Separately excited electric synchronous machine

Abstract

The present invention relates to a separately excited electric synchronous machine (100) having a rotor (101) with a rotor coil (103) which generates a rotor magnetic field during operation. The synchronous machine (100) also has a rectifier circuit (6) which supplies a DC voltage to the rotor coil (103) to generate the rotor magnetic field. Demagnetization of the rotor coil (103) is improved by a protection circuit (20) connected in parallel with the rectifier circuit (6) and the rotor coil (103) as well as by a switch (23) which is arranged between the protection circuit (20) and the rectifier circuit (6) and which is opened by a trigger circuit (24) to demagnetize the rotor coil (103).

Description

[Technical field]

[0001] The present invention relates to a separately excited electric synchronous machine having a rotor coil which, during operation, is supplied with a DC voltage by a transformer coil and a rectifier circuit to generate a rotor magnetic field. Furthermore, the present invention relates to a method of using such a separately excited electric synchronous machine. [Background technology]

[0002] A separately excited electric synchronous machine comprises a fixed stator and a rotor which rotates relative to the stator around the axis of rotation during operation, and which are hereinafter also called synchronous machine stator and synchronous machine rotor. Here, the rotor magnetic field of the rotor and the stator magnetic field of the stator interact with each other. In a separately excited electric synchronous machine, the required rotor magnetic field of the rotor is separately excited. For this purpose, the rotor generally comprises a rotor coil which is supplied with a DC voltage for generating the magnetic field. The supply of power to the rotor coil may be performed inductively. For this purpose, an AC voltage is induced in the secondary coil during operation. This induced voltage is converted into the required DC voltage via a rectifier circuit and supplied to the rotor coil.

[0003] Such a separately excited synchronous machine is known from DE 10 2016 207 392 A1. This separately excited electric synchronous machine has a smoothing capacitance in parallel with the rotor winding and the commutation circuit. In addition, a load element is connected in series with the rotor winding. This load element has two connections which are connected to associated switch terminals of a switch. The control terminals of this switch are controlled via a voltage divider. It is thus possible to demagnetize the rotor winding, if necessary, in particular in the event of a fault. Summary of the Invention

[0004] The present invention takes up the object of describing an improved or at least different embodiment of a separately excited electric synchronous machine of the kind mentioned in the introduction, in particular an embodiment of a separately excited electric synchronous machine which is characterized by an improved demagnetization of the rotor coils of the synchronous machine.

[0005] According to the invention, this object is achieved through the subject matter of independent claim 1. Preferred embodiments are the subject matter of the dependent claims.

[0006] The invention is therefore based on the idea of ​​using a protection circuit for demagnetizing the rotor coil of a separately excited electric synchronous machine, which is connected in parallel to the rotor coil and is provided for overvoltage protection of a rectifier circuit for the rotor coil, where a switch for demagnetizing the rotor coil arranged between the protection circuit and the rectifier circuit disconnects the electrical connection of the rotor coil to the rectifier circuit. The protection circuit is thus used simultaneously for protection of the rectifier circuit and for demagnetizing the rotor coil. In this way, a simple and reliable demagnetization is achieved by the protection circuit, where the energy stored in the rotor coil is dissipated by the protection circuit during demagnetization. Furthermore, a separately excited electric synchronous machine can be constructed in a simplified manner with a reduced number of components for realizing demagnetization and with relaxed installation space requirements.

