ELECTRICAL POWER SUPPLY SYSTEM

Abstract

An electrical power supply system, in particular for a microgrid, includes a DC bus, and a first rectifier and a second rectifier, with the first and second rectifiers each supplying power to the DC bus. The first rectifier is a diode rectifier and the second rectifier has switchable power semiconductors. The electrical power supply system further includes a generator supplying power to both rectifiers. The rectifiers can be connected at different times according to a load.

Claims

1.-13. (canceled)

14. An electrical power supply system, comprising: a segmented DC bus including a plurality of segments, with two of the plurality of segments each include at least one feed; a first rectifier constructed as a diode rectifier, a second rectifier comprising switchable power semiconductors; and a generator designed to supply power to the first and second rectifiers for supply of power to the DC bus.

15. The electrical power supply system of claim 14, constructed for a microgrid.

16. The electrical power supply system of claim 14, wherein one of the plurality of segments of the DC bus include only one feed designed as an external feed.

17. The electrical power supply system of claim 14, wherein the generator is a first generator for supplying power to a first one of the two segments of the DC bus, and further comprising: a second generator for supplying power to a second one of the two segments of the DC bus, and a switch segmenting the first and the second segments.

18. The electrical power supply system of claim 14, further comprising a grid connection located distal from the electrical power supply system.

19. The electrical power supply system of claim 14, further comprising a gas turbine or a diesel driving the generator.

20. The electrical power supply system of claim 14, wherein the generator is an asynchronous machine or a synchronous machine, said generator including an open circuit.

21. The electrical power supply system of claim 14, wherein the DC bus is a DC bus of a ship, supplying power to a marine propulsion motor.

22. The electrical power supply system of claim 14, wherein the two segments supply different loads.

23. The electrical power supply system of claim 22, wherein the two segments supply the different loads separately from one another.

24. The electrical power supply system of claim 14, further comprising a filter disposed in an electrical connection of the generator to at least one of the first rectifier and second rectifiers.

25. The electrical power supply system of claim 14, wherein the first rectifier has an output power which is at least ⅓ of an output power of the second rectifier, and wherein the output power of the second rectifier is at least ⅓ of the output power of the first rectifier.

26. The electrical power supply system of claim 14, wherein the second rectifier comprises an IGBT three-phase bridge.

27. The electrical power supply system of claim 14, wherein the DC bus comprises a capacitor.

28. A method for operating an electrical power supply system comprising a segmented DC bus which includes a plurality of segments, with at least two of the plurality of segments each including at least one feed, the method comprising: supplying power to the segmented DC bus from a first rectifier constructed as a diode rectifier and from a second rectifier comprising switchable power semiconductors, switching the first and second rectifiers at different times depending on a connected load, and activating the feeds of the at least two segments depending on the connected load.

29. The method of claim 28, further comprising supplying power via a generator to the first and second rectifiers for supply of power to the DC bus.

30. The method of claim 28, further comprising designing one of the plurality of segments of the DC bus with only one feed as an external feed.

31. The method of claim 28, further comprising: supplying power to a first one of the two segments of the DC bus via a first generator; supplying power to a second one of the two segments of the DC bus via a second generator, and segmenting the first and the second segments.

32. The method of claim 29, further comprising placing a filter in an electrical connection of the generator to at least one of the first rectifier and second rectifiers.

33. The method of claim 14, further comprising: designing the first rectifier with an output power which is at least ⅓ of an output power of the second rectifier; and designing the output power of the second rectifier such as to be at least ⅓ of the output power of the first rectifier.

Description

[0019] The invention will now be illustrated and explained in more detail using examples and with reference to the accompanying drawings. The features shown in the figures may be combined by persons skilled in the art to produce new embodiments without departing from the scope of the invention.

[0020] FIG. 1 shows an electrical power supply system with a diode rectifier;

[0021] FIG. 2 shows an electrical power supply system with an active rectifier;

[0022] FIG. 3 shows an electrical power supply system with a passive rectifier and a boost converter;

[0023] FIG. 4 shows an electrical power supply system with two rectifiers; and

[0024] FIG. 5 shows an electrical power supply system with a DC bus which has segments.

