Bidirectional electrical converter with a DC / AC bridge converter and a dual active bridge converter connected in series.

Abstract

A bidirectional n-phase electrical converter 1 has the following features: an input terminal 18 for connecting a DC voltage source, a DC / DC converter 10;110;210 connected to the input terminal 18 and having first switching elements 31;134, p intermediate circuits 90;190;290 connected to the DC / DC converter 10;110;210 on the output side, and a DC / AC converter 40;140;240 having a second switching element, wherein the DC / AC converter 40;140;240 is followed by the p intermediate circuits 90;190;290. The DC / AC converters 40;140;240 have output terminals for connecting to an electromechanical unit 60;160;260 or an AC network 270, and include control devices 80;280 that control the second switching elements 32;135 of the DC / AC converters 40;140;240 to provide a stepped n-phase output voltage 410, and the DC / AC converters 40;140;240 are formed as a fundamental frequency switching, rotor-controlled n-phase rotating voltage system.

Claims

1. A bidirectional n-phase electrical converter (1), An input terminal (18) for connecting a DC voltage source, A DC / DC converter (10;110;210) is connected to the input terminal (18) and has a first switching element (31;134), On the output side, there are p intermediate circuits (90; 190; 290) connected to the DC / DC converter (10; 110; 210), A DC / AC converter (40;140;240) having a second switching element (32;135), wherein the DC / AC converter (40;140;240) is connected downstream of the p intermediate circuits (90;190;290), The DC / AC converters (40; 140; 240) have output terminals for connecting to electromechanical devices (60; 160; 260) or electrical AC networks (270). The DC / AC converter (40; 140; 240) is characterized by comprising a control device (80; 280) that controls the second switching element (32; 135) to provide a step-like n-phase output voltage (410), The DC / AC converter (40; 140; 240) is characterized in that it is formed as a fundamental frequency switching, rotor-controlled n-phase rotational voltage system, and is an electrical conversion device (1).

2. The electrical converter (1) according to claim 1, characterized in that the electrical converter (1) is formed in three phases with n=3.

3. The electrical conversion device (1) according to claim 1, characterized in that the control device (80; 280) controls the first switching element (31; 134) so ​​that the output voltage of the DC / DC converter (10; 110; 210) is tracked so that it provides at least substantially sinusoidal voltage signals at n output terminals.

4. The output voltage (420) of the DC / DC converter (10; 110; 210) is tracked within a limited amplitude range. The aforementioned limited amplitude range is within the range of 0 to 50% of the intermediate circuit voltage. The electrical conversion device (1) according to claim 3, characterized in that the limited amplitude range is preferably within the range of 0 to 1 / 6 times the intermediate circuit voltage.

5. The electrical conversion device (1) according to any one of claims 1 to 4, characterized in that the control of the second switching elements (32; 135) of the DC / AC converter (40; 140; 240) is performed by the MSK method.

6. The MSK control method has 12 switching states, The electrical converter (1) according to claim 5, characterized in that the switching state depends on the rotor position.

7. The control of the current and its torque depends on the rotor displacement angle Δε. The electrical conversion device (1) according to any one of claims 1 to 6, characterized in that the rotor deviation angle Δε for different combinations of rotational speed and torque is stored in one or more lookup tables.

8. The electrical converter (1) according to any one of claims 1 to 7, characterized in that the electrical machine (60; 160; 260) has a mechanical rectifier.

9. The electrical conversion device (1) according to any one of claims 1 to 8, characterized in that the p intermediate circuits (90; 190; 290) are formed as capacitive intermediate circuits (90; 190; 290).

10. The electrical conversion device (1) according to claim 9, characterized in that the capacitive intermediate circuit (90; 190; 290) is realized by intermediate circuit capacitors (91; 191).

11. The electrical conversion device (1) according to any one of claims 1 to 10, characterized in that the switching frequency of the first switching element (31; 134) is in the range of about 500 kHz to about 1 MHz.

