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The challenges of electric vehicle chargers

Wed, 07/18/2012 - 12:08pm
Kasey Panetta, Associate Editor

Charging stations for electric vehicles are still a few years, possibly decades, away from being in every household garage—priced at upwards of $20,000 per unit. Talk about keeping up with the Jones'! Despite the challenges of price point, materials, and a general public skepticism, companies are making great strides in designing chargers that are more durable, efficient, functional, and versatile than their predecessors.

A major part of the design process for the electric vehicle charger (EVC) is figuring out what consumers want from a charger. For the major players like General Electric (the WattStation), ABB Inc (The Terra51), and ITT (EVC Charger), the answers were simple: smart, efficient, easy-to-use, easy-to-maintain, utilizes new technology, and, obviously, sleek-looking. A tall order from a demanding, busy audience, that’s not entirely sold on the idea of electric cars in the first place. Engineers from every company realized they needed to create an interactive, simple, well-designed EVC to satisfy consumers.

Make the time count
In the age of the instantaneous, one of the challenges of EVCs is the constant pressure to reduce the amount of time it takes to charge a vehicle. If the charging process takes too long, people might be unwilling to try it, as it represents a fairly large inconvenience to the driving process. No one wants to have to stop every 75 miles on road trips to charge their Nissan Leaf for an hour.

The companies took different approaches to reducing charging time. For the Terra51, designed by ABB, designers utilized a DC fast charger in place of a traditional AC charger, inputting three phase 480V or 208V grid power and producing up to 500V and 125A of DC power, says Cal Lankton, Director of EV Charging Infrastructure for North America at ABB. Because the energy isn’t routed through the onboard converter used in AC chargers, the DC fast charger delivers more power, up to 50kW to the AC’s 3.3kW. This means that a Leaf could be fully charged in about 30 minutes, according to the company.

ITT, which designs only the connector for EVCs rather than the entire charging station, has created a connector that delivers a 75A charge, allowing a charging time that is 2.5 times faster than connectors offering a 30A equivalent, says Ted Worroll, Global Product Manager at ITT.

Wise design
As with any product, there were challenges when it came to design. The EVC had to withstand harsh environments, maintain quality over long periods of time, and conform to specific ergonomic standards. Plus, it had to be versatile enough to satisfy standards and requirements for varied locations and multiple international zip codes. Because the engineers aren’t designing chargers to go in the cars, they’re not plagued by the same issues involved in electrical power management in the automotive sector, but safety must be a focus.

Utilizing their expertise and experience in electrical infrastructure, General Electric tackled the durability issue by creating the WattStation, made from an aluminum body and plastic top to prevent corrosion. The EVC earned a NEMA 3R rating, so it’s resistant to dirt, dust, rain, or sleet and won’t be affected by ice on the body. The designers at GE chose to focus much of their design on an efficient cord-management system: self-cleaning, self-contained cord that retracts—only when disconnected from the car—to avoid unnecessary damage.
The Terra51 from ABB’s team used a cross-disciplinary approach and made longevity a priority, producing a station designed to last for 10 years in harsh environments. The body is made of stainless steel to prevent corrosion, and the inner workings of the Terra51 are high-end internal components. Plus, the charger is designed to CHAdeMO specification, and future versions will incorporate the SAE J1772 standard, so it’s efficient, but up to industry codes.

With the matters of safety and design comes the issue of ergonomics, which ITT tackled with their EVC series. The system utilizes Louver Band technology designed for a minimum of 10,000 cycles and meets the UL50 Type 3R/#S sealing for weather protection. Plus, it contains monitoring systems for voltage, current, and heat and sensors to disengage the drive function while the car is plugged in. For the 2nd generation connector, designers utilized consumer feedback to create a more comfortable, ergonomic handle with no screws and a new locking latch system. The handle is made from thermal plastic with a high UV resistance and advanced plastic color particles to keep the connector looking clean and functioning well.

Getting smarter
The EVC technology, already under much scrutiny by a skeptical public, had to go above and beyond a typical product on the market. It presented a unique challenge to companies, requiring creative, dynamic thinking to design a product that was sleek, incredibly convenient, and simple. Consumers would most likely ignore any breakthroughs that made the charger complicated or not intuitive.

In a world where smartphones are a way of life, the EV chargers needed a way to utilize the opportunities afforded by a technology to which consumers have constant access. For GE and the WattStation, that meant creating the WattStation Connect app, which allows drivers of electric vehicles to locate the nearest charging station through their phone, says Seth Cutler, Product Manager, EV Infrastructure for GE Energy’s Industrial Solutions business. Additionally, the app offers driving directions to the EVC, information on pricing, and can also let the driver know if anybody is currently using the station. While the car is charging, the owner can check on the status of the charge and utilize the app for easy payment options. The WattStation connect app will be available for iPhones and Android phones. GE is currently testing a system that would allow the drivers to control the amount of current a vehicle can draw from the charger.

In addition to focusing on consumer technology, some of the companies took advantage of the Smart Grid, particularly ABB. “The Terra51 is able to dynamically control its output based on pre-defined user inputs, allowing the operator to minimize their impact on the grid during times of high demand or peak power prices,” says Lankton. The system is able to communicate with third-party smart-grid applications, enabling functions like Demand Response and Distribution System Management. Plus, they’ve designed a system that allows the owner—i.e., retailers, commercial businesses, governments, and restaurants—to monitor the system remotely.

Look to the future
A team from the Toyohashi University of Technology in Japan, led by Takashi Ohira, has been working on a charger that lives in the roadways, charging cars as they drive over the wireless-power transmission technologies. The team recently demonstrated the ability to transmit 50 to 60 watts of energy through concrete to the wheels of a car. It’s not ready just yet—drivers would need about 100 times that amount to power a car—but the team is confident this will be the road of the future. Considering the upfront cost of redesigning infrastructure to accommodate the technology, it may not be right around the corner. It’s possible that, by that point, it will just be cheaper to buy a personal charger. 

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