Wireless coupling of electric vehicles and smart homes: building-integrated bidirectional inductive charging of quasi stationary battery storage systems from battery-powered vehicles
Parking an electric car at home and ensuring an efficient energy supply within your own four walls: inductive charging and intelligent energy management are not just convenient solutions. Anyone who fills the interface between an electric car and domestic energy supply also enjoys financial benefits, as shown by the project “Drahtlos”.
How can we reduce the costs of electromobility. Instead of using an electric car only for driving, another option is to use its traction battery to support the electricity supply in a household. In light of this, bidirectional coupling of the vehicle to the house is being investigated in the project “Drahtlos”, which is funded by the Federal Ministry for Economic Affairs and Energy. This allows the energy to flow in both directions without cables, plugs and sockets, as the energy is transmitted inductively via an underground coil at the parking space and another one on the vehicle’s underside. The car battery can either be charged by using self-generated solar power, via a stationary storage unit or by using the grid supply. If the self-produced solar power is used to charge the car battery, less of this energy has to be fed into the grid. Therefore more of one’s own solar power is consumed by the user, which reduces energy costs altogether. If needed, the car battery is also able to power the house.
The loads from the household and car and the supply from a photovoltaic system are simulated on a test bench. The energy management algorithm developed at the Institute of Networked Energy Systems ensures that the power flow meets relevant needs and is cost-effective. In addition, the lithium-ion cells should degrade as little as possible when they are used; this is guaranteed by using information from the ageing model developed at the Institute. A self-learning program forecasts the amount of energy needed in the household, meaning that the user barely needs to control the system. The project “Drahtlos” also develops a safety analysis for the entire system.
Inductive charging and automatic energy management are convenient to use. The range that the electric car will need to have available at a certain time can be entered via an app, which also makes the energy flows transparent. The amount of self-generated solar power consumed and how cost-effectively the system can be operated depends on vehicle usage however: it is less suitable for commuters who are taking their electric car to work on a daily basis. On the other hand, when the car is only used for occasional journeys the house storage system could be smaller in size or even be removed to save costs.
January 2016 until December 2018
German Federal Ministry for Economic Affairs and Energy (BMWi)
B2M Software GmbH
Institute of Networked Energy Systems
e.Go Mobile AG
Project Manager at the Institute of Networked Energy Systems: