Control apparatus and control method for motor drive vehicle

• US 5,355,749 A
• Filed: 12/17/1992
• Issued: 10/18/1994
• Est. Priority Date: 12/20/1991
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Okuyama, Toshiaki, Masaki, Ryoso, Obara, Sanshiro, Shioya, Makoto, Ohmae, Tsutomu, Naoi, Keigo
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US07/992,112
• Time in Patent Office: 670 Days
• Field of Search: 74/866
• US Class Current: 477/20
• CPC Class Codes: B60K 31/04 and means for comparing one electrical quantity, e.g. voltage, pulse, waveform, flux, or the like, with another quantity of a like kind, which comparison means is involved in the development of an electrical signal which is fed into the controlling means
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 8/00 Electric propulsion with power supply from forces of nature, e.g. sun or wind
• CPC Class Codes: B60L 8/003 Converting light into electric energy, e.g. by using photo-voltaic systems
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/107 with endless flexible members
• CPC Class Codes: B60W 2050/001 Proportional integral [PI] controller
• CPC Class Codes: B60W 2050/0019 Control system elements or transfer functions
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2720/10 Longitudinal speed
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• 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 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 903/918 : Continuously variable

Abstract

A control apparatus of a motor drive vehicle includes a unit for generating a target vehicle speed; a speed instruction unit for generating a target motor rotational speed of the motor based upon a preset motor control pattern in response to the target vehicle speed; a power circuit for operating the motor at the target motor rotational speed upon receipt of the target motor rotational speed; a variable transmission unit for converting a drive output from the motor into a transmission ratio for instructing a rotational speed of the drive output, and transferring the converted transmission ratio to a drive shaft of the motor drive vehicle; and a transmission ratio calculating unit for determining the transmission gear ratio based on the target vehicle speed and the target motor rotational speed thereby to instruct the determined transmission gear ratio to the variable transmission unit. A control method sets a target vehicle speed value; produces a target motor rotational speed based upon the target vehicle speed value and a preset motor control pattern; operates the motor at the target motor rotational speed; determines a transmission gear ratio based upon both of the target vehicle speed and the target motor rotational speed; and converts a rotational speed of a drive output into the transmission ratio and transfers the converted transmission ratio to a drive shaft.

Claims

1. A control apparatus of a vehicle driven by an electric motor, comprising:

means for generating a target vehicle speed according to an operator input of an accelerator device;

vehicle speed control means, having means for detecting actual speed of said vehicle and means for calculating difference between said target vehicle speed and the actual vehicle speed, for controlling a vehicle speed so as to make the difference zero;

motor speed instruction means for receiving an instruction value corresponding to a value of said different and for generating a target motor speed according to a predetermined high efficiency pattern whereon maximum efficiency points are plotted in relation to the motor speed values and motor power values obtained from values of said difference;

motor control means for receiving said target motor speed from said motor speed instruction means and driving said electric motor in said target motor speed;

variable transmission means for receiving output of said electric motor and varying rotation speed of said output of the motor in a transmission ratio instructed so as to transfer the rotation to a drive shaft of said vehicle; and

transmission ratio calculating means for determining said transmission ratio on the basis of said target vehicle speed and said target motor speed and instructing said transmission ratio to said variable transmission means.

2. A control apparatus as claimed in claim 1, wherein said variable transmission means includes a continuously variable transmission.

3. A control apparatus as claimed in claim 1, wherein said power circuit includes:

means for detecting an actual motor output rotational speed;

means for obtaining deviation between said target motor rotational speed and said motor output rotational speed; and

a feedback loop for controlling said motor along such a direction that said deviation becomes zero.

4. A control apparatus as claimed in claim 1, wherein said power circuit includes an inverter in which a battery mounted on said motor drive vehicle is used as a power source.

5. A control apparatus as claimed in claim 1, wherein said transmission gear ratio calculating means includes:

means for calculating a ratio of said target vehicle speed to said target motor rotation speed.

6. A control apparatus as claimed in claim 1, wherein said vehicle speed control means has a variable control constant of a transfer function thereof.

7. A control apparatus as claimed in claim 6, wherein said vehicle speed control means contains a proportional integral compensating control system, and both of a proportional compensating constant and an integral constant of a transfer function of said proportional integral compensating control system are variable.

8. A control apparatus as claimed in claim 1, wherein said variable transmission means is constructed by combining a plurality of continuously variable transmissions.

9. A control apparatus as claimed in claim 1, wherein said vehicle transmission means is constructed by combining a continuously variable transmission with a transmission having a fixed transmission ratio.

10. A control apparatus as claimed in claim 1, wherein said motor is juxtaposed with said transmission means, said motor drive vehicle further includes a cooling system, and both of said motor and said transmission means are commonly cooled by said cooling system.

11. A control apparatus as claimed in claim 4, wherein said motor is an induction motor driven by said inverter.

12. A method for controlling a vehicle driven by an electric motor, comprising the steps of:

setting a target vehicle speed according to operation amount of an accelerator device;

detecting actual speed of said vehicle;

calculating difference between said target vehicle speed and the actual vehicle speed; and

controlling a vehicle speed to make the difference zero, said vehicle speed controlling step further including the steps of;

generating a target motor speed according to a predetermined high efficiency pattern whereon maximum efficiency points are plotted in relation to the motor speed values and motor power values obtained from values of said the difference;

driving said electric motor in said target motor speed;

determining a translation ratio on the basis of said target vehicle speed and said target motor speed; and

varying rotation speed of said output of the motor in said transmission ratio so as to transfer the rotation to a drive shaft of said vehicle.

13. A control apparatus of a vehicle driven by an electric motor, comprising:

a target vehicle speed generating unit providing a target vehicle speed according to an operator input of an accelerator device;

vehicle speed control unit, having an actual speed detection unit and a difference calculating unit for calculating a difference between said target vehicle speed and the actual vehicle speed, for controlling a vehicle speed so as to make the difference zero;

motor speed instruction device for receiving an instruction value corresponding to a value of said different and for generating a target motor speed according to a predetermined high efficiency pattern whereon maximum efficiency points are plotted in relation to the motor speed values and motor power values obtained from values of said difference;

motor control unit for receiving said target motor speed from said motor speed instruction device and driving said electric motor in said target motor speed;

a variable transmission for receiving output of said electric motor and varying rotation speed of said output of the motor in a transmission ratio instructed so as to transfer the rotation to a drive shaft of said vehicle; and

transmission ratio calculating unit for determining said transmission ratio on the basis of said target vehicle speed and said target motor speed and instructing said transmission ratio to said variable transmission.