[0007] According to the concept of the invention, a separately excited electric synchronous machine, also referred to below simply as a synchronous machine, comprises a rotor and a stator. In the following, the rotor is also referred to as a synchronous machine rotor and the stator is also referred to as a synchronous machine stator. The rotor comprises a rotor shaft on which a rotor coil is non-rotatably arranged. During operation, the rotor coil generates a magnetic field, also referred to below as a rotor field. The rotor coil comprises two connections, also referred to below as a first rotor coil terminal and a second rotor coil terminal. The stator comprises at least one coil fixed relative to the stator, also referred to below as a stator coil. During operation, the at least one stator coil generates a magnetic field, also referred to below as a stator field. The rotor field and the stator field interact during operation such that the rotor rotates around an axial axis of rotation. To generate the rotor field, the rotor coil requires a direct current voltage, which is supplied to the rotor coil via the coil, and during operation, an alternating current voltage is induced in the coil. This voltage is also referred to below as the transformer voltage. This coil is also referred to below as the transformer secondary coil. Thus, the transformer secondary coil serves as a power supply for the rotor coil. This transformer secondary coil is non-rotatably connected to the rotor. A rectifier circuit is connected between the transformer secondary coil and the rotor coil. In operation, the rectifier circuit converts the transformer voltage induced in the transformer secondary coil into a direct current voltage for the rotor coil. This rectifier circuit is adapted to be configured accordingly. The rectifier circuit comprises two connections, also referred to below as the first rectifier terminal and the second rectifier terminal. A protection circuit serves as protection of the rectifier circuit from overvoltages and comprises two connections, also referred to below as the first protection terminal and the second protection terminal. The first rectifier terminal is connected to the first protection terminal and the second rectifier terminal is connected to the second protection terminal. Additionally, a first protection terminal is connected to the first rotor coil terminal and a second protection terminal is connected to the second rotor coil terminal such that the protection circuit is connected in parallel between the rotor and the commutation circuit. A switch is disposed between the second commutation terminal and the second protection terminal. Additionally, the synchronous machine includes a trigger circuit connected to the switch and configured to open the switch to demagnetize the rotor coil.

[0008] The directions stated herein are relative to the axis of rotation. Thus, "axial" extends parallel to the axis of rotation. Additionally, "radial" extends transversely to the axis of rotation.

[0009] The first and second rectifier terminals serve as electrical connections to the rotor coil of the rectifier circuit and are thus output connections of the rectifier terminals. Preferably, the rectifier circuit comprises two further rectifier terminals on the inlet side for inputting the transformer AC voltage.

[0010] Preferably, the protection circuit also serves to protect the rotor coil from overvoltages.

[0011] The rectifier circuit, the protection circuit and the trigger circuit are preferably non-rotatably fixed to the rotor, which means that during operation, the rectifier circuit, the protection circuit and the trigger circuit rotate together with the rotor about the axis of rotation.

[0012] In an open state of the switch, an electrical connection between the second rectifying terminal and the second protection terminal is broken, in contrast to a closed state of the switch where an electrical connection between the second rectifying terminal and the second protection terminal is established.

[0013] Basically, the rectifier circuit can be configured as appropriate.

[0014] In a preferred embodiment, the rectifier circuit is configured to block the current flow in the direction of the transformer secondary coil. In contrast, it allows the current flow in the direction of the rotor coil. Thus, when the switch is opened, an accelerated demagnetization of the rotor coil occurs. For this purpose, the rectifier circuit may be configured accordingly. In particular, the rectifier circuit may be configured for this purpose as a bridge rectifier with four diodes.

[0015] Preferably, this switch only needs to be opened to demagnetize the rotor coils, otherwise it remains closed so that normal operation occurs, with the rotor coils being supplied with the DC voltage provided by the rectifier circuit.

[0016] Preferably, when a predetermined limit voltage is exceeded, the protection circuit consumes the voltage exceeding the limit voltage. Preferably, the protection circuit comprises at least one load element, such as a suppressor diode, a varistor, an IGBT circuit, etc.

[0017] When the switch is opened to demagnetize the rotor coil, the current has no choice but to pass through the protection circuit, which causes a reduction in the energy stored in the rotor coil. During this time, the voltage of the protection circuit rises above the threshold voltage, so that the protection circuit consumes energy. At the same time, a current commutation occurs as a result of the reduction of the electric field in the rotor, and thus a polarity reversal of the voltage in the rotor coil. This causes a rapid demagnetization of the rotor coil through the protection circuit.

[0018] The switch can essentially be configured as appropriate, provided that the switch is opened and closed using a trigger circuit.

[0019] Preferably, the switch is configured as a transistor, preferably as a MOSFET or IGBT. Preferably, in the on state, the switch can be driven further with minimal losses. Thus, the switch can be reliably and efficiently switched using a low switch voltage. The switch comprises a control terminal connected to the trigger circuit. Additionally, the switch comprises two switch terminals, also referred to as a first switch terminal and a second switch terminal. Preferably, the second rectification terminal is connected to the first switch terminal and the second protection terminal is connected to the second switch terminal.

[0020] When the switch is configured as a MOSFT, the control terminal corresponds to the gate, the first switch terminal preferably corresponds to the source, and the second switch terminal preferably corresponds to the drain.

[0021] Essentially, if the trigger circuit opens a switch to demagnetize the rotor coil, the trigger circuit can be configured accordingly.

