Externally 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, wherein the rotor coil is supplied with a direct-current voltage during operation via a transformer coil and a rectifier circuit to generate a rotor magnetic field. The present invention further relates to a method of using such a separately excited electric synchronous machine. [Background Art]

[0002] A separately excited electric synchronous machine comprises a stationary stator and a rotor that rotates relative to the stator about a rotation axis during operation, which are hereinafter also referred to as 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 that is supplied with a direct-current voltage for generating the magnetic field. The supply of power to the rotor coil can be implemented inductively. For this purpose, an alternating voltage is induced in the secondary coil during operation. This induced voltage is converted into the required direct-current voltage via a rectifier circuit and supplied to the rotor coil.

[0003] Such a separately excited synchronous machine is already known from DE 10 2016 207 392 A1. This separately excited electric synchronous machine has a smoothing capacitor in parallel with the rotor coil and the rectifier circuit. In addition, a load element is connected in series with the rotor coil. The load element comprises two connectors connected to associated switch terminals of a switch. The control terminal of this switch is controlled via a voltage divider. Therefore, if necessary, especially when a defect occurs, it is possible to demagnetize the rotor coil. [Summary of Invention]

[0004] The present invention addresses the object of describing an improved or at least different embodiment of a separately excited electric synchronous machine of the type mentioned at the beginning. In particular, the present invention addresses the object of describing an embodiment of a separately excited electric synchronous machine characterized by improved demagnetization of the rotor coil of the synchronous machine.

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

[0006] Therefore, the present invention is based on the concept of using a protection circuit, which is connected in parallel to the rotor coil and provided for overvoltage protection of the rectifier circuit for the rotor coil, for demagnetizing the rotor coil of a separately excited electric synchronous machine. Here, a switch for demagnetizing the rotor coil, placed between the protection circuit and the rectifier circuit, disconnects the electrical connection of the rotor coil to the rectifier circuit. Thus, the protection circuit is used simultaneously for the protection of the rectifier circuit and for demagnetizing the rotor coil. In this way, simple and reliable demagnetization is achieved by the protection circuit, and the energy stored in the rotor coil is consumed by the protection circuit during demagnetization. Furthermore, a simplified separately excited electric synchronous machine can be constructed with a reduced number of components and relaxed installation space requirements for achieving demagnetization.

[0007] According to the concept of the present invention, an externally excited electric synchronous machine, also hereafter simply called a synchronous machine, comprises a rotor and a stator. Hereinafter, the rotor will also be called a synchronous rotor and the stator will also be called a synchronous stator. The rotor comprises a rotor shaft on which rotor coils are mounted non-rotatably. During operation, these rotor coils generate a magnetic field, which will hereafter be called a rotor magnetic field. The rotor coils comprises two connection points, which will hereafter be called a first rotor coil terminal and a second rotor coil terminal. The stator comprises at least one coil fixed to the stator, which will hereafter be called a stator coil. During operation, this at least one stator coil generates a magnetic field, which will hereafter be called a stator magnetic field. The rotor magnetic field and the stator magnetic field interact during operation so that the rotor rotates around an axial axis of rotation. In order to generate the rotor magnetic field, the rotor coils require a DC voltage supplied to the rotor coils through the coils, and during operation, an AC voltage is induced in the coils. 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 functions as a power source 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. During operation, the rectifier circuit converts the transformer voltage induced in the transformer secondary coil into a DC voltage for the rotor coil. This rectifier circuit is configured to fit. The rectifier circuit has two connections, which are also referred to below as the first rectifier terminal and the second rectifier terminal. A protection circuit functions as protection for the rectifier circuit from overvoltage and has two connections, which are 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. In addition, the first protection terminal is connected to the first rotor coil terminal and the second protection terminal is connected to the second rotor coil terminal, so that the protection circuit is connected in parallel between the rotor and the rectifier circuit. A switch is located between the second rectifier terminal and the second protection terminal. In addition, the synchronous machine includes a trigger circuit connected to the switch and configured to open the switch to demagnetize the rotor coils.

