| 摘要 |
PURPOSE:To maintain a torque ripple at a small value at the time of low speed and to reduce noise at the time of high speed by improving a waveform by operating a current feedback circuit at the time of the low speed, and stopping the operation of the circuit at the time of the high speed to increase the linear range of a control amplifier to approach the output waveform to a sine wave. CONSTITUTION:When a rotor speed is low, a sawtooth-wave voltage generated at the terminal of a capacitor 14 becomes a large amplitude to exceed a reference voltage 15. Accordingly, no output is produced from a comparison amplifier 16. When a rotor speed is increased, the amplitude of the sawtooth wave is reduced to become lower than the reference voltage, the amplifier 16 produces an output to latch a D type FF circuit 17 to input it to a transistor 18, thereby turning ON the transistor 18. Then, the current feedback voltage side of a comparison amplifier 7 is grounded, and a control amplifier 3 is operated in a linear range. Thus, an output waveform approaches a sine wave, and variation in a winding current becomes smooth. Accordingly, an electromagnetic force generated from the winding is reduced, and an electromagnetic noise at the time of high speed can be largely reduced. |
