EXTERNALLY EXCITED SYNCHRONOUS MACHINE AND MOTOR VEHICLE

Abstract

An externally excited synchronous machine having an exciter circuit, a stator, and a rotor. The rotor carries at least one exciter winding which, in operation, generates an exciter field, wherein the exciter winding, in operation, is excited by the exciter circuit along a power supply pathway, wherein the rotor includes at least one temperature sensor device having a communication device which, in operation, transmits a communication signal regarding a temperature of the rotor to at least one evaluation device, and wherein the communication signal is transmitted from the communication device to the evaluation device by a transmission route at least partially formed by a section of the power supply pathway.

Claims

1. An externally excited synchronous machine, comprising: an exciter circuit; a stator; and a rotor that carries at least one exciter winding which, in operation, generates an exciter field, wherein the exciter winding, in operation, is excited by the exciter circuit along a power supply pathway, wherein the rotor includes at least one temperature sensor device, and a communication device which, in operation, transmits a communication signal regarding a temperature of the rotor to at least one evaluation device, and wherein the communication signal is transmitted from the communication device to the evaluation device by a transmission route at least partially formed by a section of the power supply pathway.

2. The externally excited synchronous machine according to claim 1, wherein the communication device, in operation, detects measurement values of at least one sensor element of the at least one temperature sensor device and provides temperature data, or receives the temperature data from the at least one sensor element, and wherein the communication device, in operation, generates the communication signal based on the temperature data.

3. The externally excited synchronous machine according to claim 2, wherein the at least one temperature sensor device includes multiple sensor elements arranged at a distance from each other on or in the rotor, and wherein the communication signal is based on the temperature data of the multiple sensor elements.

4. The externally excited synchronous machine according to claim 1, wherein the power supply pathway includes at least one slip ring of the rotor and a contact element that electrically and mechanically contacts the at least one slip ring, and wherein the transmission route of the communication signal includes the slip ring and the contact element.

5. The externally excited synchronous machine according to claim 4, wherein the contact element is a brush of the stator.

6. The externally excited synchronous machine according to claim 1, wherein the power supply pathway includes an inductive energy transmission from an energy transmission element of the stator to an energy transmission element of the rotor, and wherein the transmission route of the communication signal includes the energy transmission element of the stator and the energy transmission element of the rotor.

7. The externally excited synchronous machine according to claim 1, wherein the evaluation device, in operation, controls the synchronous machine based on the communication signal.

8. The externally excited synchronous machine according claim 1, further comprising: a power inverter, wherein the evaluation device, in operation, actuates the power inverter, based on the communication signal, and controls a field strength or a phase position of an alternating magnetic field of at least one stator winding of the synchronous machine, or actuates the exciter circuit to and controls a field strength of the exciter winding.

9. A motor vehicle, comprising the externally excited synchronous machine according to claim 1.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0025] Further benefits and details of the disclosure will emerge from the following exemplary embodiments as well as the accompanying drawings.

[0026] FIG. 1 shows an exemplary embodiment of an externally excited synchronous machine according to the disclosure,

[0027] FIG. 2 shows an exemplary embodiment of a motor vehicle according to the disclosure, and

[0028] FIG. 3 shows a detail view of another exemplary embodiment of an externally excited synchronous machine according to the disclosure.

DETAILED DESCRIPTION

[0029] FIG. 1 shows schematically an externally excited synchronous machine 1 having a rotor 2 and a stator 4. The rotor 2 in usual fashion comprises at least one exciter winding 5 for generating an exciter field, which can be energized by an exciter circuit 6 along a power supply pathway 10. The exciter circuit 6 is fixed at the stator. The energy transmission to the rotatable rotor 2 occurs in the example through slip rings 16, 17 of the rotor 2 and contact elements 18, 19 of the stator contacting them electrically and mechanically, which can be brushes, for example. The stator windings 3 of the stator can be energized in customary manner by a power inverter 20.

[0030] As already explained in the general section, such an externally excited synchronous machine 1 is typically rotor-critical, that is, the heaviest thermal loads occur in the rotor, so that the control of the synchronous machine 1, i.e., in particular the providing of the exciter current by the exciter circuit 6 or the current for the stator windings 3 by the power inverter 20, should be done in dependence on the temperature or the temperatures in the rotor 2, in order to avoid an overheating of the rotor and thus possible damage.

