Three-phase three-level soft-switched PFC rectifiers

摘要

A low input-current-harmonic three-phase three-level boost rectifier includes an input stage for receiving a three-phase input voltage in relation to a neutral node and an output stage adapted to couple to at least one load. The rectifier further includes one or more switching converter stages, each having a plurality of serially-connected switches coupled to the neutral node, one of the serially-connected switches operating with a fixed duty cycle while the other of the serially-connected switches operating with a variable duty cycle, the fixed duty cycle being a substantially 50% duty cycle and the variable duty cycle being less than or equal to a substantially 50% duty cycle. The serially-connected switches are coupled to clamping diodes and clamping capacitors. The rectifier further includes one or more controllers adapted to vary the switching frequency and/or duty cycle of the plurality of switches based on at least one of a condition of the at least one load or the input voltage and includes one or more decoupling stages, each including one or more inductive elements adapted to inductively decouple the output stage from at least one of the one or more switching converter stages.

主权项

1. A low input-current-harmonic three-phase boost rectifier, comprising:
an input stage for receiving a three-phase input voltage relative to a neutral node, the input stage comprising three terminals, each terminal being coupled to one of the three phases of the three-phase input voltage; an output stage adapted to couple to at least one load, the output stage comprising a plurality of serially connected output capacitors that are coupled between the neutral node and said load; one or more input capacitors each coupled between a terminal of said input stage and said neutral node; one or more switching converter stages, each switching converter comprising:
two or more pluralities of serially-connected switches, each plurality of switches being coupled to said neutral node, at least one of the switches of said plurality of serially-connected switches operating at a variable frequency with a substantially 50% duty cycle and at least one of the switches of said plurality of serially-connected switches operating with a variable duty cycle that is less than or substantially equal to 50%;one or more clamping capacitors each coupled to a common node of the switches of said pluralities of serially-connected switches;one or more clamping diodes each clamping one of the common nodes to one of the voltages across the serially connected output capacitors;one or more boost inductors each coupled to one of the terminals of the input stage to receive a corresponding one of the phases of the three-phase input voltage;one or more input rectifier diodes each coupled between one of the boost inductors and a terminal of one of said pluralities of serially-connected switches; andone or more flying capacitors coupled across said pluralities of serially-connected switches; andone or more controllers adapted to vary at least one of (a) the switching frequency and (b) the duty cycle, based on at least one of: conditions at the load, the input voltage, and the output voltage; and one or more decoupling stages, each decoupling stage provided to be connected to a corresponding one of the converter stages and each decoupling stage comprising a primary inductive element and a secondary inductive element, such that the corresponding switching converter stage is connected across a terminal of the primary inductive element and a terminal of the secondary inductive element, so as to decouple the output stage from the corresponding switching converter stage.