Patent ID: 9667063
Date: 2017-05-30
CPC Classifications: H02J,H02M,Y02E

Claim:
1. A filter for a multipulse-converter system that has characteristic harmonic currents, and causes non-characteristic harmonic resonance at harmonic frequencies including a third harmonic frequency, fifth harmonic frequency and a seventh harmonic frequency, the filter comprising: a first series capacitor; a first series inductor; a frequency-dependent impedance block providing high equivalent resistance for damping non-characteristic harmonic resonance, the frequency dependent impedance block including a second capacitor in series with a resistor, and a second inductor in parallel with the second capacitor and the resistor, the frequency-dependent impedance block having a parallel resonance frequency; the first series capacitor, first series inductor and the frequency-dependent impedance block being jointly tuned so that the filter has a tuning frequency to filter the characteristic harmonic currents, the filter having an equivalent impedance; and wherein the second capacitor has a capacitance and the second inductor has an inductance, the capacitance and inductance being selected so that the parallel resonance frequency is greater than the third harmonic frequency and less than the seventh harmonic frequency; and wherein the equivalent impedance of the filter approaches proportionality with frequency for frequencies greater than the tuning frequency; each of the first series capacitor, first series inductor, frequency-dependent impedance block being suitable for use in multipulse converter systems.