| 摘要 |
In order to rotate an asynchronous motor at various selected speeds and then maintain the speed at the chosen value, the installation comprises a pilot oscillator (9), a phase comparator (7) to which is applied the signal from the pilot oscillator and whose output signal is applied to a control oscillator (12), through a low-pass filter (10), a commutation circuit (2) controlled by the output signal from the control oscillator (12) in order to control the electronic commutation of the asynchronous motor (1), and sensor means (3, 4, 5) associated with the rotor of the motor (1) in order to deliver a signal whose frequency is proportional to the speed of the rotor, this signal being applied to the phase comparator (7), the whole in such a way that the two signals applied simultaneously to the phase comparator (7) are of identical frequencies and that the unit forms a phase-locked loop. This installation can be used in particular for controlling the driving of ultracentrifuges. <IMAGE>
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