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in the above design i have tried to design UPS but it doesnt work as have thought. any one who has know how about UPS cand comment here! the working principle is below. please help!
The designed single phase on line UPS system has two operating modes: normal mode, stored energy mode. In the normal mode of operation the power is passed from the AC/DC rectifier to the DC/AC inverter and the load is continuously supplied with high – quality AC power. Since rectifier in this section converts alternating current (AC) to direct current (DC). The four diodes (D1, D2, D3 and D4 ) in the above designed diagram are used to change the incoming power from AC to DC and allow current to flow only in one direction. The diodes D1 and D3 conduct on the positive side. While D2 and D4 conducts on the negative side.
The D1 diode conducts when the AC supply is positive and D4 conducts when the AC supply goes ne gative. This drives D1D3 more positive and D2D4 more negative. Thus, D1 and D4 converts the AC supply power in to DC power. The rectified DC supply has rippled voltage .Thus, the capacitors (C1 ) connected at the output terminal of the rectifier is used as capacitor filter to reduce the ripple voltage .after the rectification of this ripple DC voltage is supplied to the inverter section which consists of Insulated Gate Bipolar Transistor IGBT with pulse width modulation (PWM).
The principle of IGBT switches in the inverter is: Q1 and Q4 are turned ON simultaneously and remained ON for the required duration of time. When they become turned OFF, Q2 and Q4 will be turned ON and remained ON for the second half cycle. In this mode of operation the new designed converters (rectifiers) in the form of diodes are also used to convert the incoming AC main supply in to DC supply source in order to recharge the lead acid battery and this charged battery gives supply power through the control circuit to the inver ter not only during power interruption but also in the presence of electric power supply.
Static switch is used only in case of failure or maintenance of UPSs is required.
As the name implies, static switches are free of moving parts. This is made possible as a result of semiconductor technology. The “switch” in a single – phase STS is essentially comprised of two pairs of semiconductor switches called silicon controlled rectifiers (SCR), also called thyristors, which are controlled by a sensing circuit. When the circuit senses that the primary path is out of tolerance, it disconnects the primary path switch and connects the alternate path switch (back up).
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