[0008] The directions mentioned here relate to the axis of rotation. Therefore, the "axial direction" extends parallel to the axis of rotation. In addition, the "radial direction" extends laterally with respect to the axis of rotation.

[0009] The first and second rectifier terminals function as electrical connections of the rectifier circuit to the rotor coils and are therefore the output connections of the rectifier terminals. Preferably, the rectifier circuit is provided with two further rectifier terminals on the inlet side for inputting the transformer AC voltage.

[0010] Preferably, the protection circuit also functions to protect the rotor coil from overvoltage.

[0011] The rectifier circuit, protection circuit, and trigger circuit are preferably fixed to the rotor in a non-rotatable manner. This means that the rectifier circuit, protection circuit, and trigger circuit rotate together with the rotor around the axis of rotation during operation.

[0012] When the switch is open, the electrical connection between the second rectifier terminal and the second protection terminal is disconnected. In contrast, when the switch is closed, the electrical connection between the second rectifier 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 flow of current in the direction of the transformer secondary coil. In contrast, it allows the flow of current in the direction of the rotor coil. Thus, when the switch is opened, accelerated demagnetization of the rotor coil occurs. For this purpose, the rectifier circuit may be configured as appropriate. In particular, for this purpose, the rectifier circuit may be configured as a bridge rectifier with four diodes.

[0015] Preferably, to demagnetize the rotor coil, it is sufficient to simply open this switch. Otherwise, the switch remains closed so that the rotor coil is supplied with the DC voltage provided by the rectifier circuit, allowing for normal operation.

[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, or an IGBT circuit.

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

[0018] A switch can be configured in any way, provided that it is opened and closed using a trigger circuit.

[0019] Preferably, the switch is configured as a transistor, preferably a MOSFET or IGBT. Preferably, when the switch is ON, the switch can be further operated with minimal loss. Thus, the switch can be switched reliably and efficiently using a low switch voltage. The switch includes a control terminal connected to a trigger circuit. In addition, the switch includes two switch terminals, which are also called the first switch terminal and the second switch terminal. Preferably, the second rectifier 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 MOSFET, 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] Basically, 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 malfunction in the transformer secondary coil and / or when the transformer voltage is absent or insufficient.

[0023] In a preferred embodiment, the trigger circuit includes a voltage divider, which is configured to open the switch when no transformer voltage is present. "No transformer voltage" means both the absence of transformer voltage and insufficient transformer voltage. To open the switch when no transformer voltage is present, 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 to accommodate this.

[0024] In essence, a voltage divider comprises two two-terminal passive elements, particularly two electrical resistors.

[0025] A voltage divider may be connected to the rectifier circuit so that the switch opens when no DC voltage is present in the rectifier circuit. "No DC voltage" means both the absence of DC voltage and insufficient DC voltage. Therefore, when the DC voltage provided by the rectifier circuit is absent or insufficient, demagnetization of the rotor coil occurs.

[0026] Preferably, the induction of the transformer voltage in the transformer secondary coil is carried out by an electric rotary transformer, and the transformer secondary coil is part of the electric rotary transformer. This allows energy transfer to the transformer secondary coil to be achieved simply, effectively, and reliably.

[0027] Accordingly, this synchronous machine preferably comprises an electrical rotary transformer. The rotary transformer comprises a stator and a rotor, which are also referred to hereinafter as rotary transformer stator and rotary transformer rotor. The rotary transformer stator comprises a coil, which is also referred to hereinafter as transformer primary coil. The rotary transformer stator is fixed to the stator, and the rotary transformer rotor is non-rotatable relative to the rotor. Accordingly, the rotary transformer rotor is rotatable about the axis of rotation relative to the rotary transformer stator and rotates about the axis of rotation together with the rotor during operation. The rotor comprises a transformer secondary coil. During operation, the transformer primary coil and the transformer secondary coil interact inductively 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 can be arranged axially opposite one another. The transformer primary coil and the transformer secondary coil can likewise be arranged radially opposite one another.

