Theory Of Operation - Delta 3KVA User Manual

2 INTRODUCTION

2-1 Theory of operation

The main topology of the UPS consists of bypass path, AC-DC converter, DC-AC
inverter, battery charger, DC-DC converter, control circuit and detection circuit.
Moreover, the intelligent power management software is also optional. The function
and efficiency are superior to the traditional UPS.
Description of block diagram
P F C C o n t r o l
B r e a k e r R e l a y
E M I
A C - D C D o u b l e
I/P
A C
Filter
Fig. 2.1 is the hardware block diagram of the UPS.
The UPS operation is described as below:
When the utility power is applied into the UPS, it was divided into two ways after going
through the breaker and EMI filter. One way is connected to AC-DC converter which
converts the utility AC power into a DC voltage which is called DC-BUS voltage then
divide into two path. One path goes to charger which converts the DC-BUS voltage into a
proper DC voltage to charge the UPS battery. The other path goes into DC-AC half bridge
inverter. The other way works as a bypass path. The bypass relay near the output will
choose either the bypass path or inverter output. In general, the UPS will internally do the
self-diagnosis. If there is no problem, the bypass relay will choose the inverter output.
This is so called "ON-LINE mode".
B Y P A S S
L E D B o a r d
Circuit
To Control Board
To Auxiliary Power
Booster
Battery Bank
C h a r g e r D C - D C C o n v e r t e r
To Control Board
Auxiliary
To External Battery Bank P o w e r
5
SHEET 6 TO 7
Control Board
Half-bridge DC-AC Inverter
T o C o n t r o l B o a r d
B Y P A S S
R E L A Y
O / P
A C