Research Of Energy-saving Control Of The Three-phase Asynchronous Motor Driving In Variable Frequency Speed Regulation Environment

Frequency converter is used to drive the special motor, but it is always used to drive the normal three-phase induction motor in China. The normal three-phase induction motor usually works in the condition of fifty Hz to sixty Hz. When the normal three-phase induction motor is driven by the frequency converter, the voltage and current waveform are not the sine wave, because this wave has much high order harmonic. The high order harmonic may lead to the more loss, so the total system’s efficiency is not perfect. It may not only increase the more copper loss, but also generate the additional iron loss. So it is meaningful to research the three-phase induction motor’s loss when the three-phase induction is driven by the frequency converter.In this paper, I firstly made analysis of frequency control system’s various loss, including the generation mechanism of loss. Then I focused on making the qualitative and quantitative analysis by the different core materials in order to test the iron core material’s loss in the different frequency, for example the iron, silicon steel and ferrite. Moreover, I made research about the influence of high harmonic which worked on the three-phase motor’s loss. Then I Built an experimental platform to prove that high harmonic would cause the more loss when three-phase motor is driven by the frequency converter.At last, in order to solve the increases of loss I had provided two kinds of solutions to decrease the loss of the common three-phase induction motor which works in the variable frequency environment.