A method for quickly balancing the voltage difference of each single string of cells in a power battery system

Abstract

The invention provides a method for quickly balancing the voltage difference of each single string of cells in a power battery system, which comprises the following steps: 1, measuring a normal cell voltage U1 and an abnormal cell voltage U2; 2, calculate that voltage difference between the abnormal cell and the normal cell, namely the actual voltage difference U; 3, calculate that capacitance difference C between the abnormal cell and the normal cell, 4, calculating the charging or discharging current I; 5, calculate a charging or discharging time T; 6, connecting that power source or the load to the two end of the abnormal cell, setting the time as T, turning on to charge or discharge, and disconnecting the power source or the load after the time T to complete the balancing. The method provided by the invention. The invention has the advantages of simple operation and easy control, solves the problems of long constant current and constant voltage charging time in the prior art, and the inconsistent voltage difference after standing or cycling needs fine adjustment, greatly improves the working efficiency, and recovers the continuous driving range decrease of the power battery system due to the capacity difference of the single cell, and avoids the life attenuation due to the inconsistent voltage difference.

Description

technical field [0001] The invention relates to a battery equalization method, in particular to a method for quickly equalizing the voltage difference of each single string of battery cells in a power battery system. Background technique [0002] The differences caused by the production and use of power battery cells have caused the inconsistency of power battery cells. The inconsistency is mainly manifested in the monomer capacity, internal resistance, self-discharge rate, charge and discharge efficiency, etc. The inconsistency of the monomers will inevitably lead to the loss of the capacity of the power battery system, which in turn will lead to a decrease in life. Studies have shown that a 20% difference in the capacity of a single cell will cause a 40% capacity loss in the battery pack. The inconsistency of the battery cells will be further exacerbated over time under the influence of random factors such as temperature and vibration conditions. At present, there are m...

AI Technical Summary

Problems solved by technology

The inconsistency of the monomers will inevitably lead to the loss of the capacity of the power battery system, which in turn will lead to a decrease in service life

Studies have shown that a 20% difference in the capacity of a single cell will cause a 40% capacity loss in the battery pack

The inconsistency of the battery cells will be further deteriorated over time under the influence of random factors such as temperature and vibration conditions

At present, there are mainly two methods to solve the inconsistency of the voltage. First, improve the manufacturing process of the single battery and try to use the same batch of batteries in the production process for matching groups. However, this method is not absolutely effective. Over time, consistency issues still arise

Second, through the battery management system, the battery cells are constantly balanced. The balance is divided into active balance and passive balance. The so-called active balance is to use energy storage devices to transfer part of the energy of the battery cells with more energy to less energy. When the battery goes up, it is the transfer of energy; active equalization needs to be equipped with corresponding circuits and energy storage devices, which are large in size, high in cost, and low in reliability. These conditions limit the application and promotion of active equalization

Passive equalization uses resistors to consume the energy of high-voltage or high-charge batteries to achieve the purpose of reducing the gap between different batteries. It is a kind of energy-consuming equalization; High and low efficiency cannot be applied in the actual production process

Based on the advantages and disadvantages of the above two equalization methods, it is impossible to quickly cut off the voltage difference of the battery cells in the production process or after-sales process, and this method can efficiently and accurately solve the problem of inconsistency in the voltage of each single string in the battery module or system. question

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