Method of improving fuel economy
First Claim
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1. A fuel economy control method comprising:
- measuring current supplied by a battery;
determining a state of charge (SOC) of said battery;
determining a nominal optimum charging voltage of said battery; and
reducing said nominal optimum charging voltage to a fuel economy minimum charging voltage if said SOC is above a predetermined level and said current is within a predetermined range.
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Abstract
A fuel economy control method includes estimating a temperature of a battery, measuring a current of the battery, and measuring a voltage of the battery. A nominal optimum charging voltage is determined as a function of a state of charge (SOC) of the battery and the estimated temperature. The nominal optimum charging voltage is reduced to a fuel economy minimum charging voltage if the SOC is above a predetermined level and the current is within a predetermined range.
23 Citations
37 Claims
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1. A fuel economy control method comprising:
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measuring current supplied by a battery;
determining a state of charge (SOC) of said battery;
determining a nominal optimum charging voltage of said battery; and
reducing said nominal optimum charging voltage to a fuel economy minimum charging voltage if said SOC is above a predetermined level and said current is within a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
estimating a temperature of said battery; and
measuring a voltage of said battery, wherein said SOC is based upon said temperature, said voltage, and said current.
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8. The method of claim 1 further comprising:
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converting said fuel economy minimum charging voltage to a % duty cycle; and
charging said battery at said fuel economy minimum charging voltage using a generator based on said % duty cycle.
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9. The method of claim 8 further comprising:
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determining a difference between said current and a predetermined current value; and
adjusting said % duty cycle until said current is equal to said predetermined current value.
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10. The method of claim 8 further comprising:
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converting said % duty cycle to a pulse-width modulated (PWM) % duty cycle; and
operating said generator based on said PWM % duty cycle.
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11. The method of claim 1 wherein reducing said nominal optimum charging voltage is achieved at a rate of 0.05V/s.
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12. The method of claim 1 wherein determining said nominal optimum charging voltage includes:
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determining a running SOC of said battery;
interpolating a value of said nominal optimum charging voltage based on said running SOC and said temperature.
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13. The method of claim 12 wherein interpolating is based upon a plurality of calibration constants.
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14. The method of claim 12 further comprising determining said running SOC as a function of a start-up SOC, an adjusted amp-hours of said battery and battery capacity.
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15. The method of claim 14 wherein said start-up SOC is determined using a look-up table that is accessed using an estimated temperature of said battery and a last stored open-circuit voltage.
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16. The method of claim 14 wherein said start-up SOC is determined as a function of a plurality of start-up calibration constants, wherein at least one of said start-up calibrations constants is dependent upon an estimated temperature of said battery.
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17. A fuel economy control method, comprising:
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estimating a temperature of a battery;
measuring current supplied by said battery;
measuring a voltage of said battery; determining a nominal optimum charging voltage as a function of a state of charge (SOC) of said battery and said estimated temperature; and
reducing said nominal optimum charging voltage to a fuel economy minimum charging voltage if said SOC is above a predetermined level and said current is within a predetermined range. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
converting said nominal optimum charging voltage to a % duty cycle; and
charging said battery using a generator based on said % duty cycle.
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19. The method of claim 18 further comprising:
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determining a difference between said current and a predetermined current value; and
adjusting said % duty cycle to until said current is equal to said predetermined current value.
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20. The method of claim 18 further comprising:
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converting said % duty cycle to a pulse-width modulated (PWM) % duty cycle; and
operating said generator based on said PWM % duty cycle.
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21. The method of claim 17 wherein said predetermined level is 80%.
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22. The method of claim 17 wherein said predetermined range is between −
- 8 A and 15 A.
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23. The method of claim 17 wherein said reducing step is performed if an outside air temperature is within a first temperature range, a vehicle speed is less than a predetermined speed, and an accessory is off.
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24. The method of claim 23 wherein said accessory is headlamps.
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25. The method of claim 17 wherein said nominal optimum charging voltage is based on said SOC.
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26. The method of claim 17 wherein reducing said nominal optimum charging voltage is achieved at a rate of 0.05V/s.
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27. The method of claim 17 wherein determining said nominal optimum charging voltage includes:
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determining a running SOC of said battery;
interpolating a value of said nominal optimum charging voltage based on said running SOC and said temperature.
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28. The method of claim 27 wherein interpolating is based upon a plurality of calibration constants.
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29. The method of claim 27 further comprising determining said running SOC as a function of a start-up SOC, an adjusted amp-hours of said battery and a battery capacity.
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30. The method of claim 29 wherein said start-up SOC is determined using a look-up table that is accessed based on an estimated temperature of said battery and a last stored open-circuit voltage.
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31. The method of claim 29 wherein said start-up SOC is based on a plurality of start-up calibration constants and an estimated temperature of said battery.
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32. A method of protecting a battery from sulfation, comprising:
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estimating a temperature of a battery;
determining a nominal optimum charging voltage as a function of a state of charge (SOC) of said battery and said estimated temperature;
comparing said nominal optimum charging voltage to a threshold value; and
increasing said nominal optimum charging voltage to above said threshold value if below said threshold value for a first predetermined period of time. - View Dependent Claims (33, 34, 35, 36, 37)
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Specification