DESIGN AND IMPLEMENTATION OF 600VA UPS based 0n 89C51

ABSTRACT

UPS control using micro controller is highly reliable less complex and
economical when compared the conventional UPS system. This paper explains about
the design and implementation of UPS using micro controller. The micro controller is
mainly used for control applications. So, micro controller is used for this proposed
work. The main function of the UPS (uninterrupted power supply) is to provide an
uninterrupted power supply and it should function automatically when the mains
supply cutoff. This automatic function in the conventional UPS is done by control
system. It involves certain complex work. So, in this proposed work, micro controller
does the automation of the UPS. Some of the automatic functions to be done by the
micro controller are overload protection, no load release, deep discharge cutoff and
inverter operation.
There are different types of micro controller families. In this proposed work, the
micro controller-89S52 because of its high on chip ROM capacity, RAM capacity,
serial ports, input ports, etc. The micro controller 89S52 is superior in its memory
capacity. This micro controller is best suited for fast development. Since flash
memory can be erased in few seconds compared to the twenty minutes or more
needed for the 8751. By this, 89S51 is used to eliminate the waiting time needed to
erase the chip and thereby speedup the development time. It is a 40 pin micro
controller in which 3 pins are used for serial interfacing, i.e., one acts as receiver
another acts a transmitter and the third as ground. By this we can interface any
components serially, it has 4 ports, port 0, port 1,port 2 and port 3 and it is used for
various functions of UPS such as on load release, deep discharge cutoff and so on.
This micro controller can be operated at high frequencies and it consumes low power.
Thus it is ideal for many projects.

There are different types of UPS. They are OFF line UPS and ON line UPS. This
paper focuses on the design of Offline UPS. Because it is mostly prepared than ON
line UPS. For example, it finds its application in the household appliances, a personal
computer, and so on.
The transistors used in UPS design are replaced, as MOSFET’S because of its
certain special features as positive temperature coefficient so that it has high current
carrying capability. It has low switching losses and the MOSFET turn on and turn off
can be obtained rapidly. Also it is easily available and has switching performance.
The conventional UPS system involves complex control system. In order to
reduce the complexity of the control system of conventional UPS embedded
controller are currently being used. This project describes the design and
implementation of 1KVA.