| 摘要 |
PURPOSE:To prevent a rapid change in a waveform applied to an electromotor by superposing a waveform of a constant frequency higher than an audio-frequency on an alternate waveform of a commercial power source and by controlling a pulse width of the constant frequency to be converted according to an inlet temperature. CONSTITUTION:The inlet temperature detected by a sensor 5 is level-exchanged 9, and the voltage of the level-exchanged temperature and a triangular wave 11, the output of a triangular wave oscillator 10 are compared by a comparator. The output of the comparator 11 is turned to a short wave and a pulse width thereof is changed according to a change of the inlet temperature. On amplifying the pulse in an amplifying circuit 12 to enable a thyristor 13 to be driven, the electromotor 2 is resultantly applied with a voltage in the form in which the commerical frequency is superposed with a wave-form in high frequency higher than the audio-frequency. By thus controlling, the smooth rotation can be attained due to both the electrical and mechanical time constants carried with the electromotor itself lower enough than the audio-frequency. |
