Vehicle-use electric generator apparatus

• US 20080097664A1
• Filed: 06/27/2007
• Published: 04/24/2008
• Est. Priority Date: 06/27/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Aoyama, Kiyoshi, Kato, Akira, Tamura, Hiroshi
• Granted Patent: US 7,869,913 B2
• Time in Patent Office: Days
• US Class Current: 701/36
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/1438 in combination with power supplies for loads other than batteries
• CPC Class Codes: H02J 7/1446 in response to parameters of a vehicle
• CPC Class Codes: H02P 9/02 Details of the control
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
• CPC Class Codes: Y10S 903/905 Combustion engine
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

A vehicle power supply apparatus has first and second engine-driven electrical generators and first and second storage batteries, the first generator supplying a stable voltage to the first battery and a first set of loads, and the second generator supplying the second battery and a second set of loads, which can tolerate supply voltage variations. Operation of the second generator and charging/discharging of the second battery are controlled to maintain the total engine torque applied to the generators at a level whereby fuel consumption is reduced, while the supply voltage of the variation-tolerant loads is allowed to vary substantially.

Claims

1. A vehicle-use power supply apparatus comprising an electric generator apparatus driven by a vehicle engine to generate electrical power, an electrical energy storage apparatus, and a control apparatus coupled to said electric generator apparatus for controlling said generated electrical power and for controlling supplying of said generated electrical power to said electrical energy storage apparatus and to a plurality of electrical loads, with said control apparatus comprising circuitry adapted to implement power cost reduction generation control by

applying predetermined criteria to judge a generation cost of producing said generated electrical power,

when said generation cost is judged to be economical and said generated electrical power is in excess of a level of electrical power required by said electrical loads, supplying said excess electrical power to said electrical energy storage apparatus to be stored therein,

and when said generation cost is judged to be uneconomical, controlling said electric generator apparatus to produce a lower level of electrical power than required by said electrical loads and effecting discharging of said electrical energy storage apparatus to supply electrical power to said electrical loads;

wherein said power supply apparatus comprises;

a regulated voltage power supply system for supplying electrical power to a voltage-regulated electrical load, with said regulated voltage power supply system comprising a first electrical energy storage device for supplying electrical power to said voltage-regulated electrical load and a first electric generator driven by said vehicle engine for supplying electrical power to said first electrical energy storage device and to said voltage-regulated electrical load; and

a voltage variation-tolerant power supply system comprising a second electrical energy storage device for supplying electrical power to a voltage variation-tolerant electrical load, and a second electric generator driven by said vehicle engine for supplying electrical power to said second electrical energy storage device and to said voltage variation-tolerant electrical load;

and wherein said circuitry of the control apparatus is adapted to control said power supply voltage of said regulated voltage power supply system to a fixed value and to apply said power cost reduction generation control to said voltage variation-tolerant power supply system.

2. A vehicle-use power supply apparatus according to claim 1, wherein said second electrical energy storage device is configured to have a longer operating life, with respect to repetitive charging and discharging cycles, than said first electrical energy storage device.

3. A vehicle-use power supply apparatus according to claim 1, wherein said generation cost is calculated as an amount of fuel consumed in generating a unit amount of electrical energy, and wherein said electrical power generated by said second electric generator is increased when it is judged that said generation cost has fallen below a predetermined threshold value and is reduced when it is judged that said generation cost has risen above said predetermined threshold value.

4. A vehicle-use power supply apparatus according to claim 3, wherein said circuitry of the control apparatus comprises a memory having a first data map held stored therein, with said first data map relating respective values of said generation cost to corresponding amounts of a total required engine torque that is required to be applied by said engine to said first electric generator and said second electric generator in combination, and wherein circuitry of the control apparatus is adapted to

establish a target generation cost as a target value of said generation cost,

apply said target generation cost to said first data map for thereby obtaining a range of permissible torque as a range of values of said total required engine torque corresponding to generation cost values that are below said target generation cost, and

control said second electric generator to produce a level of electrical power whereby said total required engine torque is within said range of permissible torque.

5. A vehicle-use power supply apparatus according to claim 4, wherein said circuitry of the control apparatus is adapted to derive data indicative of a level of charge remaining in said second electric charge storage device and to calculate said target value based upon said level of charge.

6. A vehicle-use power supply apparatus according to claim 5, wherein

said circuitry of the control comprises a memory having a second data map stored therein which relates limit values of said target generation cost to corresponding values of said level of charge, with said limit values of target generation cost successively increasing in accordance with decrease of said level of charge, and

said control apparatus is adapted to

derive a current level of charge of said second electric charge storage device,

apply said derived level of charge to said data map for thereby obtaining a corresponding limit value of target generation cost, and

set said corresponding limit value as said target generation cost.

7. A vehicle-use power supply apparatus according to claim 4, wherein said circuitry of the control apparatus is adapted to

calculate a cost per unit amount of electrical energy currently held stored in said second electric charge storage device as an average of respective generation costs of unit amounts of electrical energy successively stored in said second electric charge storage device, and

set said calculated cost as said target generation cost.

