Researchers Submit Patent Application, “System and Method for Selective Estimation of Battery State with Reference to Persistence of Excitation and Current Magnitude”, for Approval
By a News Reporter-Staff News Editor at Life Science Weekly — From Washington, D.C., NewsRx journalists report that a patent application by the inventors Chaturvedi, Nalin (Sunnyvale, CA); Schoenleber, Michael (Sunnyvale, CA); Mayhew, Christopher (Union City, CA); Klein, Reinhardt (Mountain View, CA); Ahmed, Jasim (Mountain View, CA); Kojic, Aleksandar (Sunnyvale, CA), filed on December 26, 2012, was made available online on July 3, 2014 (see also Robert Bosch GmbH).
The patent’s assignee is Robert Bosch GmbH.
News editors obtained the following quote from the background information supplied by the inventors: “Batteries are used in a wide range of applications to supply an electrical current that drives a load during a discharge process. Primary batteries, which are also referred to as non-rechargeable batteries, are discharged during use and are unable to drive the load after completion of a single discharge. Examples of primary batteries include, but are not limited to, alkaline batteries and silver oxide batteries. Secondary batteries, which are also referred to as rechargeable batteries, also receive electrical current from a charging device to recharge the battery during a charge process. Examples of rechargeable batteries include, but are not limited to, metal-ion, metal-oxygen, lead acid, rechargeable alkaline, flow batteries, and the like. Examples of metal-ion and metal-oxygen batteries include lithium-ion and lithium-oxygen (sometimes referred to as lithium-air) batteries.
“Many applications that use either primary or secondary batteries to supply electrical power benefit from an accurate measurement of the state of the battery at various times during operation. For example, existing estimation processes generate estimates of one or more of a state-of-charge (SOC), state-of-function (SOF), and state-of-health (SOH) during operation of the battery. The SOC of the battery refers to the remaining energy capacity in the battery to drive a load. The SOF of the battery refers to the ability of the battery to produce a given level of electrical power. The SOF can be related to the SOC of the battery as the SOC varies over time. The SOH of the battery refers to internal parameters in the battery that describe the useful lifespan of the battery, such as the amount of charge a rechargeable battery can store as the battery performs multiple charge and discharge cycles.
“Monitoring systems typically lack the ability to measure the SOC, SOF, and SOH of the battery directly during operation. Instead, the monitoring systems employ various estimation techniques based on externally identifiable parameters of operation for the battery. For example, one or more of the internal voltage (V), current flow (I), and internal temperature (T) of the battery are monitored during operation of the battery. One or more estimation processes generate estimates of the SOC, SOF, and SOH using the measured voltage, current, and temperature parameters.
“The estimation processes enable estimation of the SOC, SOF, and SOH in the battery. During operation, however, the battery often experiences a wide range of operating conditions. For example, individual battery cells in a battery pack, which provides power to an electric or hybrid motor vehicle, undergo varying discharge, charge, and idle operations during relatively short time periods as the vehicle accelerates, decelerates, and stops during operation. Further, when the vehicle is parked the battery pack experiences only minimal power draw for extended time periods.
“As is known in the art, the estimation processes can generate unreliable estimates during certain operating modes of the battery. Additionally, many estimation processes generate estimates of the current state of the battery using a history of previously estimated states, meaning that even a comparatively small inaccuracy in the estimation process can compound over time to produce a large error between the actual state of the battery and the estimated state. Consequently, the estimation processes are suspended during certain operating modes, such as when the battery is disconnected from a load. Existing techniques for starting and stopping the estimation processes can, however, introduce additional inaccuracies when the state of the battery changes while the estimation process is suspended. These changes during suspension of the estimation process increase the error between the estimated state and actual state of the battery. In light of these limitations, improvements to battery monitoring systems and methods that improve the accuracy of starting and stopping estimation processes for the state of a battery would be beneficial.”
As a supplement to the background information on this patent application, NewsRx correspondents also obtained the inventors’ summary information for this patent application: “In one embodiment, a method of monitoring a battery has been developed. The method includes identifying, with a controller, a persistence of excitation in a battery, identifying, with the controller, a magnitude of an electrical current that is supplied to the battery, and performing, with the controller, a state estimation process for the battery only in response to the identified persistence of excitation exceeding a first predetermined threshold and the identified magnitude of the electrical current exceeding a second predetermined threshold.
“In another embodiment, a system for monitoring a battery has been developed. The system includes a sensor configured to identify a level of electrical current that is supplied to the battery, and a controller operatively connected to the sensor. The controller is configured to identify a persistence of excitation in a battery, identify an average magnitude of the electrical current that is supplied to the battery with reference to at least one electrical current level identified by the sensor, and perform a state estimation process for the battery only in response to the identified persistence of excitation exceeding a first predetermined threshold and the identified average magnitude of the electrical current exceeding a second predetermined threshold.
BRIEF DESCRIPTION OF THE DRAWINGS
“FIG. 1 is a schematic diagram of a battery monitoring system.
“FIG. 2 is a block diagram of a process for enabling and suspending a state estimation process while monitoring a battery.”
For additional information on this patent application, see: Chaturvedi, Nalin; Schoenleber, Michael; Mayhew, Christopher; Klein, Reinhardt; Ahmed, Jasim; Kojic, Aleksandar. System and Method for Selective Estimation of Battery State with Reference to Persistence of Excitation and Current Magnitude. Filed December 26, 2012 and posted July 3, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=\%2Fnetahtml\%2FPTO\%2Fsearch-adv.html&r=1424&p=29&f=G&l=50&d=PG01&S1=20140626.PD.&OS=PD/20140626&RS=PD/20140626
Keywords for this news article include: Robert Bosch GmbH.
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