Method and system for determining thermal management parameters of power battery based on low-temperature fast charging

Abstract

The invention discloses a method and system for determining thermal management parameters of a power battery based on low-temperature fast charging. The determining method includes: at the beginning of charging, if the lowest temperature of the battery system is , the minimum temperature and SOC of the battery system, and the corresponding coolant inlet temperature X1 and inlet flow Y1 are obtained from the query table, and X1 and Y1 are used as the coolant inlet temperature request value and inlet flow request value sent to the vehicle thermal management system; During the charging process, when the minimum temperature of the battery system is greater than Z2, calculate the coolant inlet temperature X2 and the battery system temperature difference △T, and determine the coolant inlet flow Y2, and use X2 and Y2 as the coolant sent to the vehicle thermal management system Inlet temperature request value and inlet flow request value. The invention can shorten the fast charging time and reduce the temperature difference of fast charging under the low temperature working condition, and ensure the correct logic of the fast charging time with different initial SOCs.

Description

technical field [0001] The invention belongs to the field of thermal management control of power batteries of electric vehicles, and in particular relates to a method and system for determining thermal management parameters of power batteries based on low-temperature fast charging. Background technique [0002] New energy vehicles use pure electric vehicles as the main technical route, and their batteries are mainly ternary lithium batteries or lithium iron phosphate batteries. These two batteries will have low-temperature fast charging time is too long, the temperature difference during charging is too large, Problems such as logic errors of different start and stop SOC fast charge times. [0003] The current determination strategy for power battery thermal management parameters (including coolant inlet temperature and coolant inlet flow rate) is: design in a way that keeps the coolant inlet temperature and coolant inlet flow constant at each stage of power battery charging...

AI Technical Summary

Problems solved by technology

[0004] (1) Lower coolant inlet water temperature will reduce the temperature rise rate of the battery system and prolong the charging time. Higher coolant inlet water temperature will cause unnecessary consumption of the battery system, resulting in increased energy consumption of the vehicle, seriously affecting users Use experience; (2) In a low-temperature environment, the time it takes for the vehicle to charge from a lower initial SOC displayed to full charge (that is, the SOC reaches 100%) is longer than that from a higher initial SOC displayed to full charge ( That is, the time consumed when the SOC reaches 100% is shorter, which seriously affects the user experience; (3) When the heating temperature difference of the battery module in the power battery is large, it will cause the BMS (that is, the battery management system) due to the local temperature to be too low. ) limits the charging power of the battery system, prolongs the charging time, and the long-term temperature difference problem will also cause the local capacity of the battery module to decay quickly, which will cause the capacity of the entire pack to decay quickly, causing serious economic losses to customers

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