To improve the power quality of a multi-pulse rectifier, a zigzag 18-pulse uncontrolled rectifier with an auxiliary circuit at the DC side is proposed. When the grid-side currents are sinusoidal waves, the required DC side injection currents to be compensated can be obtained by analyzing the AC-DC side relationship of diode bridge rectifiers. Then the 6 compensation currents generated by an active auxiliary circuit are injected into the DC side to eliminate the grid-side harmonics of the rectifier. The simulation results verifying the correctness of the theoretical analysis show that the proposed rectifier can mitigate the harmonic content, as the total harmonic distortion of the grid-side current is about 1.45%. In addition, the single-phase inverter used in the active auxiliary circuit has the characters of simple circuit structure and easy controllability.

Averaged models: an AC large signal, DC and AC small signals of a current-controlled buck converter are described. Only peak current mode control of a converter working in the continuous conduction mode (CCM) is considered. The model derivation differs from the typical approaches presented in the literature and doesn’t refer to the multi-loop concept of a current controlled converter. The separation of the variables method is used in the model derivation. The resulting models are presented in the form of an equation set and equivalent circuits. The calculations based on the presented models are verified by measurements and full-wave PSpice simulations.