Battery pack parallel protection method

Abstract

The invention provides a battery pack parallel protection method. The method comprises the following steps: acquiring a voltage value of each battery pack in a battery stack; acquiring a voltage difference value between the voltage value of the current battery pack and the lowest or highest voltage value of the battery pack in the battery stack; comparing the voltage difference value with a preset voltage difference threshold value to obtain a comparison result; and connecting or disconnecting the current battery pack into or out of the battery stack according to the comparison result. According to the embodiment of the invention, on the basis that the material cost is not increased, the inconsistency of lithium iron phosphate battery packs in parallel use can be effectively avoided, so that the intelligent switching of the battery packs in a parallel system is realized.

Description

technical field [0001] The invention relates to the field of battery pack management, in particular to the field of battery pack protection. Background technique [0002] One of the biggest problems with vehicles that run on fossil fuels like gasoline and diesel is that it contributes to air pollution. As a means of solving such problems, a technique of using a secondary battery capable of charging and discharging as a vehicle power source is attracting attention. [0003] Accordingly, electric vehicles (EVs) that can be operated only by batteries, hybrid electric vehicles (HEVs) that use batteries and existing engines in combination, and the like have been developed, and some of them have been commercialized. Nickel metal hydride (Ni-MH) batteries are mainly used as secondary batteries used as power sources for EVs, HEVs, and the like. Recently, however, the use of lithium-ion batteries has also been investigated. [0004] In order to use such a secondary battery as a po...

AI Technical Summary

Problems solved by technology

And the internal resistance of each battery cell is actually different. After a large number of battery cells are connected to form a battery pack, there must be differences in the consistency between the battery packs.

[0006] Especially when battery packs are used in parallel, the consistency is difficult to control

Moreover, due to the difference in internal resistance, even if two or more groups of batteries with the same voltage are connected in parallel, the voltage difference will gradually increase as the number of charge and discharge increases.

When the battery packs are connected in parallel, the pressure difference between the packs will cause backflow between the inside of the battery pack. Since the impedance is only the internal resistance of the battery when backflow occurs, a few volts of voltage difference can generate hundreds of amperes of current, which is harmful to both the battery and the circuit device. Great damage, the backflow current exceeds the capacity of the system, and even damages the device and battery

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