Electric drive arrangement

Abstract

Electrical drive arrangement (1), in particular for a motor vehicle, comprising an inverter (2) and an electrical machine (3), in particular a separately excited synchronous machine, wherein a computing device (6) arranged on the rotor (4) of the electrical machine (3) is designed to receive a voltage signal from the inverter (2) which comprises a voltage-modulated input signal (10), and to set at least one operating parameter of the rotor (4), in particular a rotor current, as a function of the voltage-modulated input signal (10).

Description

[0001] The invention relates to an electric drive arrangement, in particular for a motor vehicle, comprising an inverter and an electric machine, in particular a separately excited synchronous machine.

[0002] Electrical drive assemblies that have an electrical machine as the drive device, for example a separately excited synchronous machine, are generally known from the prior art, particularly for use in motor vehicles. As is known, a voltage signal is output via an inverter of the electrical drive assembly, so that corresponding currents are set in the electrical machine to generate a torque for the drive. In the case of separately excited synchronous machines, it is known that these can traditionally have sliding contacts for electrically contacting the rotor. In addition, it is also known to inductively transmit current from the inverter to the rotor via an inductive transformer or an inductive transmission device.

[0003] In both cases, setting an operating parameter on the rotor side, for example changing the rotor currents to be set in the rotor or recording an operating variable, in particular the temperature, is difficult because there is no controllable electronic device or computing device on the rotor side. This can, for example, lead to the corresponding operating variable, for example the rotor current or rotor temperature, being determined relatively inaccurately and thus can result in an inaccurate output torque. For example, the rotor current actually flowing in the rotor can depend on the current boundary conditions of the inductive transmission device. If, for example, the air gap in the inductive transmitter does not correspond to a target size orIf foreign substances, such as oil, have penetrated there, this can lead to a change in the coupling factor, so that the actual currents in the rotor deviate from the target currents.

[0004] The invention is based on the object of providing an improved electric drive arrangement in which, in particular, a rotor-side adjustment of operating parameters is improved.

[0005] The object is achieved by an electric drive arrangement having the features of claim 1. Advantageous embodiments are the subject of the subclaims.

[0006] As described, the invention relates to an electric drive arrangement, in particular for a motor vehicle, which has an inverter and an electric machine, which electric machine is in particular designed as a separately excited synchronous machine.

[0007] The invention is based on the finding that the electric drive arrangement has a computing device arranged on the rotor of the electric machine, which is designed to receive a voltage signal from the inverter, which comprises a voltage-modulated input signal, and to adjust at least one operating parameter of the rotor, in particular a rotor current, as a function of the voltage-modulated input signal. In other words, the inverter of the electric drive arrangement is designed to generate the voltage signal, which comprises a voltage-modulated input signal, and to transmit the voltage signal to the computing device arranged in the rotor. The voltage signal can thus in principle comprise a carrier signal, which can correspond, for example, to the operating voltage output by the inverter to the electric machine.The input signal is modulated onto the carrier signal so that it can be received by the computing device.

[0008] This makes it possible to transmit the input signal to the computing device, which in turn can adjust the rotor's operating parameter, for example, the rotor's rotor current. In other words, a communication interface is created between the inverter and the computing device of the rotor of the electric machine. For example, this allows commands to be sent to the rotor's computing device by specifically modulating an electrical operating variable of the electric machine.

[0009] In one embodiment of the electric drive arrangement, it can be provided that the inverter is designed to modulate the input signal as a command signal for the computing device onto a voltage output to the rotor, wherein the computing device is designed to demodulate the modulated command signal and execute a command defined by the command signal. As already described, the inverter can output the voltage signal, which can include the voltage-modulated input signal and the voltage to be output. Because the input signal can be transmitted as a command signal, a command can ultimately be modulated onto the voltage output by the inverter.

[0010] This means that in addition to the inverter's function of outputting the voltage, a communication task can also be performed, namely the output of the input signal, specifically the command signal for the computing device. The computing device, in turn, is designed to demodulate the command signal modulated onto the voltage signal so that the command signal can be obtained. The computing device can then execute the command defined by the command signal, for example, setting the rotor's operating parameter.

