Analysis of a Three-Phase Twelve-Pulse Voltage Output Type Rectifier

Abstract

Exact solution of a circuit model for a three-phase twelve-pulse rectifier with constant-voltage load and ac-side reactance for the continuous conduction mode is presented. Obtained results are compared to the results provided by sinusoidal approximation. It is shown that the sinusoidal approximation provides acceptable results at low output voltages, with the accuracy being decreased for the output voltages approaching to the discontinuous conduction mode boundary. In comparison to the exact solution, the sinusoidal approximation always provides slightly more optimistic prediction for the rectifier exploitation parameters. Computational complexity of the exact solution is the same as for the solution obtained applying sinusoidal approximation, having the same structure, but different parameters. In comparison to the six-pulse rectifiers of the same type, analyzed in previous publications, agreement between the solutions is better due to the increased pulse number and reduced harmonic content of the waveforms.