US 6,366,483 B1 · PWM rectifier having de-coupled power factor and output current control loops

Abstract

A PWM rectifier wherein the switching bridge has m input filter capacitors, each connected at a terminal thereof, to the line side of the bridge. These terminals are used to connect an m-phase a.c. power supply (m>=1) having a per phase system inductance to the bridge. A current smoothing inductor is connected to the load side of the bridge and enables a load to be connected thereto. A switching pattern generator controls the switches in the switching bridge based on a reference output current. A first control loop is provided for determining an active portion of the reference output current based on a desired power level of the load and an m-phase voltage at the capacitor terminals. A second control loop is provided for determining a reactive portion of the reference output current based on the m-phase voltage at the capacitor terminals. The reactive portion of the current is selected so as to obtain a desired per phase power factor, such as unity, on the power supply. In this manner the output current and power factor control loops are independent of and not coupled to one another.

Claims16

Dependent claims

A rectifier, comprising:

a switching bridge for converting alternating current into direct current, said bridge having a line side and a load side,
m input filter capacitors, each connected at a terminal thereof to the line side of the bridge, wherein an m-phase a.c. power supply having a per phase system inductance is connectable to the m terminals, m being an integer greater than or equal to one;
the load side having a smoothing inductor, a load being connectable to the smoothing inductor;
a switching pattern generator for controlling switches in the switching bridge based on a reference output current;
a first control loop for determining an active portion of the reference output current based on a desired power level of the load and an m-phase voltage at said terminals;
and
a second control loop for determining a reactive portion of the reference output current based on the m-phase voltage at said terminals, the reactive portion being selected so as to obtain a desired per phase power factor on the power supply.

4 more elements

An a.c. induction motor drive, comprising:

a rectifier, said rectifier having (a) a switching bridge for converting alternating current into direct current, said bridge having a line side and a load side, (b) m input filter capacitors, each connected at a terminal thereof to the line side of the bridge, wherein an m-phase a.c. power supply having a per phase system inductance is connectable to the m terminals, m being an integer greater than or equal to one, (c) a switching pattern generator for controlling switches in the switching bridge based on a reference output current, (d) a first control loop for determining an active portion of the reference output current based on a desired power level of the load and an m-phase voltage at said terminals, and (e) a second control loop for determining a reactive portion of the reference output current based on the m-phase voltage at said terminals, the reactive portion being selected so as to obtain a desired per phase power factor on the power supply;
a d.c. link choke connected to the load side of the switching bridge;
and
a current source inverter connected to the d.c. link choke, the a.c. induction motor being connectable to the current source inverter.

1 more element

Dependencies are inferred from the claim text.

PWM rectifier having de-coupled power factor and output current control loops

Life of this patent

PWM rectifier having de-coupled power factor and output current control loops

Life of this patent

Abstract

Claims16