| 摘要 |
PURPOSE:To reduce torque loss of an AC motor by removing a stepwise distortion of a sine wave through a low pass filter, advancing a phase delay by a phase correction processor of a CPU, and outputting it. CONSTITUTION:A phase correction processor 12 of a CPU 1 corrects a phase by adding or subtracting phase correction data to or from the counted value of a counter 11 in response to a rotating direction of an AC motor 9 based on rotary information of the motor so as to correct the delay of the value counted by the counter 11 from the phase due to the phase characteristic of a low pass filter 13. Here, a waveform to be output from a D/A converter 7 becomes remarkable in the stepwise distortion if the rotating speed of the motor 9 is increased since an output within a software processing time is not varied, but a smooth waveform can be obtained by passing the output of the converter 7 through the filter 13. |