[0022] In particular, the trigger circuit may be configured to automatically open the switch in the event of a fault in the functioning of the transformer secondary coil and / or in the event of absent or insufficient transformer voltage.

[0023] In a preferred embodiment, the trigger circuit comprises a voltage divider. The voltage divider is configured such that the switch is opened when the transformer voltage is absent. The "absence" of the transformer voltage means both the absence of the transformer voltage and also an insufficient transformer voltage. To open the switch when the transformer voltage is absent, the voltage divider is preferably connected to the control terminal and the first switch terminal of the switch. Thus, the switch can be opened and closed independently of the voltage difference between the control terminal and the first switch terminal. The voltage divider is configured accordingly.

[0024] Essentially, a voltage divider comprises two two-terminal passive elements, in particular two electrical resistors.

[0025] It is conceivable that a voltage divider is connected to the rectifier circuit such that a switch opens when no DC voltage is present at the rectifier circuit. By "no" DC voltage it is meant both the absence of DC voltage and also an insufficient DC voltage. Thus, when there is no or insufficient DC voltage provided by the rectifier circuit, demagnetization of the rotor coil takes place.

[0026] Preferably, the induction of the transformer voltage in the transformer secondary coil is performed by an electric rotary transformer, the transformer secondary coil being a part of the electric rotary transformer, so that the energy transfer to the transformer secondary coil can be realized simply, effectively and reliably.

[0027] The synchronous machine thus preferably comprises an electric rotary transformer. The rotary transformer comprises a stator and a rotor, which are also referred to below as rotary transformer stator and rotary transformer rotor. The rotary transformer stator comprises a coil, which is also referred to below as transformer primary coil. The rotary transformer stator is fixed relative to the stator, and the rotary transformer rotor is non-rotatable relative to the rotor. The rotary transformer rotor is thus rotatable about a rotation axis relative to the rotary transformer stator, and during operation rotates about the rotation axis together with the rotor. The rotor comprises a transformer secondary coil. During operation, the transformer primary coil and the transformer secondary coil inductively interact in order to induce a transformer voltage in the transformer secondary coil. This means that during operation, the transformer primary coil induces a transformer voltage in the transformer secondary coil.

[0028] The transformer primary coil and the transformer secondary coil may be disposed axially opposite one another, and the transformer primary coil and the transformer secondary coil may likewise be disposed radially opposite one another.

[0029] In a possible embodiment, the trigger circuit comprises a coil inductively coupled to the transformer primary coil and separate from the transformer secondary coil, the separate coil also referred to below as the trigger coil. During operation, the transformer primary coil induces a voltage, also referred to below as the trigger voltage, in the trigger coil. The trigger coil is connected to a voltage divider such that the switch opens in the absence of the trigger voltage. "Absence" with respect to the trigger voltage means both the absence of the trigger voltage and also an insufficient trigger voltage. Thus, as soon as no voltage is induced by the transformer primary coil or the induced voltage is insufficient, a demagnetization of the rotor coil is performed. A trigger coil separate from the transformer secondary coil prevents or at least reduces the influence of the trigger circuit on the transformer secondary coil.

[0030] Independent demagnetization of the rotor coils can be effected by transmitting a signal to a trigger circuit, which opens a switch upon receiving a control signal. This control signal can be generated and sent to the trigger circuit independently of the functioning of the rotating transformer and / or the rotor. Thus, high flexibility in demagnetization of the rotor is achieved.

[0031] For this purpose, the synchronous machine preferably comprises a signal transmission device for wireless signal transmission to a trigger circuit, which is configured to open the switch upon receiving a control signal, and for this purpose the trigger circuit comprises a receiver for receiving the signal, non-rotatably fixed to the rotor and / or communicatively connected to such a receiver.

[0032] Alternatively or additionally, the trigger circuit may initiate demagnetization of the rotor coil when a fault is present and / or excessive current flows through the rotor coil.

[0033] For this purpose, the trigger circuit preferably comprises a current sensor arranged to determine, during operation, the current flowing through the rotor coil, the trigger circuit being arranged to open the switch when the current determined by the current sensor exceeds a predefined value.

[0034] Basically, the current sensor is configured accordingly, in particular the current sensor may comprise a shunt and / or a Hall sensor.

