Bayerische Motoren Werke Aktiengesellschaft

Florian Pfattrisch

Michael Bauer

Andreas Buchner

Georg Goetz

Thomas Schimanek

Christopher Kolbeck

Sylvester Burckhardt

A method is provided for coupling at least one secondary energy source to an power supply network, in particular an on-board vehicle power supply, wherein a load is connected with a primary energy source having a first voltage characteristic. The at least one secondary energy source has a second voltage characteristic which has an operating voltage range overlapping with the first voltage characteristic. The primary energy source and the at least one secondary energy source can be connected via a power switching device to a node point of an intermediate circuit of the power supply network, to which the load is also connected. Before connecting a secondary energy source, the current drawn by the load is regulated such that the voltage connected to the node point of the intermediate circuit corresponds to a no-load voltage of the secondary energy source to be connected or is around the no-load voltage in a specified voltage range. In the case that the voltages correspond or if the voltage connected to the node point lies in the specified voltage range, the secondary energy source is electrically conductively connected to the node point via the power switching device. The current required by the load is regulated to the corresponding value, wherein the load is supplied from the primary and the secondary energy source.

Method for coupling at least one secondary energy source to an energy supply network, in particular an on-board vehicle power supply

A method of operating an electric system of a motor vehicle, consisting of a fuel cell system, an accumulator and an electric driving motor is provided. Without implementing an electric voltage conversion and therefore without an electric voltage converter, as a function of the level of the electric voltage made available by the fuel cell system and by the accumulator and the electric power demanded by the electric motor, a first switching element in the connection between the fuel cell system and a node point electrically connected with the accumulator and the electric motor, as well as a second switching element in the connection between the accumulator and this node point are opened or closed as needed. This is done such that the power requirement of the electric motor is met primarily from the fuel cell system, and in an auxiliary fashion, additionally from the accumulator. If the electric power offered by the fuel cell system exceeds the electric power demanded by the electric motor, the excess power will be fed to the accumulator for as long as its permissible charging current is not exceeded and the accumulator still has a defined residual storage capacity.

Operating method for an electric energy system of a motor vehicle comprising a fuel cell system, an accumulator and an electric motor

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Geretsried-Gelting, Germany

Florian Pfattrisch