| 摘要 |
<P>PROBLEM TO BE SOLVED: To hold the number of rotations of an induction motor and to continue an operation even in the time of short time power interruption, such as an instantaneous stop, etc. <P>SOLUTION: The speed controller of the induction motor includes a rectifier 1 for converting an AC inputted from an AC power supply 5 into a DC, an inverter 3 for converting the DC converted by the rectifier into the AC to output the AC to the induction motor 8, and an inverter control means 20 for controlling the frequency of the AC output of the inverter according to the speed instruction of the induction motor. The inverter control means field-weakening controls by lowering the exciting current component of the vector control according to the voltage drop of the AC power supply. Consequently, the inverter control means lower the induced voltage of the induction motor, and supplies sufficient current to the induction motor even if the voltage of the AC power supply is lowered. On the other hand, the output frequency of the inverter is held at the value according to the speed instruction. As a result, even in the case of the short time power interruption, such as the instantaneous stop, etc., the number of rotations of a facility device 9 driven by the induction motor is held at the instruction value. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