[0011] Ultimately, any commands can be sent to the rotor's computing device via the command signal, for example which rotor current should be set or how this should be changed. As already described, the transmission can basically be based on the voltage applied to the computing device being used as a carrier signal, whereby modulation by a defined value, for example 10V, can be used to modulate the input signal. This means that a series of pulses can be modulated onto the carrier signal, which can then be demodulated in the computing device. This means that, for example, each modulated pulse can be assigned a logical "1". The command can thus be transmitted in the form of a 1-0 transformation as a coded command signal via the modulated input signal and demodulated again in the rotor by the computing device.For this purpose, the computing device can have a voltage measuring input at which the current voltage can be measured.

[0012] In the electric drive arrangement, it can further be provided that the setting of the operating parameter comprises a setting of a rotor current and / or that the setting of the operating parameter comprises modulating an information signal onto the rotor current, wherein the inverter is designed to demodulate the information signal from the rotor current. In the described embodiment, communication is ultimately enabled in the communication direction opposite to the communication direction described above. In other words, it is proposed that communication between the computing device of the rotor and the inverter be possible by modulating the rotor current.This means that, in addition to the possibility of transmitting a command to the computing device via the voltage-modulated input signal, which the computing device executes by setting an operating parameter, a command to send an information signal can also be transmitted. Alternatively, the computing device can also transmit the information signal, for example, specifically cyclically, without requiring an explicit command.

[0013] The information signal can, for example, relate to a current rotor current or a rotor temperature. To transmit the information signal to the inverter, the rotor current is modulated or the information signal is modulated onto the rotor current. For example, the rotor current can be pulsed, i.e. switched on and off at a high frequency, with the pulses being at a significantly higher frequency than a change in the rotor current during regular operation, for example in the microsecond range. As a result, a rotor field generated by the rotor current is not affected, or only slightly affected. The inverter has, for example, a current measuring resistor or generally a suitable current measuring device to measure the rotor current. This allows the rotor current pulses that carry the information signal to be filtered.In other words, the transmission of the input signal from the inverter to the rotor may be voltage modulated and the transmission of the information signal from the rotor to the inverter may be current modulated.

[0014] As described, the computing device can transmit the information signal to the inverter by modulating the rotor current. In one embodiment of the electric drive arrangement, the computing device can be configured to modulate the information signal onto the rotor current in pulse form. Specifically, the rotor current is clocked or varied in the form of short pulses, particularly in the µs range, to modulate the information signal. The described pulses can then be demodulated on the inverter side to obtain the information signal.

[0015] The electric drive arrangement can be further developed such that the inverter is configured to demodulate the information signal based on rotor current gradient monitoring. As described, the modulation of the information signal is transmitted based on a pulsed output of the rotor current. The pulses are shorter or higher frequency, meaning they exhibit a significantly faster current change than a change in the rotor current during regular operation. Therefore, by monitoring the rotor current gradient, the inverter can determine whether a change in the rotor current is occurring or whether an information signal is being transmitted.For example, a gradient threshold can be set, whereby a change in the rotor current below the gradient threshold represents a regular rotor current change, and a change in the rotor current above the gradient threshold can be identified as a pulse for transmitting the information signal. Another possibility is to use a low-pass filter to transmit changes in the rotor current and a high-pass filter to transmit the information signal, or to use the aforementioned filters to separate the information signal from the rotor current.

[0016] According to a further embodiment of the electric drive arrangement, the computing device can be designed to detect an operating variable and to transmit the detected operating variable, in particular a rotor field and / or a rotor position and / or a rotor current and / or a rotor temperature and / or a stator field, to the inverter as a component of the information signal. Thus, by means of the computing device, certain operating variables of the rotor can be detected, which can characterize the operation of the electric machine. These can then be transmitted to the inverter as an information signal by modulating the rotor current, as described.

