Bidirectional EVSE
13Pages

Epic Power Converters, S.L. CIF: B99349623 Calle F/Oeste Nave 93, Gregorio Quejido - 50016 Zaragoza (Spain) info@epicpower.es - www.epicpower.es Author logan@epicpower.es Bidirectional EVSE Introduction The increasing electrification of the automotive industry is leading to an extensive development of power electronics linked to electric vehicles. The similarity of features with a conventional combustion car is essential for end users; therefore, the autonomy and charging time of electric vehicles are a hot topic for stakeholders and many R+D efforts worldwide are undergoing. Regarding charging station connection technologies, there are currently different types of connectors where CCS and CHAdeMO standards are the most prevalent for high power DC charging. It is essential for EVSEs (Electric Vehicle Supply Equipment) not only to achieve high power delivering (that will reduce the EV charging time) but also to implement bidirectional capabilities in order to draw energy from the connected EV when the infrastructure needs to mitigate high power peak demands. This is commonly known as V2X (Vehicle-to-X), with particularizations such as V2G (Vehicle-to-Grid) or V2V (Vehicle-to-Vehicle) among others. EVs are commonly parked outside a factory, company, commercial parking lots, homes, etc. for a relatively long period time (between 2 to 8 hours). Bidirectional EVSEs with a central neural machine-learning algorithm bring the possibility to smooth and undersize the overall demand from the utility power grid and therefore, the required infrastructure, among other benefits. Epic Power has developed a Pilot Project, with support from the Ministry for the Ecological Transition and the Demographic Challenge under grant number PGE-MOVES-SING-2019000070. This project demonstrates how to integrate our isolated DC/DC bidirectional converters (EPC) in a 20 kW EVSE that is capable of charging and/or discharging two vehicles at the same time (CCS and CHAdeMO one each). For this purpose, a small DC micro-grid has been created with a PV string supplying up to 4.6 kWp in a sunny day. PV panels are connected to the DC grid by means of another EPC converter with MPPT capability. Epic Power Converters, S.L. CIF: B99349623 Calle F Oeste, Nave 93 Grupo Quejido – Pol. Malpica 50016 - Zaragoza (Spain) info@epicpower.es www.epicpower.es

In this project, some machine-learning algorithms (in particular LSTM, Long Short-Term Memory Networks) have been implemented and take decisions based on the following predictions: - Energy demand of the manufacturing facility PV solar energy generation EV plug-in time and duration Infrastructure architecture A DC micro-grid has been implemented in our facilities with the purpose of interconnecting EVSE, PV generation and the grid energy-sharing device. The deployment of this small DC micro-grid gives us the advantage of adding more renewable energy sources (like hydrogen fuel cells, wind...

Interconnection with the main grid is done by a 20 kW Yaskawa D1000 bidirectional frontend. Thanks to the isolation incorporated between high and low sides in our DC/DC converters, the high side DC link can be shared among different EVs and feed them individually. Furthermore, our DC/DC converters are easy to parallelize, just by wiring them in the right way. Looking into Fig. 2, K3 and K4 contactors enable to parallelize both converters to feed one car with up to 20 kW (CCS or CHAdeMO). Fig. 2. Power Stage Schematic Note that energy flow is bidirectional, thus bidirectional DC contactors...

Control stage HTTPS OVER TCP/IP EPC DC/DC CONVERTERS WEB SERVER MODBUS TCP/IP COMMUNICATIONS GATEWAY ARTIFICIAL INTELLIGENCE MODBUS TCP/IP ADVANTICS SECC MODBUS TCP/IP MAIN CABINET CHARGING POINT Fig. 3. Control Stage Diagram The integration of several and different components increases the communication layer complexity. We have had to deal with five different communication protocols: - ModBus TCP/IP A communication gateway has been developed by epic power that not only translates between protocols but also implements some advance control techniques to command the EPC DC/DC converters in...

Fig. 4. Advantics SECC connection diagram Advantics has developed an easy to use state machine controlled through the CAN 2.0b bus where all the car information is filtered and shown; that gives the ability to be controlled not only through scripts inside its device but also from external ones (as we have made in this project). CCS and CHAdeMO protocols are very strict regarding timings and sequences that are being treated by Advantics SECC in a transparent way to the external controller. Protocol updates are also available through their support team and can be carried out in a simple way....

CHAdeMO Precharge stage 400 Fig. 5. CHAdeMO Precharge Stage We have designed a precharge method to avoid the use of this precharge resistor that consists of reading the battery voltage before closing our own contactor, then command our EPC converters to precharge the bus from 0V to the battery level (with no more than a ±5% of deviation) and finally close the contactor. This stage is made between the ready to charge and charging stages of the car. A precharge stage of a CHAdeMO connection can be seen on Fig. 5 Charging point On the charging point side, an IP65 anti-vandal Android touch...

The CCS charging cable is able to deliver up to 200A @ 1000 Vdc meanwhile the CHAdeMO delivers up to 125A @500 Vdc. Figure 5 shows the status of the charging post that can be customized to meet the client needs. Main cabinet The following pictures display the actual implementation of this pilot project inside an ample electric cabinet. The overall size can be optimized and reduced which was not the objective for this pilot project. Epic Power Converters, S.L. CIF: B99349623 Calle F Oeste, Nave 93 Grupo Quejido – Pol. Malpica 50016 - Zaragoza (Spain) info@epicpower.es www.epicpower.es

Epic Power Converters, S.L. CIF: B99349623 Calle F Oeste, Nave 93 Grupo Quejido – Pol. Malpica 50016 - Zaragoza (Spain) info@epicpower.es www.epicpower.es