Patent ID: 7709977
Filing Date: 2010-05-04
Classification: B60L,H01M,Y02E,Y02T

Abstract:
1. A method, for controlling a switching connection between i) electrical outputs of a fuel cell of a power supply system in a device, and ii) an isolated electrical network which supplies load elements with power from the fuel cell, wherein, the power supply system includes a further network whose voltage is lower than voltages of the isolated network, and of a storage battery connected to the isolated network; the switching connection has at least one switching contact of a switching member connected to each output of the fuel cell for connecting and disconnecting the electrically isolated network to and from the outputs of the fuel cell, which outputs are electrically isolated from conductive parts of the device; and the contacts which are connected to the outputs are part of a first switching member or members connected to a switching and control unit, which is supplied with power from the further network, said method comprising: sensors generating sensor signals indicative of an occurrence of apparatus states for which supply of power from the fuel cell to the electrically isolated network must be precluded or interrupted for safety reasons; the switching and control unit monitoring the sensors; during starting of the fuel cell, the switching and control unit releasing energy for closing contacts when the fuel cell has reached operational readiness, provided that the switching and control unit has not detected any sensor signal for precluding or interrupting closure of the contacts of the first switching member or members for safety reasons; and upon detection of at least one sensor signal for precluding or interrupting closure of contacts, the control and evaluation unit blocking or interrupting power supply from the fuel cell to the first switching member or members, a series circuit formed by a resistor and a contact of a further switching member, which is connected to the switching and control unit and can be operated separately from the other switching members, is connected in parallel with one of contacts which are connected to the outputs or poles of the fuel cell; energy for closing the contact is supplied to the further switching member at the same time as the energy for closing the contact of the first switching member or members after starting of the fuel cell and after it has reached operational readiness; and if the switching and control unit detects a sensor signal for precluding or interrupting closure of the contacts of the switching members, the power for operating the further switching member and the first switching member or members is blocked or interrupted.