Patent ID: 12199481

DETAILED DESCRIPTION

An externally excited electric synchronous machine100, in the following also referred to as synchronous machine100in brief, such as shown for example in theFIGS.1to5, can be employed in a motor vehicle200. The externally excited electric synchronous machine100can be employed as a synchronous motor110in particular for driving the motor vehicle200.

As is evident in particular fromFIG.1, the synchronous machine100comprises a rotor101. In the following, the rotor101is also referred to as machine rotor101. The machine rotor101comprises a rotor shaft102and a coil103(see alsoFIG.1) that is non-rotatably provided on the rotor shaft102(seeFIGS.2to5). The coil103is also referred to as machine rotor coil103in the following. During the operation, the machine rotor coil103generates a magnetic field which is also referred to as rotor field in the following. Further, the synchronous machine100comprises a stator104which is also referred to as machine stator104in the following. In addition, the synchronous machine100comprises a coil (105) (seeFIG.5) fixed to the machine stator, which is also referred to as machine stator coil105in the following. During the operation, the machine stator coil105generates a magnetic field which is also referred to as stator field in the following. Stator field and rotor field interact with one another in such a manner that the machine rotor101rotates about an axis of rotation90during the operation. For generating the rotor field, the machine rotor101, in particular the machine rotor coil103, requires a DC voltage. During the operation, an electric current flows through the machine rotor coil103, which is also referred to as load current.

The directions stated here relate to the axis of rotation90. Accordingly, “axial” extends parallel, in particular coaxially, to the axis of rotation. In addition, “radial” extends transversely to the axis of rotation90. Further, the circumferential direction91extends surrounding the axis of rotation90.

As is evident fromFIGS.1and2, the synchronous machine100comprises a signal transmission device20for the contactless transmission of an operating signal corresponding to the DC voltage to the machine stator104. On the machine rotor101, the signal transmission device20comprises a coil21connected in series with the machine rotor coil103, which in the following is also referred to as signal coil21. Thus, the signal coil21co-rotates with the machine rotor coil103about the axis of rotation90during the operation. Further, the signal transmission device20comprises a magnetic field sensor23on the machine stator104. Thus, the signal coil21rotates relative to the magnetic field sensor23about the axis of rotation90during the operation. The magnetic field sensor23is configured in such a manner that it detects the magnetic field generated by the signal coil21and outputs a sensor signal that is dependent on the detected magnetic field. During the operation, the same current flows through the signal coil21connected in series with the machine rotor coil103as through the machine rotor coil103. Thus, the load current flows through the signal coil21. In the process, the signal coil21generates a magnetic field the intensity of which is proportional to the load current. The magnetic field generated by the signal coil21is also referred to as signal field in the following. By detecting the signal field, an operating signal corresponding to the load current and thus to the DC voltage is transmitted to the machine stator104in a contactless manner. In the shown exemplary embodiments, the signal coil21is configured as an air-core coil22. In addition, the magnetic field sensor23in the shown exemplary embodiments is configured as a Hall effect sensor24, also referred to as Hall sensor24in brief.

As is evident from the exemplary embodiment shown inFIG.2, the signal coil21is arranged in the shown exemplary embodiment and preferably on an axial end-face of the rotor shaft102. There, the magnetic field sensor23enters the signal coil21axially. The magnetic field sensor23is thus surrounded in the circumferential direction91by the signal coil21. This results in a more reliable detection of the signal field and/or a reduction of noise signals in the magnetic field sensor23.

As is evident fromFIG.2, the signal coil21is surrounded in the circumferential direction91by an axially open sleeve25. Thus, the sleeve25is arranged on the side of the signal coil21which radially faces away from the magnetic field sensor23. In the shown exemplary embodiment, the sleeve25is non-rotatably attached to the rotor shaft102. The sleeve25serves in particular for the magnetic shielding.

