Error detection device
An abnormality detection device includes: a coupling-capacitor having a first-end and a second-end coupled with a high-voltage circuit; a signal output unit; a signal extraction unit; and a signal input unit. The signal output unit is coupled with the first-end of the coupling-capacitor via a detection-resistor, and outputs an alternating-current inspection-signal. The signal extraction unit extracts the inspection-signal, as an extraction-signal, output between the detection-resistor and the coupling-capacitor. The signal input unit detects abnormality of insulation resistance of the high-voltage circuit based on a level of the inputted extraction-signal. The signal extraction unit includes a signal removing filter and a subtraction circuit. The filter removes a signal equal in frequency to the inspection-signal and passes low-frequency noises lower in frequency than the inspection-signal. The subtraction circuit outputs a differential signal, as the extraction-signal, between a signal having passed through the filter and a signal not having passed through the filter.
1. An abnormality detection device comprising:
a coupling capacitor including:
a first end; and
a second end to be coupled with a high-voltage circuit;
a signal output unit which outputs an alternating-current inspection signal, the signal output unit being coupled with the first end of the coupling capacitor via a detection resistor;
a signal extraction unit which extracts the inspection signal as an extraction signal, the inspection signal being output between the detection resistor and the coupling capacitor; and
a signal input unit which receives the extraction signal and detects an abnormality of insulation resistance of the high-voltage circuit based on a level of the received extraction signal,
wherein the signal extraction unit includes:
a signal removing filter which removes a signal equal in frequency to the inspection signal, and passes, through the signal removing filter, a low-frequency noise lower in frequency than the inspection signal; and
a subtraction circuit which outputs a differential signal as the extraction signal, the differential signal being a difference between a signal having been passed through the signal removing filter and a signal not having been passed through the signal removing filter, and
wherein the signal removing filter is a low-pass filter which removes the signal equal in frequency to the inspection signal and passes the low-frequency noise through the signal removing filter.
2. The abnormality detection device according to claim 1 ,
wherein the signal extraction unit further includes a noise removing filter which removes a high-frequency noise higher in frequency than the inspection signal and passes, through the noise removing filter, the low-frequency noise and the signal equal in frequency to the inspection signal, and
the subtraction circuit outputs a differential signal as the extraction signal, the differential signal being a difference between the signal having been passed through the signal removing filter, and a signal that having been passed through the noise removing filter but having not been passed through the signal removing filter.
3. An abnormality detection device comprising:
a coupling capacitor including:
a first end; and
a second end to be coupled with a high-voltage circuit;
a signal output unit which outputs an alternating-current inspection signal, the signal output unit being coupled with the first end of the coupling capacitor via a detection resistor;
a signal extraction unit which extracts the inspection signal as an extraction signal, the inspection signal being output between the detection resistor and the coupling capacitor; and
a signal input unit which receives the extraction signal and detects an abnormality of insulation resistance of the high-voltage circuit based on a level of the received extraction signal,
wherein the signal extraction unit includes:
a signal removing filter which removes a signal equal in frequency to the inspection signal, and passes, through the signal removing filter, a low-frequency noise lower in frequency than the inspection signal; and
a subtraction circuit which outputs a differential signal as the extraction signal, the differential signal being a difference between a signal having been passed through the signal removing filter and a signal not having been passed through the signal removing filter,
wherein the signal extraction unit further includes a noise removing filter which removes a high-frequency noise higher in frequency than the inspection signal and passes, through the noise removing filter, the low-frequency noise and the signal equal in frequency to the inspection signal, and
wherein the subtraction circuit outputs a differential signal as the extraction signal, the differential signal being a difference between the signal having been passed through the signal removing filter, and a signal that having been passed through the noise removing filter but having not been passed through the signal removing filter.
4. The abnormality detection device according to claim 3 , wherein the noise removing filter is a low-pass filter which removes the high-frequency noise higher in frequency than the inspection signal and passes, through the noise removing filter, the low-frequency noise and the signal equal in frequency to the inspection signal.