Patent ID: 8536877

Claim:
A power cable breaking detection method comprising: (a) detecting currents of respective phases supplied to a three-phase motor from an inverter through at least one power cable, and a driving speed of the motor; (a1) supplying a current command to the motor; (b) determining whether the respective currents and the driving speed of the motor satisfy power cable breaking detection conditions by determining whether the current command supplied to the motor is more than 10% of a maximum current; (c) determining whether each of the phase currents is less than a cable breaking sensing reference value of current command, a sum of the three phase currents is more than 50% of the current command, and two of the three phase currents except for a cable breaking phase current is more than the cable breaking sensing reference value of 50% of the current command when the respective currents and the driving speed of the motor satisfy the power cable breaking detection conditions; (d) performing cable breaking timer counting when conditions of the step (c) are satisfied, and determining whether a predetermined period has elapsed; and (e) determining that a cable is broken when the predetermined period has elapsed.