In the shown exemplary embodiments, the supply of the machine rotor coil103with a DC voltage takes place inductively with an electric rotary transformer1for the inductive energy transmission shown in theFIGS.1,3and4. The rotary transformer1comprises a stator2and a rotor4. The stator2is referred to as rotary transformer stator2in the following. The rotor4is referred to as rotary transformer rotor4in the following. The rotary transformer rotor4is non-rotatable relative to the machine rotor101. The rotary transformer stator2is fixed relative to the machine stator104. Thus, the rotary transformer rotor4co-rotates with the machine rotor101relative to the rotary transformer stator2about the axis of rotation90during the operation. For the inductive energy transmission, the rotary transformer stator2comprises a primary coil3and the rotary transformer rotor4a secondary coil5. The primary coil3and the secondary coil5are arranged, as is evident from theFIGS.3and4, located axially opposite one another in the shown exemplary embodiments. During the operation, the primary coil3, which is also referred to as transformer primary coil3in the following, induces an AC voltage, which is also referred to as transformer voltage in the following, in the secondary coil5, which is also referred to as transformer secondary coil5in the following. The signal transmission device20can be part of the rotary transformer1. In order to supply the machine rotor coil103with the required DC voltage, as is evident fromFIG.1, a rectifier circuit6that is non-rotatable relative to the machine rotor101is connected between the transformer secondary coil5and the machine rotor103, which rectifier circuit6converts the transformer voltage into the DC voltage. In the exemplary embodiment shown inFIG.1, the rectifier circuit6is purely exemplarily configured as a bridge rectifier16with four diodes D1-4.

Practically, the signal coil21and the transformer secondary coil5are preferably magnetically separated from one another. For this purpose, the signal coil21and the transformer secondary coil5are radially spaced apart from one another.

For inducing the transformer voltage in the transformer secondary coil5, the transformer primary coil3requires an AC voltage. As is evident fromFIG.1, the transformer primary coil3in the shown exemplary embodiments is supplied via an electrical energy source201, which provides a DC voltage. The energy source201in the shown exemplary embodiments is a battery202of the motor vehicle200. For supplying the transformer primary coil3with the AC voltage, an inverter circuit7is provided between the energy source201and the transformer primary coil3. The inverter circuit7converts the DC voltage of the energy source201into the AC voltage for the transformer primary coil3. It is conceivable that the inverter circuit7comprises a converter. The machine stator coil105can be electrically supplied in the same manner (not shown). In the shown exemplary embodiment, the inverter circuit7is purely exemplarily configured as a sine wave inverter17, which comprises four transistors T1-4and two controls GU1, GU2.

In the shown exemplary embodiments, as is evident fromFIG.1, the signal transmission device20comprises a unit26fixed relative to the machine stator104, which is electrically connected to the magnetic field sensor23and receives and processes the sensor signal generated by the magnetic field sensor23. The unit26is also referred to as processing unit26in the following. With the processing unit26, the operation of the synchronous motor100, in particular of the rotary transformer1, can be adapted and/or changed dependent on the load current of the machine rotor coil103. For the purpose, the inverter circuit7can be communicatingly connected to at least one of the controls GU1, GU2(not shown).

As is evident from theFIGS.3and4, the rotary transformer rotor4in the shown exemplary embodiments comprises a circuit board8, which is provided with the transformer secondary coil5. The circuit board8is configured disc-like and has a round shape, i.e. is configured in the manner of a round disc or of a ring. The transformer secondary coil5in the shown exemplary embodiments comprises at least one trace9of the circuit board8, which in the following is also referred to as transformer trace9. In the shown exemplary embodiments, the transformer secondary coil5consists of the at least one transformer trace9and is configured as a planar winding10. As is evident fromFIG.3, the circuit board8can comprise two transformer traces9that are axially spaced apart from one another, which helically surround the axis of rotation90. In the shown exemplary embodiments, the at least one transformer trace9is entirely arranged in the circuit board8. The non-rotatable connection of the rotor shaft102with the rotary transformer rotor4is realised in the shown exemplary embodiments, as is evident from theFIGS.3and4, via a central opening14in the circuit board8, through which the rotor shaft102engages.

As is evident in particular from theFIGS.3and4, the transformer primary coil3in the shown exemplary embodiments is configured as a flat coil11. The transformer primary coil3and the transformer secondary coil5are arranged in the shown exemplary embodiments in a magnetic core12, in particular a ferrite core13that is fixed relative to the rotary transformer stator2. In the following, the magnetic core12is also referred to as transformer magnetic core12. The transformer magnetic core12is radially open, so that the circuit board8with the transformer secondary coil5enters the transformer magnetic core12and is arranged so as to be rotatable therein. In addition, the transformer magnetic core12comprises an axially open recess15, in which the transformer primary coil3is arranged.