Henry Ford knew, as he said back in 1923, that “saving even a few pounds of vehicle weight . . . could mean that they would also go faster and consume less fuel.” That perennial wisdom is the reason that lithium battery chemistries, with their higher specific energy (joules/kg), are leading the way toward the next generation of weight-efficient, plug-in electric vehicles. But images of exploding lithium-ion laptop battery are still vivid in our memories and are amplified when we consider the far greater total energy of an electric vehicle battery. That concern and others have given rise to an evolution in highly intelligent battery management systems (BMSes) that communicate with high-power battery charging systems to address such concerns as safety, cost, battery longevity, vehicle range (aka range anxiety) and overnight charging—all painful concessions for the promise of lower carbon emissions and higher fuel economy.

As automotive OEMs define their requirements for next-generation battery management and charging systems, semiconductor companies are advancing products that anticipate those needs.ÿThis article investigates the design requirements, architecture and challenges associated with the development of a high-power (>3-kW), off-line battery charger for automotive plug-in hybrid electric vehicles (PHEVs) and demonstrates why digital power architectures are being created for such applications.