Methods of controlling electrochemical energy storages: classification and application features

Abstract

Energy storages are the most important integral elements of both autonomous energy system based on renewable energy sources and vehicles of various purposes, where they are the main power source. Therefore, the issue of controlling their operation modes is an important one, and choosing the control methods is a relevant problem. The main operation modes of energy storages which require controlling are the work mode when the stored energy is consumed and the charging mode when the used energy is replenished. The example of on-vehicle energy storage is used to analyze basic operation modes and their particular aspects. Dynamic modes with unpredictable energy consumption caused by uncontrollable undercharging and overcharging are typical. The analysis allowed drawing the conclusion that, when controlling operation modes, it is necessary to consider the energy modes of accumulators, which reflect its efficiency most fully and objectively. The analysis of existing control methods showed that their common disadvantage is that they use such parameters as voltage and operating current to control and manage the storage modes. The fact is that due to the transient nature of electrochemical processes during the operation of the storage in dynamic modes, the values of these parameters do not correspond to the current energy state of the storage. This study aims to increase the performance of electrochemical energy storages by efficiently choosing a method for controlling their operation modes. The authors prove and experimentally confirm that when working with electrochemical energy storage devices in dynamic modes, it is necessary to choose the methods based on the application of the active material utilization ratio, information equivalent of which is the value of the area under the depolarization curve on the storage’s response signal to the charging impulse. The use of the proposed mode allows combining the functions of controlling and managing the storage.

Keywords

• energy storage
• pulsed galvanostatic method
• response signal
• material utilization ratio
• generalized energy index