Battery system monitoring apparatus and electric storage device including the same
A battery system monitoring apparatus for monitoring a cell group having a plurality of battery cells, and includes a cell controller IC which monitors and controls the states of the plurality of battery cells. A battery controller controls the cell controller IC and a plurality of voltage detection lines measure the voltage across the terminals of the battery cell. The voltage detection lines connect positive and negative electrodes of the battery cell, respectively, to a plurality of voltage input terminals of the cell controller IC. A power line connects the positive electrode of the battery cell having the highest potential among the plurality of battery cells to a power supply terminal of the cell controller IC and a ground line which connects the negative electrode of the battery cell having the lowest potential among the plurality of battery cells to a ground terminal of the cell controller IC.
1. A battery system monitoring apparatus for monitoring a plurality of battery cells connected in series, the battery system monitoring apparatus comprising:
a cell controller integrated circuit (IC) that monitors and controls discharge of the plurality of battery cells, the cell controller IC including a power supply terminal, a ground terminal, a plurality of balancing switches and a plurality of cell voltage inputs;
a power line circuit that includes:
a power line that connects a positive electrode of a first battery cell that has a highest potential among the plurality of battery cells to the power supply terminal,
a first input resistor that is connected in series between the positive electrode of the first battery cell and a first cell voltage input from the plurality of cell voltage inputs, wherein the first input resistor is connected to the first cell voltage input via a first wire,
a first capacitor that is connected to the first wire and a midpoint potential voltage detection line, and
a first balance line that is connected to the power line, the positive electrode of the first battery cell and a first balance switch from the plurality of balancing switches;
a ground line circuit that includes:
a ground line that connects a negative electrode of a last battery cell that has a lowest potential among the plurality of battery cells to the ground terminal,
a last input resistor that is connected in series between the negative electrode of the last battery cell and a last cell voltage input from the plurality of cell voltage inputs, wherein the last input resistor is connected to the last cell voltage input via a last wire,
a last capacitor that is connected to the ground line and the midpoint potential voltage detection line, and
a last balance line that is connected to the negative electrode of the last cell, the last input resistor and a last balance switch from the plurality of balancing switches, wherein the last balance includes a last balancing resistor between the negative electrode and the last balance switch; and
a plurality of RC circuits that are each connected to a respective battery cell from the plurality of battery cells other than the first cell and the last cell, wherein each respective RC circuit from the plurality of RC circuits includes:
a respective input resistor that is connected in series between a positive terminal of the respective battery cell and a respective cell voltage input from the plurality of cell voltage inputs, wherein the respective input resistor is connected to the respective cell voltage input via a respective wire,
a respective capacitor that is connected to the respective wire and the midpoint potential voltage detection line,
a first respective balance line connected to the positive terminal of the respective battery cell and a second terminal of a first respective balance switch from the plurality of balancing switches via a respective balance resistor, and
a second respective balance line connected to the first respective balance line, the positive electrode of the respective battery cell, the respective input resistor and a first terminal of a second respective balance switch from the plurality of balancing switches.
2. The battery system monitoring apparatus according to claim 1 , comprising a plurality of the cell controller ICs to monitor a plurality of cell groups.
3. The battery system monitoring apparatus according to claim 1 , wherein a resistance value for each respective balance resistor is determined based on a resistance of the first input resistor, an overcharge protection voltage value of the battery cell, and a voltage value when the battery cell has a state of change (SOC) of 100%.
4. The battery system monitoring apparatus according to claim 3 , wherein a resistance value for each respective balance resistor is determined based on a resistance of the first input resistor and a duty cycle of on and off of the plurality of balancing switches.
5. An electric storage device including the battery system monitoring apparatus according to claim 1 , and a battery system.
6. An electric drive apparatus comprising the electric storage device according to claim 5 .