How to solve the problem of active charging balance of lithium battery pack
The active balance abandons the passive balance method of consuming current and changes to the method of transmitting current. The equipment responsible for charge transfer is a power converter, which enables the small batteries in the lithium-ion battery pack to transfer charge whether in charge, discharge or idle state, so that the dynamic balance between the small batteries can be maintained frequently.
Since the charge transfer efficiency of the active balancing method is extremely high, a higher balancing current can be supplied, which means that this method has a stronger balancing ability when the lithium-ion battery pack is charged, discharged and idle.
1. Strong fast charging ability: the active balancing function can make the small batteries in the lithium-ion battery pack reach the balance faster, so the safety of fast charging is higher, and it is suitable for the high rate charging mode with larger current.
2. Idle time: even if each small battery has reached the equilibrium state during charging, due to different temperature gradients, the internal temperature of some small batteries is higher, and the internal temperature of some small batteries is lower, which will make the internal leakage rate of each small battery different. The test data shows that the leakage rate will double when the battery rises 10 ° C. the active balancing function can ensure that the small batteries in the idle lithium-ion battery pack can constantly regain balance, This is conducive to making full use of the electricity stored in the battery pack, so that the residual electricity of a single small lithium-ion battery is minimal at the end of the working capacity of the battery pack.
3. Discharge: there is no lithium-ion battery pack with a discharge capacity of 100%. This is because the end of the working capacity of a group of lithium-ion batteries is determined by a small lithium-ion battery that is discharged first. It is not guaranteed that all small lithium-ion batteries can reach the discharge capacity at the same time. On the contrary, some small lithium-ion batteries retain unused residual power. Through the active balancing method, when the lithium-ion battery pack is discharged, the internal large capacity lithium-ion battery will distribute electric energy to the small capacity lithium-ion battery. Therefore, the small capacity lithium-ion battery can be fully discharged, and there will be no residual electric energy in the battery pack. The battery pack with the active balancing function has a large actual storage capacity (that is, it can release electric energy closer to the nominal capacity).