[0029] In a conceivable embodiment, the trigger circuit comprises a coil which is inductively coupled to the transformer primary coil and separate from the transformer secondary coil, which separate coil is also referred to hereinafter as trigger coil. During operation, the transformer primary coil induces a voltage, which is also referred to hereinafter as trigger voltage, in the trigger coil. The trigger coil is connected to a voltage divider such that a switch opens when no trigger voltage is present. "Absent" with respect to the trigger voltage means both that there is no trigger voltage and also that the trigger voltage is insufficient. Accordingly, as soon as no voltage or an insufficient voltage is induced by the transformer primary coil, demagnetization of the rotor coil is performed. The trigger coil, which is 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 coil can be achieved by signal transmission to a trigger circuit, wherein the trigger circuit opens the switch upon receiving a control signal. Said control signal is generated independently of the functions of the rotary transformer and / or the rotor, and can be sent to the trigger circuit. Thus, high flexibility in rotor demagnetization is achieved.

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

[0032] Alternatively or additionally, when a defect exists and / or excessive current flows through the rotor coil, the trigger circuit can initiate demagnetization of the rotor coil.

[0033] For this purpose, the trigger circuit preferably comprises a current sensor. The current sensor is configured to detect the current flowing through the rotor coil during operation. The trigger circuit is configured to open the switch when the current detected by the current sensor exceeds a predetermined value.

[0034] Basically, the current sensor can be configured as appropriate. In particular, the current sensor may comprise a shunt and / or a Hall sensor.

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

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

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

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

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

[0040] Synchronous machines can be used in automobiles in particular, and may include a battery as a power source to operate them. These synchronous machines function specifically to drive automobiles and are therefore configured as separately excited electric synchronous motors and traction motors.

[0041] Similarly, during operation, a synchronous machine can, as a servo motor, adjust elements, particularly those in an automobile.

[0042] Further important features and advantages of the present invention can be derived from the dependent claims, drawings, and the associated description of the drawings.

[0043] It should be understood that the features described above and below may be used not only in the combinations shown, but also in other combinations or individually, without departing from the scope of the present invention.

[0044] Preferred exemplary embodiments of the present invention are shown in the drawings and described in more detail below, and the same reference numerals relate to the same, similar, or functionally identical components. [Brief explanation of the drawing]

[0045] Each is shown in a diagram. [Figure 1] Figure 1 is an isometric view, partially cross-sectional, of a separately excited electric synchronous machine with an induction rotary transformer. [Figure 2]Figure 2 is a highly simplified excerpt from a circuit diagram of an externally excited electric synchronous motor in an automobile. [Figure 3] Figure 3 is a highly simplified excerpt from a circuit diagram of an externally excited electric synchronous motor in an automobile. [Figure 4] Figure 4 is a highly simplified excerpt from a circuit diagram of an externally excited electric synchronous motor in an automobile. [Figure 5] Figure 5 is a highly simplified excerpt from a circuit diagram of an externally excited electric synchronous motor in an automobile. [Figure 6] Figure 6 is a highly simplified excerpt from a circuit diagram of an externally excited electric synchronous motor in an automobile. [Figure 7] Figure 7 is a highly simplified cross-sectional view of a separately excited electric synchronous machine. [Modes for carrying out the invention]

[0046] For example, the externally excited electric synchronous machine 100 shown in Figure 1-7, which will also be simply referred to as the synchronous machine 100 below, may be used in an automobile 200 (see Figure 2-6). This externally excited electric synchronous machine 100 may be used as a synchronous machine 110 for driving the automobile 200, i.e., as a traction motor 120. The externally excited electric synchronous machine 100 may also be used as a synchronous machine 110 for adjusting adjustment elements, i.e., as a servo motor 130.

