| 摘要 |
PURPOSE:To control the V/F of an induction motor or the like by so controlling that all the line voltages become sinusoidal waves. CONSTITUTION:A V/F converter 2 serves to convert the output voltage of an output frequency instructing unit 1 into pulse train of the frequency mf0 of m times of the output frequency f0 of an inverter. The outputs of the converter 2 is counted by an m-tuple counter 3, which in turn instructs the addresses of ROMs 4a, 4b, 4c. Since the same data are written in the addresses delayed by 120 deg. and 140 deg. from the ROM4a in the ROMs 4b, 4c, the respective phase potentials are, when the outputs Q, Q' of respective latching circuits 7b, 7c are applied to transistors VP, VN, WP, WN corresponding to the inverters, controlled, and all the line voltages are controlled to sinusoidal wave. |
