Characteristic Parameter-Based Detuned C-Type Filter Design

The C-type filter has been widely used in industry to avoid the harmonic resonance caused by the shunt capacitors. This paper provides a deep and unique insight into the C-type filter design. It will be shown that the C-type filter can be simply characterized by two parameters–the tuning frequency and the R-ratio. The tuning frequency is predetermined based on the system need, thus the entire design process comes down to determine the R-ratio. The correlation between the R-ratio with the filter’s cost and performance is then developed and an optimum value of the R-ratio is solved. Compared with the conventional design methods, the proposed method with one underdetermined variable is simpler and more straightforward. Comparative studies on actual capacitor application cases are conducted to demonstrate the usefulness of the proposed design method.