[0047] The synchronous machine 100 includes a rotor 101, which is particularly evident from Figures 1 and 7. Hereafter, the rotor 101 will also be called the synchronous machine rotor 101. The rotor 101 includes a rotor shaft 102 and a coil 103 that is non-rotatably mounted on the rotor shaft 102 (see Figure 2-6). Hereafter, this coil 103 will also be called the rotor coil 103. During operation, the rotor coil 103 generates a magnetic field, which will also be called the rotor magnetic field. In Figure 1-6, the rotor coil 103 is represented as an inductance and an ohm resistor. The synchronous machine 100 further includes a stator 104, shown in Figure 7, which will also be called the synchronous machine stator 104. The synchronous machine 100 includes at least one coil 105 fixed to the stator 104 (see Figure 7), which will also be called the stator coil 105. During operation, at least one coil 105 generates a magnetic field, also referred to below as the stator magnetic field. During 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, and in particular the rotor coil 103, requires a DC voltage. To supply a DC voltage to the rotor coil 103, the rotor coil 103 is provided with two connectors 106, 107, which are 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 described here are relative to the axis of rotation 90. Therefore, the "axial direction" extends parallel to the axis of rotation. In addition, the "radial direction" extends laterally with respect to the axis of rotation 90.

[0049] In the exemplary embodiment shown, 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. Hereinafter, the stator 2 will also be referred to as the rotary transformer stator 2. Hereinafter, the rotor 4 will also be referred to as the rotary transformer rotor 4. The rotary transformer stator 2 is fixed non-rotatably to the stator 104. The rotary transformer rotor 4 is fixed non-rotatably to the rotor 101. Thus, the rotary transformer rotor 4 is rotatable around the rotation axis 90 with respect to the rotary transformer stator 2. During operation, the rotary transformer rotor 4 rotates together with the rotor 101 around the rotation axis 90 with respect to the rotary transformer stator 2. 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. Hereafter, the primary coil 3 will also be called the transformer primary coil 3. As is clear from Figure 1, the transformer primary coil 3 and the transformer secondary coil 5 are arranged facing each other in the axial direction in the exemplary embodiment shown. During operation, the transformer primary coil 3 induces an alternating current voltage in the transformer secondary coil 5, which will also be called the transformer voltage.

[0050] To supply the required DC voltage to the rotor coil 103, as is clear from Figure 2-6, a rectifier circuit 6 is connected between the transformer secondary coil 5 and the rotor coil 103, and the rectifier circuit 6 converts the transformer voltage into a DC voltage. This rectifier circuit 6 is fixed to the rotor 101 in a non-rotatable manner and may be part of the rotary transformer rotor 4.

[0051] Furthermore, as is particularly clear from Figure 1, in the exemplary embodiment shown, the rotary transformer 1 is positioned at the axial end face of the rotor 101 and spaced apart from the rotor coil 103 and at least one stator coil 105.

[0052] The transformer primary coil 3 requires an alternating current voltage to induce a transformer voltage in the transformer secondary coil 5. As is evident from Figure 2-6, the transformer primary coil 3 in the illustrated exemplary embodiment is supplied via an electrical energy source 201, which provides a direct current voltage. The electrical energy source 201 in the illustrated exemplary embodiment is the battery 202 of the automobile 200. To supply an alternating current 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 direct current voltage of the energy source 201 into an alternating current voltage for the transformer primary coil 3. The inverter circuit 7 may include a converter.

[0053] As is clear from Figure 1, the rotary transformer rotor 4 in the illustrated exemplary embodiment has a circuit board 8, on which the transformer secondary coil 5 is provided. The circuit board 8 is configured in a disc shape, and is circular, i.e., configured in a disc or ring shape. The transformer secondary coil 5 in the illustrated exemplary embodiment has at least one trace 9 on the circuit board 8, which will also be referred to as the transformer trace 9 below. 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 Figure 1, the non-rotatable connection of the rotor shaft 102 to the rotary transformer rotor 4 is achieved through an opening 14 in the center of the circuit board 8, through which the rotor shaft 102 is inserted.

[0055] As is clear from Figure 1, the primary coil 3 of the transformer is configured as a flat coil 11. Furthermore, as is clear from Figure 1, the primary coil 3 and the secondary coil 5 of the transformer are arranged in a magnetic core 12, specifically a ferrite core 13, in the exemplary embodiment shown, which is fixed to the rotating transformer stator 2. The magnetic core 12 is also referred to below as the transformer magnetic core 12. This transformer magnetic core 12 is radially open, and as a result, the circuit board 8 with the transformer secondary coil 5 enters the transformer magnetic core 12 and is rotatably positioned therein. In addition, the transformer magnetic core 12 has a recess 15 that is axially open, in which the primary coil 3 is arranged.

