1 and λ r2 are the rotor flux linkages in rotor flux reference frame.

5 . The multiple pole induction motor of claim 1 , comprising windings driving relative movement between the stator and the rotor;
modular inverters driving the windings; a multiple leg converter; speed feedback, wherein the controller receives current and speed feedback and sets active poles in view of a commanded speed or speed change.

6 . The multiple pole induction motor of claim 1 , comprising a modulation module between the variable pole controller and an inverter that drives the plurality of flux linkage configurations.

7 . The multiple pole induction motor of claim 6 , wherein the modulation module conducts one of a sine triangle and space vector modulation.

8 . The multiple pole induction motor of claim 6 , wherein the modulation module conducts an operation to ensure a non-zero common mode.

9 . The multiple pole induction motor of claim 1 , comprising an inverter that electronically defines the plurality of flux linkage configurations.

10 . The multiple pole induction motor of claim 1 , wherein the controller comprises discrete control comprising a torque to current module that receives a torque command and outputs q-axis current for all pole configurations, a flux to current module that receives a rotor flux linkage command and outputs d-axis current command for all pole configurations, and a vector control module that switches pole configurations.

11 . The multiple pole induction motor of claim 10 , comprising a wherein the controller comprises continuous control, the continuous control comprising the discrete control arranged a master-salve arrangement.

12 . The multiple pole induction motor of claim 1 , wherein the controller conducts an optimal pole selection by conducting the droop switch at boundary points between flux configurations having a different number of poles.

13 . The multiple pole induction motor of claim 12 , wherein the optimal pole selection comprises the following optimization:
Subject to minΔt, RMS current constraint coming from drive

i

ds
,

h
1

2

+

i

ds
,

h
2

2

+

i

qs
,

h
1

2

+

i

qs
,

h
2

2

≤

I
rated
2

i

ds
,

h
1

=

λ

r
,

h
1

(
∞
)

L

m
,

h
1

Assignees

• Univ Illinois

Inventors

• Libbos Elie
• Banerjee Arijit
• Mukherjee Debranjan
• Chaubal Soumil
• Maheshwari Anuj

Classifications

• H02P25/20

  for pole-changing · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title

• H02P21/30 Primary

  Direct torque control [DTC] or field acceleration method [FAM] · CPC title

• H02P21/0021 Primary

  using different modes of control depending on a parameter, e.g. the speed · CPC title