Noise filtering

• US 9,722,484 B2
• Filed: 08/05/2013
• Issued: 08/01/2017
• 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: Halberstadt, Hans, Duerbaum, Thomas Antonius, Stahl, Juergen, Goettle, Jens, Pawellek, Alexander, Blom, Anton Cornelis, Pansier, Frans
• Primary Examiner(s): Berhane, Adolf
• Application Number:
  US13/959,039
• Publication Number:
  US 20140071719A1
• Time in Patent Office: 1,457 Days
• Field of Search: 363 37, 363 39, 363 44- 47, 307105, 307106, 307112, 307552
• 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 at which a current is selectively routed through a switch of the power converter, wherein a voltage on the switching node comprises a switch waveform which gives rise to current noise as a result of parasitic capacitance between the power converter and ground;

a processing stage electrically connected to the sensor and the power converter, wherein the processing stage is configured to process a sensor signal generated by the sensor and to provide a correction signal to a voltage line that is input into the power converter thereby to reduce the current noise.

2. The noise filter 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. The noise filter circuit as claimed in claim 1, wherein:

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

4. The noise filter circuit as claimed in claim 1, wherein:

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. The noise filter circuit as claimed in claim 1, wherein:

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

6. The noise filter circuit as claimed in claim 1, wherein:

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 the voltage line comprising a protective earth.

7. The noise filter circuit as claimed in claim 1, wherein the sensor generates an output voltage dependent on the voltage at the switching node.

8. The noise filter circuit as claimed in claim 7, wherein the processing stage comprises a voltage amplifier and a feeding stage for injecting a current dependent on the voltage amplifier output thereby providing the correction signal to the voltage line.

9. The noise filter circuit as claimed in claim 1, wherein the sensor generates an output current dependent on the voltage at the switching node or its derivative.

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

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

12. The noise filter circuit as claimed in claim 11, wherein the power converter comprises a plurality of power converter stages.

13. The noise filter circuit as claimed in claim 12, wherein the noise filter circuit comprises a plurality of power converters, wherein each power converter has an associated sensor, and a combination of sensor signals generated by the power converters is processed by a shared processing stage.

14. The noise filter circuit as claimed in claim 1, comprising a bridge rectifier between ac phase and neutral lines and the converter.