Inverter-fed finduction motor drive with additional switchings of inverter

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Dr. Halász Sándor
Department of Electric Power Engineering

Nowadays, use of inverters spread widely in households and industrial appliances. They are commonly applied, because of their variable frequency and because of the beneficial properties of asynchronous motors that are drived by them. My thesis is about the preparation of a simple inverter-fed asynchronous motor driver. The control of the inverter is based on additional commutation, which reduces the effects of the harmonics. A disadventage of this solution is an increasing switching frequency and a decreasing voltage of the 1st harmonic. I have developed a programm, that is able to calculate the optimal commutation angle according to the given voltage of the 1st harmonic. Beyond the optimal angles, the program is able to calculate the losses even in closed-form or until the 399th harmonics. Losses are plotted on graphs, so the voltage of the 1st harmonic can be easily determined at the minimum of the loss factor. I have developed the schematics and the control of a simple inverter drive as well. The optimal angles are programmed into a Procon V3D inverter. Finally I analysed the output waveform of a programmed inverter.


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