The Continued Development & Testing Of EV Charging Infrastructure
By Jim Wallace of Seaward
One of the major barriers to the faster takeup of EVs has been potential driver fear that a vehicle would have insufficient battery power to reach its destination. Over time, the introduction of plug-in hybrids (PHEVs), together with the use of higher-energy-density batteries capable of storing more energy, has helped to overcome this so called ‘range anxiety.’
However, as more EVs take to the roads, pressures on the available charging network are growing. In response, considerable effort and investment is also being made to ensure that more charge points are being installed in the right locations, supported by back-office systems providing reliable access arrangements and charging protocols for the electricity delivered.
All of these advances continue to place ever more emphasis on the availability of a recharging infrastructure. Unless steps are taken to ensure the ongoing reliability of the recharging network, however, there is a real danger that range anxiety will simply be replaced by charge anxiety as the next barrier for the EV sector to overcome.
EV Charging Equipment
Lack of charging infrastructure may have been a short-term disadvantage to EVs, fueling range anxiety, but this is now being overcome with significant activity and investment in charging networks.
This approach has seen the free installation of residential charging points being followed by an initial concentration of public electric vehicle charging stations in urban areas and parking lots. This is now being extended to workplaces and retail locations, and at key points on the transport system — such as motorway service stations — to sustaining longer EV journeys.
The most common type of EV charging installation provides ‘slow charging’ to the vehicle as an AC supply over periods from 4–12 hours for a full charge, depending on the rating of the supply. As battery capacity has improved and the capability of handling faster charging has increased, “fast charging” DC systems have also become available, particularly on motorway or highway locations, where recharging can be achieved in much shorter timescales.
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Although different modes or levels of charging have different definitions around the world, the operation and functionality of electric vehicle supple equipment (EVSE) is controlled by official product standards.
The international standard IEC 61851 defines the requirements for charging equipment and also covers aspects such as the protocol used for communication between the vehicle and charging point. In the USA, the SAE J1772 standard is a close equivalent of IEC 61851. Compliance with one or the other of these standards is mandatory to ensure the safe operation and reliable performance of the EVSE installations.
In general terms, the standards describe the characteristics and operational conditions of the charging station and its connection to the EV, the electrical safety of operators and third parties, and the characteristics to be complied with by the vehicle with respect to the power supplied when the vehicle is earthed.
For the user of an EVSE, recharging the vehicle should be as simple as connecting a normal electrical appliance to the electricity supply. However, to ensure that this operation takes place in complete safety, the charging station must perform several system safety checks. To do this, direct communication between the vehicle and the station is established when the connection is made.
To understand some of the difficulties associated with ensuring the correct performance of an EV charging point, it is important to understand how a charge point operates and the protection associated with it.
In order to avoid accidental contact with live parts (for example the terminals on the charging cable), the EVSE charging output cannot be energised unless an EV is connected (i.e. there cannot be power on the EVSE output connector or cable unless the cable is plugged into an EV and communication between the two is established).
Herein lies a fundamental problem. Operational performance and diagnosis of any EVSE system faults cannot be determined unless an EV is connected to the charging system and signal communication is established between the two parts of the system.
As a result, several of the tests defined by electrical installation standards like IEC 60364 and the National Electric Code, such as earth loop impedance and RCD testing, cannot be carried out unless the circuit under test is energized. Functional testing of the installation also requires the EVSE to be energized.
One means of checking the functionality would be to attempt to charge an EV immediately after each and every EVSE installation, but it would be impractical and extremely time consuming to do so. It should also be noted that this would not provide any information on how the EVSE would respond if there is a fault with the EV or the charging cable.
EVSE Maintenance Challenges
In addition, although many public charging points are currently free to use, when users begin paying for the electricity supplied to recharge their vehicle, confidence that the charging point is actually supplying the power it is supposed to be will take on even greater importance.
Associated with these issues, and with the growth of digital media, online databases and mapping software now enables charging point faults to be reported, logged, and identified to warn drivers (and charge point operators) of any potential problems.
In response, many EVSE suppliers provide telephone support services to users experiencing problems and operate remote monitoring systems themselves to identify charging station problems, so that fast response engineering teams can be dispatched to any faults identified.
With the rollout of new charging stations, special systems are being developed to enable EV drivers to plot, locate, and in some cases even reserve charging stations for their use. Interoperability, cross-platform standardization of EVSE connectors and the development of efficient payment protocols are other areas of focus.
All of this work is taking place with the aim of instilling greater EV owner confidence that their vehicles will be able to successfully charge in more and more locations, enabling longer distances to be traveled and eliminating range anxiety.
Of course, the fundamental requirement underlying this commitment is that the capability of the EVSE network remains robust and reliable in meeting the recharging needs of the vehicle whenever required.
In these circumstances, an important step has been taken with the introduction of a new testing and diagnostic device to allow EVSE installers to demonstrate that the charging equipment is both safe and operating in accordance with the same specification as when it was installed.
The Seaward EV100 has been designed to verify EVSE safety and operation by simulating the presence of an EV. Direct communications between the tester and the EVSE is established via a standard charging cable or through direct connection to the EVSE output terminal. This enables the instrument to control the EVSE and sequence through a number of test conditions to enable all appropriate electrical tests to be carried out.
The EV100 will also simulate a number of vehicle faults and measure the EVSE response. Test results are stored in an internal memory and can be transferred to a smartphone app using wireless communications.
As well as carrying out basic field tests, more detailed diagnostic data from the charge point is retained in the tester and can be transferred to the EVSEMobile Android app using NFC wireless communications.
The EVSEMobile app enables advanced data to be viewed, test certificates to be produced and test data to be exported as csv file and emailed back to the office.
Comprehensive technical test data can therefore be assessed by an office-based diagnostics engineer with remedial instructions being provided to the technician working in the field.
With developments in new, advanced EVSE test technology, operators of charging networks now have the opportunity to overcome their maintenance challenges, reassuring drivers that charging points will be working when they need them, and keeping the EV revolution moving forward.
More at seaward.co.uk/EV100
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