[0031] Therefore, a temperature sensor device 7 is arranged in the rotor 2, which serves, or its communication device 8 serves, for the transmission of a communication signal regarding the temperature of the rotor 2 to an evaluation device 9. The evaluation device 9 can then control the power inverter 20 in dependence on the temperature signal, in particular, in order to dictate the field strength and/or phase position of an alternating magnetic field of at least one of the stator windings 3 of the synchronous machine 1, and/or to control the exciter circuit 6 in order to dictate the field strength of the exciter winding.

[0032] In the example, the evaluation devices 9, the power inverter 20 and the exciter circuit 6 are arranged as separate components inside a housing of the stator 4 or the synchronous machine 1. However, it is also possible to configure at least parts of these components in common, for example, to integrate the evaluation device 9 in the exciter circuit 6 or the power inverter 20 or to integrate the exciter circuit 6 in the power inverter 20 or the like.

[0033] In addition or alternatively, some or all of the mentioned components can also be arranged outside the stator 4 or a housing of the synchronous machine 1. Thus, for example, when using the synchronous machine 1 in a motor vehicle, it would be possible for the evaluation device 9 to be a control device of the motor vehicle, which can also be situated at a distance from the other components of the synchronous machine 1 and which can also perform other control tasks in the motor vehicle, for example.

[0034] Basically, it would be possible to take the communication signals of the temperature sensor device 7 or the communication device 8 for example across separate slip contacts to the evaluation device 9. However, this would result in increased use of design space, greater weight of the synchronous machine 1, and more friction between stator 4 and rotor 2.

[0035] In order to avoid these drawbacks, the transmission route 10 in the synchronous machine 1 by which the communication signal is transmitted from the communication device 8 to the evaluation device 9 is formed in part by a section of the power supply pathway 11 which, as explained above, serves for the energizing of the exciter winding 5. Thus, the transmission route 10 for the communication signal includes the same slip rings 16, 17 and contact elements 18, 19 as the power supply pathway 11. This can be accomplished by powerline communication approaches known from other fields of application, such as the field of home networking.

[0036] For this, for example, a voltage drop in the power supply pathway 11 or for example between the slip rings 16, 17 can be slightly modulated by the communication device 8. For the circuitry shown in the example, this can be accomplished, for example, in that the current line leading from the slip rings 16, 17 to the exciter winding 5 can be switched in addition by the communication device 8 across a resistor or a controllable resistor, so that the impedance in the power supply pathway 11 or between the slip rings 16, 17 can be modulated.

[0037] For example, if an essentially constant current is provided by the exciter circuit 6 during the operation of the synchronous machine 1, a modulation of the impedance between the slip rings 16, 17 will result in a modulation of the voltage drop there, which can be detected in the present example by the evaluation device 9. By suitable dimensioning of the switchable or variable resistor of the communication device 8, it can be achieved that this modulation is relatively slight as compared to the total voltage drop. Furthermore, if a modulation is done at adequate frequency, this will not influence the exciter current or therefore the exciter field strength on account of the inductance of the exciter winding 5, from which a filter effect results, or such influencing can be disregarded. The explained method of powerline communication is merely an example and other known approaches can be used for this purpose.

[0038] In the example, a relatively simple communication occurs between the communication device 8 and the evaluation device 9. The communication signal here will only describe whether a high temperature of the rotor 2 is present at the moment, requiring an adapted operation of the synchronous machine 1, or not. In this case, a rather simple proprietary communication protocol can be used. For example, the impedance or voltage in the power supply pathway 11 can be modulated with a different frequency and/or a different pulse width depending on whether a trigger condition evaluated by the communication device 8 is fulfilled.

[0039] However, more complex communication is possible in addition or alternatively. For example, a bidirectional communication may be possible between the communication device 8 and the evaluation device 9, where conventional communication protocols such as an Ethernet or TCP/IP connection can be taken or tunneled along the power supply pathway 11. This may be advisable, for example, in order to allow a specific reading out of the rotor temperature by the evaluation device 9 or for example in order to separately interrogate the temperature values at different sensor elements 12, 13 of the temperature sensor device 7 as needed.

