When they enter production in the 2012-2013 timeframe, Azure Dynamics’ next-generation hybrid and electric propulsion systems will feature new approaches to battery cooling, power control, e-motor design, and systems engineering. The changes are aimed at further reducing the bill of materials and overall cost of the electrified powertrain, as well as improving performance.
“All the programs we’re doing this year basically are engineering programs in which we’re engineering cost out of the system,” said company CEO Scott Harrison. “We’re taking 40% cost out of our Balance hybrid system, but we’re also working on future component and systems designs that will provide greater customer benefits as well as lower cost.”
Azure Dynamics (AZD) currently upfits the Balance hybrid architecture on Ford’s F-450 chassis for a growing list of Class 3-5 commercial fleets including FedEx, Purolator Courier, and AT&T. AZD also is supplying its Force Drive battery-electric drivetrain for Ford’s 2011 Transit Connect EV.
The Force Drive is claimed to provide 80 miles (129 km) electric range per full charge. It features a Siemens drive motor and a new lithium-ion battery pack supplied by JCI-Saft, which in early June took a 3.4% equity stake in AZD. AZD is handling the program’s vehicle integration. Beginning this fall, it will install the electric drivetrain into Transit Connect gliders at a leased AM General facility in Livonia, MI.
New motors and controllers
In an interview with AEI at AZD’s U.S. headquarters near Detroit, Engineering Director Jim Mancuso outlined technical opportunities to improve system efficiency and reduce cost.
“We’re probably in Generation 2 in terms of our current technologies; Gen 3 is about two to 2.5 years away,” he said. “We’re moving to common parts and systems across platforms. Every vehicle we build uses a vehicle control unit (VCU) that is common to an ECM on gasoline-engined vehicles. The technology comes from a partnership we formed with the supplier back in 2004, and the volume has risen to the point where we now see some cost reduction.”
He noted the light-duty Force Drive system uses the same controller hardware as used in AZD’s medium-duty Balance hybrid. Also common among the two platforms are the DC-DC inverters, which are calibrated and wired differently for the vehicle application.
The Siemens motor on the Transit Connect EV is the identical electric machine AZD previously used on a series-type hybrid product.
“It’s all about working with our suppliers to ensure the individual components we’re developing are not going to be used only for an individual product; they’re going to be used across the board on multiple products,” Mancuso said.
“In the case of this particular motor we invested a lot of time in understanding its capabilities within our system. Using it reduces our risk immensely—and reduces the time for our engineering team to integrate it. I’d say we’re pretty good at standardizing hardware,” he asserted.
The Transit Connect EV is AZD’s first series production foray into light-duty systems. Harrison said that while the company’s focus remains on the medium-duty segment, all future product is being developed to cover a broad span of vehicle sizes and applications, in order to build scale.
“That goes for controllers and electric motors,” Mancuso explained. “The next-gen controller will feature newer IGBT (insulated-gate bipolar transistor) technology. It will be physically smaller. In motors, there’s a general trend toward permanent-magnet AC machines and we’ll be there, too.”
The company’s design engineers based in Vancouver and software designers based near Boston are working closely on motor development because the machine’s characteristics impact so much on the control side. Mancuso said AZD is “looking at some new ways to control DC-DC inverters via CAN.”
A clutched FEAD and fast charging
AZD’s incumbent battery pack is liquid-cooled, and company engineers have debated the superiority of both types. Currently they are investigating air cooling because some key suppliers are working on new approaches to air-cooled packs that are expected to be ready “in the next three to four years,” Mancuso said.
He indicated the new air-cooled designs would be integrated with the vehicle’s climate-control system or perhaps use cooling fans.
AZD’s switch to lithium-ion battery cells from the nickel-metal hydride currently used will bring a significant portion of the 40% systems-cost reduction they expect to achieve in the next year, Harrison concedes. But another new feature that Mancuso claims is an “industry first” has him excited about its potential to impact cross-vehicle efficiencies.
The new version of the Balance product adds a clutched front-end accessory drive (FEAD) system, which enables the belt-driven power steering pump, A/C compressor, etc., to be coupled and decoupled alternatively from the electric motor and combustion engine, depending on the vehicle’s drive mode.
“There was a lot of mechanical engineering that went into this system to make it robust; we erred on the ‘high side’ of robustness,” Mancuso explained. “The clutch is a heavy-duty design that we developed with a supplier.”
Without providing specifics, he said adopting the clutched FEAD opens the door for various cost reduction opportunities elsewhere in the vehicle.
Higher system voltage and fast charging are other technology areas Mancuso said AZD is investigating for the next-gen powertrains. He recalled his learnings from an early AZD vehicle built for Purolator that featured a 600-V system.
“I was responsible for that program, and I still can’t believe how the performance increased when we added a ‘boost leg’—an inverter and motor control that raised our voltage from 300 V to 600 V but added very little hardware,” he said. “We’re doing a lot of research on a similar arrangement but not yet committed to it.”
The issue of fast charging in EVs and plug-in hybrids is getting a lot of attention in the industry, but AZD’s customers aren’t yet requesting it, Mancuso noted. “They tell me it’s not yet a necessity for them, but I think two to three years down the road our next generation’s products will have to have that capability. Our battery supplier will have to design around that, and they’re talking about 480 V.”