Werbung
4. Power circuit for P.W.B
@ Fig. 4-1 shows the power circuit for P.W.B. and waveform at each point.
R505
AC220V
{
AC240V
4
Ul
O
O
3A FUSE
TRANS
FORMER
Fig. 4-1 Power circuit for P.W.B.
® In the power circuit for P.W.B., power voltage for microcomputer, peripheral circuits, and power module drive and,
as well as DV39V, are produced by switching power circuit.
® Switching power circuit performs voltage conversion effectively by switching transistor IC1 to convert DC300V
voltage to high frequency of about 70kHz to 200kHz.
@ Transistor IC1 operates as follows:
(1) Shifting from OFF to ON
© DC about 300V is applied from smoothing capacitors C510 €B and C511 © in the control power circuit. With
this power, current flows to pin @ of IC1 via R201 and R202 and IC1 starts to tum ON. Since voltage in the
direction of arrow generates at point © at the same time, current passing through R208 and D202 is positive-fed
back to IC1.
— 126 —
Werbung
