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Fuel cell stack monitoring

Testing a 95-kilowatt fuel cell suitable for vehicle integration

A fuel cell stack is a living organism and individual cell voltages report its vital signs. Which is why fuel cell vehicles are usually equipped with a monitoring system promptly drawing attention to critical operating conditions and enabling immediate response. It is absolutely necessary to reduce system costs before mass production can begin. Automated installations is a good place to start.

If you ask Markus Schuster, business line manager at Smart Testsolutions, Stuttgart, Germany, he will tell you the most important requirement of cell voltage monitoring systems, CVMs, is their availability. “The system must simply function,” he stated firmly. The product must be robust, durable and utterly reliable, meeting the highest of technical demands, he said.

Many popular CVM systems monitor the fuel cell stack as a whole, making it impossible to pinpoint the origin of a given malfunction. Monitoring each cell individually allows direct access to a stack’s inner workings. The new system signals not only stack malfunctions, but their precise location within the stack as well. You know exactly which cell or cell cluster is complicating matters. “Thus, the CVM data is suitable for operating strategy integration, such as in vehicles. It identifies critical operating conditions and shuts the stack down before irreparable damage can occur,” Schuster explained.

Hyundai and Toyota already there

A Smart Testsolutions measuring device has 1 to 42 voltage sensors with more than 10 channels each, synchronously monitoring up to 420 individual cells in a stack. The greatest CVM challenge lies in the economic viability of a single channel’s price, Schuster said. Especially when demands include an 18,000-hour lifetime and the corresponding certification. Costly manufacturer overhead.

There are already several R&D and trial solutions on the market. “So far, these have been proprietary solutions and not available on the open market,” said Schuster. But the number of providers is rising. Two large Asian automakers – Hyundai and Toyota – already have ready-to-go solutions.

Size and weight matters, for cars

Samuel Guesne is systems department manager at the DAM Group, another monitoring solutions provider. “Creating a reliable, affordable and easily integrable CVM is an enormous challenge. All the same, it is essential, playing a decisive role,” he confirmed. First and foremost, manufacturers want to know if the installed fuel cell is functioning smoothly. To this end, the CVM measures voltage between the bipolar plates. The collected data can also be used to adjust and improve control commands to the cells. A communication protocol gives drivers real-time operating conditions.

The French DAM Group is currently working on a monitoring system that accommodates any number of fuel cells, optimally adjusted to a vehicle’s weight and size and relatively quickly installed. The product is in the design and validation phase, with DAM working closely with several partners, Guesne reported.

… Read more in the latest H2-International e-Journal, Feb. 2021

Author: Niels Hendrik Petersen

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