Xtreme Power Conversion P91 - 4.2 PFC;Booster; 4.3 Inverter

Xtreme Power Conversion Corporaon
P91, TX91, TX91L, TXVR Service Manual
Page 9
Uninterrupble Power Supply
Figure 4.1 is a yback converter. When Q1 is on, all recer diodes (D1/D2/D3) are on open status and all out-
put capacitors (C1/C2/C3) 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 Q1 is o, primary cur-
rent will stop and all recer diodes (D1/D2/D3) 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 me, it will charge output
capacitors including 15V, +12V, +5V, +12V(Fan), and HFPW.
The power of 12V, +5V 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.
4.2 PFC/Booster
N
Q
1
Q
2
U
BUS+
U
BUS-
Utility
Battery
L
1
D
2
D
1
C
1
C
2
N
L
2
Q
3
Q
4
Q
5
Figure 4.2 PFC/Booster
As shown in the Figure 4.2, when Q1/Q2 is on and D1/D2 is o, the current will increase to store energy in
choke(L1/L2). When the Q1/Q2 is o and D1/D2 is on, the choke will release energy. Therefore, we can control
the current in chokes (input current) by regulang the me of Q1/Q2 on and o.
4.3 Inverter
The input of the three level inverter topology is two DC voltages, and the output is an AC voltage, as shown in
the Figure 4.3. When Q1/Q2 is on and Q/Q3 is o, the voltage of the bridge midpoint is +BUS. When Q1/Q2 is o
and Q3/Q4 is on, the voltage of the midpoint bridge is –BUS. We can get any voltage waveform between ±BUS
voltage from LC lter output by regulang the duty cycle of Q1/Q2/Q3/Q4, including sine wave form.
Figure 4.3 Three level inverter bridge