Balanced charging device applied to lithium battery and control method of charging device

Abstract

The invention discloses a balanced charging device applied to a lithium battery. Two sets of charging mechanisms are used to realizing balancing of charging. The charging device and control method thereof have the advantages that the problem in heat management does not exist compared with dissipation type balancing; the balancing current is heavy, the efficiency is high and the speed is high compared with capacitive or inductive energy storage non-dissipation balancing; and compared with balancing via a transformer, a magnetic core and a coil are not needed, there is no magnetic leakage, and the volume is controllable.

Description

technical field [0001] The invention relates to the field of lithium battery charging. Background technique [0002] Equalization is a key technology to solve the difference of battery cells. Electric vehicles can be divided into a charging phase and a discharging and idle phase according to the state of use. According to the different working characteristics of the two stages, different equilibrium strategies are formulated respectively. [0003] The purpose of equalization in the charging phase is to make all the cells fully charged, and try to avoid the situation of inconsistent power of the cells. The charging equalization reported in the literature generally uses dissipative equalization or non-dissipative equalization. [0004] In the dissipative equalization scheme, the heat dissipation resistor wastes power and generates a lot of heat, causing thermal management problems, and the equalization current is too soft compared to the charging current. [0005] Non-diss...

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Problems solved by technology

[0004] In the dissipative equalization scheme, the heat dissipation resistor wastes power and generates a lot of heat at the same time, causing thermal management problems, and the equalization current is too small compared to the charging current

[0005] Non-dissipative equalization often uses inductance and capacitance to transfer energy from high-voltage monomers to low-voltage monomers. The time required for equalization is very long, which does not meet the rapidity requirements of battery charging; and frequent switching It will also consume a lot of energy, and a part of the electric energy will definitely be consumed due to the loss of the device during the transfer process.

Coaxial coil transformer equalization circuit, because the length and shape of the wires between the winding and each single battery are different, the transformation ratio is different, resulting in inconsistent balance of each single battery

The coaxial coil itself consumes a certain amount of energy due to electromagnetic leakage and other problems; at the same time, the volume of the transformer also limits its application in many compact occasions

These problems make the above non-dissipative equalization scheme difficult to be practical

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