[0035] To switch the switch, the trigger circuit preferably comprises a comparator connected to the current sensor and a gate drive circuit connected to the comparator and to the switch, the gate drive circuit thus connected between the comparator and the switch, and preferably to a control terminal of the switch.

[0036] It should be understood that the rotor may include two or more rotor coils.

[0037] The stator preferably comprises at least two stator coils.

[0038] Preferably, the stator comprises 3 stator coils or an integer multiple of 3. Thus, the number of stator coils preferably corresponds to 3×N, where N is a natural number greater than zero.

[0039] In principle, synchronous machines can be used in any application.

[0040] The synchronous machine may be used in particular in a motor vehicle and may include a battery as a power source for driving the synchronous machine, which serves in particular to drive the motor vehicle and is therefore configured as a separately excited electric synchronous motor and a traction motor.

[0041] Likewise, during operation, the synchronous machine can act as a servo motor to adjust adjustment elements, in particular in motor vehicles.

[0042] Further important features and advantages of the invention emerge from the dependent claims, the drawings and the associated drawing description with the drawings.

[0043] It is to be understood that the features mentioned above and described below can be used not only in the respective combinations indicated, but also in other combinations or alone, without departing from the scope of the invention.

[0044] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred exemplary embodiments of the present invention are illustrated in the drawings and will be described in more detail in the following description, where like reference numbers refer to identical, similar or functionally identical components. [Brief description of the drawings]

[0045] Each is shown in the figure. [Figure 1] FIG. 1 is an isometric view, partially shown in section, of a separately excited electric synchronous machine having an induction rotary transformer. [Diagram 2]FIG. 2 is a highly simplified excerpt from a circuit diagram of a separately excited electric synchronous machine in an automobile. [Diagram 3] FIG. 3 is a highly simplified excerpt from a circuit diagram of a separately excited electric synchronous machine in an automobile. [Figure 4] FIG. 4 is a highly simplified excerpt from a circuit diagram of a separately excited electric synchronous machine in an automobile. [Diagram 5] FIG. 5 is a highly simplified excerpt from a circuit diagram of a separately excited electric synchronous machine in an automobile. [Figure 6] FIG. 6 is a highly simplified excerpt from a circuit diagram of a separately excited electric synchronous machine in an automobile. [Figure 7] FIG. 7 is a highly simplified cross-sectional view of a separately excited electric synchronous machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] A separately excited electric synchronous machine 100, for example as shown in Figures 1-7, also referred to simply as synchronous machine 100 in the following, can be used in a motor vehicle 200 (see Figures 2-6). This separately excited electric synchronous machine 100 can be used as a synchronous machine 110 for driving the motor vehicle 200, i.e. as a traction motor 120. The separately excited electric synchronous machine 100 can also be used as a synchronous machine 110 for adjusting a regulating element, i.e. as a servo motor 130.

[0047] This synchronous machine 100, as is particularly evident from Fig. 1 and Fig. 7, comprises a rotor 101. In the following, the rotor 101 is also called synchronous machine rotor 101. The rotor 101 comprises a rotor shaft 102 and a coil 103 arranged non-rotatably on the rotor shaft 102 (see Fig. 2-6). In the following, the coil 103 is also called rotor coil 103. In operation, the rotor coil 103 generates a magnetic field, also called rotor magnetic field. The rotor coil 103 is represented in Fig. 1-6 as an inductance and an ohmic resistor. This synchronous machine 100 further comprises a stator 104 shown in Fig. 7, the stator 104 being also called synchronous machine stator 104 in the following. The synchronous machine 100 comprises at least one coil 105 fixed relative to the stator 104 (see Fig. 7), the coil 105 being also called stator coil 105 in the following. In operation, the at least one coil 105 generates a magnetic field, also referred to below as the stator magnetic field. In operation, the stator magnetic field and the rotor magnetic field interact with each other so that the rotor 101 rotates around the axial axis of rotation 90. To generate this rotor magnetic field, the rotor 101, in particular the rotor coil 103, requires a DC voltage. To supply the rotor coil 103 with a DC voltage, the rotor coil 103 comprises two connections 106, 107, also referred to below as the first rotor coil terminal 106 and the second rotor coil terminal 107. This DC voltage is supplied to the rotor coil 103 by the transformer secondary coil 5, and an AC voltage is inductively induced in the transformer secondary coil 5.

[0048] The directions stated herein are relative to the axis of rotation 90. Thus, the "axial direction" extends parallel to the axis of rotation. Additionally, the "radial direction" extends transversely to the axis of rotation 90.

