Systems And Methods For Scaling A Signal In A Power Factor Correction Circuit

• US 20110235372A1
• Filed: 12/13/2008
• Published: 09/29/2011
• Est. Priority Date: 12/13/2008
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Mohr, David Paul, Garbozy, Zachary J., Bemat, Mohamed Amin
• Granted Patent: US 8,564,269 B2
• Time in Patent Office: Days
• US Class Current: 363/39
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Systems and methods for scaling a current signal in a power factor correction circuit are disclosed. An exemplary method may include providing a power factor correction circuit for a power supply, the power factor correction circuit having a first current sensing resistor connected on a return path to a rectified AC line. The method may also include measuring current across the first current sensing resistor. The method may also include switching on at least a second current sensing resistor in parallel with the first current sensing resistor if the measured current increases above a threshold value.

Claims

1. A method for scaling a signal in a power factor correction (PFC) circuit, comprising:

providing the PFC circuit for a power supply, the PFC circuit having a first current sensing resistor connected on a return path to a rectified AC line;

measuring current across the first current sensing resistor; and

switching off at least a second current sensing resistor in parallel with the first current sensing resistor if the measured current drops below a threshold value.

2. The method of claim 1 further comprising switching on the second current sensing resistor if the measured current increases above the threshold value.

3. The method of claim 1 wherein the second current sensing resistor has a lower resistance rating than the first current sensing resistor.

4. The method of claim 1 wherein the second current sensing resistor in parallel with the first current sensing resistor has a lower resistance rating than the first current sensing resistor alone.

5. The method of claim 1 wherein the second current sensing resistor switched on in parallel with the first current sensing resistor increases measurement sensitivity of a current signal on the return path.

6. The method of claim 1 further comprising increasing signal amplitude to enhance current measurement accuracy for a low amplitude current signal on the return line.

7. The method of claim 1 further comprising switching on at least a third current sensing resistor in parallel with the first and second current sensing resistors to scale a current signal on the return line across a range of current signals.

8. A system for scaling a current signal in a power factor correction (PFC) circuit, comprising:

a first current sensing resistor connected on a return path in the PFC circuit;

at least a second current sensing resistor; and

a switch operable to connect at least the second current sensing resistor in parallel with the first current sensing resistor if the measured current increases above a threshold value.

9. The system of claim 8, wherein the switch is operable to switch on the second current sensing resistor if the measured current increases above the threshold value.

10. The system of claim 8, wherein the second current sensing resistor has a resistance rating lower than or equal to a resistance rating of the first current sensing resistor.

11. The system of claim 8, wherein the second current sensing resistor has a lower resistance rating than the first current sensing resistor alone.

12. The system of claim 8, wherein the second current sensing resistor decreases power loss of a current signal on the return path.

13. The system of claim 8, wherein the second current sensing resistor decreases power loss.

14. The system of claim 13, wherein the second current sensing resistor increases current measurement accuracy for a high current signal on the return line.

15. The system of claim 13, wherein power loss is unaffected or decreases across a full range of operation for equivalent measurement accuracy.

16. The system of claim 8, further comprising at least one more than at least the second current sensing resistor switchable in parallel with the first current sensing resistor to further scale a current signal on the return line across a range of current signals.

17. A system for scaling a current signal in a power factor correction circuit, comprising:

first current sensing means connected on a return path;

at least second current sensing means provided in parallel with the first current sensing means; and

means for switching on at least the second current sensing means if current measured across the first current sensing means increases above a threshold value.

18. The system of claim 17 further comprising means for switching off the at least second current sensing means if the measured current decreases below the threshold value.