Some Safety Countermeasures on Lithium Battery of New Energy Automobile

Lithium-ion rechargeable batteries have been equipped with many portable products, but many problems have to be recycled and replaced due to battery fire accidents and failures. Battery manufacturers and product manufacturers are trying to ensure reliability and quality, but the problem has not yet been completely resolved.

To this end, the reporter interviewed Aotengzhongsi, technical director of Taiwan Celxpert, who is familiar with battery management circuit design technology in the safety design of lithium-ion rechargeable batteries. Oto has been engaged in the development and design of rechargeable battery protection circuits and charging circuits since the establishment of Canadian Moli Energy Corporation in 1987. At the same time, he is also the Director of Technology and Commodity Development of NEC Moli Energy. He is a relevant battery safety design expert such as the development of peripheral circuits for lithium-ion charging cells. Recently, it began to develop large-scale lithium-ion rechargeable batteries for automobiles, fuel cells and lithium-ion rechargeable batteries.

Q: What areas are batteries containing lithium-ion rechargeable cells used today?

Oto: In the 1990s, batteries were widely used in cameras, static cameras, and personal computers. Later, they began to be equipped with various electronic products such as mobile phones and game consoles. Recently, its use has expanded to electric tools, electric pedals and electric vehicles. In the future, it will also be expanded to electric vehicles, industry/consumer fixed type batteries and other fields.

Q: What changes have the batteries undergone?

Oto: Car lead batteries that were popular before lithium-ion rechargeable batteries did not pose much danger even if they were overcharged and over-discharged. From a safety point of view, they are easy to use. Lithium-ion rechargeable batteries need to be used carefully, and electronic circuit technology to improve safety has become indispensable. Later, lithium-ion rechargeable batteries were used in large quantities for portable products. In order to improve utilization efficiency, microcontrollers were used for microcontrol.

In the future, the control technology and circuit technology of lithium-ion rechargeable battery will be further developed. Efforts should be made to achieve a self-diagnostic system that not only avoids danger, but also predicts it.

For example, it is important to predict that the unit will lose its balance and take countermeasures. With the increase of series cells, the balance of lithium-ion rechargeable batteries becomes a problem. When the unit is out of balance and the battery voltage decreases or becomes 0V, if the battery continues to charge and discharge, it is prone to fire and smoke accidents. This problem was pointed out 10 years ago, but adding a unit balance circuit to the protective circuit can solve this problem.

In the future, it will be crucial not only to be able to use protective circuits to avoid crises, but also to predict and respond to this phenomenon. In addition, it is necessary to take countermeasures against the balance, voltage and resistance changes when the units are in parallel.

In terms of safety design, in the past, technologies such as double fault protection mechanisms(secondary protection circuits) and fuse components used to cut off circuits were actually accumulated when overcharging occurred. In addition, the protection circuit with unit balance is further introduced to achieve a more secure design. Further improvements are being attempted.

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