High-capacity LFP battery thermal runaway early warning method based on gas precipitation characteristics
A thermal runaway, large-capacity technology, applied in the direction of lithium batteries, secondary batteries, non-aqueous electrolyte batteries, etc., can solve problems such as thermocouple or temperature sensor internal and external temperature error, early warning failure, and susceptibility to external disturbances, etc.
Inactive Publication Date: 2022-07-01
XIANGTAN UNIV
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Problems solved by technology
[0004] At present, the biggest problem with the early warning method that uses temperature as a parameter is that there is a certain error in the internal and external temperatures of the thermocouple or temperature sensor in the process of measuring the battery temperature, which will lead to thermal runaway of the battery before the set warning temperature is reached. phenomenon, eventually leading to the failure of the early warning
Early warnings based on battery internal resistance and voltage signals are susceptible to external disturbances, and sometimes sudden changes are not necessarily caused by thermal runaway. Therefore, simply using voltage and resistance as parameters for early warning of LFP battery thermal runaway may not be able to provide early warnings in a timely and accurate manner. effect
Method used
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[0020] Assuming that the sampled signal is X(m), the length is N, N is 5 to 8, m∈[0,N], where n is an integer, then the DFT of x[n] is:
[0021]
[0022] because Formula (1) can be transformed into:
[0023]
[0024] define function Y k (n):
[0025]
[0026]
[0027] It can be seen that Y k (n) is the convolution of two sequences, where x(n) is the input N-point sequence, h k (n) is the filter impulse response sequence. Z-transform formula (4):
[0028]
[0029] Then the recurrence equation of the first-order system is:
[0030]
[0031] Calculate the discrete Fourier change of N points according to the Goertzel algorithm, which requires 4N 2 real multiplications and 4N 2 Addition of real numbers. When N is small, the efficiency of the algorithm is not high, so the Goertezl algorithm is improved. Multiply the denominator and numerator of formula (5) Obtaining formula (7), the transfer function H(z) of the second-order IIR filter is:
[0032] ...
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The invention discloses a high-capacity lithium iron phosphate (LFP) battery thermal runaway early-warning method based on gas precipitation characteristics, and relates to a thermal runaway early-warning scheme for a high-capacity LFP battery in the storage and charge-discharge processes, in the early stage of thermal runaway of the battery, characteristic gas is monitored, an improved Goertzel algorithm is introduced to filter concentration signals, and a high-capacity LFP battery thermal runaway early-warning result is obtained. And the precision of single detection is improved. The early warning judgment is realized by utilizing the combination of the early separated VOC and CO2, the concentration value and the concentration rising rate of the VOC are calculated in the time difference of separating out different gases in the operation process of an early warning program, and a plurality of calculation results are compared with a set threshold value, so that a more accurate early warning function is realized.
Description
technical field [0001] The present invention relates to a thermal runaway warning method for a large-capacity lithium iron phosphate (LFP) battery based on gas evolution characteristics, which relates to a thermal runaway warning scheme for a large-capacity LFP battery during storage and charging and discharging. Real-time monitoring of the generated flammable and explosive gases and start an alarm. Background technique [0002] In recent years, in order to alleviate the energy dilemma, the state has actively supported and developed the new energy industry. Lithium-ion batteries have become an important development direction in the field of new energy due to their good electrochemical performance, strong anti-interference ability, and environmental friendliness. Lithium batteries are the most important part of electric vehicles and energy storage power stations, and play an important role in energy storage and conversion. However, due to the limitations of its own material...
Claims
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Login to View More IPC IPC(8): H01M10/42H01M10/052H01M10/48G06F17/10G01N33/00
CPCH01M10/42H01M10/052H01M10/48G01N33/0063G06F17/10G01N33/0068
Inventor 易灵芝蔡鑫坤刘江永刘波陈智勇胡毕华潘瑞
Owner XIANGTAN UNIV