Harmonic Filter Design: Eliminating Harmonic Current Distortion Caused By Pulse Rectifiers

By carefully analyzing the spectral distribution between the rectifier output and the grid input, the harmonic frequencies and amplitude components can be determined. During the design phase, based on these harmonic characteristics, appropriate inductors and capacitors (LC) are configured to determine the resonant frequency and impedance matching of the harmonic filtering equipment circuit. This design allows the active harmonic filter cost circuit to provide a low-impedance path at the harmonic frequencies, thus "guiding" the harmonic current through the ahf harmonic filter circuit instead of injecting it into the public grid.

In practical engineering, a comprehensive evaluation of the system grid impedance, load conditions, and the resonance possibility between the automatic harmonic filter circuit and the power supply is necessary. If the parameters are not properly matched, the harmonic filter cost circuit may form parallel resonance with the grid, causing more serious problems.

For optimal results, it is recommended to use simulation tools (such as MATLAB/Simulink) to perform spectral analysis and tuning of the low harmonic vfd circuit. The simulation results will guide the selection of the capacitance and inductance of the filter components to filter out the main 5th and 7th harmonics, as well as some higher harmonics.