| 摘要 |
PURPOSE:To omit a reference oscillator to use a DC amplifier and a comparator in common, by using an error signal, which is subjected to pulse width modulation, directly as a modulation signal for obtaining a signal for a power amplifier which drives a load. CONSTITUTION:When the rotation speed of a motor 15 becomes lower than a reference speed, a speed error signal S1L appearing in an input terminal 1 is converted to a signal S2L by a low pass filter 20 and is compared with a DC signal SP corresponding to a phase error signal by a comparator 8A. Turning-on/off of transistors TRs 12 and 13 is controlled by a PWM signal S3L of a long pulse width appearing in the output side of the comparator 8A, and an output signal S4L of a long pulse width is outputted to the output side of a power amplifier 11. Driving of the motor 15 is controlled by a driving signal S5L obtained by smoothing the output signal S4L, and the motor 15 is accelerated to rotate in the reference speed. |
