Design and Development of On Line UPS Using EPROM

Abstract

UPS (Uninterruptible Power System) protects different types of sensitive electrical equipment: computers, workstations, sales terminals, critical instrumentation, telecommunications systems, process control systems, etc. The UPS protects them from problems associated with utility power of poor quality, or a complete loss of power. Sensitive electrical equipment needs protection from electrical interference.

There are mainly two types of UPS, first one is off line UPS and second one is on line UPS. Based on topology used in converter and inverter, they are further classified in to full bridge and half bridge. Each of this topology has its own advantage and disadvantages. We are workinwith H-bridge inverter topology based UPS.

Here 230 V supply is given to the controlled rectifier gives controlled 48 V DC. The output of the rectifier is applied to capacitor for filtration. Now from this capacitor tow outputs are taken. First is going to the battery charger to charge battery. The second one is given to SMPS circuit.

When 230 V is available from AEC at that time, battery gets charge through the output of rectifier and capacitor. And same supply from capacitor of charger is given to SMPS. So every time, even AEC supply is not available, SMPS remains in circuit.

When AEC power is not available, charging of battery gets stop. And supply from capacitor, which is supplied from charger, is given to the SMPS. Output of SMPS is taken as reference and given to different other components in different operations, such as SPWM control, Driver, Protection, etc.

For SPWM control we are using Sine waves at 50 Hz (Generated using EPROM programming) and Triangular waves at 15 KHz. SPWM pulses are used to trigger IGBT in H-bridge inverter through driver circuit. Output of inverter is applied to step up transformer whose secondary generates 230 V ac at 50 Hz.