WO2007036430A1

WO2007036430A1 - Method and device for the inductive transfer of energy to super-conductive excitation coils of an electric machine

Info

Publication number: WO2007036430A1
Application number: PCT/EP2006/066288
Authority: WO
Inventors: Ralf Cordes; Reinhard Maier; Gerd Griepentrog; Jürgen RUPP
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-09-30
Filing date: 2006-09-12
Publication date: 2007-04-05

Abstract

Electric energy is transferred to the magnet field coils of a rotor of an electric machine. The magnet field coils are made of a super-conductive material, such that the rotor is located in a shielded manner in a low temperature range. According to the invention, the electric power in inductively transferred to the magnet field coils, whereby at least one electrical transformer is provided and secondary conditions are maintained in order to produce a uniform magnetic flow in the magnetic field coils. Preferably, at least one rotating transformer and one transformer for high voltage in the low temperature area is provided.

Description

description

METHOD AND APPARATUS FOR THE INDUCTIVE ENERGY TRANSMISSION TO SUPRELEITING ENCODER PULES OF AN ELECTRICAL MACHINE

The invention relates to a method for exciting the pole wheel of an electrical machine, wherein the pole wheel is designed to rotate. The method is particularly suitable for superconducting motors or generators. In addition, the invention also relates to an associated apparatus for carrying out the method.

After the discovery and development of the high-temperature superconductor (HTS), which can be operated with liquid nitrogen, electrical machines operating therewith are becoming increasingly important, especially in the case of electric synchronous machines made of stator and rotor (Laufer). especially the rotor should have superconducting Polradspulen.

Usually, the transmission of electrical power necessary for excitation or de-excitation of the superconducting machine has been transmitted via slip rings. Slip rings require maintenance and are subject to negligible wear. They are suitable for use in aggressive environments, e.g. Salt water, not suitable or at least must be encapsulated.

The latter is especially true when such machines are to be used as propulsion engines and / or power generators on ships and inevitably come in contact with salt water when used as intended.

The object of the invention is therefore to provide suitable methods for

Specify energy transfer in the cryostat where the heat input in the cryostat due to the heat conduction of the electrical lines is low. Furthermore, an associated device is to be created.

The object is achieved according to the invention by the measure of patent claim 1. An associated device is specified in claim 11. Further developments of the method and the associated apparatus, in particular for use in an electrical machine with Polradspulen of superconducting material are the subject of the dependent claims.

The invention thus relates to the inductive transmission of the excitation or deenergization of a rotor coil and the transmission of the necessary electrical power to or from the arranged on the rotating shaft coil. It is essential that the superconducting machine itself

Transmitter for transmitting the electric power to the Polradspulen in the low temperature range are.

The basis of the invention is the recognition that due to the supply of electrical power by higher voltage in the cryostat a reduction of the warm flow in the Kry- ostaten takes place and thus a reduction of the necessary cooling power is possible.

In the context of the invention are alternative embodiments of

Transformers possible. It is crucial that now the electrical power is transmitted with a higher voltage and smaller currents and thus smaller conductor cross-sections. This results in reduced losses due to the transmission line on the electrical supply lines. In the cold part of the superconducting machine, a transformation of the high voltage / small current to a small voltage / high current must take place.

In the invention, it is advantageous that slip rings are not necessarily required. If slip rings are used, the transmission of the necessary for Er- or de-energizing the Polradspulen electrical power in the cryostat. This results in a much lower heat input into the machine, so that increases their cost-effectiveness. Since the inductive energy transfer takes place without contact, there is no mechanical wear.

Further details and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings in conjunction with the claims.

Each show in a schematic representation

Figure 1 is a block diagram with the combination of a

Schleifringubertragers and a voltage-current transformer for feeding a HTS Polradwicklung,

FIG. 2 shows a block diagram with the combination of a rotating transformer and a voltage-current converter for feeding a HTS pole-wheel winding,

FIG. 3 shows a block diagram according to FIG. 1 with a multiplex operation of individual pole wheel coils,

FIG. 4 shows a block diagram according to FIG. 1 with a parallel control of individual pole wheel coils;

5 shows a block diagram with a combination of a rotating transformer and a voltage-current transformer,

6 and 7 representations according to FIG. 1 with an additional heating resistance in two alternatives,

8 shows an axial arrangement of the rotary transformer of FIGS. 1 to 4, FIG. 9 shows a radial arrangement of the rotating transformer of FIGS. 1 to 4,

FIG. 10 shows the structure of an electrical shunt across the rotating shaft of the machine,

FIG. 11 shows an alternative embodiment of the shunt according to FIGS. 9 and

FIG. 12 shows an alternative arrangement to FIGS. 9 and 10 with a modified pot core. In the figures, identical or identically acting parts have the same reference numerals. The figures are described in groups together.

