Drive system with limited slip electric differential drive unit

Patent metadata

Field	Value
Publication number	US-9862289-B1
Application number	US-201715421580-A
Country	US
Kind code	B1
Filing date	Feb 1, 2017
Priority date	Feb 1, 2017
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A limited slip electric drive system for a motor vehicle is disclosed. The system uses an induction motor having a stator, and first and second rotors disposed for independent rotation within the stator. The rotors are each independently associated with one wheel of the vehicle and are able to slip when the vehicle goes around a turn. A traction inverter and control system monitors angular speeds of the rotors and determines which of the rotors is turning slower than the other, and controls the induction motor in accordance with the rotor having a lower speed so that a torque signal is generated in accordance with the rotor having the lower speed.

First claim

What is claimed is:

1. A limited slip electric drive system for a motor vehicle comprising:
an induction motor, the induction motor including:
a stator;
a first rotor disposed for rotation within the stator, the first rotor being associated with a first wheel of the vehicle;
a second rotor disposed for rotation within the stator, the second rotor being associated with the second wheel of the vehicle and able to rotate within the stator independently of the first rotor, each of the first and second rotors being able to slip relative to the other as needed when the vehicle is travelling around a turn; and
a traction inverter and control system for monitoring an angular speed of each of the first and second rotors, determining which of the first and second rotors is turning slower than the other, and generating a signal for controlling the induction motor in accordance with the one of the first or second rotors having a lower speed, so that a torque signal is generated in accordance with the rotor having the lower speed.

2. The system of claim 1 , wherein the traction inverter and control system includes a first encoder associated with the first rotor, and a second encoder associated with the second rotor.

3. The system of claim 2 , wherein the traction inverter and control system includes an encoder selection control system in communication with the first and second encoders, that is configured to detect which of the first and second rotors is turning at a slower speed, and for selecting a speed signal from the one of the first and second rotors that has a slower speed for use in determining a torque command to be applied to the rotor having the slower speed.

4. The system of claim 3 , wherein the traction inverter and control system further includes a slip frequency calculation system for calculating a slip frequency for the induction motor.

5. The system of claim 4 , wherein the traction inverter and control system further includes:
an inverter section; and
a field oriented control system for receiving a flux command and a torque command, and determining a three phase AC voltage signal to be applied to the inverter section.

6. The system of claim 5 , wherein the field oriented control system also receives a signal representing real time rotor angle for the one of the first and second rotors that is determined to have the slower speed.

7. The system of claim 1 , further comprising:
a first planetary gear reduction system driven by the first rotor; and
a second planetary gear reduction system driven by the second rotor.

8. A limited slip electric drive system for a motor vehicle comprising:
an induction motor, the induction motor including:
a stator;
a first rotor disposed for rotation within the stator, the first rotor being adapted to drive a first wheel of the vehicle;
a second rotor disposed for rotation within the stator, the second rotor being adapted to drive a second wheel of the vehicle, the second rotor being rotatable within the stator independently of the first rotor such that each of the first and second rotors is allowed to slip relative to the other when needed as the vehicle is travelling around a turn;
a first encoder coupled to the first rotor and configured to detect a position of the first rotor relative to the stator;
a second encoder coupled to the second rotor and configured to detect a position of the second rotor relative to the stator;
a traction inverter and control system including:
a slip frequency calculation system for calculating a real time slip frequency of the induction motor; and
an encoder selection system responsive to signals from the first and second encoders and being configured to determine a speed signal that is representative of a rotational speed of one the first and second rotors having lower rotational speed than the other one of the first and second rotors, the speed signal being based on an output of one of the first and second encoders that is associated with the one of the first and second rotors having lower rotational speed;
wherein the traction inverter and control system is configured to control the induction motor so that a torque signal is generated in accordance with the one of the first and second rotors having the lower speed.

9. The system of claim 8 , wherein the traction inverter and control system further includes a field oriented control system for generating a three phase AC voltage drive signal.

10. The system of claim 9 , wherein the traction inverter and control system further includes an inverter responsive to the field oriented control system for generating signals applied to the induction motor to commutate the induction motor.

11. The system of claim 8 , further comprising:
a first planetary gear reduction system driven by the first rotor; and
a second planetary gear reduction system driven by the second rotor.

12. A method for forming a limited slip electric drive system for a motor vehicle, the method comprising:
arranging a first rotor for rotation within a stator of an induction motor, the first rotor being associated with a first wheel of the vehicle on a driver side of the vehicle;
arranging a second rotor for rotation within the stator, the second rotor being associated with a second wheel of the vehicle on a passenger side of the vehicle and rotating about a common axis with the first rotor, the second rotor further being able to rotate within the stator independently of the first rotor so that the first and second rotors are able to rotate at different speeds as needed when the vehicle is travelling around a turn;
using a traction inverter and control system to monitor an angular speed of each of the first and second rotors while the vehicle is travelling, to determine which of the first or second rotors is turning slower than the other, and
using the traction inverter and control system to control the induction motor so that so that a torque signal is generated in accordance with the one of the first and second rotors that is turning slower than the other one of the first and second rotors.

13. The method of claim 12 , wherein using the traction and control system to control the induction motor comprises using a field oriented control system to receive motor flux and motor torque command signals and to generate a three phase AC voltage signal for driving the induction motor.

14. The method of claim 13 , wherein using the traction and control system to control the induction motor further comprises using an inverter responsive to the three phase AC signal voltage drive signal to generate signals for commutating the induction motor.

15. The method of claim 14 , wherein a first encoder is coupled to the first rotor, wherein a second encoder is coupled to the second rotor, and wherein using the traction and control system to control the induction motor further comprises using an encoder selection control to receive signals from the first and second encoders and to use the signals from the first and second encoders to determine the one of the first and second rotors that is turning slower than the other one of the first and second rotors.

16. The method of claim 15 , wherein using the traction and control system to control the induction motor further comprises using a slip frequency detection system to detect a real time slip frequency of the induction motor.

17. The method of claim 12 , further comprising:
using a first planetary gear reduction system interposed between the first rotor and the first wheel; and
using a second planetary gear reduction system interposed betw

Assignees

• American Axle & Mfg Inc

Inventors

• Crecelius David

Classifications

• B60L11/1803

  Operations & Transport · mapped topic

• B60L15/2054 Primary

  by controlling transmissions or clutches · CPC title

• H02P21/12

  Stator flux based control involving the use of rotor position or rotor speed sensors · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• B60K17/046

  with planetary gearing having orbital motion · CPC title