8. A vehicle-use power supply apparatus according to claim 4, wherein said circuitry of the control apparatus comprises a memory having a second data map stored therein which relates limit values of said target generation cost to corresponding values of a level of charge of said second electric charge storage device, with said limit values of target generation cost successively increasing in accordance with decrease of said level of charge, and

wherein said circuitry is adapted to derive data indicative of said level of charge, and obtain a corresponding limit value of target generation cost from said data map,

calculate a stored energy cost as a cost per unit amount of electrical energy currently held stored in said second electric charge storage device, by calculating an average value of respective generation costs of unit amounts of electrical energy successively stored in said second electric charge storage device, and

select a higher one of said stored energy cost and said corresponding limit value of target generation cost, as said target generation cost.

9. A vehicle-use power supply apparatus according to claim 5, wherein said circuitry of the control apparatus is adapted to compare said target generation cost with said generation cost, and

when said generation cost is judged to have fallen below said target generation cost, apply control to increase said electrical power produced by said second electric generator,

when said generation cost is judged to have increased beyond said target generation cost, apply control to decrease said electrical power produced by said second electric generator.

10. A vehicle-use power supply apparatus according to claim 5, wherein said circuitry of the control apparatus is adapted to control said electrical power produced by said second electric generator to a value whereby said total required engine torque corresponds to a minimum value of said generation cost.

11. A vehicle-use power supply apparatus according to claim 5, wherein said circuitry of the control apparatus is adapted to

judge when a difference between said target value and said generation cost exceeds a predetermined amount, and,

when said predetermined amount is judged to be exceeded, apply control for increasing a level of charge/discharge power of said second electric charge storage device to a higher value than when said difference is smaller than said predetermined amount.

12. A vehicle-use power supply apparatus according to claim 4, wherein said circuitry of the control apparatus comprises a memory having stored therein a second data map, which relates values of rotation speed at which said first and second electric generators are driven to corresponding values of available power generation torque, where each of said values of available power generation torque is an amount of torque absorbed by said second electric generator in producing a substantially maximum level of generated electrical power at a specific rotation speed,

and wherein said circuitry of the control apparatus is adapted to

calculate a value of zero-power drive torque as an amount of drive torque that is absorbed by said first electric generator and second electric generator in combination when being driven with no electrical power generated by either of said first electric generator and second electric generator,

calculate a value of generated electrical power of said first electric generator based upon detected values of output voltage and output current of said first electric generator, and calculate a corresponding value of power generation torque that is absorbed by said first electric generator in producing said calculated value of generated electrical power,

apply a current value of said rotation speed to said second data map to obtain a corresponding value of said available power generation torque,

calculate a first total drive torque as the sum of said zero-power drive torque and said power generation torque of said first electric generator,

calculate a second total drive torque as the sum of said zero-power drive torque, said power generation torque of said first electric generator, and said available power generation torque of said second electric generator,

compare each of said first total drive torque and second total drive with said permissible torque range, and

control said first electric generator and second electric generator based on a result of said comparison.

13. A vehicle-use power supply apparatus according to claim 12, wherein:

when said second total drive torque is judged to be within said permissible torque range, said control apparatus enables operation of each of said first electric generator and said second electric generator, with said second electric generator controlled to produce a level of electrical power that corresponds to said available power generation torque;

when said second total drive torque is judged to be greater than said maximum value of the permissible torque range while said first total drive torque is less than said maximum value, said control apparatus enables operation of each of said first electric generator and said second electric generator, and controls said second electric generator to produce a level of electrical power whereby said total required engine torque attains said maximum value of the range of permissible torque; and

,

when said second total drive torque is judged to be greater than said maximum value of the permissible torque range while said first total drive torque is substantially equal to said maximum value, said control apparatus enables operation of said first electric generator and halts operation of said second electric generator.

14. A vehicle-use power supply apparatus according to claim 12, comprising a power transfer apparatus controllable by said control apparatus for transferring electrical power between said regulated power supply system and said voltage variation-tolerant power supply system, wherein

when said first total drive torque and said second total drive torque correspond to respective values of power generation cost that are each higher than said target value of electrical power cost, said control apparatus halts operation of each of said first electric generator and said second electric generator, and controls said power transfer apparatus to transfer electrical power discharged from said second electric charge storage device into said regulated voltage power supply system, with said transferred electrical power being set at a level for maintaining said power supply voltage of the regulated voltage power supply system at said fixed value.

15. A vehicle-use power supply apparatus according to claim 12, wherein:

when said second total drive torque is judged to be greater than a minimum-cost torque, where said minimum-cost torque is a value of said total required engine torque which corresponds to a minimum value of said generation cost, while said first total drive torque is judged to be less than said minimum-cost torque, said control apparatus enables operation of each of said first electric generator and said second electric generator, and controls said second electric generator to produce a level of electrical power whereby said total required engine torque attains said minimum-cost torque.

16. A vehicle-use power supply apparatus according to claim 1, wherein said first electric charge storage device is a lead-acid battery.

17. A vehicle-use power supply apparatus according to claim 1, wherein said second electric charge storage device is a lithium-ion secondary battery.

18. A vehicle-use power supply apparatus according to claim 1, wherein said second electric charge storage device is a capacitor.