Here Comes Electric Propulsion

June 1, 2012
In addition to new vehicle introductions, improvements in battery technologies, the charging infrastructure, and recharging requirements may charge up the electric and plug-in electric vehicle market.

The Nissan Leaf and Chevy Volt promised to change the electric automobile landscape (Fig. 1). But so far, the market response has been underwhelming. In addition, the delay of the Fisker Karma and its battery failure at Consumer Reports as well as the demise of startup electric vehicle (EV) and plug-in electric vehicle (PEV) automakers Aptera and Bright Automotive may have prolonged the life of gas-guzzling dinosaurs (Fig. 2).

1. The Nissan Leaf (a) and Chevy Volt (b) have hit the showrooms, but sales have been disappointing, leaving many critics wondering if the EV and PEV market is more hype than reality.
2. With its six-figure pricetag, the Fisker Karma will intimidate many consumers. But a poor showing during a Consumer Reports evaluation didn’t help either.

In contrast, the impact of a new Toyota Prius model and a PEV version as well as pending introductions of more EVs, PEVs, and hybrid electric vehicles (HEVs) promise a more fuel-efficient future for the automotive marketplace (Fig. 3). However, acceptance is taking longer than predicted.

3. Toyota’s Prius dominates the hybrid market, and the company hopes for similar success with its new plug-in model.

Led by the Prius, HEVs typically use nickel-metal-hydride (NiMH) batteries and dominate the partial electric propulsion models. This classification avoids three of the major issues that confront EVs and PEVs: the very high cost of lithium-ion (Li-ion) batteries, the need for a charging infrastructure, and the disruptive, constant charging requirements. Yet three developments in these areas may excite and entice potential EV and PEV buyers.

Battery Background

Recent battery failures of the Chevy Volt during testing (resulting in fires) and the Fisker Karma during evaluation by Consumer Reports (resulting in an inoperable vehicle) may have had a serious negative impact on buyers’ attitudes towards EVs and plug-in hybrid electric vehicles (PHEVs). But Sony’s Li-ion battery failures (which included in-service explosions) in cell phones in 2006 and recall of almost 10 million batteries did not deter the acceptance of smart phones, netbooks, tablet PCs, and other portable products.

For EVs and PEVs, the improved efficiency and the lower cost of vehicles powered by internal combustion are frequently cited as the reason for their lack of consumer acceptance. A lack of understanding of EVs and PEVs also seems to have an important role.

While some potential buyers may be deterred by battery failures and explosions in crash-tested vehicles, they are not considering the far greater threat of gasoline. A century ago, the energy stored in a full tank of gasoline and its potential for an explosion initially deterred buyers as well, with steam and electric vehicles benefitting from the situation.   

However, gasoline’s explosive capability became a non-issue even though incidents continue to occur. The perception versus reality is certainly a concern for the acceptance of EVs and PEVs, but not a technology issue. With gasoline prices at record highs topping $4.00 a gallon, running on electricity should offer an excellent alternative, but the payback is not there yet for most drivers.

Cost is not the only problem that EVs and PEVs face, but it appears to be the overriding concern for buyers. It has been identified as a major shortcoming that carmakers must solve. Ford Motor Company CEO Alan Mulally put the battery cost in perspective recently. He noted that an EV battery can cost up to $15,000, compared with $6000 for a hybrid or $8000 for a PEV battery pack. (Referencing information from the Green Car Journal, Consumer Reports had previously stated that the Volt’s battery cost was $8000 or more and the Leaf’s was about $18,000.) Battery cost is certainly a technology challenge facing the industry and its battery suppliers.

In a keynote presentation at Design West, Tesla Motors’ J.B. Straubel noted that while there is no Moore’s Law equivalent for batteries, there is a steady improvement (Fig. 4). “It is somewhere in the range of 7% to 8% improvement in energy density every year,” he says. “If you wait 10 years, you get a doubling and that’s a pretty compelling change.” With a doubling in capability, Straubel notes that designers can use less battery for the same range or the same size battery and double the range.

4. Battery improvements have made slow but steady progress, doubling energy density every 10 years. (courtesy of Panasonic)

Outside of somewhat predictable improvements, other circumstances may decrease battery prices. Bloomberg New Energy Finance, a London-based research company, says the average price of Li-ion battery packs for electric vehicles fell 14% in the past year. Citing excess production capacity as the reason, the batteries cost $689 a kilowatt-hour in the first quarter of 2012, compared with $800 a year earlier (see the table).

Battery Breakthroughs

Competition in a low-demand market is one way to achieve a price reduction, but a more sustainable situation occurs with technology breakthroughs. Working with partners form the U.S. Department of Energy (DOE), ARPA-E, General Motors, Asahi Glass, and Asahi Kasei, Envia Systems has announced a record energy density between 378 and 418 Wh/kg for a 45-Ah cell. Testing to support the claim was conducted at the Naval Surface Warfare Center.