12. The electrical conversion device (1) according to any one of claims 1 to 11, characterized in that the DC / DC converter (10; 110; 210) has a three-phase high-frequency transformer (20; 120).

13. The aforementioned high-frequency transformer (20; 120) is formed as a triangular-star transformer, The electrical conversion device (1) according to claim 12, characterized in that the primary side of the high-frequency transformer (20; 120) is connected in a triangular configuration, and the secondary side of the high-frequency transformer (20; 120) is connected in a star configuration.

14. The electrical conversion device (1) according to any one of claims 1 to 13, characterized in that the DC / DC converters (10; 110; 210) are formed as DC / DC resonant converters (17; 113).

15. The DC / DC converter (10; 110; 210) is formed as a CLLC topology, The electrical converter (1) according to claim 14, characterized in that the CLLC topology has two capacitances (21;122) and two inductances (22;123) of a high-frequency transformer (20;120).

16. The electrical converter (1) according to claim 14 or 15, characterized in that the impedance arrangement of the CLLC topology has first a capacitance (21;122), followed by two inductances (22;123), and then another capacitance (21;122).

17. The electrical conversion device (1) according to claim 15 or 16, characterized in that the inductances (22; 123) of the CLLC topology are the leakage inductances (123; 124) of the high-frequency transformer (20; 120).

18. The electrical converter (1) according to any one of claims 1 to 17, characterized in that the control device (80; 280) is configured to control the first switching element (31; 134) and the second switching element (32; 135) depending on current, voltage, rotor position, and time.

19. The electrical conversion device (1) according to any one of claims 1 to 18, characterized in that the DC / DC converter (10; 110; 210) has a three-phase bridge circuit (15; 141) on the input side and the output side.

20. The three-phase bridge circuit (15; 141) has n half-bridges (36; 131), The electrical converter (1) according to claim 19, characterized in that each half-bridge (36; 131) has two switching elements (32; 135).

21. The electrical conversion device (1) according to any one of claims 1 to 20, characterized in that the first switching element (31; 134) is formed as a silicon carbide (SIC) or gallium nitride (GaN) MOSFET.

22. The electrical conversion device (1) according to any one of claims 1 to 21, characterized in that the second switching element (32; 135) is formed as an IGBT or a MOSFET.

23. The electrical conversion device (1) according to any one of claims 1 to 22, characterized in that the DC / DC converters (10; 110; 210) and the DC / AC converters (40; 140; 240) are arranged in a metal housing.

24. A method for operating the electrical converter (1), The electrical converter (1) controls at least one DC / DC converter (10;110;210) via a first switching element (31;134) and at least one DC / AC converter (40;140;240) via a second switching element (32;135) by a control device (80;280). The second switching elements (32; 135) of the DC / AC converter (40; 140; 240) are controlled such that at least one output voltage (410) of the DC / AC converter (40; 140; 240) is formed in a pulsed manner. A method for operating an electrical converter (1), wherein at least one output voltage (420) of the DC / DC converter (10; 110; 210) is tracked between multiple pulses of the output voltage (410) of the DC / AC converter (40; 140; 240) such that a substantially sinusoidal phase current (430) is formed at the output of the electrical converter (1).

25. A method for operating an electrical converter (1) according to claim 25, characterized in that the second switching elements (32; 135) of the DC / AC converter (40; 140; 240) are controlled by an MSK method, wherein the MSK method forms a 12-pulse output voltage (410) at the output of the electrical converter (1).

26. The method of operating the electrical converter (1) according to claim 25 or 26, characterized in that the DC / DC converter (10; 110; 210) is an operating unit of a rotor control rotation voltage system, thereby controlling the amplitude of the phase current (430) by the DC / DC converter (10; 110; 210).

27. A method of operating the electrical converter (1) according to any one of claims 25 to 27, characterized in that torque control is performed by a phase shift between a synchronous internal voltage and a rotor control rotation voltage system.

28. The electrical converter (1) according to any one of claims 1 to 23, characterized in that it is used to operate an electrical machine (60; 160; 260) or to supply power to an electrical n-phase AC network (270).

Images