As a core component of digital products and electric cars. Lithium-ion batteries in these products typically consist of multiple cells. During service, charging and discharging performance and battery life may be significantly reduced due to the increase in the core temperature of the cell.
Especially for the automotive lithium battery, accurate cell temperature estimation and monitoring are very important for the performance and life of the battery system.
The U.S. Patent and Trademark Office recently granted U.S. Patent 10230137 to the U.S. Army on March 12, 2019. The patent can estimate the temperature of a cell in a battery pack.
This patent provides more accurate core temperature estimation methods for battery packs that can be used for battery thermal management system operations and help maintain safety, performance and life.
At present, the monitoring of cell temperature is still inaccurate and reliable, even in some cases far from the actual situation, to take the existing technology for example, one way is to measure the surface temperature of the cell and use it as its core temperature. But this can be very inaccurate, as the temperature difference between the surface and the core can be as much as 30°C.
In another way, temperature sensors are mounted in the inner core of the cell for temperature measurement. But it would be too expensive and impractical to deploy such temperature sensors for hundreds or even thousands of cells.
In order to solve the above technical problems, the patent proposes the following treatment: An improved method of estimating the cell temperature includes measuring the surface and coolant temperatures, as well as the internal resistance by entering a mathematical formula.
In detail, estimating the core temperature of a cell in a battery pack may include the following steps:
1. Receive the surface temperature of one or more cell cells, receive the current of one or more cell cells, receive the inlet temperature of the coolant supplied to the cell pack, and receive the coolant rate.
2. Make an estimate, including the internal resistance of the battery aggregation of the cell, the conduction resistance of the battery aggregation between the core and the surface of the cell, and the convective resistance between the cell surface and the coolant.
3. Estimate the core temperature of the cell based on the received and estimated values of the previous steps.