| In “Big Data” era,various data centers come into being.For a long time,medium and large data centers generally adopt UPS to feed critical IT equipment load with AC power supply.However,there always exit problems such as low energy efficiency,system complicacy in this application.Until late in the 1990 s,a new kind of power source--High Voltage Direct Current(HVDC)was proposed,which exceeded general UPS in terms of energy efficiency all around.At present,they are widely used in data centers in telecom and internet industry.HVDC greatly improve the reliability and applicability by means of using separate modular units.This article focuses on typical topology circuit and control method of HVDC,including two cascades: the front-end PWM rectifier circuit and back-end LLC full-bridge resonant DC/DC converter.The frond-end three-phase PWM rectifier has many features as low total harmonic of distortion for current and good power factor etc.The back-end part adopts LLC full-bridge resonant DC/DC converter which has the advantages of ZVS,high efficiency etc.The thesis firstly introduces the topology and principles for three-phase PWM rectifier,establishes the mathematics models in three coordinate systems.It discusses feed-forward decoupling power model and key double closed loop control method for three-phase PWM rectifier.Then the thesis briefly analyzes the principles of LLC full-bridge resonant DC/DC converter and its three types of relationship between working frequency and resonant frequency.Also it discusses the math formulas among the key parameters for LLC resonant converter.Next the article designs a control program for three phase PWM rectifier based on DSP system.Also it completes the experimental verification in the sampling platform.In the end,it discusses some practical application issues with HVDC rectifier power. |
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