[0025] FIG. 1 shows an electrical power supply system 10 with a diode rectifier 3. A generator 7 is driven by a diesel engine (DM) 8. The generator is, for example, a synchronous machine. The generator 7 supplies three-phase power to the diode rectifier 3. The diode rectifier 3, which is an uncontrolled rectifier, supplies the DC bus 20. At full load, i.e. maximum diesel speed, the machine can be in the field weakening region. This DC bus 20, as well as other DC buses, can also be at the same time a DC link. The DC bus 20 has a capacitor 18. By means of an inverter 12 it is possible to draw electrical energy from the DC bus 20 and to drive a motor 9. The motor 9 constitutes a load.

[0026] FIG. 2 shows an electrical power supply system 20 similar to FIG. 1, wherein, in contrast to the electrical power supply system 20 according to FIG. 2 shown in FIG. 1, an active rectifier 4 is used instead of the diode rectifier as a rectifier for supplying the DC bus 20. The active rectifier 4 can comprise a conventional IGBT six-pack (rotary inverter). For example, an asynchronous/or synchronous machine can be used as generator 7.

[0027] Similarly to FIG. 1, FIG. 2 shows an electrical power supply system 20, wherein in comparison to the electrical power supply system 20 according to FIG. 2 shown in FIG. 1, a boost converter 19 is also used, in addition to the passive rectifier 3.

[0028] FIG. 4 shows an electrical power supply system 1 having two rectifiers, a first rectifier 3 and a second rectifier 4. A generator 7 is driven by a diesel engine (DM) 8. Instead of the diesel 8, a gas turbine could also be used (not shown). The generator 7 is, for example, a synchronous machine or an asynchronous machine. The generator 7 is connected in open circuit. The generator 7 supplies three-phase power to the diode rectifier 3. The diode rectifier 3, which is an uncontrolled rectifier, feeds the DC bus 2. The diode rectifier 3 comprises power semiconductor diodes 6. The generator 7 also supplies three-phase power to the second rectifier 4. The second rectifier 4 has switchable power semiconductors 5. These are distributed according to the IGBT three-phase bridge 17. Thus, as an alternative to the “conventional IGBT sixpack”, which is used alone and is shown in FIG. 2, the output of the electric machine, i.e. the generator 7, is divided between two converters 3 and 4 (an IGBT sixpack and an uncontrolled rectifier). The DC bus 2 also has a capacitor 18. Inverters 12 and 13 make it possible to draw electrical energy from the DC bus 2 and drive a motor 9 or 11. The motors 9 to 11 constitute a load. At least one of the motors is used in particular to propel a ship. A filter 14 comprising resistors 15 and capacitors enables the quality of the power supplied to the first rectifier 3 to be improved. The filter 14 is electrically connected between the first rectifier 3 and the generator 7. This AC filter is optional and can also be used for additional operating point control. In the DC bus 2, DC load distribution is produced with the connected converters for e.g. propulsion and the ship electrical system. Compared to solely using a diode rectifier, the use of two rectifiers of the type described results in optimum utilization of the electrical machine and also standardization possibilities. This applies to asynchronous machines and synchronous machines (also PEM). Compared to only using one active rectifier, the use of two rectifiers of the type described can result in the following: only half the IGBT semiconductor requirement and thus only approx. 60% of the rectifier costs.

[0029] FIG. 5 shows a DC bus 30 comprising capacitors 18, 18′ and 18″ which is subdivided into segments 31, 32 and 33. Loads 28, 29, 9 and 11 are connected to the DC bus 30 via inverters 12. A first segment 31 of the DC bus 30 has a first feed 21 comprising a first rectifier 3 and a second feed 22 comprising a second rectifier 4, wherein both rectifiers 3 and 4 can be supplied by means of a generator 7, wherein the generator 7 can be powered by means of a diesel 8. The second segment 32 has two feeds, namely feeds 23 and 24, wherein a rectifier 3′ is associated with the feed 23 and a rectifier 4′ is associated with the feed 24. The rectifier 3′ is supplied by means of a generator 7′, wherein the generator 7′ can be powered by means of a diesel 8′. The rectifier 4′ is supplied by means of a generator 7″, wherein the generator 7″ can be powered by means of a gas turbine 27. The third segment 33 has a feed 25, wherein a rectifier 4″ is associated with the feed 25 and can be connected to an electrical grid 36 via a switch 26. The grid 36 is in particular a wide area synchronous grid (interconnection). The segments 31, 32 and 33 are segmented by means of switches 34 and 35. The segments can be electrically connected or disconnected by means of the switches 34 and 35.