| 摘要 |
PROBLEM TO BE SOLVED: To use the capacities of the switching elements of a power converter in their maximum abilities and make its high speed protection possible, by making possible based on the respective signals sensed through its DC and AC current sensing portions one of a first stopping, wherein the output of its zero-voltage vector and the advancing of the phase of its rotation vector are stopped, and a second stopping wherein the driving of its inverter portion is stopped. SOLUTION: The voltage generated in a shunt resistor SR connected with the input circuit of an inverter main circuit 21 of a power converter is applied to a DC current sensing circuit 40 comprising overcurrent level and current limiting level sensing circuits. When the DC current of the power converter is not smaller than its overcurrent level, the driving of an inverter portion 20 is stopped to judge whether the DC current is not smaller than its current limiting level or not when the DC current is smaller than its overcurrent level. When judging that the DC current is not smaller than its current limiting level, the output of its zero-voltage vector and the advancing of the phase of its rotation vector are stopped, and a current limiting control is executed to limit the peak current of the inverter main circuit 21 without stopping a three-phase induction motor. On the other hand, when judging that the AC input current of the power converter is not smaller than its set value, the driving of the inverter portion 20 is stopped. |
