Patent ID: 11874339
Assignee: DENSO CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An insulation resistance detection apparatus applicable to a power system,
the power system including:
(i) a direct-current power source;
(ii) a coupling capacitor having a first end and a second end, the first end of the coupling capacitor being connected to a power-supply path that is connected to the direct-current power source and is electrically isolated from a ground portion;
(iii) a resistor connected to the second end of the coupling capacitor at a connection point therebetween; and
(iv) an oscillator connected to the resistor and configured to output a predetermined frequency signal to the resistor,

the insulation resistance detection apparatus being configured to:
sample, every predetermined period, a value of a detection voltage at the connection point between the resistor and the coupling capacitor;
determine an insulation resistance between the ground portion and the power-supply path based on a moving average of the detection voltage; and
determine whether the determined insulation resistance is lower than or equal to a predetermined reference value to thereby determine whether there is a leakage of current between the ground portion and the power-supply path, and

the insulation resistance detection apparatus comprising:
a voltage determiner configured to determine whether the detection voltage, which has changed by at least a preset value, becomes stable at a changed voltage value; and
a resistance determiner configured to determine a value of the insulation resistance between the ground portion and the power-supply path based on a currently sampled value of the detection voltage instead of the moving average in response to determination that the detection voltage, which has changed by at least the preset value, becomes stable at the changed voltage value.