New transfer functions for an accurate estimation of harmonic distortion in AC/DC converters working under unbalanced conditions

In this paper, new transfer functions for the estimation of harmonic distortion in six-pulse AC/DC controlled converters working in continuous mode are proposed. One of the objectives of the paper is extending the use of transfer functions for the case of distorted and/or unbalanced supply voltages. Moreover, important changes in the structure of these transfer functions are proposed, with the aim of achieving higher accuracy in the estimations. With this technique, it is possible to predict the harmonic components of currents not only at the DC side, but also at the AC side, even for noncharacteristic harmonics. This paper deals only with the AC/DC transfer phenomenon. The new algorithm proposed in this paper is especially suitable to distinguish between the DC current harmonic components caused by the converter and those caused by the interaction of the load.