The invention relates to a charging system for electric vehicles, having a grid charging stage that can be connected to an alternating current grid, by way of a connection point, on the input side and has an AC/DC inverter, having a microprocessor-assisted control device for monitoring a charging process, and having at least one charging connector on the output side that can be temporarily connected with a vehicle battery.
On the other hand, thought has already been given to the idea that vehicle batteries can be viewed as being part of the power grid. The vehicle battery can be charged when there is an excess of energy, while energy can be drawn from the battery when there is an energy deficiency, and returned to the power grid. In this connection, one also speaks about a vehicle-to grid system, V2G system .
The solution according to the invention essentially consists in that a buffer battery having a significantly greater charging capacity as compared with the vehicle battery is connected with the grid charging stage of the charging system, and that a quick-charging stage that comprises the control device and a DC/DC inverter and can be temporarily connected with the vehicle battery on the output side, by way of the charging connector, is connected with the buffer battery.
Furthermore, it is proposed, according to the invention, that the buffer battery can be connected to the alternating current grid, on the output side, by way of a return stage that has a microprocessor-assisted switching unit and a DC/AC inverter.
Using the measures according to the invention, together with the high-capacity buffer reservoir and the return stage, are moved out of the electric vehicle into the energy loading stations. The charging capacity of the buffer battery must be dimensioned in such a manner that it meets the needs of the charging demand of the incoming motor vehicles. The latter means that a relatively great amount of electrical energy must always be kept available in the buffer batteries of the charging stations, which energy can be temporarily returned to the alternating current grid in the event that a peak load occurs. Because direct access to the buffer battery exists by way of the charging system, a very rapid switching process is possible. In this way, the waiting time until additional peak load power plants are switched in can be bridged, while avoiding an impermissible load drop in the alternating current grid.