[0049] In the illustrated exemplary embodiment, the transformer secondary coil 5 is part of an electric rotary transformer 1. This rotary transformer 1 comprises a stator 2 and a rotor 4. In the following, the stator 2 is also called rotary transformer stator 2. In the following, the rotor 4 is also called rotary transformer rotor 4. The rotary transformer stator 2 is fixed non-rotatably with respect to the stator 104. The rotary transformer rotor 4 is fixed non-rotatably with respect to the rotor 101. The rotary transformer rotor 4 is thus rotatable around the rotation axis 90 relative to the rotary transformer stator 2. In operation, the rotary transformer rotor 4 rotates around the rotation axis 90 relative to the rotary transformer stator 2 and thus together with the rotor 101. For inductive energy transmission, the rotary transformer stator 2 comprises a primary coil 3 and the rotary transformer rotor 4 comprises a transformer secondary coil 5. In the following, the primary coil 3 is also called the transformer primary coil 3. As is evident from Fig. 1, this transformer primary coil 3 and the transformer secondary coil 5 are arranged axially opposite each other in the illustrated exemplary embodiment. In operation, the transformer primary coil 3 induces an alternating voltage in the transformer secondary coil 5, which is also called the transformer voltage in the following.

[0050] In order to supply the required DC voltage to the rotor coil 103, as is clear from Fig. 2-6, a rectifier circuit 6 is connected between the transformer secondary coil 5 and the rotor coil 103, which converts the transformer voltage into a DC voltage. This rectifier circuit 6 is fixed non-rotatably to the rotor 101 and may be a part of the rotating transformer rotor 4.

[0051] As can be seen particularly from FIG. 1 , in the exemplary embodiment shown, the rotary transformer 1 is disposed at an axial end face of the rotor 101 and spaced apart from the rotor coils 103 and at least one stator coil 105.

[0052] To induce a transformer voltage in the transformer secondary coil 5, the transformer primary coil 3 requires an AC voltage. As is evident from Figs. 2-6, the transformer primary coil 3 in the illustrated exemplary embodiment is supplied via an electric energy source 201, which provides a DC voltage. The electric energy source 201 in the illustrated exemplary embodiment is a battery 202 of the vehicle 200. To supply an AC voltage to the transformer primary coil 3, an inverter circuit 7 is provided between the energy source 201 and the transformer primary coil 3. This inverter circuit 7 converts the DC voltage of the energy source 201 into an AC voltage for the transformer primary coil 3. It is conceivable that the inverter circuit 7 includes a converter.

[0053] As is evident from Fig. 1, the rotating transformer rotor 4 in the illustrated exemplary embodiment has a circuit board 8 on which a transformer secondary coil 5 is provided. This circuit board 8 is configured in the shape of a disk, i.e. in the shape of a disk or ring. The transformer secondary coil 5 in the illustrated exemplary embodiment comprises at least one trace 9 of the circuit board 8, which trace 9 is also referred to below as transformer trace 9. In the illustrated exemplary embodiment, the transformer secondary coil 5 consists of at least one transformer trace 9 and is configured as a planar winding 10.

[0054] As shown in FIG. 1 , the non-rotatably fixed connection of the rotor shaft 102 to the rotating transformer rotor 4 is achieved via a central opening 14 in the circuit board 8, with the rotor shaft 102 passing through the opening 14.

[0055] As is evident from Fig. 1, the transformer primary coil 3 is configured as a flat coil 11. As is also evident from Fig. 1, the transformer primary coil 3 and the transformer secondary coil 5 are arranged in the illustrated exemplary embodiment in a magnetic core 12, in particular a ferrite core 13, which is fixed with respect to the rotating transformer stator 2. The magnetic core 12 is also referred to as the transformer core 12 in the following. This transformer core 12 is radially open, so that the circuit board 8 with the transformer secondary coil 5 enters the transformer core 12 and is arranged therein in a rotatable manner. In addition, the transformer core 12 comprises an axially open recess 15, in which the transformer primary coil 3 is arranged.

[0056] In the illustrated exemplary embodiment, the rectifier circuit 6 is configured as a bridge rectifier 16 with four diodes D1-D4, namely a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4, merely by way of example. The first diode D1 and the third diode D3 as well as the second diode D2 and the fourth diode D4 are connected in series and in parallel with the transformer secondary coil 5 and the rotor coil 103, respectively. Thus, the rectifier circuit 6 only allows current in the direction of the rotor coil 103 and blocks current in the direction of the transformer secondary coil 5.

