Method for measuring contact resistance of lithium ion battery pack
A technology for lithium-ion battery packs and lithium-ion batteries, which is applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve the problems of indistinguishable, battery state of charge and life evaluation errors, and unavoidable, and achieves strong practicability. , the detection method is simple, the effect of high precision
Inactive Publication Date: 2018-04-20
DONGHUA UNIV
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Problems solved by technology
However, the contact resistance of battery electrodes at all levels in a lithium-ion battery pack is an unavoidable problem in the process of measuring the ohmic internal resistance of lithium-ion batteries
[0004] Second, contact resistance affects battery voltage detection
In a lithium-ion battery pack, the voltage drop across the contact resistance of the lithium battery terminal will affect the true voltage detection of the battery, resulting in errors in the battery management system's assessment of the battery's state of charge and life
[0005] Since the ohmic internal resistance of lithium-ion batteries and the contact resistance of lithium battery electrodes are both DC impedances, the two DC impedances cannot be directly distinguished by the conventional I-V characteristics of the battery.
This brings difficulties to the detection of battery internal resistance and voltage after lithium ions are grouped
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[0018] In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.
[0019] It is found through preliminary experiments that when a lithium battery is discharged in a short pulse (for example, the discharge pulse is 200us), the terminal voltage of the lithium battery changes with the discharge current. as follows figure 1 As shown, when the discharge current is greater than 3A at this time, the characteristics of the battery terminal voltage change dU and the discharge current I reflect the ohmic internal resistance of the lithium battery. At the same time, it can be found that in figure 1 Among them, when the discharge current is less than 2A, the voltage change of the lithium battery is 0; the discharge current 2A to 3A is the transition interval.
[0020] figure 1 Among them, due to the use of short pulse discharge, when the discharge current is small, the amount of charge released during the...
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The invention provides a method for measuring the contact resistance of a lithium ion battery pack. The method comprises: determining short pulse discharge time t and a current threshold according tocharacteristics of a lithium ion battery; selecting the current lower than the current threshold to carry out short pulse discharging on a lithium ion battery pack; and measuring voltage changes of all voltage terminals in the lithium ion battery pack during the short pulse discharging by using a voltage detection circuit to obtain a contact resistance value. The method that is simple and has highpracticability and precision can be applied to the lithium-ion battery management system.
Description
technical field [0001] The invention relates to a method for measuring the contact resistance of battery electrodes at various levels in a lithium-ion battery pack. Background technique [0002] Lithium-ion battery packs are widely used in the fields of new energy vehicles and energy storage. The voltage and internal resistance detection of the single cells in the battery pack is crucial to the effective management of the battery pack. However, in the battery grouping process, the contact resistance of the electrode terminals is unavoidable, and this resistance has a great influence on the accurate detection of the battery group. [0003] First, contact resistance affects the detection of battery internal resistance. In the equivalent circuit model of a classic lithium-ion battery, the battery internal resistance includes two parts: ohmic internal resistance and polarization internal resistance. Among them, the ohmic internal resistance of the lithium-ion battery is an im...
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IPC IPC(8): G01R31/36
Inventor 鲍云
Owner DONGHUA UNIV