When a conventional vehicle needs fuel, the driver stops at a service station, fills up and drives away. Being used to an infrastructure of service stations, he never really questions the range of his vehicle.
Charging an EV is a different story altogether. Most drivers don’t consciously know how far they need to drive on an average day. Studies have shown that 80 % of drivers don’t drive more than 80 kilometres each day. Despite that, consumers want their EVs to offer them a range similar to traditional automobiles.
Since public charging infrastructures for EVs are still in their infancy and battery performance and charging times also have issues (see article in this edition of e-tech), range anxiety could become a major adoption hurdle in some countries. The same may not be true in public and commercial electrified transportation.
Extending the range of BEVs
Speaking at the recent Geneva International Motor Show during the Fully Networked Car conference co-organized by the IEC, Pierre Malaterre of 4Icom talked about extending the range of BEVs (battery electric vehicles). "Although they are being improved constantly," he said, "the performance and cost of batteries remain the main obstacles to the widespread adoption of BEVs."
According to Malaterre, Lotus estimates that a battery-powered EV would need more than 127 kWh of battery capacity to achieve a range of 500 kilometres. This would translate into a weight of around 1 300 kg (the same as that of the base vehicle) and a cost of USD 76 000, based on USD 600/kWh.
In comparison, the REV (range extender for electric vehicle) unit that Lotus is developing weighs a mere 58 kg. Adding more batteries to extend the range of EVs eventually becomes unproductive since at some point it is necessary to add more batteries to power the extra weight of the extra batteries that extend the range.
"One thing is certain, we are entering the era of the Electrical Vehicle. Some of our biggest problems are the behaviour of batteries, safety, performance, the charging process…" said Malaterre.
Underlining how various International Standards already exist for dealing with conductive charging systems, secondary batteries for the propulsion of EVs and plugs, socket-outlets and so on, Malaterre underlined the importance of the charging process itself.
"It is obvious that the charging process has to be standardized,” he said. “Everyone must be able to recharge the battery of his car, anywhere and independently of what car brand he has. Different lobbies think that they have the right solution: electricity furnishers, service providers, electrical vehicle manufacturers…. Governments too want a universal infrastructure solution, and as soon as possible."
Malaterre believes that weight and cost constraints mean that HEVs (hybrid electric vehicles), PHEVs (plug-in hybrid vehicles) and REVs are likely to dominate the EV market for the foreseeable future.
Heavier the more range
The Rolls Royce's Phantom EE (Experimental Electric) on display at the 2011 Geneva International Motor Show is reportedly able to travel about 200 km on a single charge that it obtains from a 338 volt, 71 kWh unit. The battery comprises 96 induction-charged cells —said to be the biggest battery pack ever fitted to a car. The car's NCM (Lithium-Nickel-Cobalt-Manganese-Oxide) battery holds around 230 Wh/kg, a high-energy density necessary to provide an acceptable range between recharges. Delivered on an effortless wave of torque, it can reach 96 km/h (60mph) in under eight seconds (compared to 5.7 seconds in a standard Phantom), and has a top speed of 160km/h (100 mph).
Contactless induction charging
Because of the concern about the lack of available recharging points in towns and cities and criticism of cables left trailing between power sources and vehicles, Rolls Royce has come up with what it sees as a potential convenience solution. The Phantom EE is testing contactless induction charging, which it feels will help provide a network of remote charging facilities.
"There are two main elements to induction charging: a transfer pad on the ground that delivers power from a mains source and an induction pad mounted under the car, beneath Phantom EE’s battery pack," says a Rolls Royce spokesman. "Power frequencies are magnetically coupled across these power-transfer pads."
The same but in urban transport
Another company that has used this induction technology in an industrial context is Numexia. The Numexia prototype electric van is equipped with a contact-free energy-transfer system.
"With this technology, the vehicle batteries can be quickly recharged by electromagnetic induction, without having to resort to plugging in," said Jean-Marie Van Appelghem, Chairman and CEO.