[0017] In particular, it is possible that by transmitting the voltage-modulated input signal, specific information can be queried from the computing device, which is then recorded by the computing device or has already been recorded by the computing device and can be transmitted back to the inverter as an information signal. For example, this can ensure that the desired rotor current is set in the rotor. In particular, the current rotor current can be recorded by the computing device and transmitted to the inverter. This makes it possible to identify whether there is a difference between a desired rotor current and an actual rotor current. This can then be used to determine whether the torque setting on the part of the electric machine is precise enough.If, for example, fluctuations occur in the operation of the inductive transmission device, for example caused by the air gap, oil or the like, these can be identified and the actual rotor current can be adjusted by transmitting the corresponding command signal so that it corresponds to the target rotor current.

[0018] Furthermore, the electric drive arrangement can be provided with at least one active rectifier, wherein the computing device is configured to control the at least one active rectifier as a function of a detected rotor current. As described, a comparison can be made between a desired rotor current and an actual rotor current. This makes it possible to determine what is actually being transmitted by the inductive transmission device and what is actually required in the rotor. For example, the inductive transmission device can be operated at a transmission frequency at which it exhibits optimum efficiency.

[0019] The transmission frequency does not have to match the inverter's control frequency, nor does it have to match the control frequency of the computing device or the rotor field control. The active rectifier makes it possible to adjust the rotor current or to specify how much of the current provided by the inductive transmission device should be applied to the rotor. Any surplus can be consumed in the inductive transmission device or used to maintain the field. The control of the rotor field of the electric machine's rotor can therefore be controlled by the computing device using the active rectifier, without having to change the operation of the inverter.

[0020] According to a further embodiment of the electric drive arrangement, it can be provided that the inverter and / or the computing device is configured to determine a coupling factor of an inductive transformer of the electric drive arrangement and to change the coupling factor depending on the detected rotor current, in particular by changing a transmission frequency of the inductive transformer. The described configuration makes it possible to determine and compensate for the coupling factor of the inductive transformer or the inductive transmission device of the electric drive arrangement.

[0021] For example, the rotor current can be measured by the computing device in the rotor and compared with the current to be transmitted or transmitted. From this, the coupling factor of the inductive transmission device can be determined. In other words, it is determined which current should be provided by the current operating situation of the inverter, i.e. which target current is set and which actual current arrives in the rotor. As described, the actual current can be regulated by controlling the active rectifier via the computing device. Furthermore, it is possible to optimize the coupling factor of the inductive transmission device by changing the transmission frequency of the transmission device. By changing the coupling factor, the actual current can be changed so that the actual current in the rotor corresponds to the target current.Ultimately, this allows the current in the rotor to be adjusted without changing the operation of the inverter.

[0022] In addition to the described electric drive arrangement, the invention relates to a motor vehicle comprising a previously described electric drive arrangement.

[0023] Furthermore, the invention relates to a method for controlling the operation of an electric drive arrangement, in particular for a motor vehicle, comprising an inverter and an electric machine, in particular a separately excited synchronous machine, wherein a voltage signal is received from the inverter by means of a computing device arranged on the rotor, which voltage signal comprises a voltage-modulated input signal and at least one operating parameter of the rotor, in particular a rotor current, is set as a function of the voltage-modulated input signal.

[0024] All advantages, details and features described with regard to the electric drive arrangement are fully transferable to the motor vehicle and the method.

[0025] The invention is explained below using exemplary embodiments with reference to the figures. The figures are schematic representations and show: Fig. 1 a schematic diagram of an electric drive arrangement; Fig. 2 a schematic diagram of a voltage diagram; and Fig. 3 a schematic diagram of a current diagram.

[0026] Fig. 1 schematically shows an electric drive assembly 1, in particular for a motor vehicle. The electric drive assembly 1 can thus be designed as a component of a motor vehicle (not shown in detail). The electric drive assembly 1 has an inverter 2 and an electric machine 3. The electric machine 3 is designed, for example, as a drive device of the motor vehicle that has the electric drive assembly 1. The electric machine 3 is thus intended to provide a torque for the drive.

[0027] The electric machine 3 schematically comprises a rotor 4, which is rotatably mounted relative to a stator (not shown in detail) of the electric machine 3. For example, the electric machine 3 is designed as a separately excited synchronous machine. The electric machine 3 can have an inductive transmission device 5, but can alternatively also be designed in a conventional manner, i.e., using sliding contacts to contact the rotor 4. The following description applies accordingly.

