| The objective of this dissertation was to develop a power electronics system that will be used with any existing single-phase rectifier and improve its harmonic content and power factor to an acceptable level. A switching circuit with a boost inductor and two feedback loops, is the result of this work. One of the feedback loops uses a sample of the output voltage of the rectifier to reduce line current harmonics, increase power factor, and to accomplish output voltage regulation. The second feedback loop uses a sample of the line current as the input to further reduce harmonic content in line current and increase power factor. Verification of this circuit in hardware showed that for a load resistance RL of 112 Ω, the THD has been reduced by 91.45%, power factor has increased by 39.55%, and efficiency has decreased by 8.79%. Also for a load resistance RL of 1005 Ω, the THD has been reduced by 89.21%, power factor increased by 98.66%, and efficiency decreased by 14.38%. The third harmonic level of the line current is lowered by 93.35% for a load resistance of 112 Ω, and 82.45% for a load resistance of 1005 Ω. Thus it can operate for a full range of load resistance. The advantage of this circuit is that it can operate as an add-on circuit to any commercially available rectifier. |
