Insulation deterioration monitoring apparatus and insulation deterioration monitoring method

An insulation deterioration monitoring method of monitoring motor insulation deterioration for each inverter unit, in a motor driving system comprising a plurality of inverter units including a motor driving inverter and one or more motors, and a converter for supplying power to each of the plurality of inverter units, and a ground current measuring instrument for measuring ground current flowing between an output terminal of the converter and ground,

• the insulation deterioration monitoring method comprising:
• a first step of selecting one inverter unit out of stopped inverter units during stopping of at least one of the plurality of inverter units, and causing a corresponding motor driving inverter corresponding to selected inverter unit to generate a direct current voltage;
• a second step of measuring the current value of the ground current by the ground current measuring instrument while the corresponding motor driving inverter generates the direct current voltage;
• a third step of recording the current value of the ground current measured in the second step, for each inverter unit in association with the selected inverter unit, and
• a fourth step of analyzing a tendency of insulation deterioration of each of the plurality of inverter units based on measured data of the current value of the ground current recorded for each inverter unit.

An insulation deterioration monitoring apparatus applied to a motor driving system, comprising:

• a plurality of inverters each including a motor driving inverter and one or more motors;
• a converter to supply power to each of the plurality of inverters;
• and
• circuitry configured to
• during at least one of the plurality of inverters stops, select one inverter from the at least one of stopping inverters,
• cause a corresponding motor driving inverter corresponding to the selected inverter to generate a direct current voltage,
• measure a current value of ground current flowing between an output terminal of the converter and ground while the corresponding motor driving inverter generates the direct current voltage,
• record the measured current value of the ground current in association with the selected inverter, on a basis of inverter, and
• analyze a tendency of insulation deterioration of each of the plurality of inverters based on measured data of the current value of the ground current recorded for each inverter.