Impedance Compensation Algorithm of Voltage Acquisition Line on Battery Management System

Abstract

The invention provides a voltage acquisition wire impedance compensation algorithm for a cell management system. The voltage acquisition wire impedance compensation algorithm comprises steps that: 1, voltage magnitude of each cell in a cell pack is periodically detected, whether the voltage magnitude of one cell is abnormal is determined, if the voltage magnitude of one cell is abnormal, entering to the second step, or exiting the flow; 2, an impedance compensation circuit starts, a constant current is exerted on a voltage acquisition loop from which the abnormal voltage magnitude is acquired; 3, a voltage magnitude of the voltage acquisition loop corresponding to the abnormal voltage value is re-acquired, whether the re-acquired voltage magnitude is abnormal is determined, if abnormal, entering to the fourth step, or exiting the flow; and 4, power supply of the cell pack is cut off forcibly, or power supply power of the cell pack is reduced. Through the voltage acquisition wire impedance compensation algorithm, abnormity of the acquired voltage of one cell can be timely discovered, abnormity can be eliminated without manual dust cleaning, and adaptability to a serious environment, stability and reliability of cell products are further improved.

Description

technical field [0001] The invention relates to the field of battery management systems, in particular to an impedance compensation algorithm for voltage acquisition lines on the battery management system. Background technique [0002] At present, most BMS (battery management system) voltage acquisition methods are to collect the voltage of the single battery through the voltage acquisition chip on the BMU (slave board) of the BMS, and use the voltage acquisition line as the medium to collect the voltage of the single battery, and report the collected voltage value of the single battery The BCU (main board) of the BMS directly controls the battery pack through the BCU and interacts with the entire vehicle at the same time. [0003] However, the use environment of the battery pack on the bus or mine car in the suburbs is harsh, and dust is easy to accumulate on the harness plug of the BMS voltage acquisition line inside the battery pack, resulting in an increase in contact re...

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Problems solved by technology

[0003] However, the use environment of the battery pack on the bus or mine car in the suburbs is harsh, and dust is easy to accumulate on the harness plug of the BMS voltage acquisition line inside the battery pack, resulting in an increase in contact resistance, which further causes the voltage acquisition line of the BMS to fail when the voltage is collected. There is a voltage drop, which also causes the cell voltage collected by the BMS to be lower than the actual cell voltage of the battery. If the BMS collects a false low cell voltage, it will take actions to protect the battery in advance, such as during driving. In order to protect the battery, the battery management system forcibly cuts off the power, causing the whole vehicle to lie down or force low speed, etc., which will eventually affect the use of the battery pack. In this case, it is necessary to dismantle the battery pack and check the status of the battery separately to determine the occurrence of the fault. At the same time, it is necessary to clean the dust inside the battery pack to eliminate the fault, so that the battery pack can return to the working state

[0004] figure 1 The technical analysis schematic diagram of the battery pack failure caused by the accumulation of dust on the voltage acquisition line is given, as shown in figure 1 As shown, R1-R5 represents the resistance between the battery pole and the BMS acquisition circuit (that is, the resistance on the voltage acquisition line), and C1-C4 indicates the single battery. If the accumulated voltage on the voltage acquisition line represented by R1 or R5 If there is dust, the resistance value of R1 or R5 will increase. Assuming that the resistance value of R2 and R4 is normal, due to the voltage division between R1 and R5, the voltage of C1 or C4 collected by the BMS will be lower than the actual battery voltage value, which means The voltage value of the collected single section is low; if there is dust accumulated on the voltage collection line represented by R2, the resistance value of R2 will increase. Assuming that the resistance values ​​of R1 and R3 are normal, due to the voltage division of R2, then the BMS will collect C1 or The voltage of C2 will be lower than the actual battery voltage, that is, the voltage of two adjacent cells will be low

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