Inverter system

• US 7,492,162 B2
• Filed: 12/27/2006
• Issued: 02/17/2009
• Est. Priority Date: 07/22/2002
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Senba, Minoru, Yadoori, Shuuichi, Tanaka, Masaru, Hachisuka, Seiji
• Primary Examiner(s): Nguyen; Vincent Q
• Application Number:
  US11/616,623
• Publication Number:
  US 20070103163A1
• Time in Patent Office: 783 Days
• Field of Search: 324/522, 324/127, 324/750, 324/529, 324/76.11
• US Class Current: 324/522
• 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, provided at the DC input side of said inverter, that detects magnetic flux change, which occurs in a portion of circuit wiring passing through the current detection part of said inverter based on a change in a circuit current due to discharge occurring in the overall circuit wiring of said inverter, at the DC input side of said inverter, said current detection part detecting the change in the circuit current through the medium of the magnetic flux change; and

a current change detection part that inputs a detected output of the current detection part and detects current change, the current change detection part including 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.

2. The current detection circuit of claim 1, further comprising:

a detecting conductor that is provided adjacent to said portion of circuit wiring, wherein

the detecting conductor detects the magnetic flux change occurring in said portion of the circuit wiring.

3. 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.

4. 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.

5. The current detection circuit of claim 1, wherein said rectification part is constituted by Schottky diode.

6. The current detection circuit of claim 1, 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.

7. 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 magnetic flux change occurring based on a change in a circuit current of said inverter due to discharge that occurs in circuit wiring of the inverter, said current detection part detecting the change in the circuit current through the medium of the detected magnetic flux change; and

a current change detection part that inputs a detected output of the current detection part and detects current change, the current change detection part including 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, wherein

a core of a transformer of said inverter has a gap formed in a magnetic path, and

said current detection part includes a detecting conductor provided at a space of the gap of the core of said transformer, and detects the magnetic flux change occurring at the space of the gap of the core of said transformer by said detecting conductor.

8. 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, provided at a primary side and/or a secondary side of a transformer of said inverter, detecting magnetic flux change, which occurs in a portion of circuit wiring passing through the current detection part of said inverter based on a change in a circuit current due to discharge occurring in the overall circuit wiring of said inverter, said current detection part detecting the change in the circuit current through the medium of the magnetic flux change; and

a current change detection part that inputs a detected output of the current detection part and detects current change, the current change detection part including 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,

wherein said current detection part includes a detecting conductor that is arranged in the vicinity of said circuit wiring and is print-formed on a circuit board with said circuit wiring, and detects the magnetic flux change by said detecting conductor.

9. 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, by a current detection part, detects magnetic flux change, which occurs in a portion of circuit wiring at the DC input side of said inverter based on a change in a circuit current due to discharge occurring in the overall circuit wiring of said inverter, and detects the change in the circuit current through the medium of the magnetic flux change;

a step that inputs a detected output of the current detection part to a current change detection part and outputs the detected output of the current detection part as a result of a detection, the current change detection part including 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; and

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

10. A current detection circuit comprising:

a current detection part, provided at a DC input side of an inverter, that detects magnetic flux change occurring in a portion of circuit wiring at the DC input side of said inverter based on a change in a circuit current due to discharge occurring in the overall circuit wiring of said inverter; and

a current change detection part that inputs a detected output of the current detection part and detects current change, the current change detection part including 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.