It is to be supplied with the flywheel of a synchronous machine with energy. The machine can be a motor or even a generator. The machine is a superconducting machine, i. The coils, in particular in the Laufer consist of superconducting material and thus work largely lossless. In current technology, the coils are formed of HTS material (HTS = High Temperature Superconductor), whereby a cooling with liquid nitrogen at a temperature around 80 K is possible.

In Figure 1, a voltage source 1, a slip ring 2 with subsequent inverter 2 and a transformer 5 are present. The transmitter 5 is located in a cryostat 20 to ensure a predetermined temperature at which the inductors used in the machine are superconducting.

On the secondary side of the transformer 5 is essentially the superconducting Polradinduktivitat, the switching and measuring means are assigned.

The slip ring arrangement according to FIG. 1 is used for voltage transmission to moving parts. It is advantageous that the slip rings produce no appreciable losses. The losses are generated by the thick wires.

In FIG. 2, a voltage source 1 with an inverter 2 forms an AC voltage source of predetermined frequency, a rotating transformer 3, a power converter 4 and a voltage / current transformer 5 being present.

More specifically, the power converter 4 is composed of an AC-DC converter 4a and a subsequent DC-AC converter 4b. With the voltage / current Transformer 5, a suitable voltage for feeding a HTS Polradwicklung is generated.

In FIG. 2, a voltage intermediate circuit is therefore present between the rotating transformer 3 and the voltage / current transformer 5. Inverter 4, voltage / current transformer 5 and rectifier may optionally be located in the cold part of the machine.

In FIG. 2, the units 5 ff. Are identical to FIG. 2.

The voltage / current transformer 5 here goes with its seconds on the individual Polradspulen, each individual Polradspule 10, 10 ', 10' ', ... is controlled individually. This is done by multiplexing. In this case, a current sensor 11 is connected in the voltage line.

In the case of the arrangement according to FIG. 2, only two high-current passages from the hot region to the cold region are required in the event that the connection and freewheel valves are in the cold. The current measurement can be done on the outgoing side of the transformer 5 still warm. By comparing the current measurement value with the multiplexer circuit, the measured value of each individual coil can be assigned.

Similarly, a redundancy is ensured, the

Failure of an exciter system can be bridged by an internal circuit measure.

It is also advantageous that in the arrangement according to Figure 3 for each coil individually a protection concept can be provided and dimensioned. This results in greater safety compared to the prior art.

In Figure 4, the units 1 to 4a are formed according to Figure 2. In this arrangement, the inverter 4b, the voltage / current Ubertrager and the coil for each individual Polradspule are present in parallel and are therefore driven in parallel. This results in an improvement the excitement time or the de-excitation time, resulting in a higher dynamics and a better control behavior. There is a high degree of redundancy, and if one exciter system fails, the other five or four systems can continue to operate. Thus, an emergency running is given. As in Figure 6, the protection concept for each coil can be dimensioned individually, resulting in greater security.

In Figure 5, a rotary transformer is combined directly with the voltage / current Ubertrager. This results in a functionally simplified execution. Only one single transmission element is necessary.

In principle, this variant can be combined with the embodiments according to FIGS. 1 to 3. Especially in Figure 4, the transformer is in the warm part of the machine.

It is advantageous in this embodiment that fewer components are necessary and that thereby the space requirement is reduced. There are lower power losses and continue higher reliability than in the previous figures. With a new design of the intermediate circuit voltage, faster excitation / de-excitation times are possible.

In FIGS. 6 and 7, arrangements corresponding to FIG. 1 are shown. In addition, in each of these figures, a heating resistor 55 is present. In FIG. 6, this resistor 55 is arranged between the rotary transformer 3 and the rectifier 4 and is consequently actuated by an AC switch 56. In FIG. 7, the heating resistor 55 is arranged between the rectifier and the inverter 4b and is therefore operated with a DC switch 66.

In Figures 8 and 9 is a structural realization of a

Shown transformer. Overall, the following components are required for the exciter device: The voltage-current transmission for adaptation of the intermediate circuit voltage and the DC link current to the Polradspannung and the Polradstrom, a power electronics for the rectification and for the freewheeling circuit at the Polradstrom and control electronics. The power electronics are provided on copper rails with power semiconductors and the control electronics on printed circuit boards.

Furthermore, a fixed / rotating transformer for the energy transfer to the rotating shaft is present, which consists of two ferrite half-shells, which face each other on the rotating and stationary part of the machine, and associated means for attachment to the shaft (???). Since the exciter means are at the axial, i. loose end of the shaft must be expected at the rotating transformer, a temperature-induced axial play of about 0.4 mm. This results in two possibilities for the mechanical design of the rotating transformer according to Figure 7 on the one hand and Figure 8 on the other.

In FIGS. 8 ff, the shaft is denoted by 71 and the associated shield by 72. The transformer of two half-shells 73 and 74 is designated overall by 75. He carries the electrical means. While in Figure 7 the assembly 75 is axially, i. is arranged in the axial direction of the shaft 71, it is radial in Figure 8, i. positioned perpendicular to the axial direction of the shaft 71.

