Xtreme Power Conversion Corporation
M90 & M90L Service Manual
Page 10
Uninterruptible Power Supply
Neutral Point Clamped Inverter
Charger
The function of charger is to charge and maintain the batteries at fully charged condition. The charger charges
the batteries with a constant current at initial stage. At the same time, the battery voltage keeps increasing until
reaching the constant charge voltage point. Then, the charge current will decrease accordingly, now it’s in second
stage. After constant voltage charging, the charge voltage will change to floating charge voltage, in general, the
charger will control the output voltage at a constant level to optimize battery recharge time and prolong the life
time of batteries without overcharging.
Topology of the charger
EMIBoard
Input EMI board is connected between utility and the input of rectifier. Output EMI board is
connected between the output of inverter and output terminal block.
Topology of the input/output EMI
Q1
Q2
L1
D1
Q3
D3
D2
Q4
D4
N
+Vbus
-Vbus