ELECTRIC AUTOMOBILE

• US 20130325239A1
• Filed: 02/10/2012
• Published: 12/05/2013
• Est. Priority Date: 02/25/2011
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Ozaki, Takayoshi
• Granted Patent: US 8,909,406 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 17/046 with planetary gearing having orbital motion
• CPC Class Codes: B60K 17/356 having fluid or electric motor, for driving one or more wheels disposition of motor in, or adjacent to, traction wheel B60K7/00
• CPC Class Codes: B60K 2007/0038 the motor moving together with the wheel axle
• CPC Class Codes: B60K 2007/0092 the motor axle being coaxial to the wheel axle
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60L 2220/42 with use of more than one motor
• 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 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/429 Current
• CPC Class Codes: B60L 2240/461 Speed
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 3/0061 relating to electrical machines
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: B60T 17/22 Devices for monitoring or checking brake systems; Signal devices
• CPC Class Codes: B60T 2270/402 Back-up
• CPC Class Codes: B60T 2270/406 Test-mode; Self-diagnosis
• CPC Class Codes: B60T 7/12 : for automatic initiation; for initiation not subject to will of driver or passenger limiting speed of vehicles other than rail vehicles B60K31/00
• CPC Class Codes: B60T 8/3255 : Systems in which the braking action is dependent on brake pedal data
• CPC Class Codes: B60T 8/329 : Systems characterised by their speed sensor arrangements
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

An electric vehicle includes a malfunction detector configured to continuously monitor a torque command from an ECU as well as one of the followings: signals indicating a rotational frequency of a motor unit; signals indicating a rotational frequency of a wheel driven by the motor unit; signals indicating a rotational direction of the motor unit; signals indicating a rotational direction of the wheel driven by the motor unit; and a motor current, and detect, according to a predefined rule, a malfunction of the motor unit, based on the monitoring information. The electric vehicle also includes a malfunction-responsive controller configured to cause at least one of shut-off of a drive current to the motor unit and braking with a mechanical brake, if the malfunction detector detects a malfunction.

Claims

1. An electric vehicle comprising:

a motor unit configured to drive a wheel;

an ECU which is an electronic control unit configured to perform general control of the vehicle;

an inverter unit, the inverter unit including;

a power circuitry including an inverter configured to convert a DC power from a battery unit into an AC power used to drive the motor unit; and

a motor control circuitry configured to control the power circuitry in accordance with a torque command from the ECU;

a mechanical brake configured to brake the wheel;

a malfunction detector configured to continuously monitor the torque command from the ECU as well as one of the followings;

signals indicating a rotational frequency of the motor unit;

signals indicating a rotational frequency of the wheel driven by the motor unit;

signals indicating a rotational direction of the motor unit;

signals indicating a rotational direction of the wheel driven by the motor unit; and

a motor current, and detect, according to a predefined rule, a malfunction of the motor unit, based on the monitoring information; and

a malfunction-responsive controller configured to cause at least one of shut-off of a drive current to the motor unit and braking with the mechanical brake, if the malfunction detector detects a malfunction,

wherein the motor unit comprises a plurality of motor units configured to drive respective different wheels and the malfunction-responsive controller is configured to cause, if a malfunction of one of the motor units is detected, not only shut-off of a drive current to the motor unit whose malfunction is detected but also shut-off of a drive current to one or more of the other motor units.

2. The electric vehicle as claimed in claim 1, wherein the malfunction detector includes a rotational direction command determiner configured to determine, based on the torque command from the ECU, an intended rotational direction of the motor unit and a rotational direction abnormality determiner configured to compare the intended rotational direction with a rotational direction determined based on one of the followings:

signals indicating a rotational frequency of the motor unit;

signals indicating a rotational frequency of the wheel driven by the motor unit;

signals indicating a rotational direction of the motor unit;

signals indicating a rotational direction of the wheel driven by the motor unit; and

a motor current, to determine a rotational direction abnormality of the motor unit.

3. The electric vehicle as claimed in claim 1, wherein the malfunction detector includes a rotational frequency estimator configured to determine, based on the torque command from the ECU, an intended rotational frequency of the motor unit and a rotational frequency abnormality determiner configured to compare the intended rotational frequency with one of the followings:

signals indicating a rotational frequency of the motor unit; and

signals indicating a rotational frequency of the wheel driven by the motor unit, to determine a rotational frequency abnormality of the motor unit.

5. The electric vehicle as claimed in claim 1, wherein the malfunction detector and the malfunction-responsive controller are included in the inverter unit.

6. The electric vehicle as claimed in claim 1, wherein the motor unit, the malfunction detector and the malfunction-responsive controller are configured such that two malfunction detectors are assigned to one motor unit, and the malfunction-responsive controller is either configured to cause malfunction-responsive control which includes shut-off of a drive current to the motor unit or braking with the mechanical brake, only if both of the two malfunction detectors detect a malfunction or configured to cause the malfunction-responsive control if one of the two malfunction detectors detects a malfunction.

7. The electric vehicle as claimed in claim 1, wherein the motor unit, the malfunction detector and the malfunction-responsive controller are configured such that at least three malfunction detectors are assigned to one motor unit, and the malfunction-responsive controller is configured to cause malfunction-responsive control which includes shut-off of a drive current to the motor unit or braking with the mechanical brake, if at least one half of the at least three malfunction detectors detect a malfunction.

8. The electric vehicle as claimed in claim 1, wherein the motor unit, together with a wheel bearing unit and a reducer unit interposed between the wheel bearing unit and the motor unit, forms an in-wheel motor drive system.

9. The electric vehicle as claimed in claim 8, wherein the reducer unit comprises a cycloidal reducer.

4. (canceled)