Electric vehicle control device

• US 9,550,435 B2
• Filed: 11/22/2012
• Issued: 01/24/2017
• Est. Priority Date: 11/24/2011
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Ozaki, Takayoshi, Okada, Koichi, Suzuki, Kenichi
• Primary Examiner(s): Shaawat, Mussa A
• Assistant Examiner(s): KIM, KYUNG J
• Application Number:
  US14/359,726
• Publication Number:
  US 20140330470A1
• Time in Patent Office: 1,524 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 15/2072 for drive off
• CPC Class Codes: B60L 2220/44 Wheel Hub motors, i.e. integrated in the wheel hub
• CPC Class Codes: B60L 2220/46 Wheel motors, i.e. motor connected to only one wheel
• CPC Class Codes: B60L 2220/50 Structural details of electrical machines
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/20 angular
• CPC Class Codes: B60L 2240/24 Steering angle
• CPC Class Codes: B60L 2240/26 Vehicle weight
• CPC Class Codes: B60L 2240/34 Cabin temperature
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/429 Current
• CPC Class Codes: B60L 2240/465 Slip
• CPC Class Codes: B60L 2240/622 by satellite navigation
• CPC Class Codes: B60L 2240/642 Slope of road
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2260/28 : Four wheel or all wheel drive
• CPC Class Codes: B60L 2270/145 : Structure borne vibrations
• CPC Class Codes: B60L 3/102 : of individual wheels
• CPC Class Codes: B60L 3/108 : whilst braking, i.e. ABS
• CPC Class Codes: B60L 50/51 : characterised by AC-motors
• CPC Class Codes: B60L 7/14 : for vehicles propelled by ac motors
• CPC Class Codes: B60L 7/26 : Controlling the braking effect
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

An angular acceleration monitor may monitor whether or not an angular acceleration of a wheel detected by an angular acceleration detector is equal to or smaller than an acceptable angular acceleration (W) that is calculated with the following formula: W=k1×R×Tt/m/r² where k1 is a constant, Tt is a total drive torque that is a sum of drive torques of all motor units that drive wheels of the vehicle, m is vehicle mass, r is tire radius, and R is reduction ratio of a reducer unit interposed between the motor unit and the wheel. A slip-responsive controller causes, if it is determined that the acceptable angular acceleration is exceeded, a motor controller to reduce a drive torque of the motor unit(s).

Claims

1. An electric vehicle control device comprising:

a motor controller configured to control, according to a torque command fed from a torque command generator, a torque of a motor unit that is configured to drive a wheel;

an angular acceleration detector configured to detect an angular acceleration of a wheel driven by the motor unit;

an angular acceleration monitor configured to monitor whether or not an angular acceleration of a wheel detected by the angular acceleration detector is equal to or smaller than an acceptable angular acceleration W that is calculated with one of following formulas (1) to (6);

W=k1×

R×

Tt/m/r² 

 

(1)

where k1 is a constant that takes an arbitrary value in the range of 1 to 2;

W=k2×

R×

Tt/m/r²+mg×

sin(a)/m/r 

 

(2)

where k2 is a constant that takes an arbitrary value in the range of 1 to 2 and g is a gravitational acceleration;

W=k3×

R×

Tt/m/r²+mg×

sin(a1)/m/r 

 

(3)

where k3 is a constant that takes an arbitrary value in the range of 1 to 2;

W=k4×

R×

Tmaxt/m/r² 

 

(4)

where Tmaxt is a total maximum torque that is a sum of maximum torques of all motor units that drive wheels of the vehicle and k4 is a constant that takes an arbitrary value in the range of 1 to 2;

W=k5×

R×

Tmaxt/m/r²+mg×

sin(a)/m/r 

 

(5)

where Tmaxt is a total maximum torque that is a sum of maximum torques of all motor units that drive wheels of the vehicle, k5 is a constant that takes an arbitrary value in the range of 1 to 2, and g is a gravitational acceleration; and

W=k6×

R×

Tmaxt/m/r²+mg×

sin(a1)/m/r 

 

(6)

where Tmaxt is a total maximum torque that is a sum of maximum torques of all motor units that drive wheels of the vehicle and k6 is a constant that takes an arbitrary value in the range of 1 to 2;

where Tt is a total drive torque that is a sum of drive torques of all motor units that drive wheels of the vehicle, m is a vehicle mass, r is a tire radius, R is a reduction ratio of a reducer unit interposed between the motor unit and the wheel, a is a vehicle climbing angle detected by a climbing angle detector, and a1 is a maximum vehicle climbing angle as specified by specifications of the vehicle; and

a slip-responsive controller configured to, when the angular acceleration monitor determines that the detected angular acceleration is greater than the acceptable angular acceleration W, cause the motor controller to reduce a drive torque of the motor unit.

2. The electric vehicle control device as claimed in claim 1, wherein the motor unit is configured to drive a wheel of the electric vehicle independently of other wheels.

3. The electric vehicle control device as claimed in claim 2, wherein the slip-responsive controller is configured to cause the motor controller to reduce a drive torque of only a motor unit that drives a wheel rotating at an angular acceleration detected by the angular acceleration detector that is greater than the acceptable angular acceleration W.

4. The electric vehicle control device as claimed in claim 2, wherein the motor unit, together with a reducer unit, forms an in-wheel motor drive system that is partly or entirely disposed within a wheel, and wherein the in-wheel motor drive system includes the motor unit and the reducer unit.

5. The electric vehicle control device as claimed in claim 1, wherein the electric vehicle comprises a reducer unit configured to reduce speed of rotation of the motor unit, the reducer unit including a cycloidal reducer with a high reduction ratio of 4 or greater.

6. The electric vehicle control device as claimed in claim 1, wherein the slip-responsive controller is configured to determine and set the acceptable angular acceleration W based solely on an output torque, where the vehicle mass is a fixed value.

7. The electric vehicle control device as claimed in claim 1, wherein respective wheel bearing units of two front and two rear wheels of the vehicle are associated with respective load sensors, and wherein the slip-responsive controller is configured to use a vehicle mass measured in real time by the load sensors to determine and set the acceptable angular acceleration W.

8. The electric vehicle control device as claimed in claim 1, wherein the slip-responsive controller is configured to vary amount of torque reduction, according to a degree by which an angular acceleration of a wheel exceeds the acceptable angular acceleration W.

9. The electric vehicle control device as claimed in claim 1, wherein motor units with which two or more wheels are independently driven and inverter units to respectively control the corresponding motor units are provided such that corresponding wheels are controllable independently of each other by the slip-responsive controller.

10. An electric vehicle comprising the electric vehicle control device as claimed in claim 1.