Noncharacteristic line harmonics of AC/DC converters with high DC current ripple

To investigate the basic mechanisms generating noncharacteristic line current harmonics of AC/DC converters with high DC ripple, the assumption of negligible small commutation is used. Thus, simple analytical models can be derived describing the effect of voltage unbalance in case of equidistant phase angle control and control angle asymmetry, respectively. By means of superposition of both components, the according behaviour applying individual phase angle control is described. Finally, it is shown that the effect of resonance excitation in diode rectifier circuits can also be estimated using the proposed modeling. Comparing simulations confirm the validity of the approximations. However, the strong influence of the commutation especially on the negative sequent systems requires further investigations