Current inrush limiting and bleed resistor current inhibiting in a switching power converter

• US 20020196644A1
• Filed: 06/21/2002
• Published: 12/26/2002
• Est. Priority Date: 06/21/2001
• Status: Active Grant

• Current Assignee: Champion Microelectronic Corporation
• Original Assignee: Champion Microelectronic Corporation
• Inventors: Hwang, Jeffrey H.
• Granted Patent: US 6,737,845 B2
• Time in Patent Office: Days
• US Class Current: 363/89
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/0845 digitally controlled (or with digital control)
• CPC Class Codes: H02M 1/092 the control signals being transmitted optically
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• 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
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• CPC Class Codes: Y10S 323/901 Starting circuits
• CPC Class Codes: Y10S 323/908 Inrush current limiters

Abstract

A current inrush limiting technique for a switching power converter. In one aspect, a switching power converter includes a main power switch and a current sensor. When the input current exceeds a first threshold, the main power switch is opened. When the input current exceeds a second threshold, higher than the first threshold, a current-limiting resistance is coupled to receive the input current. Accordingly, the input current is limited in two stages by two different techniques. In another aspect, a bleed resistor receives current from a power source for providing power to a controller for the power converter. After start-up, such as when an output voltage of the power converter is available to provide power to the controller, the current-limiting resistor is shorted and the bleed resistor is effectively removed. A single pin of an integrated circuit controller controls shorting of the current-limiting resistor and removal of the bleed resistor.

Claims

1. A switching power converter comprising:

a switch for receiving an input current;

a current sensor for forming a signal representative of the input current; and

a controller for controlling the switch and when the input current exceeds a first threshold, the main power switch is opened and when the input current exceeds a second threshold higher than the first threshold the input current is limited by a current-limiting resistance.

2. The power converter according to claim 1, wherein the controller performs power factor correction.

3. The power converter according to claim 2, wherein the controller performs power factor correction in accordance with average current-mode control.

4. The power converter according to claim 2, wherein the controller performs power factor correction in accordance with input current shaping.

5. The power converter according to claim 1, further comprising an output capacitor, wherein opening and closing the switch forms an output voltage across the output capacitor and wherein the current-limiting resistance is coupled in series with the output capacitor.

6. The power converter according to claim 5, wherein the current-limiting resistance is coupled between the output capacitor and a ground node.

7. The power converter according to claim 5, further comprising a second switch coupled across the current-limiting resistance and when the input current does not exceed the second threshold, the second switch shorts the current-limiting resistance.

8. The power converter according to claim 1, further comprising a source for generating the input current and wherein the current-limiting resistance is coupled to receive a return current to the source.

9. The power converter according to claim 8, wherein the current-limiting resistance is coupled between a ground node and the source.

10. The power converter according to claim 8, wherein the current sensor comprises a sensing resistor coupled to receive the return current to the source and when the input current exceeds the second threshold, a second switch inhibits current from flowing in the sensing resistor.

11. A switching power converter comprising:

a switch for receiving an input current from a power source;

a current sensor for forming a signal representative of the input current;

a bleed resistor for receiving a bleed current from the power source for providing power upon start-up;

a current-limiting resistor for limiting the input current upon start-up;

a controller for controlling the switch, wherein the controller shorts the current-limiting resistor and inhibits the bleed current through the bleed resistor after start-up.

12. The power converter according to claim 11, wherein the controller is an integrated circuit controller and wherein the shorting of the current-limiting resistor and the removal of the bleed resistor are controlled by a single pin of the integrated circuit controller.

13. The power converter according to claim 11, wherein during start-up, the controller receives power from the bleed resistor and, after start-up, the controller receives power from a voltage supply for the controller.

14. The power converter according to claim 11, wherein the controller shorts the current-limiting resistor and inhibits the bleed current through the bleed resistor after the voltage supply exceeds a first predetermined voltage level and the input current is below a predetermined current level.

15. The power converter according to claim 11, wherein the controller shorts the current-limiting resistor and inhibits the bleed current through the bleed resistor after either the voltage supply exceeds a first predetermined voltage level or the input current is below a predetermined current level.

16. The power converter according to claim 11, wherein the controller performs power factor correction.

17. The power converter according to claim 16, wherein the controller performs power factor correction in accordance with average current-mode control.

18. The power converter according to claim 16, wherein the controller performs power factor correction in accordance with input current shaping.

19. The power converter according to claim 11, further comprising an output capacitor, wherein opening and closing the switch forms an output voltage across the output capacitor and wherein the current-limiting resistance is coupled in series with the output capacitor.

20. The power converter according to claim 19, wherein the current-limiting resistance is coupled between the output capacitor and a ground node.

21. The power converter according to claim 19, further comprising a second switch coupled across the current-limiting resistance and when the input current does not exceed the second threshold, the second switch shorts the current-limiting resistance.

22. The power converter according to claim 11, further comprising a source for generating the input current and wherein the current-limiting resistance is coupled to receive a return current to the source.

23. The power converter according to claim 22, wherein the current-limiting resistance is coupled between a ground node and the source.

24. The power converter according to claim 22, wherein the current sensor comprises a sensing resistor coupled to receive the return current to the source and when the input current exceeds the second threshold, a second switch inhibits current from flowing in the sensing resistor.

26. The power supply according to claim 25, wherein the controller receives power from a voltage supply for the controller when the voltage supply exceeds a predetermined voltage.

27. The power supply according to claim 25, wherein the current from the source is inhibited during start-up by a current-limiting resistance.

28. The power supply according to claim 27, further comprising an output capacitor, wherein the regulated output voltage is formed across the output capacitor and wherein the current-limiting resistance is coupled in series with the output capacitor.

29. The power supply according to claim 28, wherein the current-limiting resistance is coupled between the output capacitor and a ground node.

30. The power supply according to claim 27, wherein the current-limiting resistance is coupled to receive a return current to the source.

31. The power supply according to claim 30, wherein the current-limiting resistance is coupled between a ground node and the source .

25. A switching power supply for drawing power from a source and for forming a regulated output voltage, the switching power supply comprising:

a switch for modulating current from the source for forming the regulated output voltage by alternately charging and discharging a reactive element;

control circuitry coupled to the switch for controlling operation of the switch;

a bleed resistor for supplying current from the source to the control circuitry during start-up; and

means for inhibiting the current supplied to the control circuitry via the bleed resistor after start-up.