| 摘要 |
PURPOSE:To improve the output characteristics of a variable frequency power source by forming a PW-modulated output via the logically operated output of a reference pulse train and a comparison pulse train and contolling the output frequency of an inverter, thereby smoothly varying the PW-modulated output. CONSTITUTION:Reference pulse train circuits 81-87 which form a pulse train having a pulse at every 360 deg. with 60 deg. of elecric angle in width and a pulse train having six sets of the prescribed frequencies in which the phase is respectively displaced by 60 deg. with 60 deg. of width, and comparison pulse train circuits 11-71 which form a pulse train having a pulse at every 360 deg. with 60 deg. of electric angle in width and a pulse train having six sets of variable frequencies in which the phase is respectively displaced by 60 deg. with 60 deg. of width, are provided. PW- modulated output is formed by logical operation circuit 91 of the reference pulse train and comparison pulse train from both the circuits, thereby controlling the fires of respective thyristors of an inverter 3. |
