| 摘要 |
PROBLEM TO BE SOLVED: To detect a ground fault or an insulation state of a DC power source based on a charging voltage of a flying capacitor even if the potential of connection points of positive and negative Y capacitors does not coincide with the potential of a ground potential portion. SOLUTION: Charged electric charges of positive and negative Y capacitors Y+ and Y- are calculated on the assumption that the capacitances of the Y capacitors Y+ and Y- are assumed capacitances (1.2 times the actual capacitance, for example) larger than actual capacitances, regardless of variations in the potential of the connection points of the Y capacitors relative to the ground potential portion at the point when the flying capacitor C1 is charged with a charge amount corresponding to a ground fault resistor RLn on the negative side or when the flying capacitor C1 is charged with a charge amount corresponding to a ground fault resistor RLp on the positive side. A voltage corresponding to the charges is subtracted from the measured charging voltage of the flying capacitor C1 to calculate a parallel composite resistance value of the ground fault resistors RLp, RLn on the positive and negative sides, respectively, thereby detecting a ground fault or an insulated state of the high-voltage DC power source B. COPYRIGHT: (C)2011,JPO&INPIT
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