| 摘要 |
A system for controlling the speed of an induction motor by controlling an output voltage and an output frequency of a power inverter in accordance with a speed command includes a computing unit (10) for determining a slip-frequency computed value omega s2; an adder (11) for outputting a slip-frequency estimated value omega s<->; an adder (12) for adding omega s<-> to a speed command value omega r<*> and outputting omega l<*>; a d-axis current commanding unit (14) for outputting a d-axis current command value id<*> which is a value greater than a normal value; an amplifier (15) for outputting a voltage command value ed<*>; a gain commanding unit (16) for commanding a gain Gd; a q-axis current limiter (17) for controlling a q-axis current iq substantially to zero in a zero speed range; and a gain commanding unit 18 for commanding a gain Gq. If the speed command value is equal to or less than a set value, the d-axis current is increased to a value greater than a normal value, a q-axis voltage command iq<*> is corrected in accordance with a detected value of a q-axis current iq, and the q-axis current is controlled in a direction in which it is suppressed. By virtue of this configuration, even if there are variations in motor parameters, the induction motor does not undergo a decline in the torque in a zero speed range and effects regenerative operation stably. <IMAGE> |
