A Kind Of On-line Detection And Display The Battery Condition Of The UPS

This paper presents two kinds of gist and practice to judge UPS battery condition. First, when the battery charged by a charging current, and the battery’s charging time exceeds a predetermined number of hours but its terminal voltage has not yet reached the full charge requirements, it can preliminarily judge that the battery has an internal short circuit. Second, after the battery is full charged and stopped, use a large current to discharge it for a few seconds. By this time, if the battery voltage drop under the discharged state is greater than a certain value, it can preliminarily judge that the battery’s internal resistance has increased. According to these two criterions to design a kind of on-line detection and display the battery condition of the UPS. The system not only has the uninterrupted power supply ability and the battery charging function, also can carry on the on-line detection of battery. By measuring the battery charging time and detecting the battery terminal voltage for large current discharge after fully charged, to make the judgment whether the battery condition is good, qualified, or damage, and then display it. The system is mainly composed of UPS circuit, battery detection circuit, display and alarm circuit, auxiliary supply and control system, etc.(1) The UPS circuit is the core to realize the uninterrupted power supply ability and the battery charging function. When the mains power supply is normal, the power can be directly supplied to the load. At this moment, if the control system detects the battery needs charging, then charges it, and let it store energy. When the mains supply interrupted, the energy stored in the battery via the inverter output, so as to realize the uninterrupted power supply to the load.(2) Battery detection circuit is working under the control of the control system, characterized in that, between the UPS battery positive and negative ends is equipped with discharge circuit and voltage detection circuit. It is the foundation of the system to realize the battery status detection.(3) Display and alarm circuit is mainly composed by some light-emitting diodes and a buzzer. When the battery condition is damaged, the red LED keeps bright and the buzzer keeps ringing; when the battery condition is qualified, the green light flashing and the buzzer ban ringing; when the battery condition is good, the green keeps bright and the buzzer ban ringing too.(4) Auxiliary supply is aimed at providing working power supply, mainly+5V and+12V DC power, for the single chip microcomputer, operational amplifier, display device, and some related chips or devices, etc.(5)The core component of control system is adopted STC12C5A60S2 single-chip microcomputer, which integrates internal 8-road 10-bit high-speed A/D converter. With some power devices, the control system can realize the control of the battery charge or discharge process, and the battery detection process. Moreover, in software design, use assembly language programming design a monitoring program to manage the subroutine.The entire system adopts the hierarchical and phased design method. On the bottom, the analog circuit is adopted to realize the closed loop control. And on the top, use a microcomputer to realize the process control. When doing Hardware design, do some simulation analysis for parts of circuit on the Multisim12 simulation software platform. Through the simulation analysis, improve the design, and determine the parameters selection. Finally, set up the experimental circuit to debug analysis. And indicate that, when on-line detection its battery, the system has no effect on UPS’s normal work. To a certain extent, it effectively improve the reliability and cost-effective of UPS, and it has good application value.