[0056] In the exemplary embodiment shown, the rectifier circuit 6 is configured simply as a bridge rectifier 16 having four diodes D1-D4, namely the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4. 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 parallel to 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 exemplary embodiment shown, the inverter circuit 7 is configured simply 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 includes two connection points 18 and 19, which are hereafter also referred to as the first rectifier terminal 18 and the 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 Figure 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 exemplary embodiment shown, the protection circuit 20 is configured as a bidirectional suppressor diode 30. The protection circuit 20 includes two connectors 21 and 22, which are hereafter referred to as the first protection terminal 21 and the 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 the closed position, switch 23 electrically connects the second rectifier terminal 19 and the second protection terminal 22, and in the open position, switch 23 disconnects the electrical connection between the second rectifier terminal 19 and the second protection terminal 22. A trigger circuit 24 is connected to switch 23 and configured to open switch 23 to demagnetize the rotor coil 103. Otherwise, switch 23 is closed so that the rotor coil 103 generates a magnetic field.

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

[0061] In the exemplary embodiment shown, 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. A trigger circuit 24 is connected to the control terminal 25. In addition, a second rectifier terminal 19 is connected to the first switch terminal 26, and a 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, in the exemplary embodiment shown, the first switch terminal 26 corresponds to the source, and the second switch terminal 27 corresponds to the drain.

[0062] In the exemplary embodiment shown in Figure 3-5, the trigger circuit 24 includes a voltage divider 31. This voltage divider 31 comprises two electrical resistors R1 and R2, known as two-terminal passive elements, namely 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 exemplary embodiment shown, the trigger circuit 24 further includes a capacitor Ct.

[0063] In the exemplary embodiments shown in Figures 3 and 4, a voltage divider is present so that the switch 23 opens when there is no transformer voltage, i.e., with no voltage or insufficient voltage. Therefore, demagnetization of the rotor coil 103 occurs, for example, when the rotary transformer 1 is stopped.

[0064] In the exemplary embodiment shown in Figure 3, the voltage divider 31 is connected to the fourth diode D4 of the rectifier circuit 6 via the first resistor R1, and thus to the secondary coil 5 of the transformer. 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 the first switch terminal 26. When there is no DC voltage supplied by the rectifier circuit 6, i.e., there is no DC voltage or the DC voltage is insufficient, 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 there is no DC voltage in the rectifier circuit 6, the switch 23 opens, demagnetizing the rotor coil 103.

[0065] In the exemplary embodiment shown in Figure 4, the trigger circuit 24 includes a trigger coil 32 inductively coupled to the transformer primary coil 3 so that during operation, the transformer primary coil 3 induces a trigger voltage in the trigger coil 32. The trigger coil 32 has one end connected to a first resistor R1 and the other end connected 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 the first switch terminal 26. When there is no induced trigger voltage, i.e., there is no induced trigger voltage or the induced trigger voltage is insufficient, 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 includes a unidirectional suppressor diode Dt to limit the control voltage of the switch 23, and the control terminal 25 and the first switch terminal 26 are connected in parallel. Furthermore, diode D5 and third resistor R3 are connected between trigger coil 32 and first resistor R1.

[0066] In the exemplary embodiment shown in Figure 5, the synchronous machine 1 includes a signal transmission device 33 for wireless signal transmission to a trigger circuit 24. The trigger circuit 24 is configured to open a switch 23 when it receives a control signal received by the signal transmission device 33. Thus, the rotor coil 103 can be demagnetized as needed, in particular independently of the rotary transformer 1.