With a speed of up to 100 km/h (64 mph), the prototype can be run either in fully electric mode, or as a hybrid vehicle using an APU (auxiliary power unit), in this case an auxiliary 33 kw diesel engine that transforms thermal energy into electricity. The BMS (battery management system) uses four Li Fe PO (lithium iron phosphate) batteries. They can be fully charged in 30 minutes.
Alternative driverless EV projects
The City of Lausanne in Switzerland has an automated driverless electric tram system that has been running since October 2008. On average, the tram transports 25 million passengers every year. Lausanne also developed an alternative transport project, the Serpentine which is basically an electric "taxi" service that runs without a driver along an underground magnetic rail that is imbedded beneath the surface of the road. The solution is cost-efficient both in terms of energy use and number of employees needed. In conventional public transport, the ratio of employees per 100 passengers is 4.25. Concerning the Serpentine, that ratio drops to 1.6. In terms of electricity, on average, the Serpentine was calculated to use only 251 W per day of use. In addition to supplying the vehicle with electricity to power the motor, the electricity also creates a magnetic field that guides the Serpentine along its path.
Vincent Bourquin, inventor of the Serpentine, believes that the automated low-speed EV is part of the future solution for urban public transport. "A vehicle need only travel at around 15 km/h in a city," he says. "At that speed there is little danger to nearby people on foot, and if you equip vehicles with sensors then you can automatically detect the presence of others. With small electrified vehicles you can run a low-cost public service that is ecologically friendly, stops frequently and is quiet."
Induction charging EVs for cargo ships
Another area of commercial transportation that has expanded into electric motors is the port.
The logistics involved in container port management are huge. In recent years ports have become increasingly technical and adopted new automated portal systems to become more energy-efficient and to save space and time in loading and unloading cargo ships. One way is to use high-charge, short-life, contactless cranes that were previously powered with highly polluting diesel engines.
By installing automated unloading portal systems in 2005, the Belgian port of Anvers today, for example, is able to unload or reload 40 containers per hour against the Dutch port of Rotterdam's 25.
With its partner TTS Port Equipment AB, Numexia has used the technology to develop a high-performance contactless AGV (automated guided vehicle) platform for loading and unloading container loads of up to 61 tons on harbour sides in ports.
The traditional diesel engines that are used to unload ships generate tremendous amounts of CO2 (carbon dioxide). To displace the huge containers from or onto the ships requires several 150-200 horsepower engines, which, although they doesn't have to move far, need a powerful acceleration for the short time they are actually in use. The rest of the time, the engines keep running and throwing out their column of black emissions.
Contactless energy-transfer technology, on the other hand, is far more energy-efficient. Using an underground power electronics element and coils, it supplies energy to the quay crane and stacking crane areas from underneath. There is also a vehicle-based system that uses the same technology in conjunction with super capacitors to store the energy that is used by the specially designed electric-wheel motors. Recharging energy takes only a few seconds. And, contrary to the Serpentine system, which transfers energy on an ongoing basis, the electric AGV uses a concentration of energy that is only transferred at key points, the remainder being stored in its supercapacitor.
IEC International Standars
Electric vehicle conductive charging system – Part 1: General requirements
Secondary batteries for the propulsion of electric road vehicles - Part 1: Test parameters
Plugs, socket-outlets, vehicle couplers and vehicle inlets - Conductive charging of electric vehicles - Part 1: Charging of electric vehicles up to 250 A a.c. and 400 A d.c.
Secondary lithium-ion cells for the propulsion of electric road vehicles - Part 2: Reliability and abuse testing
TC 69 Subcommittiees and Working Groupes
Motors and motor control systems
Power supplies and chargers
Project Team 61851-23
Electric vehicle charging station
Project Team 61851-24
Electric vehicles conductive charging system - Part 24: Control communication protocol between off-board d.c. charger and electric vehicle
Joint Working Group 69 Li
TC21/SC21A/TC69 - Lithium for automobile/automotive applications Managed by TC 21
Joint Working Group 69 Pb-Ni
TC 21/SC 21A/TC 69 - Lead Acid and Nickel based systems for automobile/automotive applications Managed by TC 21