Xtreme Power Conversion Corporation
M90 & M90L Service Manual
Page 8
Uninterruptible Power Supply
The Inverter block is the output stage of the UPS and used to convert DC power from the
BUS capacitor to sine waveform output power.
When the utility is within the acceptable range, the UPS will provide power directly from the utility input and
the Rectifier and PFC will be executed at the same time. When the utility is outside of the acceptable range, no
matter it’s because of input voltage or input frequency, the UPS will shutdown the Rectifier and PFC functions
and turn on the Battery Booster. In case of sudden interruption from input utility, the controller can detect the
interruption in very short time. During the short interval of detecting the interruption, the output power will be
provided by the power stored in the BUS capacitor. In this way, there is no any interruption on output power.
The charger charges the battery when the utility is normal. The charger converts AC input power to DC power for
recharging the battery.
The Input and Output EMI section provides EMI filter function. The input and output EMI filters can prevent the
UPS from being interference by external electronic/magnetic noise which is generated by other electronic system
and prevent other systems from the noise generated inside the UPS system.
The SPS generates DC power supply needed by operation of the circuit of the UPS itself. The Bypass provides a
path that utility can power the output directly when the Inverter is not executed.
The Maintenance Bypass provides another path that utility can power the output directly when UPS is in
maintenance status.
Working Principle of the Major Functional Block
Switch Power Supply
The Switch Power Supply (SPS) supplies DC power for UPS operation. The input source of the SPS is the battery,
or the AC input.
Basic circuit of power supply
DC
TX
7812
7912
7805
HF-
HF+
+12V.FAN
+12V.P
+12V
-12V
+5V
D2
D3
D7
D4
D9
Q5
