| Abstract |
A novel, but simple method of calculating the AC side currents in capacitor-filtered rectifiers is introduced. The describing function method, which is useful in analyzing nonlinear systems, is used in the calculation. The similarity between the waveform in the AC line current in a capacitor-filtered rectifier and that in a thyristor-controlled circuit, to which the describing function method can be applied easily, is first shown, and the relationship between various parameters in the capacitor-filtered rectifier and those in the thyristor-controlled circuit is clarified in a per-unit form for a wide range of the parameters in the rectifier. The way of calculating the AC line current in the equivalent thyristor-controlled circuit on the basis of the describing function method is then discussed. As an application of this new approach, the AC side currents in two rectifiers connected in parallel as well as in the parallel circuit consisting of a rectifier and a R-L series circuit are calculated, and the validity of this method is investigated by comparing the results calculated through the proposed method with the rigorous solution obtained from the state-space model of the circuits. Finally, the AC-line current in three rectifiers connected in parallel is predicted based on this approach, and the usefulness of the method is also shown. |
