Control system for an electric vehicle

• US 5,994,789 A
• Filed: 03/06/1998
• Issued: 11/30/1999
• Est. Priority Date: 03/07/1997
• 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: Ochiai, Shinobu
• Primary Examiner(s): Elms, Richard T.
• Application Number:
  US09/035,973
• Time in Patent Office: 634 Days
• Field of Search: 307/91.1, 307/10.1, 307/10.7, 307/46, 307/48, 307/18, 307/19, 307/20, 320/104, 320/124, 320/127, 320/134, 320/136-138, 320/166, 180/65.3, 180/65.1, 180/65.8, 318/139
• US Class Current: 307/10.1
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 2270/20 Inrush current reduction, i.e. avoiding high currents when connecting the battery
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• 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

Abstract

A system is provided to effectively use the electric charge of a capacitor provided for an inverter in an electric vehicle when the capacitor discharges and to decrease the time required for discharge. An inverter for converting the DC electric power of a main battery into AC electric power to drive a traveling motor is provided with a smoothing capacitor to be charged through a precharge contactor. A DC/DC converter is used to charge a sub-battery using the electric power from the main battery when an electric vehicle runs. When the capacitor discharges, the electric charge of the capacitor is used to charge the sub-battery through the DC/DC converter. Because no discharge circuit is used when the capacitor discharges, it is possible to complete discharge in a short time and without the generation of heat by the discharge circuit.

Claims

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

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

a smoothing capacitor connected in parallel with the inverter;

control means for controlling charge/discharge of the capacitor and the inverter;

a sub-battery coupled to the control means for supplying power to the control means; and

a DC/DC converter connected to the sub-battery for charging the sub-battery using the main battery, wherein the control means further connects the capacitor to the DC/DC converter for supplying the electric charge of the capacitor to the sub-battery through the DC/DC converter, when the capacitor discharges.

2. A control system for an electric vehicle as set forth in claim 1, wherein when the charge of the capacitor is supplied to the sub-battery for a predetermined period of time, the control means disconnects the capacitor from the DC/DC converter.

3. A control system for an electric vehicle as set forth in claim 1, wherein when the voltage across the capacitor is less than a predetermined voltage, the control means disconnects the capacitor from the DC/DC converter.

4. A control system for an electric vehicle as set forth in claim 1, wherein said control means operates with supply of power from said sub-battery, and the supply of power from the sub-battery to the control means stops when the electric discharge from the capacitor to the sub-battery stops.