Control system and method for hybrid vehicle

• US 7,857,081 B2
• Filed: 07/10/2009
• Issued: 12/28/2010
• Est. Priority Date: 07/11/2008
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kishimoto, Takeshi
• Primary Examiner(s): VANAMAN, FRANK BENNETT
• Application Number:
  US12/501,050
• Publication Number:
  US 20100006360A1
• Time in Patent Office: 536 Days
• Field of Search: 180/65.21, 180/65.22, 180/65.225, 180/65.265, 180/65.27, 180/65.285, 180/65.29, 701/48, 701/70, 290/50, 903/930
• US Class Current: 180/65.27
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/34 characterised by the absence of energy storing means
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2270/20 Inrush current reduction, i.e. avoiding high currents when connecting the battery
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 50/02 Ensuring safety in case of control system failures, e.g. by diagnosing, circumventing or fixing failures
• CPC Class Codes: B60W 50/04 : Monitoring the functioning of the control system
• CPC Class Codes: B62D 5/046 : Controlling the motor
• CPC Class Codes: B62D 5/0481 : monitoring the steering system, e.g. failures
• CPC Class Codes: B62D 5/0484 : for reaction to failures, e.g. limp home
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• 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

Abstract

A control system for a hybrid vehicle in which, even if during traveling of the hybrid vehicle, a battery defect arises in a high-voltage power source, battery-less emergency traveling can be achieved over a sufficiently long distance, and the steering assist force can be effectively prevented from changing rapidly during traveling. The control section includes high-voltage power source defect processing unit. During execution of a mode in which the high-voltage power source, is reduced so that the reduced voltage is supplied to an electric power steering device (EPS), when a defect occurs in the high-voltage power source, the high-voltage power source defect processing unit shifts to a mode in which the low voltage of a low-voltage power source is increased so that the increased voltage is supplied to the EPS. The high-voltage power source defect processing unit then disconnects the high-voltage power source and the driving circuit from each other.

Claims

1. A control system for a hybrid vehicle driven to travel using at least one of an engine and a traveling motor as a main driving source, the hybrid vehicle comprising:

a generator driven by the engine;

a high-voltage power source connected to the generator and the traveling motor via a driving circuit;

a low-voltage power source charged at a voltage lower than that of the high-voltage power source;

an electric power steering device connected to the driving circuit via a voltage-reducing circuit and driven by supplied power of a voltage intermediate between the low voltage of the low-voltage power source and the high voltage of the high-voltage power source;

a voltage-increasing circuit provided between the low-voltage power source and the electric power steering device and configured to increase the low voltage of the low-voltage power source and to supply the increased voltage to the electric power steering device; and

a control section,

wherein the control section comprises;

first mode execution unit for allowing the voltage-reducing circuit to reduce the high voltage of the high-voltage power source and supplying a resultant intermediate voltage to the electric power steering device;

second mode execution unit for allowing the voltage increasing circuit to increase the low voltage of the low-voltage power source and supplying the resultant intermediate voltage to the electric power steering device;

third mode execution unit for, with the high-voltage power source and the driving circuit disconnected from each other, allowing the voltage-reducing circuit to reduce a voltage corresponding to power generated by the generator and supplying the resultant intermediate voltage to the electric power steering device; and

high-voltage power source defect processing unit for, while the first mode is being executed and when a defect arises in the high-voltage power source, shifting from execution of the first mode to execution of the second mode, then disconnecting the high-voltage power source and the driving circuit from each other, and thereafter shifting the second mode to the third mode, while allowing the traveling motor to be driven by power generated by the generator.

2. The control system for the hybrid vehicle according to claim 1, wherein if a defect arises in at least one of the generator, the traveling motor and the driving circuit during the shift to the third mode following the occurrence of the defect in the high-voltage power source, the high-voltage power source defect processing unit shifts from execution of the third mode to execution of the second mode.

3. The control system for the hybrid vehicle according to claim 1, further comprising a second voltage-reducing circuit provided between the driving circuit and the low-voltage power source,

wherein after the shift to the second mode following the occurrence of the defect in the high-voltage power source, the high-voltage power source defect processing unit sets a second voltage-reducing circuit use start timing when a power supply from the generator to the low-voltage power source via the second voltage reducing circuit is enabled, to be different from a voltage-reducing circuit start timing when a power supply from the generator to the electric power steering device via the voltage-reducing circuit is enabled.

