GATE WAVEFORM GENERATING CIRCUIT FOR FREQUENCY CONVERTER

PURPOSE:To remove harmonic wave components of an output waveform of a frequency converter by producing a sinusoidal wave output proportional to the input frequency from a D/A converter by a sinusoidal wave peak value controller, thereby approaching the frequency-divided signal to the sinusoidal wave. CONSTITUTION:The output from a frequency divider 1 is inputted to a pulse number switching circuit 2, and an inequal pulse number is determined. The amplitude of the sinusoidal wave a of the output of the first D/A converter 4 is controlled by a sinusoidal wave peak value controller 6 to produce a waveform for controlling the voltage of the output of a 3-phase AC power source, the input signal of a frequency divider 1 is inputted to the second D/A converter 3 as it is, the triangular wave D of the frequency of 3(2n+1) of the sinusoidal frequency is synchronized with the sinusoidal wave a and is produced. In this manner the voltage of the output of the 3-phase AC power source becomes inequal width pulse, and the output waveform becomes near the sinusoidal wave.