INVERTER SYSTEM

• US 20070103163A1
• Filed: 12/27/2006
• Published: 05/10/2007
• Est. Priority Date: 07/22/2002
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tanaka, Masaru, Hachisuka, Seiji, Senba, Minoru, Yadoori, Shuuichi
• Granted Patent: US 7,492,162 B2
• Time in Patent Office: Days
• US Class Current: 324/500
• CPC Class Codes: G01R 15/18 using inductive devices, e.g. transformers
• CPC Class Codes: G01R 31/42 AC power supplies
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 31/54 Testing for continuity
• CPC Class Codes: G09G 2330/04 Display protection
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H01F 38/30 Constructions
• CPC Class Codes: H02H 1/0007 concerning the detecting means in general G01R or other subclasses of G01; reed switches H01H71/2445
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 7/122 for inverters, i.e. dc/ac converters
• CPC Class Codes: H05B 41/2851 for protecting the circuit against abnormal operating conditions
• CPC Class Codes: H05B 41/2855 against abnormal lamp operating conditions

Abstract

An inverter system which converts DC input into AC output and supplies the AC output to a load such as an FL tube detects change in a circuit current due to anomaly such as discharge without contacting with a current route. Relating to an inverter which converts DC input into AC output and supplies the AC output to a load, change in a circuit current of the inverter is detected through the medium of magnetic flux change due to the change in the circuit current caused by discharge. For example, if change in a current occurs in the circuit current of the inverter by disconnection discharge or ground-fault discharge occurring in a current route including a load of the inverter, magnetic flux change occurs in circuit wiring and a space of a core gap of a transformer of the inverter. The change in the circuit current is detected through the medium of the magnetic flux change without contacting with the circuit wiring or the transformer.

Claims

1. A current detection circuit of an inverter that converts DC input into AC output and supplies the AC output to a load, comprising:

a current detection part that detects change in a circuit current of said inverter through the medium of the magnetic flux change due to the change of said circuit current caused by discharge.

2. The current detection circuit of claim 1, wherein said current detection part detects magnetic flux change occurring in circuit wiring of said inverter by a detecting conductor that is provided adjacent to said circuit wiring.

3. The current detection circuit of claim 1, wherein said current detection part detects magnetic flux change occurring at a space of a core gap of a transformer of said inverter by a detecting conductor that is provided at the space of the core gap of said transformer.

4. The current detection circuit of claim 1, wherein said current detection part is provided at any of an optional portion of circuit wiring leading from the DC input to the load, a side of the DC input, a primary side of a transformer of said inverter and a secondary side of the transformer, or at a plurality of places not less than two of the optional portion of the circuit wiring, the side of the DC input, the primary side and the secondary side.

5. The current detection circuit of claim 1 further comprising a current change detection part, wherein said current change detection part comprises:

a rectification part that rectifies a fluctuation voltage obtained by the magnetic flux change; and

a smoothing part that smoothes a rectified voltage given from said rectification part.

6. The current detection part of claim 2, wherein said current detection part constitutes said detecting conductor and a portion of said circuit wiring as an independent discrete element.

7. The current detection circuit of claim 5, wherein said rectification part is constituted by Schottky diode.

8. The current detection circuit of claim 5, wherein said current change detection part includes a filter that extracts change in a current due to discharge including disconnection discharge and dielectric breakdown discharge.

9. The current detection circuit of claim 2 further comprising a core that forms a common magnetic path for said circuit wiring and said detecting conductor.

10. An anomaly detection circuit of an inverter that converts DC input into AC output and supplies the AC output to a load, comprising:

a current detection part that detects change in a circuit current of said inverter through the medium of the magnetic flux change due to the change in said circuit current caused by discharge; and

a detection signal output part that, based on a result of a detection of said current detection part, outputs a detection signal representative of whether or not anomaly exists in a current route including said load.

11. The anomaly detection circuit of claim 10, wherein said current detection part detects magnetic flux change occurring in circuit wiring of said inverter by a detecting conductor that is provided adjacent to said circuit wiring.

12. The anomaly detection circuit of claim 10, wherein said inverter provides a control part that receives said detection signal and stops an inverter operation at the time of behavioral anomaly.

13. The anomaly detection circuit of claim 10 further comprising a current change detection part, wherein said current change detection part comprises:

a rectification part that rectifies a fluctuation voltage obtained by the magnetic flux change; and

a smoothing part that smoothes a rectified voltage given from said rectification part.

14. The anomaly detection circuit of claim 10, wherein said current detection part is provided at any of an optional portion of circuit wiring leading from the DC input to the load, a side of the DC input, a primary side of a transformer of said inverter and a secondary side of the transformer, or at a plurality of places not less than two of the optional portion of the circuit wiring, the side of the DC input, the primary side and the secondary side.

15. The anomaly detection circuit of claim 11, wherein said current detection part constitutes said detecting conductor and a portion of said circuit wiring as an independent discrete element.

16. The anomaly detection circuit of claim 13, wherein said rectification part is constituted by Schottky diode.

17. The anomaly detection circuit of claim 11 further comprising a core that forms a common magnetic path for said circuit wiring and said detecting conductor.

18. The anomaly detection circuit of claim 12, wherein control part includes a display driving part, and gives output of the display driving part to an indicator so that the behavioral anomaly can be displayed.

19. The anomaly detection circuit of claim 12, wherein said detection signal output part and said control part are formed of an IC, which is single in number.

20. The anomaly detection circuit of claim 13, wherein said current change detection part includes a filter that extracts change in a current due to discharge including disconnection discharge and dielectric breakdown discharge.

21. A test method using an inverter that converts DC input into AC output and supplies the AC output to a load, comprising:

a step that detects change in a circuit current of said inverter through the medium of the magnetic flux change due to the change in said circuit current caused by discharge; and

a step that decides based on a result of a detection of the change in said circuit current whether or not anomaly exists in a current route including said load.

22. A test device comprising:

an inverter that converts DC input into AC output and supplies the AC output to a load; and

a current detection part that detects change in a circuit current of said inverter through the medium of the magnetic flux change due to the change in said circuit current caused by discharge, wherein

whether or not anomaly exists in a current route including said load is decided based on a result of a detection of said current detection part.