What is the equalization technology of lithium-ion battery?
Li-ion battery pack is made up of several single lithium cells combined in series and parallel. Since lithium cells have individual differences, in order to solve the problem of battery charging consistency, the industry has widely used equalization technology, which has been divided into passive equalization method, active equalization method and internal equalization method.
(A) The common equalization methods are active equalization method and passive equalization method based on power circuit. In the passive equalization method, a single rechargeable battery with high operating voltage is charged and discharged according to a power circuit connected to an input resistor, and according to more power circuits, it can be determined whether its operating voltage is the same as that of other single rechargeable batteries, and if a rechargeable battery is terminated, the disadvantages of the passive equalization method are energy consumption of individual rechargeable batteries, heat generation, and long equalization time.
The passive equalization method is characterized by relatively low component cost when the equalization current is less than a certain value, but there are two problems.
1. the consumption of energy through the resistor generates heat, and the consumption is the charging current.
(2) Static data equalization is only suitable for small batteries when it works.
(b) The active equalization method transfers the kinetic energy of the battery to a battery with a lower operating voltage based on the consumption of the resistor during charging.
The key feature of the active equalization method is the digital power amplifier equalization power circuit, which charges and discharges the battery with high efficiency and achieves static data equalization throughout the process, with high equalization current and fast equalization rate, but the main problems are high cost and complex structure. At present, this kind of large battery power management on electric vehicles basically uses the active equalization technology.
(C) Internal equalization method is to use bms during the whole charging process, according to the current adjustment and running battery charging operation voltage optimization algorithm, so that each individual charging unit to charge the lithium battery to achieve the basic consistent amount. The internal equalization technique is simple, no kinetic damage, no additional battery charging process, no harm to the number of battery cycles, no additional hardware configurator equipment, but if the battery charging phase distance is large, it takes a long time to equalize.
The inconsistency of rechargeable battery comes from the resistance, volume and capacity of the battery, and the traditional consistency evaluation method and equalization method as a safeguard can not reasonably improve the capacity and service life of lithium battery, so it can not improve the negative impact of lithium battery consistency problem on the application of combination rechargeable battery.
Since DC internal resistance, operating voltage and capacity are the main parameters of Li-ion battery, the basis of charging process will not change in one or more cycles. After scientific research, the correlation of the equalization target is determined by using soc as the balance reference object, and the equalization time is used flexibly to reduce the size of the equalization circuit.
Welcome to visit our company website: www.manlybattery.com. If you have any interests in batteries, please feel free to contact us: info@manlybattery.com
