Abstract:

With the development of power electronics technology, AC frequency conversion speed regulation system gradually replaces the traditional DC speed regulation drive with its strong advantages. It brings convenience and efficiency to people's production and life, but also causes the problem of aggravating harmonic pollution in power system. Therefore, this paper designed an open-loop sinusoidal pulse width modulation (SPWM) controlled AC variable frequency speed regulation system and built a simulation model, which realized the flexible control of the frequency and amplitude of the output voltage of the converter, as well as the motor speed. Furthermore, the harmonic characteristics of the voltage and current on the grid side of the system were analyzed. The simulation results show that the waveform of the voltage is ideal and its distortion is very small, but the current waveform distortion is serious. In addition, with the increase of the inverter output frequency, the distortion degree of voltage waveform is intensified, and the current distortion is reduced.

Key words: frequency speed regulation, inverter, asynchronous motor, harmonic analysis