Closed loop AC voltage generation using Harmonic Cancellation Technique

AC power supplies generated by means of an inverter are under very restrictive specifications regarding their AC output voltage THD, even when they are supplying both linear and nonlinear loads. The presence of the low frequency harmonic content due to nonlinear loads operation, greatly increase the THD of the AC power supply output voltage. Traditional state of the art techniques approach this problem from two main sides: filtering and fast control loops. However, the proposed technique aims to solve the aforementioned problem from a different point of view: the inverter modulation technique. Therefore, the Harmonic Cancellation Technique (HCT) has been developed. It is a modulation technique which is able to cancel out the low frequency harmonics due to the nonlinear load operation through the proper pre-distortion of the inverter output voltage. The present paper provides the experimental results and performance of the Harmonic Cancellation Technique in closed loop operation.