Efforts to standardize fast charging protocols for electric and battery electric vehicles (EVs) have recently resulted in significant progress with the publication of two new fast charging standards by the International Electrotechnical Commission (IEC).
The new standards are IEC 61851-23, Electric vehicle conductive charging system – Part 23: EC electric vehicle charging station, and IEC 61851-24, Electric vehicle conductive charging system – Part 24: Digital communication between a d.c. EV charging station and an electric vehicle for control of d.c. charging. Published in March 2014, the standards incorporate requirements for the three most-widely used fast charging technologies, and are expected to expedite the worldwide deployment of fast charging systems for EVs.
The current state of fast charging
The average EV requires approximately 15 kWh of electricity in order to travel 100 kilometers. A typical residential charging AC charging system operating at 120 to 240 volts takes 5 to 8 hours of charging time to provide sufficient power to travel that distance. Such lengthy charging periods may be acceptable when an EV is being garaged overnight or for extended periods, but not for vehicles that require intermittent charging during a longer journey.
Fast charging technology, in contrast, can provide sufficient power with just 15 to 20 minutes of charging time to travel 100 kilometers. This makes fast charging the method of choice for many of the public charging stations currently available, and an essential requirement for broader consumer acceptance of EVs.
The four most widely used fast charging systems include the following:
- CHAdeMO - The CHAdeMO system originated in Japan in 2008 and is used by a number of Japanese EV manufacturers, including Nissan, Mitsubishi and others. The CHAdeMO protocol uses separate vehicle inlets for AC charging and DC charging.
- Combo - The Combo 1 and 2 systems were first published in 2012 and have been adopted by a number of U.S. and European EV manufacturers. Combo chargers feature a single coupler that incorporates both AC and DC electric feeds, eliminating the need for coupler adaptors.
- CATARC - The CATARC (China Automotive Technology and Research Center) protocol for fast chargers is deployed in fast charging systems throughout China.
- Tesla Supercharger - The supercharger concept is a proprietary system developed by Tesla Motors. Tesla recently announced that all existing patents related to the supercharger concept are now free to be used and implemented in any vehicle.
Unfortunately, all these fast charging systems and protocols are not only incompatible with one another, they also utilize unique charging sockets. These incompatibilities place EV owners at risk of being unable to find a compatible fast charging station when they most need it.
Dual chargers could be the solution to these issues as they are capable of serving mainstream, CHAdeMO and combo charging systems. However its technical setup where components are shared within a single charger means that there are specific safety requirements which are not yet covered by any of the current standards.
Nonetheless TÜV SÜD can help to close this gap.
For manufacturers of EVs and fast charging stations, the new IEC standards narrow the scope of technology options, allowing for expanded implementation of existing fast charging technologies in new EV models. The standards will also support the more rapid deployment of a fast charging infrastructure that can meet the needs of the majority of EV vehicles on the road today and in the future. These benefits will help drive consumer demand for EVs, benefiting both consumers and manufacturers.
With over a century of German automotive safety engineering experience, TÜV SÜD is an international leader in e-mobility testing services, and provides automotive manufacturers with independent testing and certification of motor vehicles and components. For additional information, visit our e-Mobility webpage.
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