Developing a real-time degradation detection methodology without needing extra instrumentation or test interruptions

Realizing the importance of electronic reliability

As electronic device complexity and performance increases, so does the risk of overheating or failure. Advanced systems are of no use if they are unreliable. Manufacturers need to accurately assess this risk and predict the lifetime of products to gain consumer confidence and avoid field failures. In particular, as silicon carbide (SiC) chips become more widely used, understanding how they age and fail is vitally important.

The Institute for Power Electronics and Electrical Drives (ISEA), part of RWTH Aachen University in Germany, is one of the leading academic centers working on this problem. The institute’s Reliable Power Electronic Systems group focuses on finding ways to detect degradation in power modules while they are still running, rather than waiting for a system to shut down to identify what has gone wrong.

“The goal is to use detection methods that work during operation,” explains Isabel Austrup, group leader at ISEA. “Not just when you stop the system and run a dedicated test.”

A key tool used in this research is Simcenter™ Micred™ Power Tester hardware, which is part of the Siemens Xcelerator business platform of software, hardware and services.

Understanding degradation

To understand how power modules degrade, researchers need to age them quickly under controlled conditions. Active power cycling simulates years of real-world use by repeatedly stressing a device with heating and cooling cycles. This requires a platform that is precise, reliable, flexible and capable of capturing large volumes of measurement data over extended periods.

Laurids Schmitz, group leader at ISEA, explains why building a tool themselves was not feasible. “Getting to the level of flexibility and reliability you need for serious research would take years of development,” says Schmitz.

Using Simcenter Micred Power Tester, a proven, industry-standard system, allows the team to focus on the research itself rather than the infrastructure behind it. Its built-in thermal measurement capability allows researchers to characterize how heat moves through a device without transferring it to a separate test bench. It’s also well-established within the research community, so ISEA’s results are directly comparable with work from similar institutes around the world.

ISEA has worked closely with Siemens Digital Industries Software partner, Novicos, to root out problems with the power tester and ensure they could get the most value from it. Novicos’ close relationship with both parties means they can understand how it is being used and have an impact on further development.

Analyzing the data differently

The most striking outcome of ISEA’s work is not just what the Simcenter Micred Power Tester was built to do, but what the team discovered it could do.

During active power cycling, it continuously records voltage across a device, using this data to track resistance as an indicator of overall health. Austrup and her team1 found that the way voltage responds to the switching current also carries data relating to the thermal condition of the device, including subtle changes that indicate degradation. This is information that was always available but had not previously been used.

By analyzing the timing of the voltage response relative to the switching cycle, the team can track degradation in real time with no interruptions and no extra equipment. “We realized the data we needed was already being measured by Simcenter Micred Power Tester,” says Austrup. “We just needed to analyze it differently.”

Pinpointing the problem

This new method not only detects an issue, but it also shows where the problem is. A power module is built up in layers, and degradation in various layers produce a distinct signature at different test frequencies. By examining the data at more than one frequency, the team can pinpoint which layer the fault is in.

In tests using a SiC power module connected to the Simcenter Micred Power Tester, researchers simulated degradation of the thermal interface material, which is found between the module and its heat sink. At 200 millihertz, the voltage response clearly reflected each stage of degradation. At one millihertz, it did not, even though other measurements changed at both frequencies.

“On-state resistance tells you something has changed,” says Austrup. “This variance at different frequencies tell us the fault is in the thermal interface layer, not the cooling system.”

This method also removes the need for a calibration step, which standard power cycling requires, typically taking around an hour per device. With this approach, the aging test can start immediately.

Eliminating the calibration step

In traditional active power cycling tests, engineers must carry out a time-consuming calibration process before a single aging cycle can begin. Additionally, they need to periodically interrupt the aging process to take thermal measurements, meaning critical degradation data between those intervals is lost.

“Calibration often takes an hour and is something you just have to do for every measurement position before you actually start to do the thing you want to do, which is the aging,” says Schmitz. “This is removed with the new method.”

The new phase-delay method ISEA developed eliminates both problems. By analyzing the phase shift of the drain-source voltage – calculated from the voltage the Simcenter Micred Power Tester already captures as standard – engineers can monitor degradation continuously, at every cycle, with no interruptions and no upfront calibration. As Schmitz confirmed: “You don’t need a calibrated voltage measurement anymore.”

No additional hardware is necessary. Researchers can immediately extract richer degradation insights from data they were already collecting – saving at least an hour per test, per measurement position.

Going from research to industry

Austrup has presented the methodology at an international conference which she says opened the eyes of other researchers to the possibilities. “Many people said they wanted to try it on their existing data,” she says. “They already have everything they need, they just never used it in this way.”

This is only possible because Simcenter Micred Power Tester is designed to capture rich and detailed measurement data. As the research community develops new ways to analyze that data, older tests yield new insights. The value of every test run can continue to grow long after the cycling is finished. ISEA’s phase methodology is one example. It is unlikely to be the last.

For companies developing or qualifying power electronics for automotive, industrial or energy applications, this methodology is invaluable. It could potentially offer a practical path towards detecting degradation in devices while they are still in service, helping them improve reliability across their products.

“Our aim is to develop methods that can move from the research lab into the converters and drives that engineers in the industry depend on every day,” says Austrup. “The Simcenter Micred Power Tester is an important tool that helps to make this possible.”

Reference

1 I. Austrup et al., “Degradation Detection During Active Power Cycling Using Phase-Delay Change of the On-State Voltage,” International Conference on Integrated Power Electronics Systems 2026, in press.