Lux Research has ranked the relatively unknown startup high in technology value in the Li-ion battery area. Based on its intellectual property (IP) and technology licensed from Argonne National Laboratory, Envia expects its battery technology to reduce the cost of the battery pack for a 300-mile EV by 50% to $125/kWh (Fig. 5). Envia Systems does not currently supply batteries for production vehicles.

5. Several technologies contribute to Envia Systems 400 Wh/kg battery. The Si-C anode, HCMR cathode, and EHV electrolyte are Envia’s proprietary contributions to the design.

Companies that have successfully launched Li-ion batteries for EVs and PEVs are not idly waiting for others to advance the technology. “Cost reduction is a key focus for A123 and the industry at large, and we anticipate that a steady stream of technology breakthroughs will contribute to lower costs,” says Jeff Kessen, director of global marketing, Automotive Solutions Group, A123 Systems.  

Kessen does not think it is realistic to expect a near-term doubling of energy density in solutions that meet automotive requirements. “The most significant advancements are likely to be improvements on battery technologies that have already proven their commercial viability, such as A123’s proprietary Nanophosphate lithium-iron-phosphate battery chemistry,” he says.

Panasonic supplies batteries to Tesla and Toyota for the Prius plug-in hybrid and RAV4 through Tesla (Fig. 6). Nikkei has reported that in 2012, Panasonic would produce Li-ion batteries that use a silicon-alloy anode. The improvement would deliver a 30% increase in capacity (Fig. 7). The 18650 cells, the same ones in the Tesla Roadster, are slightly heavier. There would be a weight penalty, then, but the cells appear to eventually target automotive applications.

6. Panasonic provides the batteries for Toyota’s RAV4-EV, which it developed in conjunction with Tesla Motors.
7. The use of silicon-alloy anode material will break the established trend line of 11% improvement annually. (courtesy of Panasonic)

Charging Solutions

After the initial shock of the added cost of EVs and PEVs, the next deterrent for purchasing one of these vehicles is the charging requirements. As noted in the table, charging a fully depleted battery can take several hours, especially at 120 V ac (SAE Level 1) and 240 V ac (SAE Level 2). Fast charging dramatically reduces the charge time. Using 480 V, an EV can be recharged in 30 minutes or less, as indicated in the Nissan Leaf’s 480-V dc charge time.  The SAE Level 1 and Level 2 charging standard (SAE J1772) defines the accepted connector for North American EVs.

If there wasn’t enough confusion for potential buyers, the type of plug to use for fast dc charging EVs and PEVs is currently divided into at least two camps (Fig. 8). On one side are supporters of the Level 3 charger that the SAE committee expects to finalize in July or August 2012. Supporters include Audi, BMW, Chrysler, Daimler, Ford, General Motors, Porsche, and Volkswagen. On the other side, Japanese carmakers, Tokyo Electric Power, and other Japanese technology companies developed the CHAdeMO (Charge de Move) connector and protocol.

8. The SAE Level 3 (a) and CHAdeMO (b) 480-V dc connectors have different configurations, meaning designers typically must choose one or the other.

The SAE plug uses a single connection for Level 2 (240 V ac) and Level 3 (480 V dc). CHAdeMO requires a separate connector. The Nissan Leaf uses the CHAdeMO connection, and charging stations have been deployed to handle it. However, there are not many charging stations, especially outside of target cities where EVs and PEVs have been initially introduced.

The West Coast Electric Highway, Interstate 5 from Oregon to California, is the first effort to overcome this EV obstacle based on cooperation between Oregon, Washington, and California. Eight stations have been installed so far in a 180-mile stretch, spaced 20 to 25 miles apart, to provide a convenient means for charging EVs and even PEVs when drivers want to avoid or minimize using the internal combustion engine.

Based on Nissan’s involvement with the project, the newly installed stations have Level 3 CHAdeMO chargers provided by AeroVironment with Level 2 backup capability (Fig. 9a). When completed, the West Coast Electric Highway will have stations for 550 miles from the Canadian border to the Mexican border.

9. AeroVironment’s fast dc charger has the CHAdeMO connection (a). Eaton’s charger will support SAE Level 2 and 3 connections (b).

One company plans to cross the country with charging stations. On Earth Day, April 21, GoE3 announced the launching of the nation’s first coast-to-coast charging station network for EVs. Unlike metropolitan Level 2 charging stations that in many cases only provide 30 A at 240 V, the Level 2 GOe3 network will have 70-A or higher capability. That level is certainly helpful to Tesla Roadster and Model S owners.

Starting with implementation in Arizona, its home state, GoE3 will install the higher-current Level 2 and Level 3 chargers in stations every 50 to 75 miles along the I-17 to I-10 route between Flagstaff and Tucson. Ultimately, the company plans to install a total of 500 charging stations within the next 18 to 36 months.

