Nozhenko V. Induction motor drive of above resonance vibration machine with improved starting modes

The thesis is devoted to solving the urgent scientific problem of improving the start-up conditions of the above resonance vibration machines by using a frequency-controlled induction electric drive with the formation of additional control actions during passing the resonance zone. In the research, an analysis of non-stationary processes in a resonant RLC-circuit with a serial connection – an analogue of the mechanical part of a vibrating machine – was done using the method of electromechanical analogy. This made it possible to explain the change in the sign of the vibrational moment, which is the main load on the drive motors during the passage of the resonance zone during the start-up process. A method for determining the power of induction motors of electric drives without speed control of a resonant vibration machine is proposed, which is oriented to the starting mode and takes into account, in addition to the parameters of the mechanical system, the maximum value of the vibration moment and the starting parameters of the engine with consideration of the displacement of current. It is shown that the basic laws of frequency control do not provide a decrease in the amplitude of vibrations of the working body of the vibration machine and dynamic loads during the passage of the resonance zone. It was found that a quick passing of the resonance zone can be achieved by reducing the frequency of the start-up time as compared to a direct one. The dependence of the frequency sweep time on the total reduced mass of the vibrating parts of the vibrating machine is determined, which allows one to obtain a high-quality transient process and quick passage of the resonance zone as compared to a direct start. A method is proposed for the formation of a scalar control law for a frequency-controlled electric drive of a resonant vibrating machine due to a stepwise increase in voltage, which allows the use of drive motors with a lower power than the installed one has. Key words: frequency-controlled electric drive, induction motor, above resonance vibration machine, resonance zone, starting modes, motor power.