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Controller for smart vehicle-to-grid chargers

Technology News |
By Nick Flaherty


The VIGIL-ANM project combines a substation monitor from EdgeTech and the Envoy-ANM controller communicating with iHost platform from Nortech. The iHost platform determines the substation’s available capacity based on real-time network conditions from a controller deeloped by Bytesnap Design. The systems are all linked to a smart building at Aston University in Birmingham. 

“We are about half way through the two year project and we are creating a system where we are using a smart building effectively using that to buffer the grid,” said Dunstan Power, Director of ByteSnap Design. Bytesnap has developed a vehicle-to-grid (V2G) controller which provides interoperability and control of any EV charger via the new OCPP 2.0 standard from the Open Charge Alliance. The controller reduces latency and improves system robustness by allowing direct control via the building management system. ByteSnap has also created a V2G mobile application which is being delivered together with an optimised building management system.

“The system looks at how much energy the building requires and can offset what it pulls from the grid by pulling energy from the vehicles to keep the grid power within the limits that the sub-station can handle,” he said. “So in the future if you have lots of electric charging points around a shopping centre that could put a large load on the grid. Air conditioning is a major load on the building so rather than having to do a massive grid upgrade of the sub-station, the peaks of energy can be dealt with by pulling power from the vehicles.”

“We are doing a boc that sits between the charger and  building with Modbus over Ethernet to the charger and communicated wvia OCCP to the GridEdge OCCP server,” he said. This uses an NXP i.mx6 microcontroller running linux, WiFi and GPRS for communication to a local WiFi access point or the cellular network, and CAN interfaces for talking to chargers.  We designed the board to be used more widely than for VIGIL so we can sell it onto people who need to interface chargers to OCCP such as converting chargers to smart charger or managing a group of chargers”

The box itself is a low power board independently of the charger via a DC supply, charge rate, diagnositcs from the charger, but that could be a DC fast charger or AC charger.

The project team at Aston University is investigating  a prediction model for EV battery-life performance considering factors such as State-of-Charge, State-of-Health, Charging-speed, Depth-of-Discharge, and remaining energy capacity. Power quality issues for different V2G/network scenarios is also being investigated with research findings disseminated to industry and academia. Three V2G charge-posts and harmonic meters have been installed are now fully commissioned and ready for service. 

“Nortech are looking after the grid to building section while GridEdge are doing the smart building section and we are doing the vehicle to building section,” said Power. “The issue that they had was V2V charging is very new and operate on different standards so we needed a way of getting the different types of chargers on the same standard so they could work with standard servers and IT infrastructure. The main standard for charger OCCP running 1.5 and 1.6, but that doesn’t have anything around V2G so OCCP V2 will cover this in a way. It’s built more around widening the OCCP reach within the smartgrid infrastructure, not just the transaction for charging.”  

The work will also reduce the need for chargers to use apps or smartcards to charge users. 

“Going forward there’s a standard for plug and play to get rid of smartcards and apps and the finiciail side will be handled over the cable. It’s a separate standard but incorporated into V2 and into the charger,” he said. “A lot of these chargers are going ot have proprietary interfaces so we are having to code software to talk to the charger, with their own structure for comms. That’s the reason we chose Linux and we are planning to go back and do OCCP 1.6 support for legacy customers once the V2 is done for VIGIL.”

The system can be used for charger designs. 

“We have cost engineered the design and we see it being used later in the year by manufacturers of chargers,” he said.

www.bytesnap.comwww.openchargealliance.org


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