lithium battery 18650 3.7v

　　Lithium battery manufacturer explains how to choose a suitable AFE for lithium battery 18650 3.7v management system

　　Lithium battery manufacturer explains how to choose a suitable AFE for lithium battery 18650 3.7v management system? The internal structures of AFEs currently available on the market are similar, mainly focusing on hardware resources and architectural forms designed for functional safety requirements. Simply put, the main differences are the number of sampling channels, the number, type and architecture of the internal ADCs. Below, the lithium battery manufacturer explains how to choose a suitable AFE for the lithium battery 18650 3.7v management system?

　　Lithium battery manufacturer explains how to choose a suitable AFE for lithium battery 18650 3.7v management system?

　　BMS is an important component of the forklift power lithium battery system. On the one hand, it detects, collects and preliminarily calculates the real-time status parameters of the battery, and controls the on and off of the power supply circuit based on the comparison between the detected values and the allowed values; on the other hand, it collects the key data collected Report to the vehicle controller, receive instructions from the controller, and coordinate with other systems on the vehicle. Battery management system, different cell types often have different requirements for the management system.

　　The realization of BMS equalization function mainly relies on AFE, which integrates equalization control switches and related logic circuits, providing users with rich diagnostic and control interfaces. AFE is an analog front end, which specifically refers to the lithium battery sampling chip in BMS, which is used to collect data. Cell voltage and temperature, etc.

　　The balancing interface provided by AFE is mainly passive balancing, that is, discharging through resistors; it can support internal balancing and external balancing; both methods require the balancing resistor to be placed outside, but internal balancing can use the internal MOS tube as a balancing flow switch, and external balancing requires adding an external MOS tube as a balanced flow switch; basically every AFE supports two methods.

　　How to choose a suitable AFE for lithium battery 18650 3.7v management system

　　Lithium batteries have the advantages of small size, high energy density, high output power and no memory effect. In addition to being widely used in Europe and the United States, the usage rate in the Asian market has also increased rapidly recently. In response to the business opportunities of lithium-ion battery protection chips, we launched a highly integrated analog front-end (AFE) battery controller to capture the market by reducing the size and simplifying the battery system design.

　　The main standard that BMS can refer to is QC/T897-2011. The most important requirement for AFE is acquisition accuracy. The standard index requirements are not very strict, and the test conditions are very vague. The latest discussion draft is much better. The measurement and verification of AFE's voltage acquisition accuracy seems simple, but how to implement an accurate voltage reference source, especially in EMC testing, is an issue worth discussing.

　　In real applications, for cells connected in parallel, we treat them as the same cell for sampling; further, cells are basically connected in parallel first and then in series to reduce the need for sampling channels; but this gives us a headache The thing is, the number of series-connected cells in a Module is not fixed, and the total number of series-connected cells is also not uniform.

　　In this case, we need to match the number of cells of each module, but the maximum number of voltage channels of AFE is discontinuously distributed, so we need to carefully select the appropriate number of channels for matching, so that it is neither wasteful nor forced. . Therefore, especially for third-party independent BMS manufacturers, because they have limited voice and are sandwiched between the original equipment manufacturer and the battery cell factory, it is more difficult to produce a platform version of the product.

　　Although lithium batteries have many advantages, the potential dangers in their use should not be underestimated, such as intolerance to overcharge/overdischarge, voltage overload, and over-temperature situations must be avoided. Therefore, a monitoring chip must be added to the design. for protection. In addition, the circuit design of traditional battery systems is quite complex, which will delay product development to market. Therefore, the highly integrated AFE battery monitor series is launched to enhance the safety of lithium batteries and simplify the design difficulty of battery systems.

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