Method and apparatus for operating an electric vehicle drive system during periods of sensor malfunction

• US 5,661,380 A
• Filed: 11/07/1995
• Issued: 08/26/1997
• Est. Priority Date: 11/07/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi Car Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi Car Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Yoshihara, Shigeyuki, Yamada, Hiroyuki, Obara, Sanshiro, Matsudaira, Nobunori
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US08/554,498
• Time in Patent Office: 658 Days
• Field of Search: 318/139, 318/432, 318/434, 318/490, 318/798-815, 318/599, 180/170, 180/171, 180/179, 180/282, 180/287, 307/9.1, 307/10.1, 307/10.7, 361/23, 361/24, 361/33, 361/31, 388/907
• US Class Current: 318/139
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train

Abstract

The present invention provides a protection apparatus in a control system for an electric vehicle which is capable of performing back-up driving by using a back-up control method, without using output from sensors even if the sensor in the control system for ordinary driving is failed. When at least one of the current sensor, the speed sensor and the accelerator sensor is detected to be abnormal, a back-up control voltage v1 is output as an abnormal signal from a running back-up control circuit. As a result, the running back-up control circuit sets the limiter of the output of the current control circuit to zero and switches the control signal to the inverter from vector control to V/f voltage control.

Claims

1. A protection apparatus for an electric vehicle of the type comprising an inverter for converting a direct current electric power source of a battery to a variable voltage and variable frequency alternating current power source, a three-phase alternating current motor for driving the vehicle, a current sensor for detecting current flowing to said three-phase alternating current motor, a torque command calculator for determining a torque command of said three-phase alternating current motor based on a degree of opening of an accelerator detected by an accelerator sensor, an alternating current command generator for generating a current command to control current flowing to said three-phase alternating current motor based on said torque command and an output of said current sensor, a current control circuit for generating a voltage signal based on said current command and the current flowing to said three-phase alternating current motor, a limiter for limiting the voltage signal generated by said current control circuit and PWM signal generating means for generating a PWM signal to control said inverter based on an output from the limiter;

said protection apparatus comprising;

a detector for detecting abnormal operation of said current sensor; and

a back-up circuit responsive to detection of said abnormal operation for causing an output of said limiter to be set to zero, and for generating a voltage command based on a back-up control voltage output from said alternating current command generating means, said PWM signal generating means generating a PWM signal for control of said inverter using said voltage command.

3. A protection apparatus for the electric vehicle according to claim 1, wherein said current control circuit comprises a voltage utilization improving circuit for converting said voltage command to a three-phase voltage command.

2. A protection apparatus for an electric vehicle of the type comprising an inverter for converting a direct current electric power source of a battery to a variable voltage and variable frequency alternating current power source, a three-phase alternating current motor for driving the vehicle, a current sensor for detecting current flowing to said three-phase alternating current motor, a torque command calculator for determining a torque command of said three-phase alternating current motor based on a degree of opening of an accelerator detected by an accelerator sensor, a current control circuit for generating a voltage signal based on said torque command and an output of said current sensor a limiter for limiting the voltage signal generated by said current control circuit, and a PWM signal generator for generating a PWM signal to control said inverter based on an output from the limiter;

said protection apparatus comprises;

a detector for detecting abnormal operation of said current sensor;

a back-up circuit responsive to detection of said abnormal operation for causing an output of said limiter to be set to zero, and for generating a voltage command based on a back-up control voltage output from said alternating current command generator, said PWM signal generator generating a PWM signal for control said inverter using said voltage command.

6. A protection apparatus for the electric vehicle according to claim 2, wherein said current control circuit comprises a voltage utilization improving circuit for converting said voltage command to a three-phase voltage command.

4. A method for protecting an electric vehicle of the type comprising an inverter for converting a direct current electric power source of a battery to an alternating current power source, a three-phase alternating current motor for driving the vehicle, a current sensor for detecting current flowing to said three-phase alternating current motor, a torque command calculator for determining a torque command of said three-phase alternating current motor based on a degree of opening of an accelerator detected by an accelerator sensor, an alternating current command generator for generating a current command to control the current flowing to said three-phase alternating current motor based on said torque command and an output of said current sensor, a current control circuit for generating a voltage signal based on said current command and the current flowing to said three-phase alternating current motor, a limiter for limiting the voltage signal generated by said current control circuit, and a PWM signal generator for generating a PWM signal to control said inverter based on an output from the limiter, wherein a back-up signal for driving said three-phase alternating current motor is generated at an abnormal state of said sensor to make the electric vehicle capable of driving;

said method comprising the steps of;

in response to said back-up signal, causing an output of said limiter to be set to zero, generating a voltage command based on a back-up control voltage output from said alternating current command generator, and causing said PWM signal generator to generate a PWM signal for control said inverter using said voltage command.

5. A method for protecting an electric vehicle of the type comprising an inverter for converting a direct current electric power source of a battery to an alternating current power source, a three-phase alternating current motor for driving the vehicle, a current sensor for detecting current flowing to said three-phase alternating current motor, a torque command calculator for determining a torque command of said three-phase alternating current motor based on a degree of opening of an accelerator detected by an accelerator sensor, a current control circuit for generating a voltage signal based on said torque command and an output of said current sensor, a limiter for limiting the voltage signal generated by said current control circuit and a PWM signal generator for generating a PWM signal to control said inverter based on said voltage signal, wherein a back-up signal for driving said three-phase alternating current motor is generated at an abnormal state of said sensor to make the electric vehicle capable of driving;

said method comprising the steps of;

detecting abnormal operation of said current sensor;

setting an output of said limiter to zero;

generating a voltage command based on a back-up control voltage output from said alternating current command generator; and

said PWM signal generator generating a PWM signal for control of said inverter using said voltage command.