Insulation detecting device and insulation detecting method of non-grounded power supply

摘要

An insulation detecting device includes a control unit configured to monitor a measurement voltage of a flying capacitor charged through a second path, and in a case where a measurement voltage is about 0 V (zero volt), control a switching of switches, control a charging of the flying capacitor through a third path and a measuring of a charged voltage of the flying capacitor charged through the third path, and measure a first measurement voltage in a first time after the switching to the third path and a second measurement voltage in a second time different from the first time, and a calculating unit configured to calculate a ground fault resistance formed between a direct-current power supply and a ground based on the first measurement voltage and the second measurement voltage.

主权项

1. An insulation detecting device which includes a flying capacitor configured to retain a charged voltage and a measurement circuit configured to measure the charged voltage of the flying capacitor, is connected to a direct-current power supply electrically insulated from a ground, and measures a ground fault resistance formed between the direct-current power supply and the ground based on the charged voltage of the flying capacitor which is measured by the measurement circuit, the insulation detecting device comprising:
a plurality of switches configured to switch a first path from a positive electrode of the direct-current power supply to an negative electrode of the direct-current power supply through the flying capacitor, a second path from the positive electrode of the direct-current power supply to the ground through the flying capacitor, a third path from the ground to the negative electrode of the direct-current power supply through the flying capacitor, and a fourth path which releases a connection between the flying capacitor and the direct-current power supply and connects the flying capacitor and the measurement circuit; a control unit configured to monitor a measurement voltage of the flying capacitor charged through the second path, and in a case where the measurement voltage is about 0 V (zero volt), control a switching of the switches, control a charging of the flying capacitor through the third path and a measuring of the charged voltage of the flying capacitor charged through the third path, and measure a first measurement voltage in a first time after the switching to the third path and a second measurement voltage in a second time different from the first time; and a calculating unit configured to calculate the ground fault resistance formed between the direct-current power supply and the ground based on the first measurement voltage and the second measurement voltage.