Xtreme Power Conversion Corporation
M90 & M90L Service Manual
Page 9
Uninterruptible Power Supply
The figure above is a flyback converter. When Q5 is on, all rectifier diodes (D2/D3/D4/D9) are on open status
and all output capacitors supply currents to the load. The primary coil of the transformer will become a pure
inductor and the primary current will linearly increase to store energy in the coil. When Q5 is off, primary current
will stop and all rectifier diodes (D2/D3/D4/D9) will turn to “close” status. It will release the stored energy from
the primary coil of the transformer to the secondary coil to supply loads. At the same time, it will charge output
capacitors inc12V, -12V, +5V, +12V.P, +12V.Fan, and HF-power.
The power of +12V, -12V, +5V, +12V.P, +12V.Fan supplies stable voltage to all kinds of ICs and other devices
such as HCT. The +12V (Fan) is supplied to fans and relays. The HFPW supplies a high frequency power for the
switch (SCR/IGBT) driver and some other drive boards.
PFC/Booster
PFC/Booster
As shown in the Figure4.2, when Q3/Q4is on and D1/D2 is off, the current will increase to store energy in choke
(L1/L2). When the Q3/Q4 is off and D1/D2 is on, the choke will release energy. Therefore, we can control the
current in chokes (input current) by regulating the time of Q3/Q4 on and off. There are three independent PFC/
Booster for each phase.
Inverter
The input of the Neutral Point Clamped(NPC) Inverter topology is two DC voltages, and the output is an AC
voltage, as shown in the Figure4.3.When Q2is on and Q4 is off, the Q3 and Q1 are continued on and off for on
upper of sine wave. When Q3 is on and Q1 is off, the Q4 and Q2 are continued on and off for on lower of sine
wave. The L1 and C1 are AC
power filter.
L2
Q3
Q4
Q5
Q6
Q1
Q2
D1
D2
C1
C2
N
N
R/S/T
Battery
+Vbus
-Vbus
Q2
D4
Q3
D5
Q4
D6
D1
D2
L1
C1
N
N
Re
la
y
1
Vo
+Vbus
-Vbus
INV.STS