Name: Pamela Fletcher
Title: GM’s Global Chief Engineer for Volt and Plug-In Hybrid Electric Powertrains
Location: Milford Proving Grounds, Michigan
GM developed the Volt in only 29 months. Its lithium-ion battery powers the car for the first 25 to 50 miles, at which point a small gasoline engine kicks in to replenish the battery, allowing the car to travel up to another 300 miles. What were some of your biggest engineering challenges? One was the question of how to integrate the combustion engine with the generator when the car is in its extended-range mode. We wanted the “character” of the car to be as consistent as possible between electric and extended-range operation [when the battery runs down]. To do that, we created a “load-following behavior” for the engine: as power is drawn from the battery, the engine comes in to make up that power. This lets us lead with the battery, and gives the Volt some “EV-ness,” even in range extension.
At the same time, we wanted the engine to respond in a manner that drivers would expect. The Volt’s engine does not have to behave like an engine in a conventional vehicle; its speed does not have to follow the vehicle speed or the throttle directly. So we added some audible cues to assure the driver that the engine “hears” the commands that the driver is giving, such as reducing the speed or load slightly when the driver backs out of the throttle.
Other than having no tailpipe, the Volt looks like many other sedans. Why didn’t GM give the car an edgier design? I have found that people like the fact that this car has a sportiness to it without being overly aggressive. You can be green without driving a spaceship.
The EPA recently classified the Volt as a plug-in hybrid electric vehicle and not as an electric car. What is your reaction to that? Anytime you’re first, those are the kinds of issues that come up. I see the Volt as an electric car with extended range. No kidding—you can have the full performance of the car without the engine ever coming on. These blended plug-ins that are being talked about don’t do that.
What led you to this career path? My dad raced all kinds of cars as a hobby, and I had no brothers. I was the older of two girls, so I was the one who always got corralled into working on the cars and going to the track. After a while, you get addicted to the adrenaline. Not only do you get addicted to the styling, you can also get addicted to the scale and the scope of the industry. I learned to love cars, and I think cars are the greatest consumer product.
This article was originally published with the title Practically Green.