Uninterruptable power supply design using Float Cum Boost technology

Uninterruptable power supplies (UPS) units are basically used in almost all military applications with preferred voltages of 36V DC and 48V DC. In such applications, Float Cum Boost Charger (FCBC) is most commonly used power supply module. Normally, the output voltage obtained from FCBC was used to drive the ULSB MK-II devices which operates on 48V DC. In the present work, the FCBC module has been modified to drive ULSB MK-III devices resulting in better line and load regulation, power factor, efficiency, ripple voltage (lower). FCBC is basically a UPS for delivering regulated output voltage of 48V DC at 4Amps when loaded fully. Alternatively, a battery backup is also provided wherein, the battery is charged when AC mains is present. Even when the 230V AC power supply is OFF, charged battery backup of 24V, 6Amps is sufficient to deliver the required output voltage. The change over from AC supply mode to BATTERY mode is automatically done under the power failure conditions. Therefore, this work is of great interest especially for military applications due to desired outputs.