For both variants, different boundary conditions result:

While a slight axial play of the shaft 71 has no influence on the transmission of electric power in FIG. 9, the axial clearance of the transformer according to FIG. 8 influences the air gap and thus the main inductance of the transformer due to the axial play of the shaft. This can be compensated for by an active control of the air gap nachge- is presented. In this case, the detection of the air gap can optionally be effected electrically by determining the magnetizing current of the transformer and from this the main inductance of the transformer. For measuring the magnetizing current reference is made to a parallel application of the applicant.

There are various possibilities for mounting the excitation device on the machine shaft, for which reference is also made to a parallel application of the applicant.

In a first embodiment, the assembly of the ferrite cores, the control electronics and the power semiconductor within the shaft takes place. Such an embodiment has the advantage that the shaft for cable penetrations does not have to be drilled and that the ferrite cores do not have to be segmented.

In another embodiment, the ferrite cores are mounted inside the shaft, with the control electronics and the power semiconductors enclosing the shaft from the outside. This has the advantage that the electronics can be easily removed and that the ferrite cores need not be segmented.

In the arrangement described above, no shunts of the voltage / current transformer 5 may result from the machine design or the grounding. This will be clarified with reference to FIGS. 10 and 11. The shunts to be avoided are indicated there wirungsmaßig.

Specifically, from Figure 12 results in an alternative to Figures 10 and 11. Here, the voltage / current Ubertrager 5 is in a modified pot core, which is designated 110. Otherwise, the arrangement according to Figures 10 and 11 is formed.

The arrangement described with reference to the individual examples has been specially developed for implementation in so-called HTS Machinery provided in which for use as a motor or generator use of superconducting coils, in particular from coils made of high temperature conductive material is made. Optionally, this principle is also generally applicable to a synchronous machine in which the coils are made of normal conducting material.

Claims

claims

A method of exciting or de-energizing superconducting coils of a rotor (rotor) of an electric machine, in particular an electric generator or motor having a centric shaft, which are in a closed area including the pole wheel coils of the rotor and are excited for rotation with following measures: - There is an inductive transmission of the necessary for the de-energizing and deenergizing electric power to the shaft, - the supply of electrical power in the cold, the superconducting winding of the flywheel containing part, takes place with a higher voltage, - in the cold part a voltage conversion takes place.

2. The method according to claim 1, characterized in that in a superconducting synchronous machine, the Polradspulen windings of superconducting material.

3. The method according to claim 2, characterized in that the transmission of power in the cold region of the superconductor takes place at high voltages and small currents.

4. The method according to any one of the preceding claims, characterized in that each Polradspulen generates the same magnetic flux by suitable control of the individual Polradspulen.

5. The method according to any one of the preceding claims, characterized in that the transmission of electrical power to the individual Polradspulen the Laufers takes place successively in multiplex mode.

6. The method according to any one of claims 1 to 4, characterized in that the transmission of power to the individual Polradspulen the Laufers takes place simultaneously in parallel operation.

7. The method according to claims 5 and 6, characterized in that by the simultaneous and parallel transmission of electrical power to the individual Polradspulen a redundancy is given.

8. The method according to claim 5, characterized in that coils are used, each with its own protective circuit.

9. The method according to any one of the preceding claims, characterized in that slip rings are used for voltage transmission.

10. The method according to any one of claims 1 to 8, characterized in that rotating transformers are used.

11. Device for carrying out the method according to claim 1 or one of claims 2 to 10, characterized in that at least one inductively operating transformer (3) for voltage-current transmission of electrical power to the windings (10, 10 ', .. .) of the Polradspulen is present, with means for maintaining constant boundary conditions are present.

12. The device according to claim 11, characterized in that two transformers are present, of which the first transformer is designed as a rotating transformer (3) and the second transformer (5) is used for the transmission of high voltages.

13. The apparatus according to claim 11, characterized in that at least one power converter (2) is present.

14. Device according to one of claims 11 to 13, characterized in that an inverter (4a, 4b) is present.

15. The device according to claim 11, characterized in that a heating resistor (55) is present.

16. The apparatus according to claim 15, characterized in that the heating resistor (55) is located in the AC circuit and is activated by an AC switch (56).

17. The apparatus according to claim 15, characterized in that the heating resistor (55) is in the DC circuit and is activated by a DC switch (66).

18. Device according to one of claims 11 to 17, characterized in that at least one current sensor is present.

19. Device according to one of the preceding claims, character- ized in that the rotating / fixed transmitter is arranged axially with respect to the rotating shaft (70).

20. Device according to one of claims 11 to 17, characterized in that the rotating / fixed transmitter is arranged radially with respect to the rotating shaft (70).

21. Device according to one of the preceding claims, characterized in that the rotating / fixed Uber- transformer is arranged in a pot core (110).