| 摘要 |
PURPOSE:To improve the stability in operation by sequentially switching through an intermediate pulse mode when switching between a modulating range and a non-modulating range, thereby reducing the variation amount of an output voltage. CONSTITUTION:When a modulating range for controlling an output by generating a gate signal from a carrier and a modulation wave and a non-modulating range secured to the maximum value at the output voltage are switched, the carrier is not abruptly switched but sequentially switched through the carrier of the intermediate frequency. To this end, carrier oscillators 42-44 are, for example, provided to generate several types of carriers. The outputs of phase waveform selectors 46-48 are sequentially switched to the carrier of next stage by the command of a waveform mode switching circuit 45, compared with the output of a modulation wave oscillator 53 by comparators 49-51 to output a gate signal. |
