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This paper presents a three-phase voltage-source 36-pulse converter that draws almost sinusoidal currents. The converter results from the combination of a series-connected 12-pulse voltage-source rectifier with a passive voltage-injection circuit and a bidirectional switch, referred to as hybrid injection. The voltage-injection circuit uses a single-phase rectifier bridge and a single-phase transformer. Both the voltage-injection circuit and the bidirectional switch operate at six times the supply frequency and have a low rating. In this paper, the converter operation is explained and analyzed. Subsequently, the converter is evaluated experimentally using a 4-kW 400-Hz prototype, where the [THD.sub.I] of the line currents was measured to be below 1.2%. Index Terms--AC-DC power conversion, aircraft power systems, power quality, rectifiers.

A two-phase buck–boost converter utilizing dual interleaving is presented in this article. The dual interleaving consists of an interphase transformer (IPT) that doubles the ripple frequency together with two conventional buck–boost switching arms, mitigating the inductor ripple current and aiding to increase the power density of the converter. A description of the design and selection of the power devices is presented for a 32-kW, 75-kHz dual interleaved SiC prototype with an IPT, such that a power density of 7.4 kW/kg is achieved. The operation of the circuit is verified experimentally using a prototype with 315–385 V supply range and 350-V output voltage, achieving 97.1% peak efficiency at 32 kW. The experiments reveal that the interleaved coupled currents are equalized without an active balancer. [ABSTRACT FROM AUTHOR]

Two techniques are presented to balance the filter capacitor voltages of a multipulse rectifier with the active injection operating on a variable-frequency supply. The active injector consists of a low-rated bidirectional switch that modifies the behavior of a 12-pulse rectifier at either low or high frequency, resulting in 24-pulse or multilevel pulse width modulation operation, respectively. The operation of the rectifier and the injector, the practical issues that unbalance the capacitor voltages, and the methods to correct this imbalance are explained together with experimental results obtained with a 4-kW prototype. [ABSTRACT FROM AUTHOR]