Audi and Haige Electric Co., Ltd. develop two-way charging to reduce electric vehicle owners

The vision of Audi and Hager Group is to increase grid stability, reduce electricity costs, and contribute to climate protection. Integrating electric vehicles into the home grid is the core of the two-way charging innovation research project of the two companies. The combination of photovoltaic systems will have more advantages because it can temporarily store excess PV (solar photovoltaic) electricity and output it when needed.

Audi has been committed to achieving the goals of the Paris Climate Agreement, and strives to make its vehicles carbon neutral by 2050. In order to achieve this goal, Audi is conducting an extensive electric offensive, including the launch of about 20 pure electric models by 2025. Not only that, electric vehicles will also become part of its growing range of mobility products and an integral part of its transition to sustainable energy.

In the first half of 2020, the proportion of renewable energy in Germany's electricity structure reached more than 50% for the first time. However, this increase in proportion is also accompanied by the dilemma of wind and solar energy: the power generation is not constant, and when the sun is shining and strong winds, there is a lack of capacity to store wind and solar energy that cannot be used by the grid.

As the number of electric vehicle registrations increases, so does the number of mobile energy storage units. As long as such energy storage units can be used intelligently to store capacity, they can bring huge potential. Therefore, according to foreign media reports, Audi and Haige Electric are cooperating on research to develop solutions that can bring economic incentives and provide safer power supply-two-way charging, also known as vehicle-to-grid (V2G) technology.

Electric car becomes a flexible energy storage unit

The idea is simple and creative: the high-voltage battery of an electric car is charged by a wall-mounted charger in the home, but it can also be used as a decentralized energy storage medium to power the home. If the customer has a photovoltaic system, the electric car can be used as a temporary energy storage medium for environmentally friendly power generation at home. When there is no sun, electric cars can supply stored electricity to households. The realization of two-way charging at home is also called car-to-home (V2H), which can greatly reduce the cost of household electricity and increase the stability of the grid. For further expansion, combined with home energy storage units, the home can achieve nearly complete energy independence and increase power supply security in the event of a power outage.

Adopt near-series technology

Things that sound simple in theory often require high-level technical knowledge and coordinated interaction between different technical components, including infrastructure and vehicles used. In this research project, the researchers used an Audi e-tron model equipped with near-series charging technology. In the test grid, Audi pure electric models use DC wall-mounted charging devices (charging power up to 12 kW), and retractable household energy storage units with a capacity of up to 9 kWh. Due to the DC voltage level of the entire grid, the connection between the PV system and the vehicle no longer requires an inverter, which has become a particularly effective solution.

Charging with PV system can save costs

Two-way charging mainly focuses on such use cases, that is, the owner uses his own photovoltaic system to obtain the optimized cost and the electricity generated by the family for charging. Electric vehicles store the surplus power in the PV system, and household appliances do not use the power of the PV system. If the price of electricity changes, then the owner can let the electric car power the whole family when the price of electricity is high. In the evening or off-peak hours, the car can use cheap electricity to charge to a satisfactory state of charge (SOC). In addition to cost optimization, two-way charging can also achieve power supply security. In the event of a power failure, the system can also supply power to the home through high-performance high-voltage batteries, or it can operate the entire building independently when it is not connected to the grid.

The focus of the researchers is daily usability

Developers make daily usability their top priority. The researchers said: "Maintaining mobility is our focus. Therefore, customers do not need to limit themselves and can use two-way charging in daily life. Intelligent charging management can make the best use of the battery, thereby maximizing the entire system. Cost-effectiveness. The system is very simple for the customer, just plug in the car and the rest can be done automatically."

The joint research project conducted by Audi and Haige Electric has proved two important things: Those with their own PV system can design their own travel mode, optimize costs and carbon dioxide consumption, and reduce the burden on the grid. Customers with Audi electric vehicles can make an important contribution to the successful transformation of energy. The intelligent use of high-voltage batteries in vehicles also opens up the possibility of sustainable use of existing resources that were previously only used for Travel. (Yu Qiuyun)