| 摘要 |
<p>Device for controlling electric motors of the asynchronous motor type operated by means of three-phase alternating current. For producing the operating current of the motor (5) a voltage-controlled oscillator (2) is foreseen and a generator (4, 6) controlled by the same and conditionally fed from a direct current source (1). The control device (3, 7, 8) is arranged to receive the pulse which arises upon operation of the motor (5) in its feed conductors (10-12) for alternating current and is thereby arranged to detect changes in the pulse shape of the operating voltage which occur due to electromotive forces induced from the motor windings when these are passed by the induced field of the rotor. These changes vary with the size of the slip. On the basis of the level of said deviations, a proportional voltage is induced which is transferred to the oscillator for its frequency control. With changes in the rotational torque loading on the motor, the control voltage is thereby changed and also the frequency of the oscillator and consequently the rotational speed of the motor, so that an adaptation to the operating resistance is obtained.</p> |
