Adjustable UPS protection

• US 8,606,425 B2
• Filed: 04/27/2010
• Issued: 12/10/2013
• Est. Priority Date: 04/27/2010
• Status: Active Grant

• Current Assignee: Toshiba International Corporation (Toshiba Corporation)
• Original Assignee: Toshiba International Corporation (Toshiba Corporation)
• Inventors: Morishima, Yoichi, Westmoreland, David M.
• Primary Examiner(s): Padmanabhan, Kavita
• Assistant Examiner(s): LEE, DOUGLAS S
• Application Number:
  US12/768,306
• Publication Number:
  US 20110264292A1
• Time in Patent Office: 1,323 Days
• Field of Search: 700/297, 700/298, 363/37, 363/40, 363/96, 363/142, 307/43, 307/66, 323/258, 320/163
• US Class Current: 700/298
• CPC Class Codes: H02J 9/062 for AC powered loads

Abstract

An uninterruptable power supply (UPS) designed to switch power inputs between an alternating current mode and a battery mode by adjusting the amplitude and/or frequency windows of the input voltage so that the uninterruptible power supply accepts the unstable voltage and/or frequency. This prevents the uninterruptible power supply to switch back to the battery mode during a transfer time between the battery mode and the AC mode. The uninterruptable power supply includes a control circuit. The control circuit modifies the monitored value and/or actual amplitude and/or the frequency window when unstable amplitude and/or an unstable frequency are detected at the input terminal of the input voltage.

Claims

1. An uninterruptable power supply (UPS) configured to switch power inputs between an alternating current (AC) mode and a battery mode, comprising:

a DC bus having a main capacitor module for storing energy to hold up a DC bus voltage across the main capacitor module;

a circuit for monitoring an amplitude and frequency of an input voltage at an input of the UPS;

a DC bus voltage detection circuit for detecting the DC bus voltage across the main capacitor module;

a load current sensing circuit for detecting a load current at an output of the UPS;

a control circuit; and

a boost-up control circuit communicating with said control circuit and said DC bus,

said control circuit configured to generate an adjustment value for said DC bus based on the amplitude and frequency detected at the input of the UPS by said circuit, the load current detected at the output of the UPS by said load current sensing circuit, and the DC bus voltage across the main capacitor module detected by said DC bus voltage detection circuit,

wherein said boost-up control circuit configured to provide the adjustment value generated by the control circuit to the DC bus of the UPS to modify said amplitude and/or said frequency when an unstable amplitude and/or an unstable frequency are detected at the input terminal of the input voltage.

2. The uninterruptable power supply as set forth in claim 1, wherein:

said monitored value of unstable amplitude at the input terminal of the input voltage is modified by adjusting a voltage window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

3. The uninterruptable power supply as set forth in claim 1, wherein:

said monitored value of unstable frequency at the input terminal of the input voltage is adjusted by adjusting a frequency window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

4. The uninterruptable power supply as set forth in claim 2, wherein:

said voltage window has input voltage protection values that are greater than an operating voltage range values of the UPS, said input voltage protection values are selected by the control circuit based on an output current of the UPS.

5. The uninterruptable power supply as set forth in claim 3, wherein:

said frequency window has a range that is wider than the operating frequency range of the UPS.

6. An uninterruptable power supply method for switching power inputs between an alternating current (AC) mode and a battery mode, comprising:

storing energy to hold up a DC bus voltage across main capacitor module of a DC bus;

monitoring an amplitude and frequency of an input voltage at an input of an uninterruptable power supply (UPS) by a circuit;

detecting the DC bus voltage across the main capacitor module by a DC bus voltage detection circuit;

detecting a load current at an output of the UPS by a load current sensing circuit;

generating an adjustment value for said DC bus based on the amplitude and frequency detected at the input of the UPS by said circuit, the load current detected at the output of the UPS by said load current sensing circuit, and the DC bus voltage across the main capacitor module detected by said DC bus voltage detection circuit by using a control circuit; and

providing the adjustment value generated by the control circuit to the DC bus of the UPS to modify said amplitude and/or said frequency when an unstable amplitude and/or an unstable frequency are detected at the input terminal of the input voltage by using a boost-up control circuit communicating with said control circuit and said DC bus.