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

[0068] In the exemplary embodiment shown in Figure 6, the trigger circuit 24 includes a current sensor 34 that determines the current flowing through the rotor coil 103 during operation. The trigger circuit 24 is configured to open a switch 23 when the current determined by the current sensor 34 exceeds a predetermined value. Therefore, when an excessive current flows through the rotor coil 103, it is possible to demagnetize the rotor coil 103.

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

[0070] Although Figure 2-6 simply shows one rotor coil 103, as shown in Figure 1, the rotor 101 may also have two or more rotor coils 103.

Claims

1. A separately excited electric synchronous machine (100), The separately excited electric synchronous machine has a rotor (101), the rotor comprises 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 comprises a first rotor coil terminal (106) and a second rotor coil terminal (107), The separately excited electric synchronous machine has a stator (104), the stator comprises at least one stator coil (105) fixed to the stator (104) that generates a stator magnetic field during operation, the stator magnetic field interacts with the rotor magnetic field such that the rotor (101) rotates around an axial axis of rotation (90) during operation, The separately excited electric synchronous machine has a transformer secondary coil (5) for supplying electricity to the rotor coil (103), and the transformer secondary coil is fixed to the rotor (101) in a non-rotatable manner. 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 converts the transformer voltage induced in the transformer secondary coil (5) during operation into a DC voltage, and is equipped with 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 overvoltage, and the protection circuit comprises 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) positioned between the second rectifier terminal (19) and the second protection terminal (22), The separately excited electric synchronous machine has a trigger circuit (24) connected to the switch (23) and configured to open the switch (23) in order to demagnetize the rotor coil (103), The trigger circuit (24) includes a current sensor (34), and the current sensor (34) 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. When the switch (23) is open, the current from the rotor coil (103) flows to the protection circuit (20). Externally excited electric synchronous machine.

2. The switch (23) is characterized by comprising a control terminal (25) connected to the trigger circuit (24), a first switch terminal (26) connected to the second rectifier terminal (19), and a second switch terminal (27) connected to the second protection terminal (22). The externally excited electric synchronous machine according to claim 1.

3. The trigger circuit (24) includes a voltage divider (31), The voltage divider (31) is connected to the control terminal (25) and the first switch terminal (26) such that the switch (23) opens when there is no transformer voltage. The externally 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) opens when there is no DC voltage in the rectifier circuit (6). The externally excited electric synchronous machine according to claim 3.

5. The separately excited electric synchronous machine (100) is equipped with 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 to the stator (104), The rotary transformer comprises a rotary transformer rotor (4) having a transformer secondary coil (5) that is not rotatable relative to the rotor (101), The primary coil (3) and secondary coil (5) of the transformer are characterized in that they inductively interact with each other during operation in order to generate the transformer voltage in the secondary coil (5). The externally excited electric synchronous machine according to claim 3 or 4.

6. The trigger circuit comprises a trigger coil (32) inductively coupled to the primary coil (3) of the transformer, and the primary coil (3) of the transformer induces a trigger voltage in the trigger coil during operation. The trigger coil (32) is connected to the voltage divider (31) such that the switch (23) opens when no trigger voltage is present. The externally excited electric synchronous machine according to claim 5.

7. The separately excited electric synchronous machine (100) is equipped with a signal transmission device (33) for wireless signal transmission to the trigger circuit (24), The trigger circuit (24) is configured to open the switch (23) when it receives a control signal from the signal transmission device (33). The externally excited electric synchronous machine according to claim 1.

8. The trigger circuit (24) is characterized by comprising a comparator (35) connected to the current sensor (34) and a gate drive circuit (36) connected to the comparator (35) and the switch (23). The externally excited electric synchronous machine according to claim 1.

9. The rectifier circuit (6) is characterized by being configured to interrupt the flow of current in the direction of the transformer secondary coil (5). The externally excited electric synchronous machine according to claim 1.

10. The number of stator coils (105) is characterized by being 3 or an integer multiple of 3. The externally excited electric synchronous machine according to claim 1.

11. A method of using the separately excited electric synchronous motor (100) according to claim 1 as a driving motor (120) in an automobile (200).

12. A method of using the externally excited electric synchronous motor (100) according to claim 1 as a servo motor (130).

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