[0057] In the illustrated exemplary embodiment, the inverter circuit 7 is configured, purely by way of example, as a full-bridge inverter 17, which comprises four transistors Ta-d and two switches Sa-b.

[0058] On the output side, the rectifier circuit 6 comprises two connections 18, 19, also referred to below as a first rectifier terminal 18 and a second rectifier terminal 19. In the exemplary embodiment shown, the transformer secondary coil 5 is connected to the rectifier circuit 6 between the first diode D1 and the third diode D3 and between the second diode D2 and the fourth diode D4.

[0059] As is clear from Figs. 2-6, a protection circuit 20 is provided in parallel between the rotor coil 103 and the rectifier circuit 6, and the protection circuit 20 protects the rotor coil 103 from overvoltage. In the illustrated exemplary embodiment, the protection circuit 20 is configured as a bidirectional suppressor diode 30. The protection circuit 20 comprises two connections 21, 22, which are also referred to below as a first protection terminal 21 and a second protection terminal 22. The first protection terminal 21 is connected to the first rotor coil terminal 106, and the second protection terminal 22 is connected to the second rotor coil terminal 107. In addition, the first protection terminal 21 is connected to the first rectifier terminal 18. The second protection terminal 22 is connected to the second rectifier terminal 19 via a switch 23. Thus, the protection circuit 20 is connected in parallel between the rotor 101 and the rectifier circuit 6. In a closed state, the switch 23 electrically connects between the second rectification terminal 19 and the second protection terminal 22, and in an open state, the switch 23 disconnects the electrical connection between the second rectification terminal 19 and the second protection terminal 22. A trigger circuit 24 is connected to the switch 23 and configured to open the switch 23 to demagnetize the rotor coil 103. Otherwise, the switch 23 is closed so that the rotor coil 103 generates a magnetic field.

[0060] When the switch 23 is open, the current flow from the rotor coil 103 can only go through the protection circuit 20 due to the arrangement of the open switch 23 and the commutator circuit 6. This causes the voltage of the protection circuit 20 to rise so that the limit voltage of the protection circuit 20 is quickly reached. In addition, a current commutation occurs by reducing the rotor magnetic field. This results in a polarity reversal of the voltage of the rotor coil 103. Thus, a rapid demagnetization of the rotor coil 103 occurs through the protection circuit 20.

[0061] In the illustrated exemplary embodiment, the switch 23 comprises a control terminal 25 and two switch terminals 26, 27. The switch terminals 26, 27 are also called the first switch terminal 26 and the second switch terminal 27. The switch 23 is configured, for example, as a transistor 28, preferably a MOSFET 29. The trigger circuit 24 is connected to the control terminal 25. In addition, the second rectification terminal 19 is connected to the first switch terminal 26 and the second protection terminal 22 is connected to the second switch terminal 27. Thus, a low voltage is required to switch the switch 23. Thus, the trigger circuit 24 can be operated reliably and efficiently. In the case of the switch 23 configured as a MOSFET 29, the control terminal 25 corresponds to the gate. In addition, the first switch terminal 26 in the illustrated exemplary embodiment corresponds to the source and the second switch terminal 27 corresponds to the drain.

[0062] 3-5, the trigger circuit 24 comprises a voltage divider 31. The voltage divider 31 comprises two electrical resistors R1 and R2, known as two-terminal passive elements, i.e. a first resistor R1 and a second resistor R2, and is connected to the control terminal 25 and the first switch terminal 26. In the illustrated exemplary embodiment, the trigger circuit 24 further comprises a capacitor Ct.

[0063] 3 and 4, there is a voltage divider so that the switch 23 opens when the transformer voltage is not present, i.e. without voltage or with insufficient voltage, thus causing demagnetization of the rotor coil 103, for example when the rotating transformer 1 is stopped.

[0064] In the exemplary embodiment of Fig. 3, the voltage divider 31 is connected via a first resistor R1 to the fourth diode D4 of the rectifier circuit 6 and thus to the transformer secondary coil 5. Furthermore, the first resistor R1 is connected to the control terminal 25. The second resistor R2 is connected to the second rectifier terminal 19 and to the first switch terminal 26. When the rectifier circuit 6 provides no DC voltage, i.e. no DC voltage or insufficient DC voltage, the voltage difference between the control terminal 25 and the first switch terminal 26 falls below the threshold voltage of the switch 23 and the switch 23 opens. As a result, when no DC voltage is present in the rectifier circuit 6, the switch 23 opens and demagnetizes the rotor coil 103.

