Comparative Analysis of Two Novel Passive Harmonic Suppression Circuits for Industrial Applications

The 12-pulse diode rectifier (12-PDR) fails to comply with the limits of total harmonic distortion (THD) of supply current to be less than 5% specified in the IEEE Standard 519. Passive harmonic suppression circuits (PHSCs) have been observed to be a viable and cost-effective solution to improve the THD of AC-mains current at a reduced cost. PHSCs increase the number of rectification pulses without leading to significant changes in the installations and yield harmonic reduction in both AC and DC sides. This paper presents a comparative analysis of two novel PHSCs connected at the DC-bus of 12-PDR. One is PHSC-I based on four tapped reactors (FTRs) and four auxiliary diodes; the other is PHSC-II, with two tapped reactors (TTRs) and two auxiliary diodes. The operation modes and optimal parameters of both PHSCs are analyzed with similar inputs (AC side) and outputs (DC side). Both 12-PDR are connected to the same AC source as input, and both PHSCs supplied similar DC loads at their outputs, thus leading to an accurate and fair comparison between the two PHSCs. The results show that the input current THD of a 12-PDR with PHSC-II is lower than that of a PHSC-I and lower than existing passive harmonic suppression circuits. In addition, PHSC-II leads to lower connection losses, current stress, and cost than PHSC-I, so in industrial applications that require low input current THD, low connection losses/current stress, and low cost, PHSC-II is highly recommended.