Abstract: A system and method for estimating internal parameters of a lithium-ion battery to provide a reliable battery state-of-charge estimate. The method uses a two RC-pair equivalent battery circuit model to estimate the battery parameters, including a battery open circuit voltage, an ohmic resistance, a double layer capacitance, a charge transfer resistance, a diffusion resistance and a diffusion capacitance. The method further uses the equivalent circuit model to provide a difference equation from which the battery parameters are adapted, and calculates the battery parameters from the difference equation.

Abstract: A method for controlling charging and discharging of a battery pack for an electric or hybrid vehicle to prevent overheating damage. Current flowing into or out of the battery pack is monitored, and root mean square (RMS) current is integrated over a time window and compared to a threshold to determine if power needs to be regulated in order to prevent damage to the cells in the battery pack. If the time-integrated RMS current exceeds the threshold, a closed-loop proportional-integral (PI) controller is activated to regulate power input or output. The controller will continue to regulate power until the time-integrated RMS current drops below the threshold. Various thresholds can be defined for different time windows. The gains used in the PI controller can also be adjusted to scale the amount of power regulation.

Abstract: Methods and systems are provided for calibrating one or more limits of a battery of a vehicle, the battery having state of charge limits and power limits. A history of environmental conditions for the vehicle is obtained and stored in a memory. One or more of the state of charge limits, one or more of the power limits, or both are adjusted based on the history of environmental conditions and usage severity using a processor.

Abstract: Methods and systems for determining a state of charge of a battery exhibiting a transient response are provided. At least one property of the battery is measured. The state of charge of the battery is determined based on the at least one measured property and a transient response of the battery.

Abstract: A system and method for use with a vehicle battery pack having a number of individual battery cells, such as a lithium-ion battery commonly used in hybrid electric vehicles. In one embodiment, the method evaluates individual battery cells within a vehicle battery pack in order to obtain accurate estimates regarding their average transient voltage effect, open circuit voltage (OCVCell) and/or state of charge (SOCCell) so that a cell balancing process can be performed. These cell evaluations may be performed fairly soon after the vehicle is turned off and in a manner that utilizes a minimal amount of in-vehicle resources.

Abstract: A method for controlling charging and discharging of a battery pack for an electric or hybrid vehicle to prevent overheating damage. Current flowing into or out of the battery pack is monitored, and root mean square (RMS) current is integrated over a time window and compared to a threshold to determine if power needs to be regulated in order to prevent damage to the cells in the battery pack. If the time-integrated RMS current exceeds the threshold, a closed-loop proportional-integral (PI) controller is activated to regulate power input or output. The controller will continue to regulate power until the time-integrated RMS current drops below the threshold. Various thresholds can be defined for different time windows. The gains used in the PI controller can also be adjusted to scale the amount of power regulation.

Abstract: Methods and systems for determining a state of charge of a battery are provided. A first component of the state of charge is calculated based on a first property of the battery. A second component of the state of charge is calculated based on a second property of the battery. The first component of the state of charge is weighted based on a rate of change of the first property relative to a change of the state of charge. The second component of the state of charge is weighted based on a rate of change of the second property relative to a change of the state of charge. The state of charge is determined based on the first and second weighted components.

Abstract: A system and method for estimating internal parameters of a lithium-ion battery to provide a reliable battery state-of-charge estimate. The method uses a two RC-pair equivalent battery circuit model to estimate the battery parameters, including a battery open circuit voltage, an ohmic resistance, a double layer capacitance, a charge transfer resistance, a diffusion resistance and a diffusion capacitance. The method further uses the equivalent circuit model to provide a difference equation from which the battery parameters are adapted, and calculates the battery parameters from the difference equation.

Abstract: A system and method for use with a vehicle battery pack having a number of individual battery cells, such as a lithium-ion battery commonly used in hybrid electric vehicles. In one embodiment, the method evaluates individual battery cells within a vehicle battery pack in order to obtain accurate estimates regarding their average transient voltage effect, open circuit voltage (OCVCell) and/or state of charge (SOCCell) so that a cell balancing process can be performed. These cell evaluations may be performed fairly soon after the vehicle is turned off and in a manner that utilizes a minimal amount of in-vehicle resources.

Abstract: Methods and systems for determining a state of charge of a battery exhibiting a transient response are provided. At least one property of the battery is measured. The state of charge of the battery is determined based on the at least one measured property and a transient response of the battery.

Abstract: Methods and systems for determining a state of charge of a battery are provided. A first component of the state of charge is calculated based on a first property of the battery. A second component of the state of charge is calculated based on a second property of the battery. The first component of the state of charge is weighted based on a rate of change of the first property relative to a change of the state of charge. The second component of the state of charge is weighted based on a rate of change of the second property relative to a change of the state of charge. The state of charge is determined based on the first and second weighted components.