Single-phase active front end rectifier system for use with three-phase variable frequency drives

Abstract

A voltage source inverter comprises a rectifier having an input for receiving single-phase AC power from an AC source and converting the AC power to DC power on a DC bus. The DC bus has first and second rails to provide a relatively fixed DC voltage. A DC bus capacitor is across the first and second rails to smooth voltage ripple. An inverter receives DC power from the DC bus and converts the DC power to AC power. An active front end circuit comprises a pair of filter capacitors in series across the first and second rails to create a midpoint. A bidirectional switch is connected between the rectifier input and the midpoint. The bidirectional switch is controlled to inject current into the midpoint of the DC bus.

1 . A voltage source inverter comprising:
 a rectifier having an input for receiving single-phase AC power from an AC source and converting the AC power to DC power on a DC bus, the DC bus having first and second rails to provide a relatively fixed DC voltage, and a DC bus capacitor across the first and second rails to smooth voltage ripple;   an inverter for receiving DC power from the DC bus and converting the DC power to AC power; and   an active front end circuit comprising a pair of filter capacitors in series across the first and second rails to create a midpoint, and a bidirectional switch connected between the rectifier input and the midpoint, the bidirectional switch being controlled to inject current into the midpoint of the DC bus.   
     
     
         2 . The voltage source inverter of  claim 1  wherein the bidirectional switch comprises two switches connected in a common emitter or common collector configuration. 
     
     
         3 . The voltage source inverter of  claim 1  further comprising first and second inductors connected between opposite sides of the AC source and the rectifier. 
     
     
         4 . The voltage source inverter of  claim 3  wherein the first and second inductors are of equal inductance. 
     
     
         5 . The voltage source inverter of  claim 1  wherein the DC bus capacitor comprises an electrolytic capacitor and the filter capacitors comprise film capacitors. 
     
     
         6 . The voltage source inverter of  claim 1  wherein the filter capacitors each are about 10 to 15% of the DC bus capacitor value. 
     
     
         7 . A boost converter comprising:
 a rectifier having an input for receiving single-phase AC power from an AC source and converting the AC power to DC power on a DC bus, the DC bus having first and second rails to provide a relatively fixed DC voltage, and a DC bus capacitor across the first and second rails to smooth voltage ripple; and   an active front end circuit comprising a pair of filter capacitors in series across the first and second rails to create a midpoint, and a bidirectional switch connected between the rectifier input and the midpoint, the bidirectional switch being controlled to inject current into the midpoint of the DC bus to provide a regulated DC source.   
     
     
         8 . The boost converter of  claim 7  wherein the bidirectional switch comprises two switches connected in a common emitter or common collector configuration. 
     
     
         9 . The boost converter of  claim 7  further comprising first and second inductors connected between opposite sides of the AC source and the rectifier. 
     
     
         10 . The boost converter of  claim 9  wherein the first and second inductors are of equal inductance. 
     
     
         11 . The boost converter of  claim 7  wherein the DC bus capacitor comprises an electrolytic capacitor and the filter capacitors comprise film capacitors. 
     
     
         12 . The boost converter of  claim 7  wherein the filter capacitors each are about 10 to 15% of the DC bus capacitor value.