[0040] The temperature in the rotor 2 is detected in the example by separate sensor elements 12, 13 at multiple points of the rotor at a distance from each other. The communication signal here depends on the temperature data of the multiple sensor elements 12, 13, and for example the above explained trigger condition can then always be fulfilled if the temperature data of at least one of the sensor elements 12, 13 indicates a local temperature which is too high and thus exceeds a limit value. However, it is also possible for the communication signal to describe all acquired temperature data.

[0041] The measurement values of the sensor elements 12, 13 are digitally acquired in the example, in order to provide digital temperature data, depending on which the communication signal is generated. The acquisition or digitization of the measurement values is done in the example by separate analog-digital converters 14, 15 of the communication device 8, by which the sensor elements 12, 13 can be configured for example as thermal resistors, which are energized by the communication device 8, and the voltage drop at the particular thermal resistor is acquired as a measurement value by the analog-digital converters 14, 15. Alternatively, it would also be possible, for example, to use only one analog-digital converter which acquires in succession the measurement values of the different sensor elements 12, 13 with the aid of a multiplexer. It would also be possible for the sensor elements 12, 13 to directly provide digital measurement data.

[0042] As already explained in the general section, the temperature acquisition by a rotor-side temperature sensor device 7 and the co-opting of part of the power supply pathway 11 as part of the transmission route 10 for the transmission of the communication signals makes it possible to design high-performance externally excited synchronous machines 1 in an especially compact, light and advantageous manner. This is relevant, for example, when the synchronous machine 1 is supposed to be used as the main drive machine in a motor vehicle 21, as shown for example in FIG. 2. In the example shown, the synchronous machine 1 is coupled by a differential 22 to the rear axle 23 in order to drive the motor vehicle 21.

[0043] The explained approach of using a temperature sensor device 7 in the rotor 2, where the transmission route 10 for the transmission of the communication signals of the temperature sensor device 7 is formed at least in part by a power supply pathway 11 for the exciter winding 5, can also be applied to synchronous machines which employ an inductive energy transmission between a stator-side exciter circuit 6 and the rotor 2. A detail view of one example of such a synchronous machine is shown in FIG. 3.

[0044] The energy transmission pathway 11 here comprises energy transmission elements 24, 25 at the rotor side and the stator side, which may be coils for example. In the configuration shown, at first a direct current is provided by the exciter circuit 6 in usual manner and this is converted by an inverter 26 into an alternating current. The energy transmission element 24 is a coil which produces, thanks to the energization with the alternating current, an alternating electric field in the axial direction of the synchronous machine, i.e., in the transverse direction in FIG. 3. This alternating field is thus coupled into the energy transmission element 25, likewise formed by a coil, basically independently of the rotation position of the rotor 2, so that an alternating voltage or an alternating current results, which can be rectified by a rectifier 27.

[0045] The further components of the rotor 2 can be configured as was explained in regard to FIG. 1. For example, as explained in regard to FIG. 1, if a switchable or variable resistor is used by the communication device 8 between the terminal lines of the power supply pathway 11, this will modulate the overall impedance of the system energized by the exciter circuit 6 and the resulting voltage drop varying in time can be detected by the evaluation device 9.

[0046] For the layout of the transmission route 10 which is shown, the frequency range or the carrier frequency of the communication signal should be chosen such that it lies significantly below the frequency provided by the inverter 26 for the energy transmission. Alternatively, in an example not shown, it would be possible to couple in the communication signal between the energy transmission element 26 and the rectifier 27 and to pick it off at the stator side by the evaluation device 9 between the inverter 26 and the energy transmission element 24. In this case, the communication signal would be modulated onto an alternating voltage, in which case it may be advantageous to select the carrier frequency of the communication signal significantly above the frequency used for the energy transmission.

[0047] German patent application no. 102022116680.5, filed Jul. 5, 2022, to which this application claims priority, is hereby incorporated herein by reference, in its entirety.

[0048] Aspects of the various embodiments described above can be combined to provide further embodiments. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.