| 摘要 |
PURPOSE:To enable to obtain a stabilized revolution with which the error generated due to the offset voltage and the like of an amplifier can be neglected by a method wherein the sine wave type output of an amplifier is sliced in between the amplifier, to be used for amplification of Hall element output voltage, and a stator current supplying output circuit at the level in proportion to a speed controlling signal. CONSTITUTION:The explanation relating to a C phase is given as follows. A sufficient output voltage VH (a), with which the offset voltage of the amplifier 17 can be neglected, is obtained in between output terminals 7a and 7b by flowing a sufficient input current on the Hall element 7. The output voltage VC (b) of the Hall element 7 which was amplified by the amplifier 17 is controlled by a speed controlling signal sent from the generator coil 14 of a frequency generator in proportion to the speed of revolution as shown in (c) of slicing circuits 18 and 19, and the slicing is performed at the level VD which is lowered when the revolution speed is fast and is raised when the speed is slow. In accordance with the sliced waveform VE, the current in proportion to the waveform VE is driven through an output circuit 20 and flown to a stator winding LA. The waveform VF of the output of slicing circuits 22 and 23 of phase D is formed by deviating 90 deg. to the waveform VE as shown in (d). |
