Patent Application
20190176657
This application is based on and derives the benefit of Indian Provisional Application 201641026864, the contents of which are incorporated herein by reference.
Embodiments herein relate to vehicle systems, and more particularly to lead acid batteries in vehicles.
In today's automotive scenario, when emission control and dependence of conventional fossil fuel are seen as bigger challenges, a variety of propulsion technologies are being considered to power vehicles. The increasing demand to improve fuel economy and reduce emissions in present vehicles calls for a big push towards powertrain electrification (development of hybrid and electric vehicle).
Lead-acid batteries have been widely used in the automotive industry for starting-lighting-ignition (SLI) applications. But they are typically used as backup energy storage for powering vehicle ECU's during conventional engine off condition and for engine cranking and only add weight to the conventional powertrain during normal running. For optimization of lead acid battery system, it is required to increase the usage (battery cycling) of the battery during normal vehicle running conditions.
Typical applications wherein these batteries are being used are stop start applications and low voltage hybrid vehicle applications. In the stop start application, the engine can be automatically stopped and re-started which typically occurs at traffic signals. This application avoids unnecessary idling of vehicle, hence saving fuel. Low voltage battery systems (lead acid battery based systems with management systems) are being used as cranking device during vehicle re-start. In the low voltage hybrid vehicle application with an electric machine (which can act as alternator and motor) using low voltage battery, hybrid function (torque assist, brake energy recovery) can be achieved. This helps in supporting engine during acceleration and recovering braking energy and hence increasing the overall efficiency of the system.
Both the above said applications, as compared to standard vehicles driven by an ICE (Internal Combustion Engine), bring in improved fuel economy and consequently reduced emissions. For efficient operation, a lead-acid battery needs to operate near to its optimal SOC to maximize its discharge, charge power capabilities and defined life.
Determination of state of charge (SOC) of a lead acid system is a challenging task, as discharge and charge characteristics of a lead-acid battery system are not symmetric. The discharge battery resistance is typically lower than the charge battery resistance. Direct prediction of SOC based on voltage and throughput is not straightforward.
The principal object of embodiments as disclosed herein is to provide methods and systems for determining State of Charge (SOC) of a lead acid battery in a vehicle.
Another object of embodiments as disclosed herein is to provide methods and systems for determining State of Charge (SOC) of a lead acid battery in a vehicle using discharge and charge correction factors.
Another object of embodiments as disclosed herein is to provide methods and systems for determining State of Charge (SOC) of a lead acid battery in a vehicle using a master OCV table based SOC estimation (SOCOCV) after the vehicle has been powered off, and a current throughput based SOC estimation (SOCEST) based on coulomb count integration (amp-second (As) integration) when the vehicle is operational.
Another object of embodiments as disclosed herein is to provide methods and systems for determining State of Charge (SOC) of a lead acid battery in a vehicle considering ageing of the battery and temperature.
This invention is illustrated in the accompanying drawings, through out which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The embodiments herein provide methods and systems for determining State of Charge (SOC) of a lead acid battery in a vehicle. Referring now to the drawings, and more particularly to
The vehicle, as referred to herein can be any vehicle comprising of a lead acid battery. In an embodiment herein, the vehicle can be a hybrid vehicle. In an embodiment herein, the vehicle can comprise of only a conventional engine based powertrain. Example of the vehicle can be a car, truck, van, bus, and so on.
The battery controller 201 can check if the vehicle 200 has been powered off. If the vehicle has been powered off, the battery controller 201 can estimate the SOC of the battery 202 is estimated (102) based on OCV. The battery controller 201 can generate a master OCV table by measuring the OCV of the battery 202, once the battery is full rested with no charge throughput, at pre-defined measurement intervals for a pre-defined time period (for example, every 30 minutes for a 4 hour duration). The master OCV table, comprising of a matrix with a pre-defined number of indices (for example, 8), is fully populated in the pre-defined time period. In an embodiment herein, the battery 202 achieves chemical, electrical and thermal equilibrium in the pre-defined time period. If battery is not rested for the pre-defined time period, but is in rest for more than the pre-defined measurement intervals, the battery controller 201 generates a running OCV table. The battery controller 201 can correct the running OCV table dynamically using a previous master OCV table (if present). The battery controller 201 determines the SOCOCV based on the OCV table (which can be either the master OCV table or the running OCV table) for the current ignition cycle. If the battery is not rested for more than 30 minutes, the battery controller 201 can consider the SOC from the previous ignition cycle as the battery SOC.
If the vehicle 200 has not been powered off, the battery controller 201 can estimate the SOC of the battery 202 based on coulomb counting. Dynamic (run-time) energy throughput, also known as Coulomb Counter, is an integration of current over time (Ampere-second) and the battery controller 201 can be calculated using the charging rates, discharge rates and the battery temperature. The battery controller 201 can update the coulomb counter to a pre-defined level, if the battery charge current is saturated for a defined temperature to a pre-defined level. The battery controller 201 can perform dynamic charge and discharge correction using factors such as discharge and charge related efficiency on the overall system. With coulomb counter and correction factor, the battery controller 201 determines the SOCEST for a current vehicle ignition cycle. The battery controller 201 applies battery-ageing factor, to accommodate capacity degradation, to the overall SOC calculation.
In an embodiment herein, the vehicle 200 comprises of a memory storage location, wherein the battery controller 201 can store data (such as the OCV values, master OCV table, estimated SOC, and so on) in the memory storage location. The battery controller 201 can also fetch data from the battery storage location, as and when required.
Coulomb counting(charge)=I*(Ktc*Kcc)
I is the current throughput;
Ktc is the charging temperature factor; and
Kcc is the charge rate factor.
The battery controller 201 further determines (403) a correction factor that is applied to the SOC. If the battery 202 is currently not being charged, the battery controller 201 determines (404) the coloumb counter for battery discharge. The battery controller 201 can determine the coulomb counter as follows:
Coulomb counting(discharge)=I*(Ktd*Kdc)
Ktd is the discharging temperature factor; and
Kdc is the discharge rate factor.
The battery controller 201 determines (405) the SOC by adding the determined coulomb counter to an initial SOC, at pre-defined estimation time intervals and applying the correction factor. The initial SOC can depend on the previous state of the vehicle. If the vehicle 200 is starting after power off, the battery controller 201 can consider SOCOCV as the initial SOC. If the vehicle 200 is not starting after power off, the battery controller 201 considers a previously estimated SOC using coulomb counting as the initial SOC. The battery controller 201 further sets (406) the flag for SOC based on coulomb counting flag to high. The various actions in method 400 may be performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some actions listed in
The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The network elements shown in
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201641026864 | Aug 2016 | IN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IN2017/050307 | 7/26/2017 | WO | 00 |
