Active filtering system

Patent metadata

Field	Value
Publication number	US-9806598-B2
Application number	US-201615341324-A
Country	US
Kind code	B2
Filing date	Nov 2, 2016
Priority date	Dec 1, 2015
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

An active filtering system designed to be connected in parallel with an electric power supply network providing a main power supply current including a disturbing current, the system including at least one capacitor, a controlled current generator including an electric power supply intended to generate a positive determined voltage or a negative determined voltage and connected in series with the capacitor, a device for controlling the controlled current generator, designed to generate a compensation current to be applied to the main current in order to compensate the disturbing current while keeping a decoupling current measured at the connection point between the current generator and the capacitor at a value suitable for not saturating the current generator.

First claim

The invention claimed is:

1. An active filtering system designed to be connected in parallel with an electric power supply network providing a main power supply current including a disturbing current, said system comprising:
at least one capacitor;
a controlled current generator comprising an electric power supply configured to generate a positive determined voltage or a negative determined voltage and being connected in series with at least one the capacitor; and
a control device configured to determine a control value for said controlled current generator so that the controlled current generator generates a compensation current to be applied to the main power supply current in order to compensate the disturbing current, said control value being determined by implementing:
a first current loop designed to filter the main power supply current in order to obtain a first high-frequency current,
a second control loop designed to correct the first high-frequency current with a second current that is proportional to a decoupling voltage measured at a connection point between the controlled current generator and said at least one capacitor,
an adder designed to determine a control parameter by means of a difference between the first high-frequency current and the second current, and
a hysteresis comparator designed to output said control value to be applied based on said control parameter, which is input.

2. The filtering system according to claim 1 , wherein the control device is further configured to keep the decoupling voltage at a value comprised between said positive determined voltage and said negative determined voltage.

3. The filtering system according to claim 2 , wherein the control device is further configured to keep said decoupling voltage at a value of about 0 volts.

4. The system according to claim 1 , wherein the controlled current generator further comprises a voltage converter comprising two switches and an inductance connected at a middle point situated between the two switches, the two switches being controlled in a complementary manner by the control device so as to apply a voltage to said middle point equal to said positive determined voltage or to said negative determined voltage.

5. The system according to claim 4 , wherein the two switches are each composed of a fast-switching transistor configured to switch at a frequency greater than 500 kHz.

6. The system according to claim 1 , wherein the control device comprises means for determining the second current, configured to apply a dummy impedance to the decoupling voltage in order to deduce therefrom the second current, said dummy impedance being determined so as to eliminate a low-frequency component of the decoupling voltage.

Assignees

• Schneider Electric Ind Sas

Inventors

• Franchino Roger

Classifications

• Y02E40/40

  Arrangements for reducing harmonics · CPC title

• H02M7/217

  using semiconductor devices only · CPC title

• H02M1/126 Primary

  using passive filters · CPC title

• H02J3/01 Primary

  Arrangements for reducing harmonics or ripples · CPC title

• H02M1/15

  using active elements · CPC title