Patent Application
20230037217
This disclosure relates to the control of automotive batteries and electrified powertrains.
An alternatively powered vehicle may include a traction battery arranged to provide power to an electric machine. The electric machine may transform electrical energy from the traction battery to mechanical energy to move wheels of the vehicle. The electric machine may also transform mechanical energy from the wheels to electrical energy for storage in the traction battery.
A vehicle includes an electric machine, a traction battery arrangement, and a controller. The controller, responsive to a difference being greater than a threshold value, prevents the traction battery arrangement from powering the electric machine. The difference is between an actual voltage change per actual amp hours change over a predetermined time for a cell of the traction battery arrangement and an expected voltage change per expected amp hours change over the predetermined time.
A method includes preventing at least one contactor electrically between a traction battery arrangement and electric machine from closing to prevent electrical power flow from the traction battery arrangement to the electric machine after a difference between an actual voltage change per actual amp hours change over a predetermined time for a cell of the traction battery arrangement and an expected voltage change per expected amp hours change over the predetermined time exceeds a threshold value.
A powertrain includes an electric machine and a controller. The controller selectively prevents electrical power flow from a traction battery to the electric machine based on an actual rate of charge acquired by a cell of the traction battery per unit of actual increase in amp hours and an expected rate of charge acquired per unit of expected increase in amp hours.
Embodiments are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale. Some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.
Various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
An interesting area of research relates to the detection of battery internal short circuit resistances, which may have many causes. One of the causes is copper dissolution. Dissolved copper grows through the separator and eventually creates a short circuit between the anode and cathode.
Detection of an internal short circuit resistance can be difficult because the cell with the internal short circuit resistance does not show a large voltage deviation as illustrated in
Voltage-based detections are widely used for a variety of fault detections. In one example, the voltage threshold for detecting cell voltage deviation is 0.715V, which may be ineffective for identifying an internal short circuit resistance. The voltage threshold cannot be tuned to a smaller number (e.g., 0.25V or less) because that will result in false positive results. In addition, even if existing methods detected the voltage deviation, it may not take effective action to prevent thermal issues from occurring. Instead, it may trigger a message indicating a voltage deviation condition. For other faults, this level of action is sufficient. Generating a message, however, may not be sufficient to prevent thermal issues during charging.
The inventors have recognized that the problems described above may be addressed by apparatuses and methods that utilize model predictive control to detect presence of internal short circuit resistances. The proposed techniques take advantage of a characteristic parameter (i.e., the rate of accumulated voltage change divided by the accumulated amp hour increase at time t). The equation to calculate the rate Et_calc is listed below:
Et_calc=(Vt−V0)/(Ct−C0) (1)
where Vt, V0, Ct, and C0 denote the cell voltages and the accumulated amp hour increase at times t and 0, respectively. This rate indicates how much the cell voltage changes for a given change of amp hour value. When a cell with an internal short circuit resistance is charged, its Et_calc has a different profile than a healthy cell.
Regarding the model predictive control, a deep neural network (e.g., long short term memory, autoencoder, etc.) is built to predict the rate of healthy cells Et_pred. Et_pred represents the predicted rate of the accumulated voltage change divided by the accumulated amp hour increase at time t. Since the neural network is trained using data from cells that do not have internal short circuit resistances, the difference between the predicted rate Et_pred and the calculated rate Et_calc using (1) is relatively small as shown in
When data from a cell that has an internal short circuit resistance is fed into the neural network however, the difference between Et_pred and Et_calc becomes significant as illustrated in
To ensure the robustness of this method, a threshold Te and a counter threshold Tc may also be used. The thresholds Te and Tc can be set for example to 0.1 V/Ah and 3, respectively. When the difference between Et_pred and Et_calc is greater than 0.1, the counter increments 1. Once the counter reaches 3, an internal short circuit resistance condition is declared.
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The algorithms, methods, or processes disclosed herein can be deliverable to or implemented by a computer, controller, or processing device, which can include any dedicated electronic control unit or programmable electronic control unit. Similarly, the algorithms, methods, or processes can be stored as data and instructions executable by a computer or controller in many forms including, but not limited to, information permanently stored on non-writable storage media such as read only memory devices and information alterably stored on writeable storage media such as compact discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes can also be implemented in software executable objects. Alternatively, the algorithms, methods, or processes can be embodied in whole or in part using suitable hardware components, such as application specific integrated circuits, field-programmable gate arrays, state machines, or other hardware components or devices, or a combination of firmware, hardware, and software components.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. With reference to
As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
