The Application Of Three-level Boost Converter In The UPS

With a wide range of applications of UPS(Uninterruptable Power System) in finance, communications, military, and medical and other industries, requirements of users for UPS become more and more demanding while selecting them. To meet the needs of users, it is crucial to improve UPS reliability, flexibility and stability in the context of UPS continuing to supply. Besides, the rated capacity and robustness of the UPS also put forward higher requirements.First of all, this paper carries out analysis on its operation principle, mathematical modeling and digital average current control of the pre-UPS single-phase three-level Boost converter. What’s more, the influences on the input current caused by the second harmonic of DC bus voltage are suppressed through introducing a notch filter; At the same time, the basic working principle, modulation method and LC filter of a single-phase three-level inverter is simply analyzed.Secondly, in order to improve the anti-disturbance performance of the UPS and achieve effective control of the UPS, load current feedforward control and optimization of feedforward control teo kinds of methods in this paper is introduced respectively to suppress the DC bus voltage fluctuation.Thus, the dynamic response of the UPS capacity is dramatically improved.Finally, the single-phase UPS digitized experimental platform is established with a core-TI’s digital signal processor TMS320F2810. Through simulation and experiments, it is demonstrated that high power factor correction is feasible, notch filter has an inhibiting effect on the input current which is limited by the second harmonic of the DC bus voltage and optimization feedforward control inhibits the fluctuation of DC bus voltage. Meanwhile,it shows that a single-phase digital UPS based on this circuit topology has high practical value.