Battery leakage current elimination in UPS units

• US 9,166,423 B2
• Filed: 08/17/2012
• Issued: 10/20/2015
• Est. Priority Date: 01/24/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Kim, Sangsun, Wang, Jianshui
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): BUKHARI, AQEEL H
• Application Number:
  US13/588,249
• Publication Number:
  US 20130187471A1
• Time in Patent Office: 1,159 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H02J 1/001 Hot plugging or unplugging of load or power modules to or from power distribution networks
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: H02J 7/0045 concerning the insertion or the connection of the batteries
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 9/00 Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems

Abstract

Aspects of the disclosure relate generally to uninterruptible power supply (“UPS”) units for systems requiring back up power. The UPS units include circuitry for controlling charging and allowing discharging of a battery. The circuitry includes a controller as well as a pair of metal-oxide semiconductor field effect transistors (“MOSFET”) switches. The pair of MOSFET switches includes a charging and a discharging MOSFET switches in series with the battery operating as a bidirectional switch. A UPS unit may be charged and subsequently stored for period of time. During this time, plurality of features may prevent current leakage from the batteries. For example, PNP bipolar transistors and additional MOSFET switches may be used to prevent current leakage. These features alone or in combination may allow for long term storage of the uninterruptible power supply units without current leakage.

Claims

1. An uninterruptible power supply unit comprising:

a battery;

a first MOSFET switch and a second MOSFET switch connected in series to the battery, and when the second MOSFET is in a fully on condition of a switching mode, the uninterruptible power supply unit is configured to provide power to a load;

a controller for controlling charging of the batteries through the first MOSFET switch when the first MOSFET switch is in a linear operation mode and the uninterruptible power supply is connected to a power supply; and

a first transistor arranged between the controller and the first MOSFET switch such that when the uninterruptible power supply unit is not connected to the external power supply, the first transistor reduces current leakage at the controller.

2. The uninterruptible power supply unit of claim 1, wherein the first transistor is a PNP bipolar transistor.

3. The uninterruptible power supply unit of claim 1, further comprising:

a second transistor;

a protection circuit connected to the first MOSFET and the second MOSFET, the protection circuit being configured to protect the uninterruptible power supply unit during abnormal conditions by switching the first MOSFET switch and the second MOSFET switch to an off condition at the second transistor to disconnect the uninterruptible power supply unit; and

a third transistor arranged between the protection circuit and the second transistor such that when the uninterruptible power supply unit is not connected to the external power supply, the third transistor reduces current leakage at the protection circuit.

4. The uninterruptible power supply unit of claim 3, wherein the second transistor is an NPN bipolar transistor and the third transistor is a PNP bipolar transistor.

5. The uninterruptible power supply unit of claim 3, wherein the uninterruptible power supply unit, including the first transistor and the third transistor, is configured to eliminate leakage current.

6. The uninterruptible power supply unit of claim 1, further comprising:

a voltage divider associated with the battery;

a third MOSFET switch connected in series with the voltage divider; and

a second transistor associated with the voltage divider;

wherein the third MOSFET switch and second transistor reduce current leakage at the voltage divider.

7. The uninterruptible power supply unit of claim 6, wherein the second transistor is a PNP bipolar transistor.

8. An uninterruptible power supply unit comprising:

a battery;

a first MOSFET switch and a second MOSFET switch connected in series to the battery, and when the second MOSFET is in a fully on condition of a switching mode, the uninterruptible power supply unit is configured to provide power to a load;

a first transistor;

a protection circuit connected to the first MOSFET and the second MOSFET, the protection circuit being configured to protect the uninterruptible power supply unit during abnormal charging conditions by switching the first MOSFET switch and the second MOSFET switch to an off condition at the first transistor to disconnect the uninterruptible power supply unit; and

a second transistor arranged between the protection circuit and the second transistor such that when the uninterruptible power supply unit is not connected to the external power supply, the second transistor reduces current leakage at the protection circuit.

9. The uninterruptible power supply unit of claim 8, wherein the first transistor is an NPN bipolar transistor and the second transistor is a PNP bipolar transistor.

10. The uninterruptible power supply unit of claim 8, further comprising:

a voltage divider associated with the battery; and

a third MOSFET switch connected in parallel with the voltage divider; and

a third transistor associated with the voltage divider;

wherein the third MOSFET switch and second transistor reduce current leakage at the voltage divider.

11. The uninterruptible power supply unit of claim 10, wherein the third transistor is a PNP bipolar transistor.

12. The uninterruptible power supply unit of claim 8, wherein the uninterruptible power supply unit, including the second transistor, is configured to eliminate leakage current.

13. An uninterruptible power supply unit comprising:

a battery;

a first MOSFET switch and a second MOSFET switch connected in series to the battery, and when the second MOSFET is in a fully on condition of a switching mode, the uninterruptible power supply unit is configured to provide power to a load;

a voltage divider associated with the battery; and

a third MOSFET switch connected in series with the voltage divider; and

a first transistor associated with the voltage divider;

wherein the third MOSFET switch and first transistor reduce current leakage at the voltage divider.

14. The uninterruptible power supply unit of claim 13, wherein the first transistor is a PNP bipolar transistor.

15. The uninterruptible power supply unit of claim 13, further comprising:

a controller for controlling charging of the batteries through the first MOSFET switch when the first MOSFET switch is in a linear operation mode and the uninterruptible power supply is connected to a power supply;

a second transistor arranged between the controller and the first MOSFET switch such that when the uninterruptible power supply unit is not connected to the external power supply, the second transistor reduces current leakage at the controller;

a third transistor;

a protection circuit connected to the first MOSFET and the second MOSFET, the protection circuit being configured to protect the uninterruptible power supply unit during abnormal charging conditions by switching the first MOSFET switch and the second MOSFET switch to an off condition at the third transistor to disconnect the uninterruptible power supply unit; and

a fourth transistor arranged between the protection circuit and the third transistor such that when the uninterruptible power supply unit is not connected to the external power supply, the second transistor reduces current leakage at the protection circuit.

16. The uninterruptible power supply unit of claim 15, wherein the second transistor is a PNP bipolar transistor.

17. The uninterruptible power supply unit of claim 15, wherein the third transistor is an NPN bipolar transistor.

18. The uninterruptible power supply unit of claim 15, wherein the fourth transistor is a PNP bipolar transistor.

19. The uninterruptible power supply unit of claim 15, wherein the uninterruptible power supply unit, including the third MOSFET switch, the first transistor, the second transistor, the third transistor, and the fourth transistor, is configured to eliminate leakage current.