Multi-channel voltage monitoring for batteries and fuel cells

PEWATRON AG: For many years, numerous research institutes and industrial establishments have been carrying out an intensive process of development of fuel cell systems. These initiatives have for some time been refi ned by activities in the area of battery systems and electrical mobility. Both research fi elds make similarly high demands in terms of measurement engineering. The aim is to achieve the high operating voltages required by creating series circuits consisting of up to several hundred fuel cells or battery cells in large stacks. Depending on the application, these voltages range up to 1,000 V, which makes particularly demands on the insulation capacity of the measuring devices. It is essential to monitor all individual cells for low voltage, especially during the fuel cell development stage. Low voltage is an indication of material fatigue or insuffi cient supply of hydrogen and/or oxygen. In the event of a defect, this could cause the cell to short circuit as a result. In the maritime sector, for example, where the fuel cell is operated with pure oxygen, this represents a serious risk of explosion. Monitoring the voltage of individual cells enables proactive control intervention to prevent damage to people and machinery.

In the area of rechargeable batteries, both low voltage and excess voltage are important in terms of operation. In the case of low voltage, there is a risk of loss of voltage throughout the entire system, and in the case of excess voltage, the charging process has to be terminated to prevent the storage battery from overheating.

In order to provide the development engineers with the necessary measurement technology, PEWATRON offers a Cell Voltage Measurement System (‘CVM’) manufactured by SMART Electronic Development GmbH. SMART Electronic Development GmbH has been developing measurement technology for this area for over 14 years. The third generation of the Cell Voltage Measurement System is now on the market and offers individual cell monitoring in real time with up to 90 channels per device. Data transmission takes place via CAN on two separate data buses. In addition, all measurement channels can be monitored in real time for two threshold values. The vehicle control unit or the test rig computer therefore receive precise information regarding the state of the cells at any particular time and can carry out regulatory or control intervention measures, thus recognising and preventing critical system states.

One of the leading research institutes in the area of fuel cells and battery development is the Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW) (Baden-Württemberg Centre for Solar Energy and Hydrogen Research) in Ulm. Here, the CVMpro90-R3 measurement system has been in use for many years, and the new MCM system was recently introduced to carry out fuel cell and battery tests, cell optimisation, and validations.

At Bayer MaterialScience AG in Brunsbüttel, CVMpro60-R3 units have been in use for years to monitor the voltage characteristics of hydrochloric acid electrolysers on an industrial scale. Customised control centre software was developed for this purpose to facilitate data evaluation and logging. In the mobile sector, numerous systems have been supplied to German vehicle manufacturers over recent years and are used successfully in trial vehicles like Daimler AG’s NEBUS and NECAR. The unit’s particular advantages are its compact size, high resistance to EMC radiation, and sudden potential change, as well as automotive compatibility.

About PEWATRON

PEWATRON, with headquarters in Switzerland, specialises in sensors (physical and geometrical), power supplies, e-components and drives. PEWATRON delivers a wide assortment of electronic components ranging from standard products, semi-custom products to custom products. PEWATRON works closely with developers and can be involved right from the start of a product development process to ensure that together with the customer, the best fitting component for the application is found.

PEWATRON, an independent company that belongs to the Angst+Pfister Group, has been serving customers in Europe with prompt and individual service for over 30 years. Through the Angst+Pfister Group, PEWATRON belongs to a world-wide network of over 900 employees and 75,000 satisfied customers.