[Introduction]Demand for lithium-ion (Li-ion) batteries has grown rapidly in recent years and does not appear to be slowing down anytime soon. Booming industries such as electric vehicles and grid infrastructure are leading the use of lithium-ion batteries.
Demand for lithium-ion (Li-ion) batteries has grown rapidly in recent years and does not appear to be slowing down anytime soon. Booming industries such as electric vehicles and grid infrastructure are leading the use of lithium-ion batteries. As these demands increase, so does the need for high-accuracy, high-current battery testing and formation equipment in the industry.
The performance and lifespan of each battery is determined by the formation process, and battery testing and formation equipment is designed for a specific application. Low-current devices use converters with integrated switching field-effect transistors (FETs) to charge and discharge. Medium current devices use single-phase controllers with external switching FETs. High-current devices use multiphase controllers, and as current capacity increases, so does the number of phases (and the size and cost of components).
TI’s Modular Battery Tester Reference Design for 50A, 100A and 200A Applications uses a combination of 50A and 100A battery test designs to create a modular version capable of reaching a maximum charge and discharge level of 200A, enabling the use of a modular design to Meet the needs of different levels of high current battery testers. The modular design provides new options for using multiple low-current battery tester channels in parallel for high-current applications for increased flexibility and cost savings.
The Modular Battery Tester Reference Design uses two battery tester reference design boards for polyphase high-accuracy 0.5 to 100A battery formation (100 A maximum per board), or four for high current applications Battery tester reference design boards (50A max per board), paralleled to achieve a max current of 200A while maintaining high accuracy. Figure 1 demonstrates the flexibility of the modular battery tester reference design—two 100A boards can be paralleled to deliver a maximum of 200A without sacrificing any accuracy.
Used in parallel, these two boards based on the battery formation battery tester reference design can maintain current and voltage control accuracy of 0.02% or less. These boards also increase the current to 200A while maintaining a high level of accuracy. Figure 2 shows the level of current control accuracy maintained over the entire 200A range.
Figure 2: Constant Current Buck Accuracy
When calibrating the system, each board must be calibrated individually. Each board has its own control loop, so the system should handle each control loop separately to maximize its accuracy. Figure 3 shows the calibration error for each board used in the system. Since each board can be used individually or in parallel, the system must calibrate the boards individually.
Figure 3: Two board configuration for constant current calibration
Modular battery testers for 50A, 100A and 200A applications demonstrate high accuracy, high current and flexibility, which are key considerations for battery test equipment. With this design, you can invest in lower current battery test equipment and be able to use that equipment in parallel without investing in different architectures for different current levels. You can now test a range of currents with your test equipment without having to use high-current devices that cannot be used in low-current applications or low-current devices that cannot be used in high-current applications, increasing flexibility and saving costs.
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