Active filtering

• US 7,443,229 B1
• Filed: 07/23/2004
• Issued: 10/28/2008
• Est. Priority Date: 04/24/2001
• Status: Expired due to Term

• Current Assignee: Picor Corporation (Vicor Corporation), VLT Incorporated (Vicor Corporation)
• Original Assignee: Picor Corporation (Vicor Corporation)
• Inventors: Vinciarelli, Patrizio, Dumas, Jeffrey Gordon, Briere, Michael
• Primary Examiner(s): LE, DINH THANH
• Application Number:
  US10/897,537
• Time in Patent Office: 1,558 Days
• Field of Search: 323281-285, 327/551, 327/331, 327530-532, 361/18
• US Class Current: 327/531
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection

Abstract

Techniques for adjusting the voltage across an active filter element include a controlled circuit element and a control circuit element adapted to control the voltage across the controlled circuit element to increase transient load response and to reduce power dissipation.

Claims

1. An apparatus comprising:

an input for receiving power from a power source;

an output for supplying an output voltage and an output current to a load;

a control circuit for controlling a headroom voltage defined as the voltage difference between the input and the output; and

a controlled circuit element connected between said input and said output and configured to provide said output current;

wherein the control circuit is coupled to said input and said output and configured to compare the headroom voltage to a reference signal and output a signal to the controlled circuit element to adjust the headroom voltage, wherein adjusting the headroom voltage comprises decreasing the headroom voltage in response to an increase in the output current.

2. The apparatus of claim 1 wherein the control circuit is constructed and arranged to increase the headroom voltage in response to a decrease in the output current.

3. The apparatus of claim 1 wherein the control circuit is constructed and arranged to provide a signal to the power source to adjust a voltage level at the input and maintain the output voltage at a predefined level.

4. The apparatus of claim 1 wherein the control circuit is constructed and arranged to reduce at the output, undesirable voltage variations presented at the input.

5. The apparatus of claim 1 wherein the control circuit is constructed and arranged to set the headroom voltage to a first level in response to a characteristic of the power from the power source.

6. The apparatus of claim 5 wherein the characteristic is a peak variation in voltage at the input and the control circuit sets the headroom voltage to a value that is greater than the peak variation.

7. The apparatus of claim 1 wherein the control circuit is further constructed and adapted to sense the output current and to adjust the headroom voltage based on the output current and a characteristic of the power received at the input.

8. The apparatus of claim 7 wherein the characteristic is a peak AC component of voltage at the input.

9. The apparatus of claim 7 wherein the characteristic is a DC component of voltage at the input.

10. The apparatus of claim 7 wherein the control circuit is constructed and arranged to increase the headroom voltage in response to a decrease in the output current to maintain a nearly constant output voltage.

11. The apparatus of claim 7 wherein the control circuit is constructed and arranged to provide a signal to the power source to decrease the voltage level at the input as the headroom voltage is decreased to maintain the output voltage at a predefined level.

12. The apparatus of claim 7 wherein the control circuit is constructed and arranged to provide a signal to the power source to increase the voltage level at the input as the headroom voltage is increased to maintain the output voltage at a predefined level.

13. The apparatus of claim 8 wherein the control circuit is constructed and arranged to reduce at the output, the AC component of the voltage presented at the input.

14. The apparatus of claim 8 wherein the controlled circuit element comprises a MOSFET, and the headroom voltage is maintained at a value greater than the peak AC component of the voltage at the input.

15. Apparatus comprising:

a power sharing array having a common input terminal for receiving power from a power source;

a common output terminal for delivering a load current and a load voltage to a load; and

a common reference terminal;

the array including a plurality of N first circuits, where N is an integer greater than 1;

each first circuit comprising the apparatus of claim 1 and further comprising a reference terminal for coupling to a reference signal;

wherein the input of each first circuit is connected to the common input terminal, the output of each first circuit is connected to the common output terminal, and the reference terminal of each first circuit is connected to the common reference terminal to couple to a common reference signal; and

wherein the control circuit is constructed and arranged to automatically set the output current of its respective first circuit to an equal share, 1/N, of the load current.

16. The apparatus of claim 15 wherein each of the first circuits is constructed and arranged to adjust the headroom voltage as a function of the common reference signal.

17. The apparatus of claim 15 wherein each first circuit is constructed and arranged to adjust the common reference signal at the reference terminal as a function of its respective output current.

18. The apparatus of claim 15 wherein:

each of the first circuits is constructed and arranged to adjust its respective headroom voltage as a function of the common reference signal and to adjust the common reference signal at the reference terminal as a function of its respective output current.

