US 8,274,803 B2 · Low stress soft charge circuit for diode front end variable frequency drive

Abstract

A variable frequency drive comprises a diode rectifier receiving multiphase AC power from a source and converting the AC power to DC power. An inverter receives DC power and converts the DC power to AC power to drive a load. A link circuit is connected between the diode rectifier and the inverter and comprises a DC bus to provide a relatively fixed DC voltage for the inverter. A bus capacitor is across the bus. A soft charge circuit limits inrush current to the bus capacitor. The soft charge circuit comprises an inductor connected between the source and the link circuit and a switch circuit in the link circuit for selectively providing a semiconverter configuration or a full bridge converter configuration to provide two stage charging of the bus capacitor.

Claims20

Dependent claims

A voltage source inverter comprising:

a rectifier having an input for receiving multi phase AC power and converting the AC power to DC power at an output;
an inverter for receiving DC power and converting the DC power to AC power;
a link circuit connected between the rectifier circuit and the inverter circuit and comprising a DC bus having first and second rails to provide a relatively fixed DC voltage for the inverter, and a bus capacitor across the first and second rails;
and
a soft charge circuit to limit inrush current to the bus capacitor, the soft charge circuit comprising an inductor connected between the rectifier input and the second rail and a switch circuit in the second rail between the rectifier output and the bus capacitor to provide two stage charging of the bus capacitor.

2 more elements

Dependencies are inferred from the claim text.

Low stress soft charge circuit for diode front end variable frequency drive

Life of this patent

Low stress soft charge circuit for diode front end variable frequency drive

Life of this patent

Abstract

Claims20