Engineers at Ruhr-Universität Bochum (RUB) have developed a new concept for current and voltage sensors for batteries that may be particularly relevant for electric vehicles (EV). In EV batteries, monitoring typically requires a current sensor and voltage sensors—as many as there are individual cells. The RUB innovation has reduced the number of necessary current and voltage sensors to one each, regardless of the number of cells. Moreover, both sensors support the function of cell balancing.
Each cell reacts differently during charging and discharging; by the end of the process, some are more charged than others. Once one cell is fully charged, charging of the other cells is discontinued. If one of the cells is empty, no energy is extractable from the other cells, either. The older the system, the bigger the problem. Cell balancing counteracts this phenomenon. It ensures that older systems keep providing maximum energy yield.
The measurement system from Bochum is scalable; that means it can be deployed in batteries with different numbers of cells. It is not only suitable for batteries in electric vehicles; but also works well in a wealth of other battery systems, for example in mobile devices such as tablets or laptops, wireless electrical tools, uninterruptible power supply systems that are crucial in hospitals, and in home storage systems such as for solar systems.
Just like the cells, the sensors are a considerable weight and cost drive. Some industrial enterprises have already expressed their interest in our innovation.—Philip Dost, designer
The sensor system exists as a lab prototype, realized by Florian Langner in his Master’s thesis at the Institute of Power System Technology and Power Mechatronics.
In the next step, the Ruhr-Universität engineers intend to characterize and evaluate their prototype in detail, and will also replace individual components, in order to meet the requirements of the automotive industry.