Method for operating an inverter for an electric motor, control device, inverter, assembly and vehicle

Abstract

The present invention relates generally to a method of operating an inverter (10) for an electric motor (12), the inverter (10) comprising at least one switching arm (16) comprising a high-side power switch (18) and a low-side power switch (20) connected to a central node, for providing an AC signal to the electric motor (12), and a control device (36) configured to apply a modulation signal (40), the modulation signal (40) alternately places the switching arms in a high configuration, in which the high-side power switch is closed and the low-side power switch is open, and a low configuration, in which the high-side power switch is open and the low-side power switch is closed, in which interference is caused during operation of the inverter (10), resulting in a noise signal (66), and the noise signal (66) is transmitted to the inverter (10). The method (56) comprises at least the step of adjusting the modulation signal (40) from a first modulation sequence to a second modulation sequence such that an amplitude minimum in the frequency domain of the noise signal (66) lies within the operating bandwidth of the electromagnetic wave receiving device (42), the first modulation sequence being different from the second modulation sequence.

Description

Technical Field

[0001] The present invention generally relates to a method of operating an inverter for an electric motor, a control device, an inverter for an electric motor, an assembly and a vehicle. Background Art

[0002] An electric motor is operated by using an inverter, which provides alternating current to the windings of the electric motor. Typically, a device including an electric motor, such as a vehicle, also includes other components, such as an electromagnetic wave receiving device, such as a radio. However, when operating the electric motor and the inverter, interference may be caused, resulting in noise signals that affect the signal quality within the operating bandwidth of the electromagnetic wave receiving device. Therefore, there is a need to reduce interference, particularly with respect to the operating bandwidth of the electromagnetic wave receiving device.

[0003] According to known methods, filter components are used to at least reduce these interferences with respect to the operating bandwidth of the electromagnetic wave receiving device. However, these filter components are complex and costly. In addition, this method of reducing interference represents an indirect measure to reduce interference within the operating bandwidth of the electromagnetic wave receiving device, because the occurrence of interference itself is not reduced.

[0004] Therefore, there is a need for a method of operating an inverter such that disturbances are reduced in a more efficient manner both from a compensation point of view and with respect to the required costs. Summary of the invention

[0005] The subject matter of the independent claims satisfies the corresponding needs. Preferred embodiments are indicated in the dependent claims and in the following description, each of which may represent aspects of the disclosure alone or in combination. Some details of the disclosure are described for the apparatus, and other details are described for the corresponding methods. However, the advantages and preferred embodiments described with respect to the illustrated apparatus are correspondingly transferred to the corresponding methods and vice versa.

[0006] The following describes an overview of certain embodiments disclosed herein. It should be understood that these aspects are presented only to provide a brief overview of these specific embodiments, and these aspects are not intended to limit the scope of the present disclosure. The present disclosure may include multiple aspects that may not be described below.

[0007] According to one aspect, a method of operating an inverter for an electric motor is provided. The inverter comprises at least one switching arm and a control device, the switching arm comprising a high-side power switch and a low-side power switch connected to a central node for providing an AC signal to the electric motor, the control device being configured to apply a modulation signal, the modulation signal alternately placing the switching arm in a high configuration and a low configuration, in which the high-side power switch is closed and the low-side power switch is open, and in which the high-side power switch is open and the low-side power switch is closed, wherein interference is induced during operation of the inverter, resulting in a noise signal having a frequency-dependent amplitude. The method comprises at least the following steps:

[0008] The modulation signal is adjusted from a first modulation sequence to a second modulation sequence so that the amplitude minimum value of the noise signal in the frequency domain is located within the operating bandwidth of the electromagnetic wave receiving device, and the first modulation sequence is different from the second modulation sequence.

