Xtreme Power Conversion Corporation
M90S Service Manual
Page 9
Uninterruptible Power Supply
4.2 PFC/Boost circuit
Figure 4.2 Boost circuit topology
As shown in the Figure 4.2, when Q1/Q2 are on, and D1/D2 are off, the choke (L1/L2) will store energy
and the current following through the choke will increase as time passes. When the Q1/Q2 are off, the
choke releases energy and the D1/D2 are on, the current of the choke will decrease as time passes.
Therefore, we can control the current waveform of chocks (intput current) by regulating the duration of
Q1/Q2 on and off.
4.3 Inverter circuit
Figure 4.3 “T”three level topology
The topology works as the following. Q1&Q4 and Q2&Q3 are switched on at alternate half cycles. The junction
voltage of Q1 and Q2 is a high frequency rectangular waveform. This rectangular wave through the LC filter will
become a standard sine wave.
