Design And Reaearch On Locomotive Power Test DC Electronic Load With AC Grid-connected

In recent years, with the rapid development of power electronic technology, and various power equipment in various production processes of society are widely applied, these are in need to supply the factory strict load, aging and other testing laboratories. However, the traditional power load test solutions made a lot of consumption on the resistance in vain. Given the lack of traditional power test solutions, this paper mainly selects locomotive power testing AC grid-connected DC electronic load as the research object.Firstly, Analyzes the basic principle of DC electronic load, discusses the main circuit topology of three-stage, two-stage grid-connected DC electronic load, and gives a comparative analysis of two topologies of the electronic load in principle, control strategy, the actual work efficiency, etc. And finally chooses the two-stage topology as the main circuit topology for the object in this study. Electronic load simulation unit DC/DC phase-shifted full-bridge converters and power feedback unit DC/AC single-phase grid-connected inverters’ s working principle is described respectively.Different from traditional PSFB control strategies, this paper uses the output inductor current inner ring and input inductor current outer ring current double closed loop control strategy, the establishment of a small signal model of load simulation unit based on state-space averaging method and analyzed from the perspective of control theory, theory demonstrates good stability and dynamic response characteristics based on the current double closed loop control strategy system. Systematic analysis of the basic working principle and process of the on-stage energy feedback unit DC/AC single phase grid-connected inverter, building single-phase grid-connected inverter with small-signal model, respectively, based on the single-cycle grid-connected current feedback and PI double closed loop control strategy for grid-connected inverter control performance are studied. Accurate obtaining of the grid voltage phase for the network side is the key to achieve unity power factor energy fed into the grid, the software for single-phase locked loop has been studied and given simulation model. Building a whole system simulation model in MATLAB, the simulation results show that the two AC-grid connected DC electronic load’s topology is feasible, the system control strategy on electronic analog converter load current double closed loop control strategy makes that the system has good stability and rapid response characteristics, DC/AC energy feedback portion of the control strategy makes that the system has good steady tracking features, strong anti-jamming and robustness.AC grid-connected DC electronic load system control panel’s main controller selects TI company TMS320F2812DSP+ Lattice company’s CPLD as the core controller. Given the overall structure functional block diagram of the system hardware of the control section, the principles of the control circuit hardware is analyzed in detail and some hardware debugging results are given; the core control framework of the software program control portion is given software design and some core idea program flow is described in detail. Low-power experiment results show that main circuit, control circuit and control strategy for the AC grid-connected DC electronic load have feasibility and validity.