Patent ID: 7492160
Filing Date: 2009-02-17
Classification: G01R

Abstract:
1. A device for measuring individual cell voltages of cells in a cell stack of an energy accumulator, comprising: a series circuit of two diodes connected in parallel with each cell of the cell stack and connected to conduct current in a direction from a minus pole to a plus pole of the cell; a changeover switch having a number of terminals assigned to switch positions corresponding to a number of the cells of the cell stack, and a capacitor connecting each of said terminals to a respective node between said diodes assigned to the cells; a reference circuit having first and second diodes connected in series, said first diode having an anode connected to reference potential and to a cathode of said second diode; a differential amplifier having a non-inverted input connected to an output of said changeover switch, an inverted input connected via a capacitor to a node between said first and second diodes of said reference circuit, and an output; a controlled rectifier having an input connected to said output of said differential amplifier and an output carrying a direct current with a voltage, relative to reference potential, proportional to a cell voltage of the cell respectively selected with said changeover switch; a first controlled alternating current source connected between said non-inverting input of said differential amplifier and reference potential; a second controlled alternating current source connected between said inverting input of said differential amplifier and reference potential; and a clock control having an oscillator outputting an oscillator clock signal and a frequency divider outputting a divider signal, wherein said first and second alternating current sources and said rectifier are controlled by the oscillator clock and said changeover switch is controlled by the divider signal.