Alpha Technologies Continuity: 1000_2000_3000 - Manual (Page 43)

41 0170009-J0 Rev B
Appendix A
A-1 Theory of Operations
The UPS System Block Diagram below illustrates the true on-line double conversion architecture of the
UPS system.
The major modules consist of the following:
• AC to DC power converter (rectifier) with a Power Factor Correction
• DC to AC power high frequency inverter
• Isolated intelligent battery charger
• Bank of stationary maintenance-free batteries
• DC to DC converter
• Static bypass loop
• Input and output EMI filters
The following table summarizes the UPS operating modes during various utility AC power conditions:
Utility Conditions UPS Operating Modes
LED Display
indications
Utility normal
Rectifier converts AC to DC. Battery charges. Inverter
converts DC to AC and supplies the loads with clean, stable
power.
, , LEDs
illuminated
Utility abnormal
(under or over
voltage) or absent
Rectifier and charger stop operating. Battery discharges
via DC-DC boost circuit and supplies the inverter. Loads
continue to receive supply from the inverter. Buzzer beeps.
UPS on battery mode.
green LED
extinguished
Utility abnormal or
absent, battery low
voltage
Rectifier and charger stop operating. Battery discharges via
the DC-DC boost circuit and supplies the inverter. Buzzer
sounds short and frequent beeps, indicating that the battery
power is low and the inverter will stop working at any
moment.
LED extinguished
LED illuminated
LOW
symbol on LCD
The following sections describe the operation of the UPS under different conditions.
PFC
AC/DC INVERTER
DC/AC
BOOST
DC/DC
CHARGER BATTERY
Control
Circuit