Reconfigurable voltage inverter with tolerance to failures

1. Voltage inverter provided with four switching cells (Q 1 to Q 4 ) to be connected to the terminals of a DC voltage source (Vdc), each comprising two semiconductor switches (I 11 , I 12 , I 21 , I 22 , I 31 , I 32 , I 41 , I 42 ) installed in series, these switches having a common point (A 0 ) to be connected to an AC current source (Mac) with three phases (p 1 , p 2 , p 3 ) and a neutral (n), the connection being made onto one phase (p 1 , p 2 , p 3 ) for three of the cells (Q 1 , Q 2 , Q 3 ) and onto the neutral (n) for the fourth cell (Q 4 ), wherein each of the four cells (Q 1 to Q 4 ) cooperates with a semiconductor electrical isolating device (S 1 , (S 2 . 1 and S 2 . 2 )) to be put into a turn-off state if the cell should fail, this isolating device (S 1 , (S 2 . 1 and S 2 . 2 )) being arranged either on the connection to the AC current source (Mac), or on connections to the terminals of the DC voltage source (Vdc).

2. Voltage inverter according to claim 1 , wherein the electrical isolating device has a controllable electronic switch function that is bi-directional in current and in voltage.

3. Voltage inverter according to claim 1 , wherein, when the electrical isolating device (S 1 ) is arranged on the connection to the AC current source (Mac), said electrical isolating device (S 1 ) comprises at least two parts (I′ 11 , I′ 12 ) in an antiparallel circuit.

4. Voltage inverter according to claim 3 , wherein each part comprises a diode (D 1 ′, D 2 ′) and a transistor (T 2 ′, T 1 ′) in series.

5. Voltage inverter according to claim 3 , wherein each part comprises a thyristor (Th 1 , Th 2 ).

6. Voltage inverter according to claim 1 , wherein when the electrical isolating device (S 2 . 1 and S 2 . 2 ) is arranged on the connections to the terminals of the DC voltage source (Vdc), the electrical isolating device (S 2 . 1 , S 2 . 2 ) includes at least two thyristors (Th 1 ′, Th 2 ′) installed in antiparallel on each connection.

7. Voltage inverter according to claim 1 , wherein when the electrical isolating device (S 2 . 1 and S 2 . 2 ) is arranged on the connections to the terminals of the DC voltage source (Vdc), the electrical isolating device (S 2 . 1 , S 2 . 2 ) includes at least one diode (D 1 ″, D 2 ″) and a thyristor (Th 1 ″, Th 2 ″) installed in antiparallel on each connection.

8. Voltage inverter according to claim 1 , wherein when the electrical isolating device (S 2 . 1 and S 2 . 2 ) is arranged on the connections to the terminals of the DC voltage source (Vdc), the electrical isolating device (S 2 . 1 , S 2 . 2 ) includes at least one diode (D 1 ″, D 2 ″) and one transistor (T 1 , T 2 ) installed in antiparallel on each connection.

9. Voltage inverter according to claim 1 , wherein when the electrical isolating device (S 2 . 1 and S 2 . 2 ) is arranged on the connections to the terminals of the DC voltage source (Vdc), the electrical isolating device (S 2 . 1 , S 2 . 2 ) includes at least two assemblies each having one diode (D 1 , D 2 ) and one transistor (T 1 , T 2 ) installed in series, on each connection, these two assemblies being mounted in antiparallel.

10. Voltage inverter according to claim 1 , wherein a protection device (Pi′, Pi″) cooperates with the electrical isolating device (S 1 , (S 2 . 1 and S 2 . 2 )).

11. Voltage inverter according to claim 10 , wherein the protection device (Pi′) comprises at least one transit diode (DT′) in parallel with the electrical isolating device (S 1 ).

12. Voltage inverter according to claim 6 , wherein a thyristor (Th 1 ′, Th 2 ′, Th 1 ″, Th 2 ″) or a transistor (T 10 , T 1 ) of the electrical isolating device (S 2 . 1 , S 2 . 2 ) is mounted in series with a filter device (L C).

13. Voltage inverter according to claim 12 , wherein the filter device (LC) is of the inductive capacitive type.

14. Voltage inverter according to claim 1 , wherein the switch (I 11 , I 12 , I 21 , I 22 , I 31 , I 32 , I 41 , I 42 ) comprises a transistor (T) and a diode (D) in an antiparallel circuit.

15. Voltage inverter according to claim 1 , wherein the switch (I 11 , I 12 , I 21 , I 22 , I 31 , I 32 , I 41 , I 42 ) is provided with a protection device (Pi).

16. Voltage inverter according to claim 1 , wherein each switching cell (Q 1 to Q 4 ) cooperates with a failure monitoring and control device (S 0 ) specific to it.

17. Voltage inverter according to claim 16 , wherein when the monitoring and control device (S 0 ) detects failure of one (Q 1 , Q 2 , Q 3 ) of the three cells (Q 1 to Q 3 ), it forces the switches (I 11 , I 12 , I 21 , I 22 , I 31 , I 32 , I 41 , I 42 ) of this cell and the electrical isolating device (S 1 , S 2 . 1 , S 2 . 2 ) associated with it into a turn-off state.

18. Voltage inverter according to claim 17 , including a supervisor device (OS), wherein when the monitoring and control device (S 0 ) detects failure of one (Q 1 , Q 2 , Q 3 ) of the three cells (Q 1 to Q 3 ), the supervisor device (OS) puts the fourth cell (Q 4 ) into operation and puts the electrical isolating device (S 1 , (S 2 . 1 , S 2 . 2 )) associated with the fourth cell (Q 4 ) into a turn-on state.

19. Voltage inverter according to claim 16 , wherein the monitoring and control device (S 0 ) cooperates with a current measurement device (Mi) placed on the connection to the alternating current source (Mac).

20. Voltage inverter according to claim 16 , wherein the monitoring and control device (S 0 ) cooperates with a device for measuring the temperature of the switches (I 11 , I 12 , I 21 , I 22 , I 31 , I 32 , I 41 , I 42 ).