Research On On-line Digital Uninterruptible Power Supply System

With the rapid development of information technology, networking and theconstant emergence of high-precision instruments, protection for device and data isbecoming more and more important. Greater stress is laid on the application of UPSwhich is regard as the safeguard of power. And there is an increasing demand forUPS. The requirement to the performance of UPS becomes higher and higher. Atpresent, UPS can implement high frequency and complex digital control to improveits performance because of the development of high frequency, efficiency powerdevice and the elevation of the performance of digital controller. To achieve thecontinuous improvement of the performance of the UPS and meet the demand forenergy of high quality this paper illustrates the design of On-line Digital UPSSystem.Inverter which is a core part of the UPS affects the output performance of theUPS directly. So inverter control becomes a key point. A new kind of compositecontrol technology is proposed. This technology can make a combination ofrepetitive control and deadbeat control. With this method the UPS will realizeconstant frequency and voltage output what’s more it can output voltage waveformwith low harmonic level and high precision steady state in a variety of load cases andthe dynamic response is also good. Repetitive controller is used to improve steadystate performance of the system and deadbeat controller is employed to enhance thedynamic performance. Saber software is a powerful power electronic simulationsoftware. A comparison of different waveforms and parameters impact is made bysetting models of each part of the circuit and controller of the UPS and using Sabersoftware to simulate the power technology and control method of the UPS.Combing with the simulation analysis, the hardware circuit was set up and DSPwas the core controller. Designing of the active power factor correction based on UC3854link, this paper is focused on designing inverter circuit and relevantauxiliary circuit and written A/D sampling, digital filtering, digital phase lockedfunction DSP through using of various resources reasonably. On the basis of thecomposite control strategy designed the closed-loop control circuit of the system.The results of simulation and experiment show that On-line Digital UPS System hashigh power factor, reliable and stable output, flexible control manner and betteroutput characteristic.