36-pulse hybrid ripple injection for high performance aerospace rectifiers

This paper presents a 3-phase, voltage-sourced, 36-pulse converter that draws almost sinusoidal currents. The converter results from the combination of a series connected, 12-pulse, voltage-sourced rectifier with a passive voltage injection circuit and a bi-directional switch. The voltage injection circuit uses a single-phase rectifier bridge and a single-phase transformer. Both the voltage injection circuit and the bi-directional switch operate at six times the supply frequency and have a low rating. In this paper, the converter operation is explained and analysed. Subsequently, the converter is evaluated experimentally using a 4 kW, 400 Hz prototype, where the THD_I of the line currents was measured to be below 1.2%.