| 摘要 |
PURPOSE:To maintain input control amount constant even if power frequency is changed to or from 50/60Hz by providing a means for making the height of triangular wave synchronized with the power frequency constant irrespective of the change in the power frequency. CONSTITUTION:A power source circuit 1 generates DC power source Vcc and a full wave rectification circuit 2 generates wave form rectifying the full wave of AC 100V power source to send the outputs to a main control circuit 3. The output voltage vf of a filter circuit constituted of resistances 4, 5, 6 and a capacitor 7 in 50Hz of the AC 100V power frequency becomes higher than that in 60Hz of the same. On the other hand, the DC power source Vcc is constant irrespective of 50 or 60Hz. Assuming the output potential of an operation amplifier 9 is Vpp, the potential Vpp(in 50 Hz)<Vpp(in 60Hz) is generated. The charge voltage Vpp having triangular waveform is changed over automatically in 50Hz and 60Hz by the filter circuit so that said voltage Vpp in 60Hz is higher than that in 50Hz and as a result the height X of triangular waveform is set to the same in 50Hz and 60Hz. The a/A in 50Hz and b/B in 60Hz become identical with each other and the ignition timing of a bidirectional thyristor is equalized even if the triangular waveform is identical with the compared potential. |
