| 摘要 |
PURPOSE:To achieve phase control with good response by a method wherein a sine wave output and a cosine wave output from an oscillator are supplied to a third Hall element and a fourt Hall element respectively and the added output of both element outputs is supplied to the first and second Hall elements. CONSTITUTION:Two-phase AC voltage shifted by pi/2 respectively from Hall elements H1, H2 are applied to stator coils L1, L2 through a DC amplification system consiting of power amplifiers 25, 25'. Even if coil current varies, rotating speed is constantly maintained by a feedback circuit providing with a resistor Rs for counter electromotive force voltage detection and an operational amplifier 27. Meanwhile, a sine wave output e3 and a cosine wave output e4 in a two- phase sine wave oscillator 29 are supplied to a Hall element H3 and a Hall element H4 respectively and the added voltage E5 of each output voltage E3, E4 of the Hall elements H3, H4 is fed into an operational amplifier 22 and the output in the operational amplifier 22 is supplied to Hall elements H1, H2. Said E5 becomes the voltage which is directly proportional to phase difference theta and phase control is achieved. |
