A method for estimating the internal temperature of a battery throughout its life cycle based on bode diagrams

Abstract

The invention discloses a method for estimating the internal temperature of a battery with a full life cycle based on a Bode diagram, which includes three steps: (1) analysis of factors affecting the Bode phase shift value and determination of the optimal frequency interval: obtaining different temperatures and different states of charge 1. The electrochemical impedance phase shift value of the battery under different health states, and determine the phase shift value within the test excitation frequency range, which is not disturbed by the state of health and state of charge, but is sensitive to the internal temperature frequency range; (2) establish an internal The mapping relationship between temperature and electrochemical impedance phase shift value: determine the optimal excitation frequency point in the selected frequency band interval, and find the mapping relationship between the phase shift value and internal temperature at this frequency point; (3) The internal temperature estimation process of the battery: Place the battery to be tested at different ambient temperatures, and use the optimal frequency point to give the battery to be tested for vibration, obtain the phase shift value at this frequency point, and use the phase shift value obtained in step (2) to map with the internal temperature of the battery The relationship estimates the internal temperature of the battery under test.

Description

technical field [0001] The invention belongs to the technical field of temperature measurement of lithium batteries used in electric vehicles, and in particular relates to a method for estimating the internal temperature of a battery in a full life cycle based on a Bode diagram. Background technique [0002] When the battery is charging and discharging, complex chemical reactions are going on inside it, accompanied by the generation of various heat, resulting in real-time changes in the internal temperature of the battery. At present, the temperature monitoring of lithium-ion batteries is mainly to detect the surface temperature. By pasting temperature measuring resistors and thermocouples on some single batteries, the temperature of single batteries can be monitored in real time. Due to the structural characteristics of the lithium-ion single battery, the thermal conductivity in each direction is very different. The traditional method of measuring the surface temperature of...

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Problems solved by technology

At the same time, the research on battery internal temperature estimation based on electrochemical impedance spectroscopy features is mostly in the theoretical analysis stage, and the mapping relationship between electrochemical impedance spectroscopy features and battery internal temperature has not been explored in depth, and it is effectively applied to the online temperature estimation of battery pack internal temperature. Estimated

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