Characterizing and designing LC filters by contour maps

Three commonly used inductor-capacitor (LC) filters are characterized by their associated contour maps of the power factor, the total harmonic distortion, and the DC-link voltage. It is proven that the per-unit contour maps remain unchanged under different input voltages, line frequency, and load powers. The contour maps with actual quantities can be obtained by converting the per-unit values into the actual values. By observing the contour maps, a suitable filter circuit with smaller component values can be selected under the limitations of the power factor and the harmonic distortion. A design example is used to illustrate the implementation of the LC filters with the contour maps.