Gm Global Technolgoy Operations, Inc.

Kurt M Johnson

Damon R Frisch

Robert Charles Baraszu

Brian James Koch

Patrick Frost

Patricia M Laskowsky

Zachary D Bylsma

James C Gibbs

Ashley McAllister

Brett B Stawinski

George Robison

Joon Hwang

Wei Liu

Gregory E Smith

David S Maxwell

Ramesh Rebba

Daniel R Brouns

Joseph Bisbing

System and methods for determining battery system energy capability in a vehicle are presented. A voltage offset of a battery system may be determined based on comparison of an open circuit voltage of the battery system and a measured voltage. An estimated remaining pack energy may be determined based, at least in part, on the voltage offset. Similarly, an estimated total pack energy may be determined based, at least in part, on the voltage offset. An energy capability of the battery system may be determined based on the estimated remaining pack energy and the estimated total pack energy.

Systems and methods for estimating battery system energy capability

A method for dynamically adjusting a battery current limit in a system having a battery pack includes determining a battery pack current as a charge current flowing into or a discharge current flowing from the battery pack, and also calculating a time-windowed average current for each of the charge current, the discharge current, and an RMS current of the battery pack. The battery current limit may be dynamically adjusted when any or all of the calculated time-windowed averages exceeds a corresponding calibrated control threshold. The battery current limit is a window-specific current limit that is greater than the calibrated control threshold and less than a static/fixed current limit for the battery pack. A system includes the battery pack, a sensor operable for measuring a current inflow/outflow to/from the battery pack, and a controller programmed to dynamically adjust the battery current limit using the above method.

Dynamic adjustment of battery current limits based on usage

System and methods for estimating a capacity of a battery are presented. A measure of data skewness may be calculated from a battery system terminal voltage measurement. Inflection points in the data skewness of the terminal voltage measurement may align with transition points associated with a battery system. These transitions points may be associated with known SOCs determined from testing and/or characterization of the battery system. Using the detected transitions and associated SOCs and an indication of an accumulated charge provided to/from the battery between the transitions, an estimated capacity of the battery system may be determined.

Systems and methods for estimating battery pack capacity

Adaptive estimation techniques to create a battery state estimator to estimate power capabilities of the battery pack in a vehicle. The estimator adaptively updates circuit model parameters used to calculate the voltage states of the ECM of a battery pack. The adaptive estimation techniques may also be used to calculate a solid-state diffusion voltage effects within the battery pack. The adaptive estimator is used to increase robustness of the calculation to sensor noise, modeling error, and battery pack degradation.

Battery state-of-charge estimation for hybrid and electric vehicles using extended kalman filter techniques

System and methods for estimating a capacity of a battery are presented. In certain embodiments, charge and discharge current throughput data may be separately accumulated during operation of a battery system (e.g., during a charge sustaining operation of vehicle associated with the battery system). Charge and discharge voltage-based state of charge movement data may be further separately accumulated. Upon accumulating sufficient data, estimated charge and discharge battery capacities may be determined based on the accumulated data.

Systems and methods for estimating battery pack capacity during charge sustaining use

System and methods for balancing a vehicle battery system are presented. In certain embodiments, a method for balancing battery system having multiple battery sections may include receiving estimated states of charge of the battery sections. Based on the estimated states of charge, a determination may be made whether the battery sections have states of charge within one of plurality of regions included in a state of charge window. Based on the determination, one of a plurality of different balancing algorithms may be utilized to control transfer energy between the battery sections to balance the battery sections.

Systems and methods for balancing a vehicle battery system

A battery system may include a plurality of subdivisions, such as battery cells or sub-packs. A measurement system configured to determine a subdivision electrical parameter associated with each of a plurality of subdivisions. A battery control may identify a subdivision satisfying a criterion based on the plurality of subdivision electrical parameters. According to some embodiments, the battery control system may determine a ratio of the subdivision electrical parameter of the identified subdivision to the electrical parameter of the battery pack. The ratio may be used to scale the electrical parameter associated with the battery pack by the ratio. According to other embodiments, the subdivision electrical parameter associated with the identified subdivision may be provided to a battery state estimation system. The scaled electrical parameter or the electrical parameter associated with the identified subdivision may be used by a battery state estimation system to generate an estimated battery state.

Systems and methods to protect against over-discharge in a battery system

Systems and methods for improvements in battery state of charge accuracy, charge termination consistency, capacity estimation, and energy delivery consistency. More specifically, embodiments herein detail systems and methods using an algorithm to calculate the change in state of charge for a given voltage change (dSOC/dV) at a given temperature in a region around the present voltage measurement or estimation and to set a signal indicating when the measurement should not be used due to potential error.

