The UK’s first private electric-vehicle rapid-charging station was launched yesterday, highlighting the need for infrastructure to encourage the sale of EVs.
Power-technology firm ABB claims its Terra 51 DC charger reduces charging times from eight hours to 15–30 minutes for an 80 per cent top-up, and is currently the only rapid model that can connect to networks of other charging stations via the internet.
The installation of a Terra 51 at the site of Nottinghamshire printing company RCS is seen as the start of the creation of a network of privately owned rapid-charging stations needed to help overcome consumers’ fears about running out of power (referred to as ’range anxiety’).
The charging technology uses specialised software to enable it to continuously talk to the car’s battery-management system, in order to control how the large amount of power needed for rapid charging is fed into the battery without damaging it and reducing its life.
ABB’s software follows the Japanese CHAdeMO standard, making it compatible with cars such as Nissan’s Leaf, but also uses freely available open-source software and additional programming to allow the charging station to connect to the internet.
‘[Terra 51] is the world’s only DC rapid charger that can connect interoperably with other systems using something called OCPP, Open Charge Point Protocol,’ ABB’s UK head of sales for EV charging, Martin Hale, told The Engineer.
Applying OCPP to rapid chargers enables them to connect to back-office infrastructure so their use can be monitored for customer billing and for remote diagnostics. It also allows them to link to networks of conventional chargers that already run payment schemes.
‘Before this there was no way of taking any income or managing it,’ said Hale. ‘All these different regional membership schemes will be able to link up so when you buy a car you can use one RFID card, for example, to have access to all that.’
Rapid chargers need complex software to manage the charging process because they deliver much larger amounts of power, typically charging at around 50kW as opposed to the 3kW of slow chargers, which can have a more detrimental effect on the battery.
Crijn Bouman, ABB’s vice-president of business development for EV charging, told The Engineer: ‘The trick to fast charging a lithium-ion battery is to do it in a very controlled manner, especially when you want to reach charge times of 15–30 minutes.
‘During charging, the voltage and current have to be adjusted all the time to anticipate on reactions of the battery chemistry… The car will continuously send information on the battery and preferred settings to the charger and the charger responds to that.’
The other impact of supplying more power is that the converter that turns mains alternating current in direct current for battery charging becomes too large and expensive to place inside the car and so rapid chargers have their own converter and produce DC.
In order to make the Terra 51 more reliable, ABB has developed a modular system that manages the power supply in a way that allows it to keep working even if one of the modules breaks down.
‘We see that most of the competing products have a single power system, which is basically a single point of failure,’ said Bouman. ‘If there is a problem the system will shut down totally. People cannot charge and they will be stranded.’
ABB’s technology also uses a distributed cooling system to help reduce the noise of the charger. Using a computer simulation of the thermal flow inside the charger, the company developed an array of multiple small ‘ultra-silent’ fans to cut noise to less than 45 decibels.
Hans Streng, head of ABB’s EV charging division, said: ‘The possibility to quickly recharge will help potential buyers overcome the hurdle of range anxiety. That’s why the UK needs DC charging — in addition to the existing AC infrastructure — to further drive electric mobility.’