Overvoltage detecting apparatus for combination battery

An overvoltage detecting apparatus, for a combination battery, which detects an overvoltage of each cell of said combination battery constituted by connecting a plurality of secondary battery cells in serial or in serial-parallel with each other, comprising:

• first reference voltage generation means for generating a reference voltage corresponding to a charge end voltage by using a terminal voltage of said cell, and second reference voltage generation means having the same arrangement as that of said first reference voltage generation means;
• first voltage division means for dividing the terminal voltage of said cell at a predetermined division ratio, and second voltage division means having the same arrangement as that of said first voltage division means;
• insulating type switching means for switchably outputting an output from said first reference voltage generation means and a ground potential in accordance with a control signal, the control signal being insulated from an input/output;
• comparison means for comparing an output from said insulating type switching means and an output from said first voltage division means;
• a first block constituted by first switching means for switchably outputting an output from said second reference voltage generation means and a ground potential in accordance with the control signal, a first amplification means for sending an output for inverting a first inversion means when a difference between an output from said first reference voltage generation means and an output from said first switching means exceeds a predetermined allowance error, and said first inversion means connected to an output of said first amplification means;
• a second block constituted by second switching means for switchably outputting an output from said first reference voltage generation means and a ground potential in accordance with the control signal, a second amplification means for sending an output for inverting a second inversion means when a difference between an output from said second reference voltage generation means and an output from said second switching means exceeds a predetermined allowance error, and said second inversion means connected to an output of said second amplification means;
• a third block constituted by third switching means for switchably outputting an output from said second voltage division means and a ground potential in accordance with the control signal, a third amplification means for sending an output for inverting a third inversion means when a difference between an output from said first voltage dividing means and an output from said third switching means exceeds a predetermined allowance error, and said third inversion means connected to an output of said third amplification means;
• a fourth block constituted by fourth switching means for switchably outputting an output from said first voltage division means and a ground potential in accordance with the control signal, a fourth amplification means for sending an output for inverting a fourth inversion means when a difference between an output from said second voltage dividing means and an output from said fourth switching means exceeds a predetermined allowance error, and said fourth inversion means connected to an output of said fourth amplification means;
• said means and blocks being arranged for each cell,
• said first to fourth blocks being arranged in an arbitrary order, and being sequentially connected to each other such that an output from said comparison means is given as a control signal of said switching means of the first block, and an output from said inversion means of each block is used as a control signal of said switching means of said next block, and
• said cell blocks of said combination battery being sequentially connected to each other such that an output from said inversion means of said last block of said cell block whose cell potential is higher by one is used as a control signal of said insulating type switching means, and
• control means for supplying a control signal to said insulating type switching means of a cell block having the highest potential, inputting an output from said inversion means of said last block of a cell block having the lowest potential as a detection signal, fixing the control signal in a normal operation, determining an overvoltage by the detection signal, changing the control signal in a predetermined order in inspection, and determining the normality/abnormality of an overvoltage detecting function by checking whether the detection signal follows the change of the control signal.