[0065] In the exemplary embodiment of FIG. 4, the trigger circuit 24 comprises a trigger coil 32 inductively coupled to the transformer primary coil 3, such that during operation the transformer primary coil 3 induces a trigger voltage in the trigger coil 32. The trigger coil 32 is connected at one end to a first resistor R1 and at the other end to a second resistor R2. The first resistor R1 is connected to the control terminal 25. The second resistor R2 is connected to the second rectifier terminal 19 and to the first switch terminal 26. In the absence of an induced trigger voltage, i.e. in the absence of an induced trigger voltage or insufficient induced trigger voltage, the voltage difference between the control terminal 25 and the first switch terminal 26 falls below the threshold voltage of the switch 23 and the switch 23 opens. Thus, the rotor coil 103 is demagnetized. In the exemplary embodiment shown, the trigger circuit 24 comprises a unidirectional suppressor diode Dt, which is connected in parallel with the control terminal 25 and the first switch terminal 26, in order to limit the control voltage of the switch 23. Furthermore, a diode D5 and a third resistor R3 are connected between the trigger coil 32 and the first resistor R1.

[0066] 5, the synchronous machine 1 comprises a signal transmission device 33 for wireless signal transmission to a trigger circuit 24. This trigger circuit 24 is configured to open the switch 23 upon receipt of a control signal received by the signal transmission device 33. Thus, it is possible to demagnetize the rotor coil 103, if desired, in particular independently of the rotary transformer 1.

[0067] In the exemplary embodiment shown in Fig. 5, the signal transmission device 33 comprises a coil 37 fixed to the rotor 101 in a non-rotatable manner, the coil 37 being also referred to as the rotor signal coil 37 in the following. In addition, the signal transmission device 33 comprises a coil 38 fixed relative to the stator 104, the coil 38 being also referred to as the stator signal coil 38 in the following. Furthermore, the signal transmission device 33 comprises a signal generating unit 39 connected upstream of the stator signal coil 38. When demagnetization of the rotor coil 103 is required, the signal generating unit 39 generates a control signal and transmits this control signal to the rotor signal coil 37 by means of the stator signal coil 38. In doing so, the rotor signal coil 37 functions substantially similarly to the trigger coil 32 in the exemplary embodiment of Fig. 4. Thus, the rotor signal coil 37 is connected at one end to a first resistor R1 and at the other end to a second resistor R2. The first resistor R1 is connected to the control terminal 25. A second resistor R2 is connected to the second rectifier terminal 19 and the first switch terminal 26. In the exemplary embodiment of Figure 5, a unidirectional suppressor diode Dt is also connected in parallel with the control terminal 25 and the first switch terminal 26, and a diode D5 and a third resistor R3 are connected between the rotor signal coil 37 and the first resistor R1.

[0068] 6, the trigger circuit 24 comprises a current sensor 34 which determines the current flowing through the rotor coil 103 during operation. The trigger circuit 24 is configured to open the switch 23 when the current determined by the current sensor 34 exceeds a predetermined value. Thus, when an excessive current flows through the rotor coil 103, it is possible to demagnetize the rotor coil 103.

[0069] 6, the trigger circuit 24 includes a comparator 35 connected to a current sensor 34 and a gate drive circuit 36 ​​connected to the comparator 35 and the switch 23. The current sensor 34 may include a shunt 40 and / or a Hall sensor 41.

[0070] Although only one rotor coil 103 is shown in each of FIGS. 2-6, the rotor 101 may also include two or more rotor coils 103, as shown in FIG.

