2013 Ford C-MAX Energi (Ford)
Dearborn – — To make electric cars run farther and cost less, most attention by automakers has been on batteries. Ford Motor Co. has also been working on the power electronics box: Among other functions, it converts direct-current electricity from the battery to alternating-current electricity in order to power the electric motor.
“Power electronics is almost as expensive as batteries,” said Anand Sankaran, chief engineer and executive technical leader of energy storage and hybrid vehicle systems, in a recent roundtable discussion with reporters. “And the costs of both are coming down at similar rates.”
Sankaran declined to identify cost savings, citing confidential agreements with suppliers.
But even suppliers — including Johnson Controls, which makes battery cells but not power electronics boxes — agree that cost savings will need to be shared between the two components to make electric vehicles more affordable.
“It’s being worked on,” Brian Kesseler, president of Johnson Controls’ power solutions business, said in a recent interview about cost reductions for battery cells. “But the cell costs aren’t the whole story; it’s not the only answer” for cost savings.
Though the price of hybrids has come down in the past few years, it is difficult to pinpoint the true cost of hybridization because costs vary depending on the powertrain and how many battery cells are included in each battery pack, said Jim Hall, analyst at 2953 Analytics LLP.
Much of the industry focus has been on reducing size and cost of battery packs while increasing power and efficiency.
For instance, Ford has reduced the number of battery cells — which together comprise a battery pack — in its hybrid vehicles from more than 250 in the last production model of the Escape hybrid (discontinued in 2012) to just 76 in the new C-Max and Fusion hybrids.
But increasing efficiency of the battery is only part of the story: The power electronics box is responsible for transferring as much of the current as possible without wasting or losing energy. Ford’s most recent production-ready box transfers 93 percent of the energy.
“You want a box that is really efficient,” Sankaran said. “Otherwise in every process you’re losing energy.”