| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of vibration, heating, etc., due to flowing of a large higher harmonic current, in the case of controlling an induction motor with a relation V/F=fixed by PWM controlling an inverter device. SOLUTION: In a microcomputer, based on an output frequency command input from an input device 9 and information from a DC voltage detection circuit 7, a DC voltage control circuit 8 and a transistor module control circuit 5 are controlled, a transistor module 3, by maintaining a relation in which V/F=fixed, is PMW controlled, an induction motor 4 is efficiently driven. In order to realize this relation V/F=fixed, a rectifier circuit output voltage of a DC voltage variable rectifier circuit 2 is controlled, so as to generate output voltage of minimum value during the time from Fmim to F1, and increase the output voltage by a fixed ratio during the time from F1 to Fmax. On the other hand, driving of the transistor module 3 is controlled, so as to increase a PWM modulation factor by fixed ratio during the time from Fmin to F1 and fix the modulation factor during the time from F1 to Fmax. |
