Fuel cell/battery hybrid power system for vehicle

• US 5,631,532 A
• Filed: 10/31/1994
• Issued: 05/20/1997
• Est. Priority Date: 02/24/1994
• Status: Expired due to Term

• Current Assignee: Aisin AW Company Limited (Aisin Corp.), Kabushikikaisha Equos Research
• Original Assignee: Aisin AW Company Limited (Aisin Corp.), Kabushikikaisha Equos Research
• Inventors: Azuma, Ryuji, Hara, Takeshi, Kato, Kenji
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US08/332,818
• Time in Patent Office: 932 Days
• Field of Search: 320/2, 320/5, 320/39, 320/40, 320/61, 320/1 J, 320/6, 180/65.3, 180/65.4, 429/12, 429/19
• US Class Current: 320/102
• CPC Class Codes: B60K 1/04 of the electric storage means for propulsion exchanging batteries for electric propulsion of vehicles B60L53/80; for auxiliary purposes only B60R16/04; supplying batteries to, or removing batteries from, vehicles B60S5/06
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: B60K 6/32 characterised by the fuel cells
• CPC Class Codes: B60L 3/0053 relating to fuel cells
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 53/11 DC charging controlled by the charging station, e.g. mode 4
• CPC Class Codes: B60L 58/13 Maintaining the SoC within a determined range
• CPC Class Codes: B60L 58/40 for controlling a combination of batteries and fuel cells
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 10/28 including control of fuel cells
• 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 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: H01M 16/006 of fuel cells with rechargeable batteries
• CPC Class Codes: H01M 2250/20 Fuel cells in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 8/04619 of fuel cell stacks
• CPC Class Codes: H01M 8/04626 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04947 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04955 : Shut-off or shut-down of fuel cells
• CPC Class Codes: H02J 2310/46 : for ICE-powered road vehicles
• CPC Class Codes: H02J 7/1415 : with a generator driven by a prime mover other than the motor of a vehicle
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02E 60/50 : Fuel cells
• 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 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y02T 90/40 : Application of hydrogen technology to transportation, e.g. using fuel cells
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/907 : Electricity storage, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/908 : Fuel cell
• CPC Class Codes: Y10S 903/944 : Characterized by control of fuel cell

Abstract

A hybrid type power source control system controls the output of a fuel cell, with disregard of the operation of the vehicle accelerator pedal, responsive to the detected amount of residual charge of the battery, which amount fluctuates as the vehicle travels. For example, the output of the fuel cell system 3 might be 3 kW when the residual charge is from 70% to 90%, 5 kW when the residual charge is from 70% to 60% and 10 kW when the residual charge is below 60%. Consequently, the fuel cell system 3 can generate power with an efficiency of from 30% to 33% and can charge the battery 1 effectively. Because the output of the fuel cell is fixed for each of the rather broad ranges of residual battery charge, thermal fatigue of the fuel cell is prevented because of little output fluctuation. When the electric motor is continuously operated, the fuel cell continuously charges the battery to maintain a fully charged stated, optionally with some allowance for fluctuation thereof. When a fixed charge time is manually input, the output of the fuel cell is selected to fully charge (90%) the battery during the time selected.

Claims

1. A hybrid type power source for an electric vehicle, comprising:

a rechargeable battery for supplying electric power to drive an electric motor;

a fuel cell for generating electric power to charge said battery;

battery residual charge detection means for detecting the residual charge contained in said battery; and

fuel cell output control means for defining a plurality of different ranges of residual battery charge, for determining which one range of the plurality of ranges encompasses the detected residual charge and for commanding the fuel cell to charge the battery at one of a plurality of different power levels corresponding, respectively, to the plurality of different ranges of residual battery charge, each of said power levels serving to charge the battery, which one power level remains constant so long as the detected residual charge remains within said one range.

2. A hybrid type power source according to claim 1, wherein said plurality of different power levels are defined on the basis of a predetermined correlation between power output and efficiency of said fuel cell in converting fuel to electric power for driving the electric motor.

3. A hybrid type power source according to claim 1, further comprising:

electric power detection means for detecting the amount of electric power demanded for driving the vehicle;

fuel cell output detection means for detecting electric power generated by said fuel cell; and

wherein said battery residual charge detection means determines the battery residual charge as a function of the electric power detected by said electric power detection means and the electric power detected by said fuel cell output detection means.

4. A hybrid type power source according to claim 1 further comprising:

approval means for operating said electric motor by permitting flow of current to said electric motor;

approval state detection means for detecting operation of the electric motor; and

wherein said fuel cell output control means commands the fuel cell to charge the battery at said one power level, when a signal from said approval state detection means indicates that the electric motor is inoperative.

5. A hybrid type power source according to claim 4, wherein said approval means includes on-off means for connecting and disconnecting said electric motor to and from said battery and a switch for operating said on-off means.

6. A hybrid type power source according to claim 4, further comprising electric power detection means for detecting electric power demanded for driving the electric motor and fuel cell output detection means for detecting electric power generated by said fuel cell, and wherein said battery residual charge detection means detects the battery residual charge as a function of both the demanded electric power detected by said electric power detection means and the generated electric power detected by said fuel cell output detection means.

7. A hybrid type power source according to claim 4, further comprising electric power detection means for detecting electric power demanded for driving the electric motor and fuel cell output detection means for detecting electric power generated by said fuel cell, and wherein said battery residual charge detection means detects the battery residual charge as a function of both the demanded electric power detected by said electric power detection means and the generated electric power detected by said fuel cell output detection means.

8. A hybrid type power source according to claim 1, further comprising:

charge time input means for setting and inputting a charging time for the battery by output of said fuel cell;

motor operation detection means for detection of an operative state or an inoperative state of the electric motor; and

wherein said fuel cell output control means determines a command signal to said fuel cell in accordance with a targeted, fixed residual charge of the battery, the detected battery residual charge and the charge time input from said charge time input means, provided the inoperative state of the electric motor is detected.

9. A hybrid type power source according to claim 4, wherein said battery residual charge detection means detects a rate of change of the battery residual charge, and wherein said fuel cell output control means determines the command to said fuel cell in accordance with the detected rate of change.