[0028] A computing device 6 is also arranged on the rotor 4. As indicated by an arrow 7, the computing device 6 can receive a voltage signal from the inverter 2, for example, by means of a voltage measuring input or a voltage detection device of the computing device 6. Accordingly, an arrow 8 further indicates that the inverter 2 can receive a current signal from the electrical machine 3, in particular from the computing device 6, in particular by means of a current measuring device, for example, a current measuring resistor.

[0029] In particular, the computing device 6 is designed to receive a voltage signal from the inverter 2, which comprises a voltage-modulated input signal 10. The voltage signal, which is, for example, Fig. 2, can thus have a carrier signal 9, in particular the current operating voltage of the electric drive arrangement 1, for example 400V. The operating voltage varies depending on the design and operating situation of the electric drive arrangement 1 and is therefore to be understood as an example and can be changed as desired. The input signal 10 is modulated onto the carrier signal 9, i.e. the voltage output by the inverter 2 to the computing device 6. The amplitude of the modulated input signal 10 is, for example, 10V, whereby the numerical value is also chosen accordingly merely as an example and can be changed as desired.

[0030] Accordingly, the input signal 10 from the inverter 2 can be modulated onto the operating voltage provided to the electric machine 3, as shown in Fig. 2. The computing device 6 has, for example, a voltage measurement input to measure the Fig. 2, consisting of carrier signal 9 and input signal 10. Knowing the operating voltage, input signal 10 can thus be demodulated or extracted based on the pulse-shaped fluctuations of the voltage signal. For example, input signal 10 can be modulated onto the operating voltage by means of a 1-0 transformation and demodulated by computing device 6.

[0031] Specifically, the input signal 10 comprises a command signal that the computing device 6 can process by executing a command defined by the command signal. For this purpose, the computing device 6 specifically sets an operating parameter of the rotor 4, specifically a rotor current. This can be used, on the one hand, to control the rotor current of the rotor 4, for example, to change an operating point of the electric machine 3. It is also possible, as in Fig. 3 shows that by changing the operating parameter of the rotor 4, an information signal 11 can be output and received by the inverter 2. The information signal 11 can, as in Fig. 3, can be modulated onto the rotor current by pulsing the rotor current, i.e., rapidly switching it on and off. In this way, any influence on the rotor magnetic field due to the short pulse duration, especially in the µs range, can be avoided or eliminated.

[0032] Purely as an example, in Fig.3 shows an information signal 11 consisting of three pulses. The inverter 2 can determine the information signal 11, for example, using a current measuring input or a current measuring resistor. For example, the inverter 2 can have or carry out gradient monitoring that monitors the gradient of the rotor current. If the gradient is above a gradient limit value, which corresponds in particular to the pulse-shaped change in the rotor current due to the modulation of the information signal 11, the inverter 2 can identify corresponding pulses that define the information signal 11. If, as shown, for example, in an area 12, the gradient of the rotor current is below a gradient limit value, there is a change in the rotor current that corresponds to the current operation of the electric machine 3.For example, a high-pass filter and / or low-pass filter can also be used to separate the information signal 11 from the rotor current. Thus, the inverter 2 is also designed to demodulate the information signal 11 from the rotor current.

[0033] As described, the computing device 6 can be designed to detect operating variables of the electric machine 3 or the rotor 4. Specifically, the computing device 6 can detect a rotor temperature and a rotor current of the rotor 4. The detected operating variable can further relate to a rotor field, a rotor position, a rotor current, or a stator field. The operating variable can be transmitted to the inverter 2 as part of an information signal 11, in particular triggered by a corresponding command transmitted as an input signal 10 from the inverter 2 to the computing device 6.

[0034] For example, a current rotor current can be detected by the computing device 6 and transmitted to the inverter 2. This makes it possible to compare a target current, which is to be transmitted to the rotor 4, in particular via the inductive transmission device 5, with an actual current detected by the computing device 6 in the rotor 4. This improves the control of the rotor current, since the computing device 6 can detect which actual rotor current is actually being set, which can be compared with the target current controlled by the inverter 2. The computing device 6 can in particular be designed to control at least one active rectifier of the rotor 4. For example, the active rectifier can be controlled as a function of the detected rotor current, in particular in order to regulate the target current.

