A rapid measurement method for vehicle battery impedance
A vehicle-mounted battery and measurement method technology, which is applied in the direction of measuring resistance/reactance/impedance, measuring devices, measuring electrical variables, etc., can solve battery monitoring occasions where the measurement time is long and cannot meet high real-time requirements, and cannot be well Adapt to vehicle conditions and other issues
Active Publication Date: 2019-05-14
苏州湛云科技有限公司
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In view of the fact that the measurement of impedance has been applied in the research on the understanding of the electrode process in the laboratory, and the application in automobiles has gradually attracted more and more attention with the development of electric vehicles in recent years. The existing technology requires a separate The external excitation source, through the single-frequency sinusoidal excitation, cannot be well adapted to the vehicle conditions, and cannot be carried out when the vehicle is running normally. At the same time, the measurement time is long and it cannot be used in battery monitoring occasions with high real-time requirements, such as real-time faults. Monitoring, etc.
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[0036] For a continuous signal f(t), its continuous wavelet variation is defined as follows:
[0037]
[0038] In formula (1), is the wavelet transform coefficient, which is obtained by convolving the original signal f(t) with the mother wave ψ(t), s is the scaling factor, and τ is the time parameter. Wavelet transform is to realize the stretching and translation of the mother wave ψ(t) by adjusting the values of s and τ, just like using a lens to focus and translate the target signal, so as to achieve higher time resolution at higher frequencies. Lower frequencies have the effect of higher frequency resolution. The battery signal includes a voltage signal and a current signal, and the voltage signal and the current signal are both vector signals, so in order not to lose the vector information of the original signal, the complex Morlet function should be selected as the wavelet basis function, which is defined as follows. where f c Indicates the center frequency of th...
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The invention relates to a method for rapidly measuring the impedance of a vehicle mounted battery, which is designed to measure the impedance of a vehicle mounted battery at a frequency contained in a measurement frequency set. The method comprises the following steps: 1) according to the impedance values of a to-be-measured vehicle mounted battery, determining its corresponding measurement frequencies so as to construct a measurement frequency set; 2) determining whether the pre-sampling this time causes effective current or voltage change trend or not; and if true, performing the real sampling of the voltage and the current at the battery end; and performing synchronized treatment to the voltage and the current through the real sampling before proceeding to the step 3); and if not true, performing another round of pre-sampling until effective current or voltage change trend arises; 3) making a wavelet analysis, and through the wavelet transform coefficient ratio of the voltage to the current, obtaining the impedance value; and 4) changing the mother wave scale parameters of the wavelet analysis for another wavelet analysis to calculate the battery impedance corresponding to the next frequency of the frequency set. Compared with the prior art, the method of the invention combines the pre-sampling and the real sampling together, and is rapid and effective as well as free of an externally connected excitation source.
Description
technical field [0001] The invention relates to the field of battery management of pure electric vehicles, plug-in hybrid vehicles and fuel cell vehicles, in particular to a method for quickly measuring the impedance of a vehicle battery. Background technique [0002] With the promotion and application of electric vehicles and plug-in hybrid vehicles, there are very high requirements for the safety and reliability of vehicle battery packs. For the battery management system, it is possible to know the current life state of the power battery in a timely and accurate manner. , power output capability, and internal temperature are of great significance to predict thermal failure and prevent abuse, and the above characteristics are all closely related to the impedance of the battery at a certain frequency point or within a certain frequency range. [0003] At present, there are two main methods for measuring battery impedance, one is the single frequency injection method, and the...
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IPC IPC(8): G01R27/08G06F17/14
CPCG01R27/08G06F17/148
Inventor 魏学哲戴海峰王学远
Owner 苏州湛云科技有限公司