[0009] The operating bandwidth of the electromagnetic wave receiving device refers to the frequency domain. In other words, the bandwidth describes the frequency range in which the receiving device operates and can receive the corresponding signal. This means adapting the modulation signal so that the noise signal is minimized in the operating bandwidth of the electromagnetic wave receiving device with respect to its amplitude. In other words, at least within the boundaries of the operating bandwidth of the electromagnetic wave receiving device, the occurrence of unnecessary high noise signal amplitudes is actively avoided. Therefore, the operation of the electromagnetic wave receiving device is less disturbed, thereby obtaining a better signal-to-noise ratio. In addition, even if additional filter components are considered to further improve the signal characteristics with respect to the operating bandwidth of the electromagnetic wave receiving device, the effort required for it is reduced. For example, fewer filter components or smaller filter components can be applied, thereby reducing the required installation space and total manufacturing cost. In general, by appropriately adjusting the modulation signal, additional filter components can also be completely avoided, because a sufficient signal-to-noise ratio can be achieved for the operating bandwidth of the electromagnetic wave receiving device. In other words, the known method is based on indirect measurement by using a filter component, and the present invention relates to a direct method, because the amplitude of the noise signal part is minimized with respect to the operating bandwidth of the electromagnetic wave receiving device itself. The noise signal has, for example, an amplitude that depends on the frequency.

[0010] The noise signal is generated, for example, due to the interaction between certain components connected to the inverter.

[0011] For example, in the case of an electric motor, a number of different stray capacitances appear, namely the capacitance Cwr between the stator winding and the rotor, the capacitance Cwf between one stator winding and the motor housing, the capacitance Crf between the rotor and the motor housing, and the capacitance Cb for each roller bearing between the housing and the rotor.

[0012] In other words, the noise signal may be generated by the voltage variation between the terminals of at least one of the following stray capacitances:

[0013] The capacitance between the stator winding and the rotor of the motor,

[0014] The capacitance between the stator winding and the housing of the motor,

[0015] the capacitance between the motor’s rotor and housing, and

[0016] Capacitors for the roller bearings between the housing and the rotor.

[0017] According to another aspect, a control device for an inverter of an electric motor is provided. The control device includes a data processing circuit. The inverter includes at least one switching arm, the switching arm including a high-side power switch and a low-side power switch connected to a central node, for providing an AC signal to the electric motor. The control device is configured to apply a modulation signal, the modulation signal alternately placing the switching arm in a high configuration and a low configuration, in which the high-side power switch is closed and the low-side power switch is disconnected in the high configuration, and in which the high-side power switch is disconnected and the low-side power switch is closed in the low configuration, wherein interference is caused during the operation of the inverter, resulting in a noise signal, and the control device is also configured to adjust the modulation signal from a first modulation sequence to a second modulation sequence so that the amplitude minimum of the noise signal in the frequency domain is consistent with the operating bandwidth of the electromagnetic wave receiving device, and the first modulation sequence is different from the second modulation sequence.

[0018] The control device may, for example, include a data processing circuit, based on which the control device may be configured to determine the modulation signal. Based on the modulation signal, one or more output signals may be provided to control the state of the power switches of the inverter. Thus, the state of the power switches may be controlled by the control device. For example, a gate voltage may be applied to the power switches so that their state is determined based thereon.

[0019] Essentially, with regard to the control device, the advantages explained with respect to the above method are also achieved.

[0020] In order to switch between different configurations, for example, switching from a high configuration to a low configuration, the high-side power switch is first disconnected so that both power switches are disconnected for a short time. Then, the low-side power switch is closed. This short time avoids short circuiting of the voltage source. In fact, this short time is called the first dead time. The first dead time can also be considered as the time delay between the command high-side power switch and the low-side power switch, that is, the short time between the command to disconnect the high-side power switch and the command to close the low-side power switch. In a similar manner, when switching from a low configuration to a high configuration, a second dead time is defined.

[0021] Preferably, the modulation signal is adjusted so as to adapt a first dead time between opening of the high-side power switch and closing of the low-side power switch and / or a second dead time between opening of the low-side power switch and closing of the high-side power switch caused by the modulation signal.

