Software tools make automotive control-system design engineers 'greener' and faster: Part 2 - Transitioning from oil with plug-in hybrids and hydrogen fueled vehicles

While wringing the most out of the traditional IC engine will provide a notable reduction in oil dependency and carbon emissions across millions of vehicles, the core problem still remains: Such power trains need oil to operate. To truly attack the problem at its core, alternative fuel vehicles are needed.

One of the limiting factors of the first generation of electric vehicles was the battery technology available. Hybrid vehicles have stepped in as an ideal transition technology to allow smaller, more modest electric drivetrains to enter production while maintaining consumer-desirable features and providing a platform that can take advantage of incremental battery improvements. First-generation hybrids such as the Toyota Prius (here's a "teardown" of the hybrid car's technology) have been following this path, with newer Prius prototypes demonstrating larger battery capacities and plug-in capabilities.

Plug-in hybrids—control is critical
While battery technology is the high-profile enabler of hybrid vehicles, advanced measurement and control once again plays a critical part in the efficiency of these vehicles. With a system that now has multiple outputs including the combustion engine, electric motor, and various transmission configurations; multiple inputs such as vehicle speed, driver input, and battery charge; and multiple requirements such as maintaining the battery state of charge and optimizing fuel efficiency and performance, system control has great impact on the final overall efficiency of the power train.

The high-voltage batteries found in today's current hybrids as well as future plug-in hybrids and electric vehicles present significant control challenges. Accurately monitoring the state of a battery charge is a difficult task that requires higher-end measurements and control to prevent excessive charging or discharging. Poorly controlled batteries can suffer from shortened lifetimes or, in extreme cases, completely fail.

High-power batteries can consist of hundreds of individual cells, all of which need to be individually measured for voltage and temperature to identify potential problems. To respond to these applications, measurement companies have released portable high-voltage, high-resolution, isolated measurement modules capable of reading the small incremental voltages found in these packs.