EP-4739529-A1 - INDUCTION MOTOR CONTROL SYSTEM FOR A VEHICLE

EP4739529A1EP 4739529 A1EP4739529 A1EP 4739529A1EP-4739529-A1

Abstract

A vehicle comprises an induction motor (22) comprising a stator (80) and a rotor (90). An induction motor control system (50) is configured to: operate the induction motor (22) in a first operating mode and a second operating mode to achieve a first torque value. In the first operating mode the induction motor (22) is operated with a first stator current and a first rotor current and has a first efficiency. In the second operating mode the induction motor (22) is operated with a second stator current and a second rotor current and has a second efficiency, wherein the second rotor current is less than the first rotor current, the second stator current is greater than the first stator current, and the second efficiency is lower than the first efficiency.

Inventors

KIRALY, ISTVAN
MALUMBRES RUIZ, Jose
MUHAMMED, Fasil

Assignees

Jaguar Land Rover Limited

Dates

Publication Date: 20260513
Application Date: 20240704

Claims (15)

1 . An induction motor control system for a vehicle comprising an induction motor, the induction motor comprising a stator and a rotor, the induction motor control system comprising one or more processors collectively configured to: operate the induction motor in a first operating mode in which, to achieve a first torque value, the induction motor is operated with a first stator current and a first rotor current and has a first efficiency; and operate the induction motor in a second operating mode in which, to achieve the first torque value, the induction motor is operated with a second stator current and a second rotor current and has a second efficiency, wherein the second rotor current is less than the first rotor current, the second stator current is greater than the first stator current, and the second efficiency is lower than the first efficiency.
2. The induction motor control system of claim 1 configured to select an operating point for the second operating mode from a plurality of possible operating points, wherein each of the possible operating points comprise a value for the second stator current and a value for the second rotor current to achieve the first torque value.
3. The induction motor control system of claim 2 configured to select an operating point for the second operating mode based at least in part on a temperature of the rotor.
4. The induction motor control system of claim 3 wherein the temperature of the rotor is a measured temperature of the rotor or a predicted temperature of the rotor.
5. The induction motor control system of any one of claims 2 to 4 wherein there is a maximum stator current associated with the induction motor and the control system is configured to select an operating point for the second operating mode having a value for the second stator current which is less than the maximum stator current.
6. The induction motor control system of any one of claims 2 to 5 wherein there is a maximum rotor current associated with the induction motor and the control system is configured to select an operating point for the second operating mode having a value for the second rotor current which is less than the maximum rotor current.
7. The induction motor control system of any one of the preceding claims configured to operate the induction motor in the first operating mode or in the second operating mode in dependence at least in part on a temperature of the rotor.
8. The induction motor control system of claim 7 wherein the temperature of the rotor is a measured temperature of the rotor or a predicted temperature of the rotor.
9. The induction motor control system of any one of the preceding claims configured to determine a required torque for the induction motor and to operate the induction motor in the first operating mode or in the second operating mode in dependence on a magnitude of the required torque.
10. The induction motor control system of any one of the preceding claims configured to operate the induction motor in the second operating mode when the magnitude of the required torque is above a threshold value of torque.
11 . The induction motor control system of any one of the preceding claims configured to operate the induction motor in the second operating mode when the magnitude of the required torque has been above a threshold value of torque for a predetermined period of time.
12. A propulsion system for a vehicle comprising an induction motor and the induction motor control system of any one of the preceding claims.
13. A vehicle comprising the induction motor control system of any one of claims 1 to 11 or the propulsion system of claim 12.
14. A method for controlling an induction motor for a vehicle, the induction motor comprising a stator and a rotor, the method comprising: operating the induction motor in a first operating mode in which, to achieve a first torque value, the induction motor is operated with a first stator current and a first rotor current and has a first efficiency; and operating the induction motor in a second operating mode in which, to achieve the first torque value, the induction motor is operated with a second stator current and a second rotor current and has a second electrical, wherein the second rotor current is less than the first rotor current, the second stator current is greater than the first stator current, and the second efficiency is lower than the first efficiency.
15. Computer readable instructions which, when executed by a computer, are arranged to perform the method according to claim 14.

Description

INDUCTION MOTOR CONTROL SYSTEM FOR A VEHICLE TECHNICAL FIELD The present disclosure relates to an induction motor control system for a vehicle. Aspects of the invention relate to an induction motor control system for a vehicle, a propulsion system for a vehicle, a vehicle comprising the induction motor control system, a method for controlling a vehicle and a non- transitory computer readable medium. BACKGROUND Electric vehicles (EVs) comprise an Electric Drive Unit (EDU) which drives wheels of the vehicle. An EDU may use a permanent magnet (PM) motor or an induction motor (IM). IM-based EDUs have some advantages, but also have some challenges, such as operation with high torque demands. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide an induction motor control system for a vehicle. Aspects of the invention relate to an induction motor control system for a vehicle, a propulsion system for a vehicle, a vehicle comprising the induction motor control system, a method for controlling a vehicle and a non-transitory computer readable medium as claimed in the appended claims. According to an aspect of the present invention there is provided an induction motor control system for a vehicle comprising an induction motor, the induction motor comprising a stator and a rotor, the induction motor control system comprising one or more processors collectively configured to: operate the induction motor in a first operating mode in which, to achieve a first torque value, the induction motor is operated with a first stator current and a first rotor current and has a first efficiency; and operate the induction motor in a second operating mode in which, to achieve the first torque value, the induction motor is operated with a second stator current and a second rotor current and has a second efficiency, wherein the second rotor current is less than the first rotor current, the second stator current is greater than the first stator current, and the second efficiency is lower than the first efficiency. An advantage of the control system is that the induction motor can meet a torque demand for a longer period of time without overheating. The second operating mode has lower rotor conduction (l2R) losses to achieve the same torque value and therefore the induction motor generates less heat in the rotor when it is operated in the second operating mode. Optionally, the induction motor control system is configured to select an operating point for the second operating mode from a plurality of possible operating points, wherein each of the possible operating points comprise a value for the second stator current and a value for the second rotor current to achieve the first torque value. This has an advantage of controlling an amount of heat reduction in the rotor. For example, considering a range of torque demands, a torque demand at a low end of the range may only require a low reduction in rotor current, while a torque demand at a high end of the range may require a high reduction in rotor current. Operating in the second operating mode is less efficient, as it uses more electrical energy to achieve the same torque. Therefore, an ability to adjust an amount of the reduction in rotor current can allow a reduction in generated heat while minimising the reduction in efficiency. Optionally, the induction motor control system is configured to select an operating point for the second operating mode based at least in part on a temperature of the rotor. The temperature of the rotor may be a measured temperature of the rotor, such as a temperature measured by a temperature sensor. Alternatively, the temperature of the rotor may be a predicted temperature of the rotor, such as a predicted temperature calculated by a thermal model of the induction motor. An advantage of predicting the temperature of the induction motor, rather than measuring an actual temperature of the induction motor, is that is possible to obtain a temperature for a part of the induction motor which it is not possible to reliably measure with a temperature sensor. The control system may operate the induction motor in the first operating mode or in the second operating mode by comparing the temperature of the rotor with a threshold value. Additionally, or alternatively, the control system may operate the induction motor in the first operating mode or in the second operating mode in dependence on an increase or a decrease in temperature over a period of time (i.e. a positive or negative temperature delta). Optionally, there is a maximum stator current associated with the induction motor and the control system is configured to select an operating point for the second operating mode having a value for the second stator current which is less than the maximum stator current. Optionally, there is a maximum rotor current associated with the inductio