| 摘要 |
PURPOSE:To enable to stably control a motor even if line voltage of the motor becomes excess due to external disorder by controller V/F in response to a load. CONSTITUTION:A current signal C from a current detector 8 is inputted to a sample-holding circuit 11. It is sampled by the rise of the output pulse (b) from an oscillator 6, and the sampled output (d) is produced. An adder 9 adds an analog voltage (a), the sampling output (d), a bias signal (e) in the shown polarity, and the added result is inputted to a pulse width setter 10. If a constant load is altered to a light load, the sampled output (d) accordingly varies, with the result that the pulse width of the signal (f) becomes small. In this manner, an AND gate 2 is operated to set the output voltage of the inverter 3 to a low value, V/F is altered, and an adequate voltage in response to the load is supplied to a motor M. |
