Sanchenko O. Adjustable Asynchronous Drive of Ventilation System with Pulse Width Control

The thesis contains the results of theoretical and experimental studies of an adjustable asynchronous electric drive with a voltage regulator based on pulse-width control. The obtained performance characteristics of the development (power consumption, efficiency) had improved performance compared with the ventilation system based on a thyristor voltage regulator with phase-pulse control. It is established that the spectrum of the output voltage and current consists of higher harmonics multiples of the switching frequency of the power transistor switch. In particular, at a switching frequency of fK = 2000 Hz (к = 40), the higher harmonics appear at the levels of 39 and 41, 79 and 81, 159 and 161 etc. The voltage spectrum, due to the distortion of the output voltage form by reverse voltage pulses, has a slight background of other harmonics, the magnitude of which does not exceed 10 %. The magnitude of the reverse voltage pulse decreases sharply with a switching frequency fK = 2.0...2.5 kHz. The dependences of the amplitudes of the higher harmonics of the output voltage and current depending on the output voltage of the regulator are obtained. A refined method was developed using the results of computer simulation of the choice of the power element base of a voltage regulator with pulse-width control, which made it possible to reduce the voltage pulse when the electronic transistor switch was turned off from 60 to 1.1 kV. The results of production tests are presented and the economic efficiency of an experimental sample of an adjustable asynchronous electric drive axial fan with a pulse-width voltage converter is determined.