US 11,921,138 B2
Insulation resistance detection device
Masakazu Kouda, Kariya (JP); Ryota Kubokawa, Kariya (JP); Yusuke Shindo, Kariya (JP); and Toru Wakimoto, Nisshin (JP)
Assigned to DENSO CORPORATION, Kariya (JP)
Filed by DENSO CORPORATION, Kariya (JP)
Filed on Jun. 7, 2021, as Appl. No. 17/340,906.
Application 17/340,906 is a continuation of application No. PCT/JP2019/047398, filed on Dec. 4, 2019.
Claims priority of application No. 2018-229897 (JP), filed on Dec. 7, 2018.
Prior Publication US 2021/0293865 A1, Sep. 23, 2021
Int. Cl. G01R 27/02 (2006.01); B60L 3/00 (2019.01); G01R 27/18 (2006.01); G01R 31/52 (2020.01)
CPC G01R 27/025 (2013.01) [B60L 3/0046 (2013.01); G01R 27/18 (2013.01); G01R 31/52 (2020.01)] 9 Claims
OG exemplary drawing
 
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.