Research On An Asymmetric Topology Of Three-phase Active Power Filter

Under the background of global energy revolution,using cleaner energy has become a consensus.Driven by the "dual carbon" goal,new energy power generation systems,new energy vehicles and a variety of new electrical equipments have developed rapidly.However,a large number of power electronic devices are used in these electrical equipments,and that these connect with grid will inject a large number of harmonic currents into the public power grid,resulting in a series of power quality problems.To ensure the safety and stability of the public power grid and other electrical equipments,the installation of hybrid active power filter is one of the most effective measures at present.Aiming to solve the problems existing in traditional APF,this thesis proposes an asymmetric topology of three-phase active power filter.The topology combines passive filter and low power active power filter to reduce the capacity of Voltage Source Inverter（VSI）and systemic loss.The topology consists of a three-phase bridge,a two-phase dual resonant LC passive filter and a coupled inductor.the topological scheme designed in this thesis reduces the number of devices,discusses the influence of device parameters’ difference on the compensation effect of APF,and proposes a compensation control strategy based on virtual capacitance to realize the effective control of the system.In view of the proposed new HAPF topology,this thesis mainly studies the following three parts: firstly,as the new topology structure is put forward in this thesis,the topology structure and designing purposes are introduced.By making contrasts of the three-phase symmetrical and asymmetrical topology on the mathematical model and the control thought,it is concluded that the asymmetric topology of virtual capacitance compensation control scheme design.According to mathematical model set up the in the abc stationary coordinate system and dq reference frame system,the structure diagram of the control object is established and the rationality of the control scheme principle is verified by simulation.Secondly,the device selection and APF operation parameters design of asymmetric topology circuit are carried out,including filter output branch inductances and capacitors design,dc-side voltage selection of the converter and dc-side capacitor parameter selection.The corresponding design basis is given.This thesis analyzes the asymmetric control strategy,the scheme of harmonic current extraction and digital filter designing parameters,discusses the influence of LC filter circuit parameters difference on HAPF harmonic compensation and carries out the corresponding Simulink simulation experiments to prove.Thirdly,experimental platform based on TMS320F28335 as the core control chip is analyzed in detail,including the design of power circuit,its driving circuit and so on.Besides,the steady-state and dynamic experiments of HAPF system are carried out by using the experimental platform,which verifies the effectiveness of the topology structure and control algorithm proposed in this thesis.