Delta Electronics 3KVA, 700VA manual Introduction, Theory of operation

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

B r e a k e r

A C I/P

E M I Filter

		B Y P A S S
P F C C o n t r o l	L E D B o a r d		C o n t r o l B o a r d
Circuit
T o C o n t r o l B o a r d
		To Auxiliary Power
R e l a y					B Y P A S S
					R E L A Y
A C - D C D o u b l e			Half - bridge DC - AC Inverter	A C	O / P
Booster
Battery Bank
C h a r g e r		D C - D C C o n v e r t e r
		T o C o n t r o l B o a r d
T o C o n t r o l B o a r d
		Auxiliary
To External Battery Bank		P o w e r

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”.

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SHEET 6 TO 7