| This paper proposed a novel UPS topology which is a single-phase series-parallel compensation UPS based on high-frequency isolation bidirectional full-bridge DC-DC converter(Referred to a single-phase series-parallel compensation UPS).Firstly,by analyzing the direct and indirect control strategies,the direct control strategy is more suitable for single-phase series-parallel compensation UPS.Under the direct control strategy,the working principle of the single-phase series-parallel compensation UPS system and the power flow of the system under different states are analyzed.Secondly,the nonlinear load characteristics are analyzed in this airticle,and the reason of the output voltage distortion is introduced.Based on the mathematical model of parallel converter,the corresponding control strategy for different load is put forward,it mainly compares the voltage and current double closed-loop PI control,quasi PR control through theoretical analysis and simulation.Then,the mathematical model of the series converter is established and the control target and the control strategy of the series converter are given in this airticle which also introduced the calculation of the input current of the grid,and the voltage control principle of the DC bus about parallel side.In order to realiz the energy of the UPS system flowing in both directions,when the grid voltage fluctuation,the mathematical model of bidirectional full bridge DC-DC converter is also established.The current stress,system reactive power and soft switching characteristics under single phase shift control strategy are analyzed in detail,at the same time,parameter design is also given in this paper.Finally,the MATLAB / Simulink simulation software is used to simulate the UPS system under different conditions,and build the related experimental platform.Simulation and experimental results verify the theoretical analysis and the feasibility of the topology proposed in this article. |
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