Impedance measurement system and method for secondary batteries

Abstract

The invention discloses an impedance measurement system and method for secondary batteries and belongs to a battery measurement technology. The system comprises a battery module, a charging and discharging module, an alternating current frequency scanning module and a signal collecting and processing module. A 203c point of a 203 three-position switch of the charging and discharging circuit is connected with the negative electrode of the battery module 1, and by selecting a switch arm connected with the 203c point, the negative electrode of the battery module 1 is connected with a 202 electronic load and the positive electrode of the battery module 1 through a 203a point to form a discharging circuit. The impedance measurement system and method for the secondary batteries are applied to tests on impedance of the secondary batteries in the working state and can be used for measuring all the single secondary batteries contained in a secondary battery pack in parallel through multiple channels. The Ohm internal resistance, the electrochemical polarization impedance and the concentration polarization impedance of each secondary battery are tested out, the impedance of each secondary battery is analyzed, and the impedance measurement system and method are used for analyzing the charging and discharging performance of the batteries. The service life of the batteries is estimated, and the batteries can run more safely, stably and reliably.

Description

technical field [0001] The invention belongs to the technical scope of battery measurement, and in particular relates to an impedance measurement system and an impedance measurement method of a secondary battery. Background technique [0002] Secondary batteries, chemical power sources that can be charged and discharged, such as lithium-ion batteries, lead-acid batteries, nickel-metal hydride batteries, etc., due to the different voltage platforms and energy densities of various batteries, are used in electric vehicles, power , energy storage, mobile phones, notebook computers, etc. are more and more widely used. The impedance of the secondary battery is an important parameter of the battery, which can be used for battery charge and discharge performance analysis, battery pack consistency analysis, remaining capacity estimation, battery operating life estimation, battery pack consistency analysis and safety performance analysis, etc. . Therefore, it is of great significanc...

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Problems solved by technology

[0008] The direct current method can be used for fast measurement, which can be measured under the charging and discharging operation of the battery, but the disadvantage is that 1) only the total impedance of the battery can be measured, and the charge transfer impedance and concentration polarization impedance cannot be measured; 2) the battery is assumed to be in two The polarization impedance is equal when charging and discharging at different currents, so the measurement results are not accurate and can only be used for rough estimation

The pulse method overcomes the defects of the DC method 2). In a small square wave change cycle, the ohmic internal resistance of the battery can respond instantaneously, and the polarization impedance of the battery has no time to change. Therefore, the ohmic internal resistance of the battery can be measured. However, the polarization impedance part cannot be measured

The AC impedance method can measure the high-frequency impedance of the battery, but it is only measured at a certain frequency or at a constant frequency near this frequency, and cannot measure the entire impedance of the battery, and the existing methods are all measured in an open-circuit state of the battery. , there is a certain deviation from the measurement results of the battery under charging or discharging working conditions

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