Control system for an electric vehicle

• US 6,002,221 A
• Filed: 03/09/1998
• Issued: 12/14/1999
• Est. Priority Date: 03/11/1997
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Hara, Kazuhiro, Ochiai, Shinobu
• Primary Examiner(s): MARTIN, DAVID S
• Application Number:
  US09/037,046
• Time in Patent Office: 645 Days
• Field of Search: 318/139, 318/140-158, 318/798-817
• 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

A system is provided to clearly determine a problem in the discharge of a capacitor provided for an inverter of an electric vehicle and its cause. If a capacitor voltage drops below a predetermined value at the end of a first predetermined time period after a main contactor is turned off, it is determined that the main contactor and a discharge circuit are normal. If the capacitor voltage drops below the predetermined value for the first time after a second predetermined time period, it is determined that the discharge circuit has failed and discharge is performed by a discharge resistor. If the capacitor voltage is still above the predetermined value after the second predetermined time period, it is determined that the main contactor has failed and is fixed in a turned-on state.

Claims

1. A control system for an electric vehicle, comprising:

a main battery;

a traveling motor;

an inverter for converting DC electric power of the main battery into AC electric power to drive the traveling motor;

a contactor connected between the main battery and the inverter;

a smoothing capacitor connected in parallel with the inverter;

a discharge circuit connected in parallel with the inverter to discharge electric charge of the capacitor, within a first predetermined time period;

a discharge resistor connected in parallel with the capacitor, for discharging the electric charge of the capacitor within a second predetermined time period, the second time period being longer than the first predetermined time period; and

control means for starting the discharge of the capacitor by operating a discharge circuit when opening the contactor;

wherein the control means determines a failure of the discharge circuit if a capacitor voltage is equal to or greater than a reference value at the end of the first predetermined time period and is lower than the reference value at the end of the second predetermined time period, and further determines a failure of the contactor if the capacitor voltage is equal to or greater than the reference value at the end of the second predetermined time period.

2. A control system for an electric vehicle as set forth in claim 1, wherein said first and second predetermined time periods begin when the capacitor starts to discharge.

3. A control system for an electric vehicle as set forth in claim 1, wherein the first predetermined time period is 40 seconds.

4. A control system for an electric vehicle as set forth in claim 3, wherein the second predetermined time period is 5 minutes.