Patent EP-2256852-A1 (EP)
Inventor: TOTH ANTOINE
IPC: H01M8/04
Filed: 2009-05-27
Abstract: The bypassing system comprises branch circuits (27) connected between a positive pole and a negative pole of an electrochemical block, and a control circuit for sending a control signal to bypass circuits for deviating the electrochemical block between the poles with which it is connected. The bypass system comprises control modules each having its own reference voltage. Each branch circuit belongs to one of the modules comprising multiple branch circuits and to a control that is connected between the poles of contiguous electrochemical blocks. The bypassing system comprises branch circuits (27) connected between a positive pole and a negative pole of an electrochemical block, and a control circuit for sending a control signal to bypass circuits for deviating the electrochemical block between the poles with which it is connected. The bypass system comprises control modules each having its own reference voltage. Each branch circuit belongs to one of the modules comprising multiple branch circuits and to a control that is connected between the poles of contiguous electrochemical blocks so that the control modules divide the cell into several groups of electrochemical blocks. Each control module comprises a communication unit (23) with the control circuit so that the branch circuits belonging to different control modules are controlled. The branch circuit is associated with a voltage measuring unit (22) for measuring the potential difference between the poles of the electrochemical block to which the bypass circuit is connected, and a computing unit arranged to receive signals from the control circuit. The bypass unit has a variable impedance that is controlled by the computing unit according to signals received from the control circuit and the potential difference between the poles of the blocks to which the bypass unit is respectively associated. The branch circuits further comprise a first device for measuring the current intensity in the derivation so that the computing unit takes into account the current intensity to control the impedance of the bypass circuit, and a bypass transistor connected between the terminals of each block. The bypass transistor is controlled by two steering transistors mounted in series and controlled by a calculation unit (20). The current of two controlling transistors is controlled by a second device for measuring the current intensity so that the calculation unit takes into account the current intensity in its transistors for controlling the bypass circuit. The measuring unit is connected to the computing unit to convert the potential difference extracted by a numerical value. The communication unit comprises galvanic isolation unit. The measuring unit comprises many differential amplifier (26) to be connected, two entrances to the two terminals of a block to provide electrochemical voltage outputs representative of the potential difference present between the terminals of the electrochemical block. Each differential amplifier measures the voltage difference between terminals of two electrochemical cells. The control module further comprises a feeding system for functioning even if the control system of a pile of electrochemical blocks does not work. The differential amplifiers have a maximum input voltage. The addition of the potential differences of the different blocks does not exceed the maximum voltage. Each group of electrochemical blocks comprises eight electrochemical blocks and two fuel cells.