| 摘要 |
PURPOSE:To enable the number of an AC motor rotation to be controlled at a target number of rotation even when the source voltage varies by correcting an indicted value transmitted to a motor drive circuit in consideration of a difference between a rated voltage and a detected source voltage. CONSTITUTION:A microcomputer 3 corrects an indicated value transmitted to a motor drive circuit 2 in consideration of a difference between a rated voltage and a source voltage detected by a voltage detection circuit 7. For example, when a difference between the rated voltage and the detected voltage is positive, the microcomputer 3 judges that a voltage of a commercial power source 10 has dropped and corrects an indicated value so as to be larger than an indicated value large enough to obtain the number of autorotation upon rated voltage impressing. In the reverse case, that is, when a difference between the rated voltage and the detected voltage is negative, the microcomputer 3 corrects an indicated value so as to be smaller than an obtained indicated value by which a target number of rotation can be obtained upon rated voltage impressing. This can maintain the number of rotation of an AC motor 1 at a target number of rotation even when the source voltage varies. |
