Significance of working point determining line current harmonics in controlled AC/DC converter

Determining line current harmonics in controlled AC/DC power converters, the actual working point given by the average DC voltage and the DC mean current is of significant importance. For good DC smoothing, the consideration of a sufficient control margin in many applications leads to a distinct reduction when evaluating harmonics. To investigate the general case including commutation and DC current ripple, IEEE-Std. 519 as well as the recent FFT-proposal deal with approximated angles. This simplification causes the problem of realization of the required DC mean current in cases of higher DC ripple. To avoid this, a modified version of the selection method is proposed. A comparison of time simulations shows that only this procedure determines line current harmonics with sufficient small error.