Claims

1. A separately excited electric synchronous machine (100), The separately excited electric synchronous machine has a rotor (101), the rotor includes a rotor shaft (102) and a rotor coil (103) that is non-rotatably mounted on the rotor shaft (102) and generates a rotor magnetic field during operation, the rotor coil includes a first rotor coil terminal (106) and a second rotor coil terminal (107); The separately excited electric synchronous machine has a stator (104) with at least one stator coil (105) fixed relative to the stator (104) which generates a stator magnetic field during operation, the stator magnetic field interacting with the rotor (101) such that the rotor rotates about an axial axis of rotation (90), The separately excited electric synchronous machine has a transformer secondary coil (5) for supplying electricity to the rotor coil (103), the transformer secondary coil being fixed to the rotor (101) so as not to rotate; The separately excited electric synchronous machine has a rectifier circuit (6) connected between the transformer secondary coil (5) and the rotor coil (103), the rectifier circuit converting a transformer voltage induced in the transformer secondary coil (5) during operation into a direct current voltage, and having a first rectifier terminal (18) and a second rectifier terminal (19); The separately excited electric synchronous machine has a protection circuit (20) for protecting the rectifier circuit (6) from an overvoltage, the protection circuit including a first protection terminal (21) connected to the first rectifier terminal (18) and a second protection terminal (22) connected to the second rectifier terminal (19); the first protection terminal (21) is connected to the first rotor coil terminal (106) and the second protection terminal (22) is connected to the second rotor coil terminal (107) so that the protection circuit (20) is connected in parallel between the rotor (101) and the rectifier circuit (6); The separately excited electric synchronous machine has a switch (23) arranged between the second rectification terminal (19) and the second protection terminal (22), the separately excited electric synchronous machine having a trigger circuit (24) connected to the switch (23) and configured to open the switch (23) to demagnetize the rotor coil (103). Separately excited electric synchronous machine.

2. the switch (23) comprises a control terminal (25) connected to the trigger circuit (24), a first switch terminal (26) connected to the second rectification terminal (19), and a second switch terminal (27) connected to the second protection terminal (22), 2. A separately excited electric synchronous machine according to claim 1.

3. The trigger circuit (24) comprises a voltage divider (31); the voltage divider (31) is connected to the control terminal (25) and to the first switch terminal (26) such that the switch (23) is open when no transformer voltage is present.

3. A separately excited electric synchronous machine according to claim 2.

4. the voltage divider (31) is connected to the rectifier circuit (6) such that the switch (23) is open when no DC voltage is present in the rectifier circuit (6), 4. A separately excited electric synchronous machine according to claim 3.

5. The separately excited electric synchronous machine (100) comprises a rotary transformer (1), The rotary transformer (1) comprises a rotary transformer stator (2) having a transformer primary coil (3); The rotary transformer stator (2) is fixed relative to the stator (104); The rotary transformer comprises a rotary transformer rotor (4) having a transformer secondary coil (5) which is non-rotatable relative to the rotor (101); characterised in that the transformer primary coil (3) and the transformer secondary coil (5) inductively interact in order to generate the transformer voltage in the transformer secondary coil (5) during operation.

5. A separately excited electric synchronous machine according to claim 3 or 4.

6. the trigger circuit comprises a trigger coil (32) inductively coupled to the transformer primary coil (3), the transformer primary coil (3) in operation inducing a trigger voltage in the trigger coil; The trigger coil (32) is connected to the voltage divider (31) such that the switch (23) is open in the absence of a trigger voltage.

6. A separately excited electric synchronous machine according to claim 5.

7. The separately excited electric synchronous machine (100) includes a signal transmission device (33) for wirelessly transmitting a signal to the trigger circuit (24); The trigger circuit (24) is configured to open the switch (23) upon receiving a control signal by the signal transmission device (33).

2. A separately excited electric synchronous machine according to claim 1.

8. The trigger circuit (24) comprises a current sensor (34), the current sensor (34) determining a current flowing through the rotor coil (103) during operation; the trigger circuit (24) is configured to open the switch when the current determined by the current sensor (34) exceeds a predetermined value.

2. A separately excited electric synchronous machine according to claim 1.

9. The trigger circuit (24) comprises a comparator (35) connected to the current sensor (34), and a gate drive circuit (36) connected to the comparator (35) and the switch (23).

9. A separately excited electric synchronous machine according to claim 8.

10. The rectifier circuit (6) is configured to block current flow in the direction of the transformer secondary coil (5).

2. A separately excited electric synchronous machine according to claim 1.

11. The number of the stator coils (105) is 3 or an integer multiple of 3.

2. A separately excited electric synchronous machine according to claim 1.

12. 10. Use of the separately excited electric synchronous machine (100) of claim 1 as a traction motor (120) in a motor vehicle (200).

13. 10. Use of the separately excited electric synchronous machine (100) of claim 1 as a servomotor (130).

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