NOISE FILTERING

• US 20140071719A1
• Filed: 08/05/2013
• Published: 03/13/2014
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: DUERBAUM, Thomas Antonius, BLOM, Anton Cornelis, HALBERSTADT, Hans, PANSIER, Frans, STAHL, Juergen, GOETTLE, Jens, PAWELLEK, Alexander
• Granted Patent: US 9,722,484 B2
• Time in Patent Office: Days
• US Class Current: 363/44
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 1/123 Suppression of common mode voltage or current
• CPC Class Codes: H02M 1/15 using active elements
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters

Abstract

A noise filter circuit uses open loop signal processing to process the signal that causes the noise and generate a signal to be fed back into the system to cancel noise currents.

Claims

1. A noise filter circuit for a power converter comprising one or more stages, comprising:

a sensor coupled to a switching node of the power converter (10), wherein the voltage on the switching node comprises a switch waveform which gives rise to current noise as a result of parasitic capacitance;

a processing stage for processing the sensor signal and for providing a correction signal to a voltage line associated with the power converter thereby to reduce the current noise.

2. A circuit as claimed in claim 1, wherein the voltage line comprises:

a protective earth;

or

an ac neutral and/or ac phase line at an input to the converter;

or

a dc voltage supply line.

3. A circuit as claimed in claim 1, wherein:

the supply sources of the processing stage are referenced to protective earth, and the correction signal is provided to a voltage line comprising an ac neutral and/or ac phase line at an input to the converter or a dc voltage supply line.

4. A circuit as claimed in claim 1, wherein:

the supply sources of the processing stage are referenced to an ac neutral or ac phase line at an input to the converter or a dc voltage supply line, and the correction signal is provided to protective earth.

5. A circuit as claimed in claim 1, wherein:

the supply sources of the processing stage are referenced to a converter circuit ground, and the correction signal is provided to a voltage line comprising a protective earth.

6. A circuit as claimed in claim 1, wherein:

the supply sources of the processing stage are referenced to circuit ground, the sensor is referenced to circuit ground, and the correction signal is provided to a voltage line comprising a protective earth.

7. A circuit as claimed in claim 1 , wherein the processing stage comprises an amplifier.

8. A circuit as claimed in claim 7, wherein the sensor generates an output voltage dependent on the voltage at the switching node.

9. A circuit as claimed in claim 8, wherein the processing stage comprises a voltage amplifier and a feeding stage for injecting a current dependent on the voltage amplifier output thereby providing a correction signal to the voltage line.

10. A circuit as claimed in claim 7, wherein the sensor generates an output current dependent on the voltage at the switching node or its derivative.

11. A circuit as claimed in claim 10, wherein the processing stage comprises a current amplifier and a feeding stage for injecting a current dependent on the current amplifier output thereby providing a correction signal to the voltage line.

12. A power converter circuit comprising a noise filter circuit as claimed in claim 1 and the power converter.

13. A circuit as claimed in claim 12, wherein the power converter comprises a plurality of power converter stages.

14. A circuit as claimed in claim 13, wherein each power converter has an associated sensor, and a combination of the sensor signals is processed by the shared processing stage of the power converter circuit.

15. A circuit as claimed in claim 1, comprising a bridge rectifier (62) between ac phase and neutral lines and the converter.