Design of modular rectifiers with magnetic AC coupling for large current and low voltage applications

Rectifiers designed to deliver large DC currents at very low voltages deal with high conductive losses. Single way SCR rectifiers become the standard topology if controlled currents are required; however recent approaches propose using Magnetic Coupled Converters (MCC). These topologies work by connecting a frequency changer with a single way diode based rectifier across a magnetic AC coupling. This solution was originally designed for low power and high efficiency DC sources, but efficiency issues make the MCC topology interesting for medium and high power applications. This work proposes a modular approach for MCC, integrating concepts taken from medium voltage current converters as: (a) stacking of standard topologies, (b) using simple current control loops and (c) using optimized multilevel current patterns. Finally, mathematical models are analyzed and theoretical results are validated by simulation.