Galvanic isolation device for direct current electrical signals or electrical signals likely to include a direct current component

• US 5,321,597 A
• Filed: 10/13/1993
• Issued: 06/14/1994
• Est. Priority Date: 03/22/1991
• Status: Expired due to Term

• Current Assignee: GEC Alsthom SA
• Original Assignee: GEC Alsthom SA
• Inventors: Alacoque, Jean-Claude
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US08/135,587
• Time in Patent Office: 244 Days
• Field of Search: 363/15, 363/16, 363/20, 363/21, 363/24, 363/25, 363/26, 363/95, 363/97, 363/124, 323/266, 323/282, 323/355
• US Class Current: 363/25
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: H03K 17/6874 in a symmetrical configuration
• CPC Class Codes: H03K 17/785 controlling field-effect transistor switches
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Galvanic isolation device for direct current electrical signals or electrical signals likely to include a direct current component, which includes a transformer (T), reversible switch I for chopping the incident signal applied to one wind of this transformer reversible switch I'"'"' for chopping the signal obtained at the other winding of this transformer, controlled either in phase or in phase opposition with each other and filters (F1,F2) for filtering the chopped signals respectively obtained at windings of the transformer.

Claims

1. A galvanic isolation device for one of direct current electrical signals and electrical signals likely to include a direct current component, said galvanic isolation device comprising:

a transformer having a first winding and a second winding, wherein signals having different polarities are applied across said first winding and said second winding,

first reversible means, connected to said first winding of said transformer, for chopping said signals applied across said first winding of said transformer, said first reversible means being arranged for chopping said signals of different polarities,

second reversible means, connected to said second winding of said transformer, for chopping said signals applied across said second winding of said transformer, said second reversible means being arranged for chopping said signals of different polarities, wherein said second reversible means is controlled in one of phase opposition with said first reversible means and in phase with said first reversible means, and

first and second filter means for filtering signals obtained across said first winding and said second winding of said transformer, respectively,

wherein said first reversible means and said second reversible means are arranged to provide for reversible operation of said galvanic isolation device.

2. The galvanic isolation device according to claim 1, wherein said galvanic isolation device is reversible in operation and comprises said first and said second reversible means and said first and said second filter means associated with said first and said second windings of said transformer, respectively.

3. The galvanic isolation device according to claim 1, wherein said signals comprise an alternating current component, and wherein said first and said second reversible means are controlled at a frequency more than twice a highest frequency to be transmitted in an input signal.

4. The galvanic isolation device according to claim 1, wherein each of the first and the second reversible means comprises semiconductor switches.

5. The galvanic isolation device according to claim 1, wherein each of said first and said second reversible means includes two basic semiconductor switches called half-switches which include internal parasitic diodes, wherein said half-switches are connected in series and have opposite conduction directions, a conduction direction for each of said half-switches of said first reversible means being identical to a conduction direction of the internal parasitic diodes of said half-switches of said second reversible means.

6. The galvanic isolation device according to claim 5, wherein for high operating frequencies, first and second diodes having required speed characteristics are associated with each of said half-switches respectively to eliminate operation of said internal parasitic diodes and to substitute for the operation of said internal parasitic diodes.

7. The galvanic isolation device according to claim 1, wherein each of said first and second reversible means includes two semiconductor basic switches called half-switches connected in anti-parallel having opposite conduction directions and each connected in series with a diode having a conduction direction opposite to that of said internal parasitic diode of a corresponding half-switch.

8. The galvanic isolation device according to claim 5, wherein said two semiconductor basic switches known as half-switches are connected each on one side of the transformer.

9. The galvanic isolation device according to claim 5, wherein control signals for said half-switches are derived from a common clock and applied to a control input of each of said half-switches via means for galvanically isolating an output signal of said common clock.

10. The galvanic isolation device according to claim 9, wherein said control signals of said half-switches are applied thereto via an electronic control means which operates an output signals of said common clock and specific to each of said half-switches, the half-switches having a local power supply applied to a reference terminal of each of said half-switches.

11. The galvanic isolation device according to claim 10, wherein said local power supply is obtained by taking energy from signals passing through the galvanic isolation device.

12. The galvanic isolation device according to claim 10, wherein said galvanic isolation device comprises means for disabling one of the power supply of said electronic control means and said electronic control means for that of tow of said half-switches which are not caused to conduct.

13. The galvanic isolation device according to claim 12, wherein said disabling means comprises means for detecting absence of current in said half-switches.

14. The galvanic isolation device according to claim 12, wherein said disabling means comprises means for detecting presence of current in an external diode which is substituted for the internal parasitic diode of said half-switch.