A full Level 3 charge will cost $12.50 and take 10 to 45 minutes, depending on the battery’s state of charge. Bringing a cool factor to EVs, the initial installations will occur in conjunction with a road rally and reality TV show being produced this summer.

GoE3 founder Bruce Brimacombe engaged Eaton to provide a modular design for the charging system (Fig. 9b). This prevents the major disruption that will occur for charging stations dedicated to one approach, if the alternative ultimately wins. GoE3’s modular design is much simpler. “We open the door, pull out one drawer, and put in another,” Brimacombe says.

Brimacombe identified a revenue stream from carmakers and local business sponsors as well as Web-based advertising. Other involved parties indicate that the project should have sufficient financial justification to succeed despite low income from the Level 2 and 3 charging in 2012 and 2013.

Autonomous Charging

Today, charging an EV or PEV at home is still a significant departure from established vehicle usage. The hassle of continually plugging and unplugging to recharge the battery may be another detraction. John M. Miller, distinguished R&D staff, National Transportation Research Center, Energy and Transportation Science Division of Oak Ridge National Laboratory (ORNL), thinks simplifying the charging process to make it autonomous and essentially transparent will provide another level of satisfaction to EV and PEV owners.

“The approach I have taken at Oak Ridge National Lab is to absolutely minimize what a manufacturer has to add to a car,” he says. The system’s complexity is on its grid side. The ORNL wireless power transfer (WPT) design uses a light compact secondary coil in the vehicle operating at a single fixed frequency of 20 kHz (Fig. 10a).

10. Oak Ridge National Laboratory’s wireless charger design meets international standards and addresses safety issues including fault management (a). Delphi has demonstrated its wireless charger at several recent automotive events (b).

The WPT is integrated into the chassis floor pan with a direct connection to the vehicle’s regenerative energy storage system. In addition to the coil and a few other components for power transfer, the vehicle communicates with a base unit in the external loop. Miller says the magnetic resonance coupling using an 800-mm diameter coil for charging at 7 kW (SAE Level 2) has been demonstrated at over 200 mm of nominal ground clearance.

In addition to stationary charging, Miller also sees the possibility of dynamic charging in a burst mode. The power level would be in the 100-kW range. However, many challenges exist to implementing such a scheme. In the near term, SAE’s J2954 Wireless Charging Task Force is pursuing the standards aspect of wireless charging.

As the establishment of an SAE committee might indicate, the interest in wireless charging for EVs and PEVs goes beyond the national laboratory. At the 2012 SAE Congress, Delphi demonstrated a Nissan Leaf with wireless charging (Fig. 10b). The Level 2 wireless system delivered 3.3 kW with 90% energy transfer efficiency for the ac-dc conversion. The system can operate with air gaps up to 30 cm depending on the size of the coil that it uses.

Government Requirements

Legislation and regulations in the U.S. and Europe continue to count on the success of electric propulsion. The U.S. emissions standard for cars is equivalent to 70 to 80 g/km by 2025, and the European Union’s target of 70 g/km, which is suggested for 2025, cannot be achieved with traditional internal combustion engines.

The U.S. goal of 1 million EVs on the road by 2015 is supported by tax credits for purchasing EVs that range from $2500 to $7500 depending on the size of the battery. In addition to federal justification, several other states are embracing California’s zero-emissions mandates. At the low end of the battery capacity, an EV purchaser in California could obtain $4000 worth of government-supported consumer incentives: a $2500 federal tax credit and $1500 from the State of California’s Clean Vehicle Rebate Program.

In the near term, these incentive programs will help buyers justify the purchase of a vehicle in spite of the long payback for the increased cost compared to a vehicle powered by internal combustion. For luxury vehicles, payback is not an issue. As a result, Fisker launched its Karma Sedan in December 2011 and soon surpassed BMW, Mercedes, and Audi to become the second highest-selling brand in the Dutch luxury vehicle segment for high-end four-door models based on sales in the first quarter of 2012. It appears that cool PEVs and EVs can cut into established vehicle sales even at today’s price premiums.

Driving Forward

While the torque of EVs and speed from 0 to 60 mph can be impressive, mainstream buyer attraction has yet to be established. However, the need to replace vehicles powered by fossil fuels will ultimately drive EVs and PEVs into a more favorable position. This has CEOs exuding high confidence in electric propulsion.

In his keynote address at the 2012 New York International Auto Show in April, Nissan CEO Carlos Ghosn repeated his prediction that pure electric cars will capture 10% of the market by 2020 wherever they are available. He certainly is not alone in his enthusiasm. Ford’s Mulally expects that hybrids, PEVs, and EVs may represent as much as 25% of Ford’s new vehicles by 2020 with the lion’s share going to hybrids.

As the major EV and PEV stumbling blocks get resolved, buyers may soon have the same confidence as carmakers’ CEOs. With all the investment occurring in batteries, Ghosn concludes, “The life of the battery is going to be longer than the life of the car.” When that’s true, the EV will have arrived.

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