(Second teardown article in a series) for more info: http://www.driveforinnovation.com/teardown/powertrain-teardown/
By John Scott-Thomas, TechInsights
The Chevrolet Volt, GM’s entry in the electric car market, is one of the most complex vehicles on the road, using almost 100 microprocessors that are controlled by about 10 million lines of code. By comparison, a Boeing 787 Dreamliner gets by with only 6.5 million lines. One of the real wizards in the Volt is the Power Inverter Module. Sophisticated hardware and control systems sit in this breadbox-sized component. In this article we’ll take a look inside.
The Power Inverter is responsible for transferring power between the main battery pack, the gas engine, and the wheels of the vehicle. To understand why this is important we first need to appreciate the severe limits of the battery pack.
In a previous article, we looked at the Lithium Ion battery pack inside the Volt. The 435-pound battery stores 10 kiloWatt-hours of energy (the maximum capacity is actually 16 kW-h, but it uses only a fraction of this in order to extend the battery life), and can move the vehicle about 35 miles on a full charge. In contrast, a single gallon of gas has about 36.6 kW-h of energy and can move a car about the same distance.
From this comparison two things follow: gas engines are terribly inefficient, and battery packs are, even today, poor reservoirs of energy. We can make a rough equivalence; the 435 pound Volt battery pack is about the same as a gallon of gas weighing only 6 pounds.