Computer-aided design and analysis of power-harmonic filters

Power harmonic filters for rectifiers, motor drives and uninterruptible power systems are usually designed by characterizing currents and voltages by their harmonic components. Usually, no attempt is made to determine the effect of switching of the filters, or of the system operation during a fault in the filter. A superior design method is to use modeling tools to characterize the currents and voltages by their instantaneous values as a function of time. Computer modeling using PSpice is a suitable alternative. In the computer modeling approach, the filter load, for example, a six-pulse phase-controlled converter can be represented accurately. Switching of the power harmonic filters can be accurately represented to determine the turn-on transients. The effect of unbalanced system operation with one filter phase open can be determined. A computer model of an elevator drive system using a full-compliment six-pulse phase-controlled converter with fifth and seventh harmonic tuned filters, connected to an enhanced DC machine model is presented. Resulting waveforms show that the computer model can accurately simulate the static and dynamic characteristics of the entire elevator drive system for four test conditions in just one simulation run.