Electric Cars Get Boost from New Test System

Known as the MicReD Power Tester 600A, the new product can test large numbers of devices and can be coupled with computational fluid dynamics (CFD) simulation software. By doing so, it provides more data and more accurate lifetime estimates, while operating in an automated fashion. “It’s a highly scalable and automated solution for something that was previously done manually,” John Parry, electronics industry manager for Mentor Graphics’ Mechanical Analysis Division, told Design News. “A lot of the interaction between the operator and the equipment is now in the software.”

Coupled with CFD software, Mentor Graphics’ MicReD Power Tester 600A can provide lifetime estimates for the power electronics used in EV powertrains.

The new technology could be particularly important for insulated gate bipolar transistors (IGBTs), which are commonly used in the drive electronics of electric cars and hybrids. In those vehicle applications, IGBTs can go through millions, or even tens of millions of on-off cycles, making reliability a key issue. The high number of cycles, in tandem with thermal changes, can potentially cause wire bond degradation and metallization damage to the devices. Ultimately, such failures can potentially lead to vehicle recalls.

”As hybrids and electric vehicles become a greater part of the market, we expect to see some recall issues,” Parry told us. “Clearly, that’s something that car manufacturers are keen to avoid.”

The new power testers can be chained together in groups of eight to allow users to power-cycle up to 128 IGBTs simultaneously.

Mentor Graphics’ engineers say the new technology will help automakers prevent those issues. The 600A does that through three key features. First, it yields real-time “failure-in-progress” data for IGBT under test, recording such parameters as electrical current, voltage and die temperature. That enables engineers to know, not only that a part failed, but how it failed. Second, it couples with Mentor’s FloTHERM and FloEFD 3D CFD software, which works with the tester to generate IGBT lifetime failure estimates. Third, the new power testers can be chained together to allow users to power-cycle up to 128 IGBTs simultaneously.

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”By being a scalable solution, it can provide more data on which to base the lifetime estimates,” Parry said. “You need a certain amount of statistical data in order to calculate, with any degree of accuracy, the number of cycles to failure.”

Mentor Graphics engineers said the comprehensive hardware/software solution constitutes an improvement for power electronics suppliers on two fronts. The automated system minimizes test time and provides real-time insight into failure mechanisms. In the past, they said, companies tested parts to failure and then struggled to understand the failure mechanisms of the “dead” parts.

"This represents a huge improvement in the quality of the results,” said Zoltan Sarkany, product specialist at Mentor Graphics. “And accordingly, it’s a huge improvement in the accuracy of the lifetime estimates.”

[images via Mentor Graphics]

Senior technical editor Chuck Murray has been writing about technology for 32 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and autos.