Power Electronics and Drive Systems
IEEE 1999 International Conference on Power Electronicsand Drive Systems, PEDS’99, July 1999, Hong Kong.
Accurate Prediction of Backup Time in an U P S and its Display on User Computer Monitor Screen
Pratik Mukberjee, Biswajit Majumdar, FazaI k Talukdar, StUdentMember, IEEE Ashim GanguIy* and Sujit K. Biswas, Sr. Member, E E E
Department of Electrid Engineerins JadavpurUmve.rsily, Calcutta 700032,N I A .
*TataConsultancyServices calartta700 091, INDJA
E-maik p a i - u h r e @ t a l a rtkmkejebmi.m
Abstract -In an UPS the battery acts as a resetvoir of energy.
However the available energy is dependent upon several parametels like the c h a w time, charging rate, self discharge, aging of the cells and the permitted voltage upto which discharge is to be allowed. Thus the stored eneqy content must be kmwn accurately to predict the backup operation time left in the event of abnormal mains supply, after which the Ups has to be shut down. This paper presents a method of on-line calculation o the f battery backup time depending on the actual rate of discharge and its terminal voltage This technique takes into account the charge condition of the battery, the self-discharge, aging and change in load current to give a tme estimate of backup t m ie Thii information is sent to the computer via a serial port and is displayed at one corner of the e r monitor screen,Such a hcility helps the user to save and close all the running programs before the shut down of the UPS
L INTRODUCTION
The computer interfaced Ups has a greater impact on the user as the system can make the user aware about the status of the battery backup directly via the computer monitor. As a result, during a power outage, information on the backup time left can help the user to save and close all the running software on the computer before the shutdown of the UPS due to low battery condition. In UPS, the battery acts as an energy reservoir. When the power line condition is good, it takes energy from the
Accurate Prediction of Backup Time in an U P S and its Display on User Computer Monitor Screen
Pratik Mukberjee, Biswajit Majumdar, FazaI k Talukdar, StUdentMember, IEEE Ashim GanguIy* and Sujit K. Biswas, Sr. Member, E E E
Department of Electrid Engineerins JadavpurUmve.rsily, Calcutta 700032,N I A .
*TataConsultancyServices calartta700 091, INDJA
E-maik p a i - u h r e @ t a l a rtkmkejebmi.m
Abstract -In an UPS the battery acts as a resetvoir of energy.
However the available energy is dependent upon several parametels like the c h a w time, charging rate, self discharge, aging of the cells and the permitted voltage upto which discharge is to be allowed. Thus the stored eneqy content must be kmwn accurately to predict the backup operation time left in the event of abnormal mains supply, after which the Ups has to be shut down. This paper presents a method of on-line calculation o the f battery backup time depending on the actual rate of discharge and its terminal voltage This technique takes into account the charge condition of the battery, the self-discharge, aging and change in load current to give a tme estimate of backup t m ie Thii information is sent to the computer via a serial port and is displayed at one corner of the e r monitor screen,Such a hcility helps the user to save and close all the running programs before the shut down of the UPS
L INTRODUCTION
The computer interfaced Ups has a greater impact on the user as the system can make the user aware about the status of the battery backup directly via the computer monitor. As a result, during a power outage, information on the backup time left can help the user to save and close all the running software on the computer before the shutdown of the UPS due to low battery condition. In UPS, the battery acts as an energy reservoir. When the power line condition is good, it takes energy from the