Design of a center-point-clamped AC-AC converter based power-line conditioner

A new approach for power line conditioning has been presented in the paper. State of the art line-conditioning devices like Static Voltage Restorer (SVR), Dynamic Voltage Restorer (DVR) and AC-AC power line conditioner offer higher bandwidth and low filter size requirement due to their high switching frequencies. However, commercial utilization of such devices is limited by the voltage blocking capability of power semiconductor devices employed in these converters. Recent literature reports a center-point-clamped converter topology in which the grid voltage is clamped to its midpoint to reduce the voltage stress on the bi-directional switches in the converter by 50%. This paper introduces a line conditioner based on the center-point-clamped ac-ac converter topology. A duty cycle control scheme has also been implemented for feedback control of the line conditioner. Simulation results verify that proposed line conditioner offers superior spectral content, high power transfer efficiency and reduced voltage stress on the bi-directional switches. Furthermore, the control scheme has been shown to provide up to 10% load voltage regulation under dynamic line voltage and loading conditions. Detailed experimental results from a scaled down laboratory prototype rated 500 W, verifying the operation and closed loop control of the proposed power line conditioner have been presented in this paper.