Research And Design On The Uninterruptible Power Supply In High Voltage DC Power Supply System

With the large-scale application of various non-linear devices,the harmonic current into the grid is very large,seriously affecting the quality of power supply.Communications,medical,military industry and other important departments,usually using uninterruptible power supply to improve the quality of electricity,reduce the harmonic pollution on the grid.However,with the popularity of uninterruptible power supply(UPS)popular application,its limitations become more and more obvious.The problem is mainly one of the inverter failure rate is high,poor reliability,complex structure,protection,energy consumption.In this thesis,the design of the inverter using the high voltage DC uninterruptible power supply to replace the AC uninterruptible power supply,simplifies the system structure,improve the conversion efficiency and power supply reliability.Firstly,the difference between high voltage DC uninterruptible power supply and traditional AC uninterruptible power supply is analyzed.In view of the transition scheme of 240V voltage level of high voltage DC power supply system,this thesis designs an uninterruptible power supply with output voltage of 380V.The design of the DC uninterruptible power supply is designed in detail.In view of the uncontrollable rectifier bridge commonly used in the rectifier module,an improved bridgeless power factor correction structure is proposed to improve the power factor and reduce the total harmonic distortion of the input current,So that the power factor is close to 1.For the battery charge and discharge module using a parallel interleaved bi-directional Buck/Boost structure,can reduce the current through the switching device,while reducing the current ripple,improve battery performance.Secondly,the capacitance inductance parameter of the improved bridgeless power factor correction structure is designed,and the mathematical model is modeled on the continuous mode based on the state space averaging method.According to the different requirements of the crossing frequency and the phase angle margin,the parameters of the current loop and the voltage loop PI controller are analyzed in detail.The simulation model is built and the simulation analysis is carried out to verify the design of the input side power factor and the input current harmonic distortion Claim.Finally,based on the detailed analysis of the working principle of the interleaved two-way Buck/Boost converter,the mathematical model is established based on the state-space averaging method in charge and discharge mode respectively.According to the different requirements of crossing frequency and phase margin,the parameters of the controller are designed and analyzed,and the simulation circuit of the two modes is built.It is verified that the battery can output the power quickly and suddenly reach the steady State,peak voltage peak to meet the design requirements;at the same time on the battery constant current and constant voltage mode of charging,made a simulation to meet the design requirements.