Active Compensation Filter

• US 20080278229A1
• Filed: 05/08/2008
• Published: 11/13/2008
• Est. Priority Date: 05/10/2007
• Status: Active Grant

• Current Assignee: Compact Dynamics GmbH (INA-Holding Schaeffler GmbH & Co. KG)
• Original Assignee: Compact Dynamics GmbH (INA-Holding Schaeffler GmbH & Co. KG)
• Inventors: Hoffmann, Bernhard, Grundl, Andreas, Kleimaier, Alexander
• Granted Patent: US 7,622,985 B2
• Time in Patent Office: Days
• US Class Current: 327/559
• CPC Class Codes: H02M 1/15 using active elements
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters

Abstract

An active compensation filter for the application in the electric power supply in a land vehicle, which comprises a high-pass filter which is to be coupled with a supply voltage line which carries a supply voltage, in order to detect frequency and amplitude of interference voltage components of the supply voltage. A signal amplifier which is connected in series with the high-pass filter amplifies the detected interference voltage components and supplies them to a coupling element as output signals, which is connected in series with the signal amplifier and comprises a primary side and a secondary side. The primary side is fed with the output signals of the signal amplifier and the secondary side is looped into the supply voltage line.

Claims

1. An active compensation filter for the application in the electric power supply in a land vehicle, with the compensation filter comprising:

a high-pass filter (HP) which is to coupled with a supply voltage line which carries a supply voltage in order to detect frequency and amplitude of interference voltage components of the supply voltage,

a signal amplifier connected in series with the high-pass filter, which amplifies the detected interference voltage components and

supplies them as output signals to a coupling element which is connected in series with the signal amplifier and comprises a primary side and a secondary side, with the primary side being fed with the output signals of the signal amplifier and the secondary side being looped into the supply voltage line, characterised in that

the coupling element comprises a transformer with at least three galvanically separated, magnetically coupled turns, with

a tertiary winding being provided in a negative feedback path of the signal amplifier, and with

the negative feedback path leading from an output of the signal amplifier to an input of the signal amplifier.

2. The active filter according to claim 1, wherein the high-pass filter is a single stage or a multistage high-pass filter of the first or higher order.

3. The active filter according to claim 1, wherein the high-pass filter has cut-off frequency of approx. half the fundamental frequency of the interference voltage components.

4. The active filter according to claim 1, wherein the high-pass filter (HP) has cut-off frequency of approx. half to one fourth of the clock frequency of a DC/DC converter.

5. The active filter according to claim 1, wherein the output signals of the signal amplifier are inverted with respect to their amplitudes relative to the detected interference voltage components, and wherein the primary side and the secondary side of the coupling transformer have the same sense of winding.

6. The active filter according to claim 1, wherein the output signals of the signal amplifier are not inverted with respect to their amplitudes relative to the detected interference voltage components, and wherein the primary side of the coupling transformer has a sense of winding opposite to that of the secondary side.

7. The active filter according to claim 1, wherein the secondary side of the coupling transformer has a low number of turns, which is below 50.

8. The active filter according to claim 1, wherein the secondary side of the coupling transformer has a single turn.

9. The active filter according to claim 1, wherein a low-pass filter is connected in series with the coupling transformer in the supply voltage line.

10. The active filter according to claim 9, wherein the low-pass filter has a cut-off frequency of approx. five to fifty times the fundamental frequency of the interference voltage components.

11. The active filter according to claim 1, wherein the signal amplifier is a single stage or multistage inverting or non-inverting AC voltage signal amplifier.

12. The active filter according to claim 1, wherein a tap for interference voltage components downstream of the secondary winding of the coupling transformer in a negative feedback path leads to an input of the signal amplifier.

13. The active filter according to claim 1, wherein a direct current component whose polarity is directed opposite to the supply voltage is impressed on the supply voltage.