Methods and systems for determining whether a voltage measurement is usable for a state of charge estimation

System and methods for identifying a weak subdivision in a battery system are presented. In certain embodiments, a system may include a battery pack that includes multiple subdivisions. A measurement system may be configured to determine multiple subdivision electrical parameters associated with the subdivisions. A battery control system may identify a weakest subdivision based one on or more calculated derivative ratios of a subdivision electrical parameter associated with one subdivision of the battery pack relative to a subdivision electrical parameter associated with another subdivision.

Systems and methods for detecting a weak subdivision in a battery system

Methods and systems for adjusting the voltage limits of a battery. In some implementations, voltage data may be received from each of a plurality of battery sections of a vehicle battery. A voltage offset for the vehicle battery may be calculated using the voltage data. The voltage offset may be calculated by determining a difference between an average voltage taken from each of the plurality of battery sections and at least one of a minimum voltage of all of the battery cells and an average cell voltage from a battery section having the lowest average cell voltage. The voltage offset may be applied to dynamically adjust a voltage limit associated with the vehicle battery so as to prevent any of the battery cells in the vehicle battery from exceeding the voltage limit.

Methods and systems for adjusting battery voltage limits

A method and system for use with a vehicle battery pack having a number of individual battery cells, where the method estimates, extrapolates or otherwise determines individual cell resistances. According to an exemplary embodiment, the method and system use a voltage and temperature reading for each of the individual battery cells, as well as a voltage and current reading for the overall battery pack to determine one or more cell resistance values, such as a minimum and maximum cell resistance for the battery pack. This approach relies upon temperature deviations in the battery pack to make assumptions or estimates regarding individual battery cell resistances. By having individual cell resistance values&#x2014;instead of using an overall pack resistance value and building in a buffer to account for cell variations&#x2014;better and more accurate cell-level data can be obtained that, in turn, can improve charging, discharging, cell balancing and/or other battery-related processes.

Method and system for estimating cell resistances within a vehicle battery

A method for modeling changes in the state of charge vs. open circuit voltage (SOC-OCV) curve for a lithium-ion battery cell as it ages. During battery pack charging, voltage and current data are gathered for a battery cell. A set of state equations are used to determine the stoichiometry and state of charge of the cathode half-cell based on the charging current profile over time. The voltage and current data, along with the stoichiometry and state of charge of the cathode half-cell, are then used to estimate maximum and minimum solid concentration values at the anode, using an error function parameter regression/optimization. With stoichiometric conditions at both the cathode and anode calculated, the cell's capacity and a new SOC-OCV curve can be determined.

Modeling changes in the state-of-charge open circuit voltage curve by using regressed parameters in a reduced order physics based model

Systems and methods for estimating the relative capacity of individual battery subdivisions in a battery system are presented. In some embodiments, a system may include calculation system configured to analyze the electrical parameters to generate derivative values of the parameters over a period of time. The calculation system may further calculate summation values associated with individual battery subdivisions based upon the derivate values. A battery control system may utilize the summation values to generate one or more commands configured to control an aspect of an operation of the battery pack based on using the summation values. The summation values associated with battery subdivisions may be used to determine a relative capacity for storing electrical energy, according to some embodiments. The determination of relative capacity may be used by a control system to prevent over-discharge of a battery subdivision having the lowest energy storage capacity.

Systems and methods for evaluating and controlling a battery system

A vehicle battery and charging method that may be used to balance cell voltages during a battery charging operation, and may do so in a way that protects the individual cells from over-charging and improves the overall efficiency of the operation. According to one example, the vehicle battery includes a number of cell-balancing current paths, each of which is connected in parallel to an individual battery cell and can shunt or bypass the corresponding cell when its voltage exceeds some maximum amount. This may enable under-charged battery cells to be charged at the same time that over-charged battery cells are bypassed. Each of the cell-balancing current paths may include a series-connected electronic switch and zener diode combination, where the electronic switch is controlled by a battery control module so that cell-balancing can be enabled during a battery charging operation and disabled at other times.

Vehicle battery with cell balancing current paths and method of charging the same

A method for estimating the capacity of a vehicle battery while in service. The method includes providing a previous battery state-of-charge, battery temperature and integrated battery current amp-hours, and determining that battery contactors have been closed after they have been opened and disconnected from a load. The method determines if the battery has been at rest for a long enough period of time while the contactors were open, where the battery rest time is based on battery temperature, and determines an initial battery voltage from a last time step when the battery contactors were closed prior to the contactors being open during the battery rest time. The method determines a present battery state-of-charge from the initial battery voltage and the battery temperature and calculates the battery capacity based on the battery integrated current amp-hours divided by the difference between the present battery state-of-charge and the previous battery state-of-charge.

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Brighton, MI, United States of America

Kurt M Johnson