7. The method as set forth in claim 6, wherein said unstable amplitude at the input terminal of the input voltage is modified by:

adjusting a voltage window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

8. The method as set forth in claim 6, wherein said unstable frequency at the input terminal of the input voltage is adjusted by:

adjusting a frequency window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

9. The uninterruptable power supply as set forth in claim 7, wherein:

said voltage window has input voltage protection values that are greater than an operating voltage range values of the UPS, said input voltage protection values are selected by the control circuit based on an output current of the UPS.

10. The uninterruptable power supply as set forth in claim 8, wherein:

said frequency window has a range that is wider than the operating frequency range of the UPS.

11. An uninterruptable power supply (UPS) system configured to switch power inputs between an alternating current (AC) mode and a battery mode, comprising:

a switch configured to switch between a plurality of ac power sources;

a DC bus having a main capacitor module for storing energy to hold up a DC bus voltage across the main capacitor module;

a circuit for monitoring an amplitude and frequency of an input voltage at an input of the UPS;

a DC bus voltage detection circuit for detecting the DC bus voltage across the main capacitor module;

a load current sensing circuit for detecting a load current at an output of the UPS;

a control circuit; and

a boost-up control circuit communicating with said control circuit and said DC bus,

said control circuit configured to generate an adjustment value for said DC bus based on the amplitude and frequency detected at the input of the UPS by said circuit, the load current detected at the output of the UPS by said load current sensing circuit, and the DC bus voltage across the main capacitor module detected by said DC bus voltage detection circuit,

wherein said boost-up control circuit configured to provide the adjustment value generated by the control circuit to the DC bus of the UPS to modify said amplitude and/or said frequency when an unstable amplitude and/or an unstable frequency are detected at the input terminal of the input voltage.

12. The system as set forth in claim 11, wherein:

said unstable amplitude at the input terminal of the input voltage is modified by adjusting a voltage window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

13. The system as set forth in claim 11, wherein:

said unstable frequency at the input terminal of the input voltage is adjusted by adjusting a frequency window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

14. The system as set forth in claim 12, wherein:

said voltage window has input voltage protection values that are greater than an operating voltage range values of the UPS, said input voltage protection values are selected by the control circuit based on an output current of the UPS.

15. The system as set forth in claim 13, wherein:

said frequency window has a range that is wider than the operating frequency range of the UPS.

16. A non-transitory computer-readable storage medium having instructions encoded thereon for enabling a processor to execute an operation for switching power inputs between an alternating current (AC) mode and a battery mode in an uninterruptable power supply, comprising the steps of:

storing energy to hold up a DC bus voltage across main capacitor module of a DC bus;

monitoring an amplitude and frequency of an input voltage at an input of an uninterruptable power supply (UPS) by a circuit;

detecting the DC bus voltage across the main capacitor module by a DC bus voltage detection circuit;

detecting a load current at an output of the UPS by a load current sensing circuit;

generating an adjustment value for said DC bus based on the amplitude and frequency detected at the input of the UPS by said circuit, the load current detected at the output of the UPS by said load current sensing circuit, and the DC bus voltage across the main capacitor module detected by said DC bus voltage detection circuit by using a control circuit; and

providing the adjustment value generated by the control circuit to the DC bus of the UPS to modify said amplitude and/or said frequency when an unstable amplitude and/or an unstable frequency are detected at the input terminal of the input voltage by using a boost-up control circuit communicating with said control circuit and said DC bus.

17. The non-transitory computer-readable storage medium as set forth in claim 16, wherein the judgment of said unstable amplitude at the input terminal of the input voltage is set by:

adjusting a voltage window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

18. The non-transitory computer-readable storage medium as set forth in claim 16, wherein the judgment of said unstable frequency at the input terminal of the input voltage is set by:

adjusting a frequency window for a predetermined number of cycles during a transfer time between the battery mode and the AC mode.

19. The non-transitory computer-readable storage medium as set forth in claim 17, wherein:

said voltage window has input voltage protection values that are greater than an operating voltage range values of the UPS, said input voltage protection values are selected by the control circuit based on an output current of the UPS.

20. The non-transitory computer-readable storage medium as set forth in claim 18, wherein:

said frequency window has a range that is wider than the operating frequency range of the UPS.