CURRENT INTEGRATING CIRCUIT DEVICE AND SECONDARY BATTERY PACKAGE USING THE SAME
A current integrating circuit device, including a current sensor to detect a current flowing through a current path, a first-order lag filter to filter an output of the current sensor, an A/D converter to convert an analog signal filtered by the first-order lag filter into a digital signal, and a proportional integrator to proportionally integrate the digital signal outputted from the A/D converter.
1 . A current integrating circuit device, comprising:
a current sensor to detect a current flowing through a current path;
a first-order lag filter to filter an output of the current sensor;
an A/D converter to convert an analog signal filtered by the first-order lag filter into a digital signal; and
a proportional integrator to proportionally integrate the digital signal outputted from the A/D converter.
2 . The current integrating circuit device as recited in claim 1 , wherein:
the first-order lag filter has a cutoff frequency lower than a sampling frequency of the A/D converter.
3 . The current integrating circuit device as recited in claim 1 , wherein:
the proportional integrator has a turning point frequency approximately equal to a cutoff frequency of the A/D converter.
4 . The current integrating circuit device as recited in claim 1 , wherein:
the current sensor includes a Hall CT.
5 . The current integrating circuit device as recited in claim 4 , wherein:
the Hall CT is operated only by a single power source.
6 . The current integrating circuit device as recited in claim 4 , wherein:
the first-order lag filter includes an input terminal, an output terminal, a resistor and a capacitor;
an end of the resistor is connected to the input terminal, and another end of the resistor is connected to the output terminal; and
an end of the capacitor is connected to the output terminal, and another end of the capacitor is earthed.
7 . The current integrating circuit device as recited in claim 1 , wherein:
the current sensor ( 5 ) includes a shunt resistor.
8 . The current integrating circuit device as recited in claim 7 , wherein:
the first-order lag filter includes an operational amplifier.
9 . A secondary battery package, comprising:
the current integrating circuit device as recited in claim 1 ;
a secondary battery connected in series with the current sensor; and
a remaining capacity estimating unit configured to estimate a remaining capacity of the secondary battery using a current integration result obtained by the proportional integrator in the current integrating circuit device.
10 . The secondary battery package as recited in claim 9 , wherein:
the first-order lag filter has a cutoff frequency lower than a sampling frequency of the A/D converter.
11 . The secondary battery package as recited in claim 9 , wherein:
the proportional integrator has a turning point frequency approximately equal to a cutoff frequency of the A/D converter.
12 . The secondary battery package as recited in claim 9 , wherein:
the current sensor includes a Hall CT.
13 . The secondary battery package as recited in claim 12 , wherein:
the Hall CT is operated only by a single power source.
14 . The secondary battery package as recited in claim 12 , wherein:
the first-order lag filter includes an input terminal, an output terminal, a resistor and a capacitor;
an end of the resistor is connected to the input terminal, and another end of the resistor is connected to the output terminal; and
an end of the capacitor is connected to the output terminal, and another end of the capacitor is earthed.
15 . The secondary battery package as recited in claim 9 , wherein:
the current sensor ( 5 ) includes a shunt resistor.
16 . The secondary battery package current integrating circuit device as recited in claim 15 , wherein:
the first-order lag filter includes an operational amplifier.
17 . The secondary battery package as recited in claim 9 , wherein:
the remaining capacity estimating unit estimates the remaining capacity of the secondary battery using a temperature of the secondary battery, a voltage of the secondary battery and the digital signal sent from the A/D converter, along with the current integration result sent from the proportional integrator.