| 摘要 |
PURPOSE:To enable a speed control without necessary of a tachometer generator mounted on a motor shaft as heretofore by electrically detecting a speed feedback signal. CONSTITUTION:A Scherbius speed controller has an instrument transformer 14 at the input side of a converter 3, and an instrument transformer 15 and a voltage detector 17 at the output sides of a voltage detector 15 and an inverter 4. A multiplier 18 multiplies the output of the detector 17 by the turn ratio of an inverter transformer 5 to obtain the primary side voltage of the transformer 5, i.e., a motor voltage. Then, a multiplier 20 multiplies the output of a multiplier 18 by the turn ratio of the motor 1 to obtain the secondary voltage when the motor stops. A divider 22 calculates 'a slip' of the motor from the outputs of the detector 15 and the multiplier 18, and a converter 23 converts the 'slip' calculated by the divider 22 into a signal capable of collating to a speed setter 8. Thus, an inverter 4 is controller. |
