Patent ID: 11921138
Assignee: DENSO CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  B | IPC B  G

Claim 0:
1. An insulation resistance detection device for a power supply system,
the power supply system comprising:
a DC power supply;
a coupling capacitor, one end of which is connected to a power supply path connected to the DC power supply and insulated from a ground portion;
a resistance that is connected to the other end of the coupling capacitor; and
an oscillation unit that is connected to the resistance and outputs a predetermined frequency signal to the resistance,

the insulation resistance detection device detecting, in a predetermined cycle, a voltage at a connection point between the coupling capacitor and the resistance in a case where the oscillation unit outputs the frequency signal to the resistance,
the insulation resistance detection device detecting an insulation resistance between the ground portion and the power supply path based on a moving average value of a detection voltage, and
the insulation resistance detection device comprising a processor programmed to:
determine whether the detection voltage is changed by a predetermined value or more;
in response to a determination that the detection voltage is changed by the predetermined value or more, detect the insulation resistance based on a first moving average value calculated by using the detection voltage in a first range;
after the determination that the detection voltage is changed by the predetermined value or more, determine whether pulsation of the detection voltage is attenuated; and
in response to a determination that the pulsation of the detection voltage is attenuated, detect the insulation resistance based on, instead of the first moving average value, a second moving average value calculated by using the detection voltage in a second range including a smaller number of detection voltages than in the first range.