19. The apparatus of claim 15 wherein:

a resistance is connected to the common reference terminal;

each of the first circuits is constructed and arranged to output a reference current to its respective reference terminal as a function of its respective output current;

the reference currents from the first circuits are summed by the common reference terminal and a reference voltage is developed at the common reference terminal;

the common reference signal is the reference voltage; and

the first circuits are constructed and arranged to adjust their respective headroom voltages as a function of the reference voltage.

20. The apparatus of claim 19 wherein the reference currents are also as a function of the output voltage.

21. An apparatus comprising:

a power converter having a converter input for receiving power from a source and a converter output for supplying power to a load;

an output circuit connected between the power converter output and the load, the output circuit having an input connected to receive a converter voltage from the converter output and an output for supplying an output voltage and an output current to the load;

the output circuit including a controlled circuit element connected between said input and said output and configured to provide said output current and a control circuit for controlling a headroom voltage defined as the voltage difference between the input and the output;

the output circuit being coupled to said input and said output and configured to compare the headroom voltage to a reference signal and output a signal to the controlled circuit element to adjust the headroom voltage in response to changes in the output current to reduce power dissipation in the output circuit and enhance a response of the power converter to rapid changes in the output current.

22. The apparatus of claim 21 wherein the output circuit is constructed and arranged to increase the headroom voltage in response to decreases in the output current.

23. The apparatus of claim 21 wherein the output circuit is constructed and arranged to decrease the headroom voltage in response to increases in the output current.

24. The apparatus of claim 21 further comprising a feedback circuit connected to the power converter to adjust the converter voltage to maintain the output voltage at a predefined level.

25. The apparatus of claim 24 wherein the feedback circuit is constructed and arranged to adjust the converter voltage to accommodate the headroom voltage.

26. The apparatus of claim 21 wherein the output circuit is constructed and arranged to attenuate at the output, undesirable variations present in the converter voltage at the input.

27. The apparatus of claim 21 wherein the controlled circuit element comprises a MOSFET, and the output circuit maintains the headroom voltage at a level greater than the peak AC component of the converter voltage.

28. A method comprising:

providing an input for receiving power from a power source;

providing an output for supplying an output voltage and an output current to a load; and

controlling a headroom voltage defined as the voltage difference between the input and the output, wherein controlling the headroom voltage comprises comparing the headroom voltage to a reference signal using a control circuit coupled to the input and the output and controlling, based on the comparing, a controlled circuit element that is connected between the input and the output in order to adjust the headroom voltage, wherein adjusting the headroom voltage comprises decreasing the headroom voltage in response to an increase in the output current.

29. The method of claim 28 further comprising increasing the headroom voltage in response to a decrease in the output current.

30. The method of claim 28 further comprising providing a signal to the power source to adjust a voltage at the input and maintain the output voltage at a predefined level.

31. The method of claim 28 further comprising reducing at the output undesirable voltage variations presented at the input.

32. The method of claim 28 further comprising monitoring the output current.

33. The method of claim 32 further comprising increasing the headroom voltage in response to a decrease in the output current.

34. The method of claim 32 further comprising providing a signal to the power source to adjust a voltage at the input and maintain the output voltage at a predefined level.

35. The method of claim 32 further comprising reducing at the output undesirable voltage variations presented at the input.

36. A method comprising:

receiving power from a power source at an input;

supplying an output voltage and an output current at an output; and

controlling a headroom voltage, where the headroom voltage is a difference in voltage between the input and the output, wherein controlling the headroom voltage comprises comparing the headroom voltage to a reference signal using a control circuit coupled to the input and the output and controlling based on the comparing, a controlled circuit element that is connected between the input and the output in order to adjust the headroom voltage wherein adjusting the headroom voltage comprises reducing the headroom voltage in response to an increase in the output current.

37. A method comprising:

providing a power converter for converting power from a power source for delivery to a load at a load voltage;

providing a filter between the power converter and the load;

controlling a headroom voltage across the filter, wherein controlling the headroom voltage comprises comparing the headroom voltage to a reference signal using a control circuit coupled to the input and the output and controlling, based on the comparing, a controlled circuit element in the filter to adjust the headroom voltage;

monitoring an output current of the filter;

adjusting the headroom voltage in response to changes in the output current to reduce power dissipation in the filter.

38. The method of claim 37 further comprising decreasing the headroom voltage in response to an increase in the output current and increasing the headroom voltage in response to an decrease in the output current.