4. The control system for the hybrid vehicle according to claim 1, further comprising a voltage-detecting unit for detecting a voltage of the driving circuit,

wherein if an abnormality occurs in the detected voltage value of the driving circuit after the shift to the third mode following the occurrence of the defect in the high-voltage power source, the high-voltage power source defect processing unit stops the power supply from the generator to the traveling motor.

5. The control system for the hybrid vehicle according to claim 1, the driving circuit comprising a switch provided between the high-voltage power source and both the generator and the traveling motor and configured to be turned on and off;

a second voltage-reducing circuit provided between the driving circuit and the low-voltage power source; and

a voltage-increasing circuit and reducing provided between the switch and both the generator and the traveling motor and configured to reduce the voltage supplied by the generator and to supply the reduced voltage to the voltage-reducing circuit and the second voltage reducing circuit, the voltage-increasing and reducing circuit being configured to increase the voltage supplied by the high-voltage power source and to supply the increased voltage to at least one of the generator and the traveling motor.

6. A control method for a hybrid vehicle driven to travel using at least one of an engine and a traveling motor as a main driving source, the hybrid vehicle comprising:

a generator driven by the engine;

a high-voltage power source connected to the generator and the traveling motor via a driving circuit;

a low-voltage power source charged at a voltage lower than that of the high-voltage power source;

an electric power steering device connected to the driving circuit via a voltage-reducing circuit and driven by supplied power of a voltage intermediate between the low voltage of the low-voltage power source and the high voltage of the high-voltage power source;

a voltage-increasing circuit provided between the low-voltage power source and the electric power steering device and configured to increase the low voltage of the low-voltage power source and to supply the increased voltage to the electric power steering device; and

a control section,

wherein the control section comprises;

first mode execution unit for allowing the voltage-reducing circuit to reduce the high voltage of the high-voltage power source and supplying a resultant intermediate voltage to the electric power steering device;

second mode execution unit for allowing the voltage-increasing circuit to increase the low voltage of the low-voltage power source and supplying the resultant intermediate voltage to the electric power steering device; and

third mode execution unit for, with the high-voltage power source and the driving circuit disconnected from each other, allowing the voltage-reducing circuit to reduce a voltage corresponding to power generated by the generator and supplying the resultant intermediate voltage to the electric power steering device, and

the method comprises a high-voltage power source defect process step in which while the first mode is being executed and a defect arises in the high-voltage power source, the control section shifts from execution of the first mode to execution of the second mode, then disconnects the high-voltage power source and the driving circuit from each other, and thereafter shifts the second mode to the third mode, while allowing the traveling motor to be driven by power generated by the generator.

7. The control method for the hybrid vehicle according to claim 6, wherein in the high-voltage power source defect process step, if a defect arises in at least one of the generator, the traveling motor and the driving circuit during the shift to the third mode following the occurrence of the defect in the high-voltage power source, the control section shifts from execution of the third mode to execution of the second mode.

8. The control method for the hybrid vehicle according to claim 6, wherein the hybrid vehicle further comprises a second voltage-reducing circuit provided between the driving circuit and the low-voltage power source, and

in the high-voltage power source defect process step, after the shift to the second mode following the occurrence of the defect in the high-voltage power source, the control section sets a second voltage-reducing circuit use start timing when a power supply from the generator to the low-voltage power source via the second voltage-reducing circuit is enabled, to be different from a voltage-reducing circuit use start timing when a power supply from the generator to the electric power steering device via the voltage-reducing circuit is enabled.

9. The control method for the hybrid vehicle according to claim 6, wherein the hybrid vehicle further comprises a voltage-detecting unit for detecting a voltage of the driving circuit, and

in the high-voltage power source defect process step, if an abnormality occurs in the detected voltage value of the driving circuit after the shift to the third mode following the occurrence of the defect in the high-voltage power source, the control section stops the power supply from the generator to the traveling motor.