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Hybrid Vehicles = More Verification

In the design of anything that touches a hybrid electric vehicle, expect more verification requirements.

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While it is probably no surprise to anyone even slightly familiar with the complexity of hybrid electric vehicle systems, these designs require more intense verification than traditional combustion engine systems.

To fill out the picture, Mick Tegethoff, director, AMS product marketing at Mentor Graphics, reminded that verification is a very broad term. “Let’s say you are doing circuit simulation with SPICE on something that goes into a computer. You design it, you simulate it, you’re happy with your design, and you have to do some amount of verification/characterization to make sure this device will work across all operating conditions, all temperatures, all voltages.”

He paused here to stress that the amount of characterization is increasing across the board. “On one hand when you go to nanometer technologies, they’re doing more and more characterizations because they need to understand effects of the device noise, low voltage margins, variability on the ICs and so forth. When you look at these automotive chips, yes, there is a huge number of characterizations that go beyond the traditional issues of what are the corners, what are the voltages, what are the operating conditions.”

Tegethoff also stressed there is a significant verification challenge with mixed signal because automotive ICs, even though they are driving 400v, they’ve got regular, digital circuitry that’s interfacing with a microprocessor, and the engineering teams like to use standard microcontrollers. “Because of this, mixed signal verification is a huge deal to make sure that the digital and the analog will all be able to coexist by modeling the various temperatures, etc.”

Reliability is another huge area of concern that engineering teams are applying various verification technologies to because providers across the automotive ecosystem are under tremendous pressure to reduce failure rates. “Failure rates are measured in parts per million in the semiconductor industry, so if you have something that is 100PPM, you’re a hero. Now, they are talking about parts per billion failures,” he said.

The good news is that there are commercially available tools that can, for example, simulate the aging of circuits to look at the degradation on the transistors. How are they going to degrade after 10 years in a particular application?

Other technologies starting to be used more widely include electro-thermal simulation, as well as variability and sensitivity analysis, and statistical variation.

The key point is harsh environment, added Ahmed Eisawy, product marketing manager for the Eldo product line at Mentor Graphics. “You have more electronics in a harsh environment where it operates in temperature from -4 degrees C to about 175 degrees C — and this is the normal operating range, with spikes of temperature that go beyond 300 degrees C. When it comes to voltages, there is 5v for the microcontrollers that must communicate with the high voltage that could go to 800 or 1200v — the expression worst case scenario, it’s redefined. Also, everything for safety and security also goes through the roof, and you have to make sure the wireless network on your car doesn’t get hacked while you are operating in those harsh environments.”

Just understanding all of the new requirements in this fast growing market segment is quite an undertaking. It’s all part of the big picture as to how the increase in electronic content and the exciting new features in vehicles is impacting the lives of that consumers that will drive the vehicles, as well as the engineers designing these incredibly sophisticated systems.

The ride might be bumpy at times, but is sure to be a thrill!