Study Of FPGA-based Active Power Filter

With the rapid development of power electronics technology, a wide rangeof power electronic devices are applied to industry and daily life. The powerelectronic devices have replaced transformers and asynchronous motor to becomethe most important source of harmonics, resulting in the emergence of a largenumber of harmonic and reactive current in the grid. Therefore, how to governthe harmonic and reactive compensation has become a biggest concern in thepower quality issues.First of all, the paper introduces the generation causes and harms ofharmonic, and illustrates the operating principles of the active power filter,indicating that active filter can achieve good filtering and compensation effects.It summarizes several active filter structures, harmonic detection methods andcontrol methods.In the three-phase three-wire balanced load system, it gives a theoreticalanalysis and structure comparison of the ip-iqdetection method and only-requiredsource current method. It builds an active filter system model with theMatlab/Simulink software, and makes the simulation. It shows that the activepower filter only required source current in the paper not only has a simplestructure, but also has feasibility and effectiveness. Finally, it brings the neuralnetwork control in the control system, proving that it makes good effects inharmonic suppression and reactive power compensation.Given the formula of the capacity, the capacitor voltage and the outputinductor of the main circuit in the active power filter, and through the analysis ofthe DC side capacitor and AC side inductance influencing the main circuit of theactive filter in the supply and current detection method, it determines thecapacitance, inductance and other parameters. With the loss calculation methodof an insulated gate bipolar transistor (IGBT) module in the engineering tocalculate the loss of the selected IGBT, it selects a suitable heat sink through theswitching loss. It uses Ansys software to simulate the designed cooling system, and the simulation results show that the selected radiator meets the requirements.Experimental circuit is built. Measuring the actual temperature of the heat sinkand comparing to the simulation results prove them to have consistency andverify the reasonableness of simulation experiments.It completes FPGA’s logic design processes, and does simulation with theAD control and data storage module, the PI algorithm module, the zero-crossingdetection module, the stagnation ring comparison module, the PWM pulsegenerator and dead zone protection module in the Modelsim environment. Aftergetting the simulation graphics and making the QuartusII comprehensiveplacement and routing, the simulation results show the correctness of FPGAcompilation process.Finally, on the basis of theory and simulation, the successful compiledprogram is downloaded to the FPGA and the active filter system is tested. Theexperimental results show that using FPGA to implement the supply and currentdetection control of the active filter can achieve the effect of the harmonicsuppression and reactive power compensation.