Skip to Main Content
The probabilistic approach is an efficient mean for harmonic prediction since it allows to take into account the randomly varying operating conditions of static converters. Although the six-pulse ac/dc converter has been the subject of probabilistic modeling, little consideration has been given to the 12-pulse ac/dc converter. In high-power applications, such as large rated dc power supplies and large rated dc and ac drives, 12-pulse ac/dc converters are usually preferred since they allow to reduce system disturbances due to harmonic currents. This paper presents an analysis of the random properties of harmonic currents produced by 12-pulse ac/dc converters that operate under random variations of their dc load and voltage unbalance. The probability density functions of the amplitudes and phase angles of the harmonic currents (of orders 12 k±1 and 12 k-6±1) are established and validated by results obtained from Monte Carlo simulations.