INDUCTION MOTOR CONTROLLER

摘要

PROBLEM TO BE SOLVED: To ensure stability of a system against temperature fluctuation by generating a harmonic voltage of a frequency designated through carrier frequency modulation, varying the harmonic frequency and detecting the corresponding harmonic current. SOLUTION: The induction motor controller utilizes carrier frequency sine wave modulation for generating a harmonic voltage component of a frequency designated through carrier frequency modulation. A voltage of a designated frequency is generated from a harmonic voltage generating means 4 of designated frequency (output basic frequency f1 of inverter-frequency Δ of carrier frequency sine wave modulation function). The frequency is then varied and a harmonic current corresponding to that frequency is detected by a means 8 for detecting harmonic current of designated frequency and a frequency (f1-fΔ) designated when the harmonic current is minimized is estimated as the rotational frequency of an induction motor 1.