Damped High Passive Filter—A New Filtering Scheme for Multipulse Rectifier Systems

Multipulse rectifier systems are commonly used to reduce harmonic emission. However, they still require the installation of noncharacteristic harmonic filters to prevent harmful resonance between its high-pass filter and the system impedance. The advantage of a multipulse configuration-very low noncharacteristic harmonic emission-is, therefore, not fully utilized. In view of this shortcoming, a novel filter called the damped high-pass filter is proposed. The filter does not cause resonance at the noncharacteristic harmonic frequencies. As a result, traditional noncharacteristic 5th and 7th harmonic filters are no longer needed, resulting in significant cost and space savings for the multipulse systems. The core idea behind this filter is a frequency-dependent resistor block that provides high damping at the noncharacteristic harmonic frequencies. The design procedure for the proposed filter is presented. Performance and usefulness of the new filtering scheme has been demonstrated through comparative studies on two actual industry cases.