دانلود رایگان مقاله انگلیسی یک مدل فرکانس بالا برای پیش بینی رفتار باتری های لیتیوم یون متصل به الکترونیک قدرت - الزویر 2018

ABSTRACT

Battery powered energy systems such as electric vehicles utilize power electronics for controlling energy flows between the battery and the load or generation, respectively. Therefore, the battery is under high frequency stress due to fast switching power electronic devices. However, most battery models throughout the literature are not able to cope with high frequency excitation. This paper proposes an easy to implement equivalent circuit model that covers aforementioned frequency regions with a series of inductors that are each connected in parallel with an ohmic resistance. This circuit is parameterized by electrochemical impedance spectroscopy (EIS) up to 100 kHz. For further regions that reach regions of megahertz a skin effect model is investigated and compared to the RL-model. It is shown that such semi-empirical models can be motivated by geometrical considerations that can be found in the literature. Moreover, the proposed model is validated by simulating the voltage response from an input current that originates from an actual back-to-back half bridge DC/DC converter. The promising results indicate that such models might be implemented in future battery energy systems to improve insights on how batteries react to perturbations such as EMI noise or high frequency current ripple.

Conclusion

A battery model to represent the behavior under high frequency excitation, e.g. induced by the current ripple of power electronics, has been proposed. It is based on an equivalent circuit that consists of an inductive constant phase element that is approximated by an almost arbitrary number of RL-circuits. In this work, using three RL-circuits has shown good results continuously within a frequency range up to 100 kHz which should suffice for a broad variety of applications. Moreover, a capacitive constant phase element has been added to take mid frequency effects down to 1 Hz into account so that the simulation can remain accurate as the inductive behavior is affected by the capacitive one and vice versa [18]. It is convenient to also model the capacitive CPE with corresponding RC-circuits. To obtain the parameters of the model, electrochemical impedance measurements have been conducted in a frequency range from 1 Hz to 1 MHz. However, the data has been cropped at 100 kHz to achieve higher accuracy in the most important range for a lot of power electronic applications, see Fig. 10 and the middle part of graphic Figure 12. The equivalent circuit has been implemented into MATLAB/Simulink as a block diagram that has been given a battery current with severe ripple, originating from a half bridge DC/DC-converter, to validate its calculated voltage response. The results clearly indicate that the model delivers the anticipated results so that it might be considered to improve commercial battery models in battery energy systems such as electric vehicles or larger scale stationary battery systems, for they all have their battery systems connected to power electronics that induce high frequency ripple. At the present day, it is not yet well known, how the aforementioned current ripple affects the battery performance and especially if there is any severe effects on battery aging. A model like the one that is introduced in this work can play a key role in further investigating battery systems and answer questions that have arisen in this context.