[0035] For example, with the described active rectifier, the current available to the rotor can be regulated via pulse-width modulation, in particular high-frequency pulse-width modulation. This allows the rotor current to be adjusted so that it corresponds to the desired current. This makes it possible to operate the inductive transmission device 5 more efficiently, since it can be operated at its optimal transmission frequency or the transmission frequency can be changed.

[0036] Furthermore, it is possible to determine the coupling factor of the inductive transmission device, in particular by means of the computing device 6. For example, the output voltage or the output current, i.e., the operating voltage and the target current, can be transmitted from the inverter 2. This can be set in relation to the actual rotor current measured by the computing device 6 and the voltage measured on the rotor 4. This makes it possible to adjust the rotor current within certain limits by the computing device 6 without implementing any control intervention on the inverter 2.

[0037] The method described herein can be carried out using the electric drive assembly 1. As described, the electric drive assembly 1 can be assigned to a motor vehicle or arranged in a motor vehicle. The preceding description is therefore also applicable to the method and the motor vehicle.

[0038] The advantages, details and features shown in the embodiments can be combined with one another, are interchangeable and are transferable to one another. Reference symbol 1 electric drive arrangement 2 inverters 3 electric machine 4 Rotor 5 inductive transmission device 6 Computing device 7, 8 arrow 9 Carrier signal 10 Input signal 11 Information signal 12 Area

Claims

[1] Electric drive arrangement (1), in particular for a motor vehicle, comprising an inverter (2) and an electric machine (3), in particular a separately excited synchronous machine, characterized by a computing device (6) arranged on the rotor (4) of the electrical machine (3), which is designed to receive a voltage signal from the inverter (2) which comprises a voltage-modulated input signal (10), and to set at least one operating parameter of the rotor (4), in particular a rotor current, as a function of the voltage-modulated input signal (10). [2] Electric drive arrangement (1) according to claim 1, characterized byin that the inverter (2) is designed to modulate the input signal (10) as a command signal for the computing device (6) onto a voltage output to the rotor (4), wherein the computing device (6) is designed to demodulate the modulated command signal and to execute a command defined by the command signal. [3] Electric drive arrangement (1) according to claim 1 or 2, characterized by that the setting of the operating parameter comprises a setting of a rotor current and / or that the setting of the operating parameter comprises modulating an information signal (11) onto the rotor current, wherein the inverter (2) is designed to demodulate the information signal (11) from the rotor current. [4] Electric drive arrangement (1) according to claim 3, characterized by that the computing device (6) is designed to modulate the information signal (11) in pulse form onto the rotor current. [5] Electric drive arrangement (1) according to claim 3 or 4, characterized by that the inverter (2) is designed to demodulate the information signal (11) based on a gradient monitoring of the rotor current. [6] Electric drive arrangement (1) according to claim 3 or 4, characterized by that the computing device (6) is designed to detect an operating variable and to transmit the detected operating variable, in particular a rotor field and / or a rotor position and / or a rotor current and / or a rotor temperature and / or a stator field, to the inverter (2) as a component of the information signal (11). [7] Electric drive arrangement (1) according to one of the preceding claims, characterized by that the rotor (4) has at least one active rectifier, wherein the computing device (6) is designed to control the at least one active rectifier as a function of a detected rotor current. [8] Electric drive arrangement (1) according to one of the preceding claims, characterized by that the inverter (2) and / or the computing device (6) is designed to determine a coupling factor of an inductive transformer (5) of the electric drive arrangement (1) and to change the coupling factor as a function of the detected rotor current, in particular by changing a transmission frequency of the inductive transformer (5). [9] Motor vehicle comprising an electric drive arrangement (1) according to one of the preceding claims. [10] Method for controlling the operation of an electric drive arrangement (1), in particular for a motor vehicle, comprising an inverter (2) and an electric machine (3), in particular a separately excited synchronous machine, characterized bythat a voltage signal comprising a voltage-modulated input signal (10) is received from the inverter (2) by means of a computing device (6) arranged on the rotor (4), and at least one operating parameter of the rotor (4), in particular a rotor current, is set as a function of the voltage-modulated input signal (10).

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