Process for monitoring the charge level of a battery, and for informing the user of the battery when the monitored charge level is no longer reliable
First Claim
1. In a method of monitoring state of charge of a battery comprising the steps of:
- detecting charging and discharging current of said battery;
integrating said charging and discharging current over time to determine a net charge quantity extracted from and supplied to said battery;
determining a charge level limit of said battery as a function of physical battery values, including at least one of battery voltage and battery temperature;
comparing said net charge quantity with said charge limit value to determine a charge level of said battery; and
resetting said determination of a net charge quantity to zero whenever said charge level of said battery reaches said charge level limit;
a process for informing a user of said battery that a determined charge level is no longer reliable, said method comprising the steps of;
calculating at least one error variable indicative of a range of error of said charge level of said battery determined in said comparing step; and
activating an alarm signal when said error variable exceeds a predetermined maximum value.
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Accused Products
Abstract
The invention relates to a method of monitoring the state of charge of the battery of a hybrid vehicle, in which the charge level of the battery is determined by balancing the charge quantities extracted and supplied, and is indicated to the driver. Because of the inaccuracy of the charge balancing, resetting of the balancing from a reliable limit value must be carried out from time to time. In order to assist the operator of the hybrid vehicle in monitoring the battery charge level, according to the invention an error variable is calculated which indicates a discrepancy between the indicated charge level and the actual charge level, and the vehicle operator is provided with an indication if this variable exceeds a maximum value. In a representative embodiment, the error variable is set to be proportional to the current through the battery.
55 Citations
14 Claims
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1. In a method of monitoring state of charge of a battery comprising the steps of:
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detecting charging and discharging current of said battery; integrating said charging and discharging current over time to determine a net charge quantity extracted from and supplied to said battery; determining a charge level limit of said battery as a function of physical battery values, including at least one of battery voltage and battery temperature; comparing said net charge quantity with said charge limit value to determine a charge level of said battery; and resetting said determination of a net charge quantity to zero whenever said charge level of said battery reaches said charge level limit; a process for informing a user of said battery that a determined charge level is no longer reliable, said method comprising the steps of; calculating at least one error variable indicative of a range of error of said charge level of said battery determined in said comparing step; and activating an alarm signal when said error variable exceeds a predetermined maximum value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. In a device comprising a charge balance computer for monitoring state of charge of a battery by integrating charging and discharging current of said battery to determine a net charge quantity, comparing said net charge quantity with a charge limit value to determine a charge level of said battery and resetting said determination of a net charge quantity when said net charge level reaches said charge limit, apparatus for detecting inaccuracy of a determined charge level of the battery, said apparatus comprising:
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an error calculation unit for determining a range of error in said determined charge level; an interface coupling said error calculation unit in communication with said charge balance computer; an error assessment unit which compares said range of error with predetermined criteria; and an alarm for indicating excessive inaccuracy when said range of error does not comply with said predetermined criteria. - View Dependent Claims (13, 14)
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Specification