SIMPLE AND PASSIVE SOLUTION FOR PROVIDING POWER INTERRUPTION CAPABILITY WITH CONTROLLED INRUSH CURRENT IN CRITICAL POWER SUPPLY

• US 20090230771A1
• Filed: 03/11/2008
• Published: 09/17/2009
• Est. Priority Date: 03/11/2008
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Saxena, Sunit Kumar, DE, SUKUMAR
• Application Number:
  US12/046,306
• Publication Number:
  US 20090230771A1
• Time in Patent Office: Days
• US Class Current: 307/44
• CPC Class Codes: H02M 1/0096 Means for increasing hold-up time, i.e. the duration of time that a converter's output will remain within regulated limits following a loss of input power
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters

Abstract

An electrical power supply system is provided with capacitor-based hold-up protection. Inrush current to the capacitor is passively limited with a combination of a resistor and a rectifying device connected to a hold-up capacitor. During start-up, the rectifying device may be reverse-biased and a portion of input current is shunted to charge the hold-up capacitor. In the event of input power failure, the rectifying device is forward biased and the capacitor may be discharged to a load of the power supply thereby providing hold-up protection for the load.

Claims

1. An electrical power supply apparatus comprising:

a hold-up capacitor connected to at least one bus;

a resistor interposed between the capacitor and a second bus; and

a rectifying device interposed between the capacitor and the second bus.

2. The apparatus of claim 1 wherein the resistor is connected in parallel with the rectifying device.

3. The apparatus of claim 1 wherein the rectifying device is reverse biased when input voltage is present across the buses.

4. The apparatus of claim 1 wherein the rectifying device is forward biased when input voltage is not present across the buses.

5. The apparatus of claim 1 further comprising:

a converter;

the converter having an output; and

the hold-up capacitor is connected to an output power bus of the output.

6. The apparatus of claim 1 further comprising:

a direct-current (DC) to alternating current (AC) converter;

the converter having an input and an output;

the hold-up capacitor is connected to an input power bus of the converter; and

the output is connected to a load.

7. The apparatus of claim 1 wherein the rectifying device is a transistor.

8. A hold-up circuit for an electrical power supply comprising:

a hold-up capacitor connected to a resistor and a rectifying device; and

the resistor and the rectifying device being connected in parallel with one another.

9. The apparatus of claim 8 wherein the capacitor, the resistor and the rectifying device are packaged as a two-terminal device.

10. The apparatus of claim 9 wherein:

a first terminal of the two-terminal device is connected with the capacitor; and

a second terminal of the two-terminal device is connected to the resistor and the rectifying device.

11. The apparatus of claim 8 wherein the rectifying device permits discharge of the capacitor when the rectifying device is forward biased.

12. The apparatus of claim 8 wherein the rectifying device is a diode.

13. The apparatus of claim 8 wherein the rectifying device is a transistor.

14. A method for providing hold-up protection for an electrical power supply comprising the steps of:

reverse biasing a rectifying device when input power is supplied to the power supply at a desired voltage;

forward biasing the rectifying device in the event of input power failure; and

discharging a capacitor through the rectifying device to a load of the power supply when the rectifying device is forward biased.

15. The method of claim 14 comprising the further step of passing a capacitor-charging portion of input current through a resistor to a capacitor to charge the capacitor.

16. The method of claim 15 wherein the step of passing current through the resistor ceases after the capacitor is charged.

17. The method of claim 14 wherein the step of reverse biasing the rectifying device produces a blockage of a capacitor-charging portion of input current from passage to an output of the power supply.

18. The method of claim 14 wherein the step of discharging the capacitor comprises discharging the capacitor directly into a load at an output side of the power supply.

19. The method of claim 14 wherein the step of discharging the capacitor comprises discharging the capacitor to an input side of a converter.

20. The method of claim 19 wherein the capacitor is discharged into DC/AC converter that supplies power to a load.