[0022] For example, the first and / or second dead time can be increased or shortened. Due to interactions occurring within the electric motor, and due to interactions within the underlying circuits, such as the inverter being coupled to windings located within the electric motor, the modulation signal has an influence on the noise occurring within the entire system, for example also depending on the rotation speed of the electric motor. Therefore, when the modulation signal is adjusted taking into account the first and / or second dead time, the noise occurring is affected. It has been found that by adapting the first and / or second dead time caused by the modulation signal, the minimum value of the noise signal can be shifted in the frequency domain. Therefore, the first and / or second dead time can be selected so that the minimum value of the noise signal in the frequency domain is contained within the operating bandwidth of the electromagnetic wave receiving device. Since the modulation signal is usually applied by a data processing circuit, a simple, direct and effective way to appropriately customize the noise signal is achieved.

[0023] Optionally, before adjusting the modulation signal, the control device receives a notification signal indicating the operating bandwidth of the electromagnetic wave receiving device. In this case, the adjustment of the modulation signal is generally variable in view of the operating bandwidth of the electromagnetic wave receiving device. For example, the electromagnetic wave receiving device can operate at a variety of different operating bandwidths. Then, when the control device is informed of the actual operating bandwidth of interest, the modulation signal can be appropriately adjusted with respect to the operating bandwidth.

[0024] In some embodiments, the modulation signal is adjusted so that a minimum value of the noise signal in the frequency domain is included in the operating bandwidth of the electromagnetic wave receiving device.

[0025] Optionally, the modulation signal is adjusted so that a portion of the noise signal centered around the minimum value of the noise signal in the frequency domain contains the operating bandwidth of the electromagnetic wave receiving device. For example, the control device can be configured to perform such adjustment as described above. Typically, the noise signal exhibits a repetitive behavior based on the basic modulation signal. By appropriately adjusting the modulation signal, the minimum value of the noise signal in the frequency domain can be shifted in the frequency domain. Therefore, the minimum value can be shifted in the frequency domain so that the portion of the noise signal in the frequency domain centered around the minimum value contains the operating bandwidth of the electromagnetic wave receiving device.

[0026] Preferably, the portion of the noise signal centered around the minimum value of the noise signal in the frequency domain has a larger frequency range than the operating bandwidth. The modulation signal is adjusted so that the operating bandwidth is completely within the portion of the noise signal. In other words, the operating bandwidth of the electromagnetic wave receiving device is narrower than the portion of the noise signal.

[0027] Optionally, the modulation signal is based on a pulse width modulation (PWM) algorithm. The PWM algorithm may be output, for example, by a data processing circuit that controls the power switch using the PWM algorithm. The PWM algorithm is well suited for determining different states of the power switch of the inverter, for example by applying corresponding gate voltages. In particular, a specific PWM algorithm may be selected such that common-mode electromagnetic radiation occurring within an electric motor coupled to the inverter is reduced.

[0028] In some embodiments, the modulation signal is based on a remote state switching modulation algorithm. These modulation algorithms represent specific algorithms that can be used to reduce common mode electromagnetic radiation occurring in electric motors because the portion of the noise signal centered around the minimum value of the noise signal in the frequency domain containing the basic noise signal is wider in the frequency domain than the operating bandwidth of the electromagnetic wave receiving device of interest. Therefore, if the modulation signal is appropriately adjusted, the remote state switching modulation algorithm can be advantageously used to ensure that the entire operating bandwidth can be located within the portion of the signal noise.

[0029] In some embodiments, the noise signal at least partially includes a shape in the frequency domain that is similar to a sin(x) / x waveform (also known as a sinc function). Here, x corresponds to the first and / or second dead time. In this regard, the noise signal is described in the frequency domain with respect to its shape. At least above a certain threshold frequency, for example, above about 100kHz, more preferably above 400kHz, the shape of the noise signal can be similar to a specified function. In other words, a rectangular pulse in the time domain, for example due to the use of a PWM algorithm, produces a functional waveform as described above in the frequency domain. It is worth noting that the minimum value (notch) of such a function is only related to the width of the rectangular pulse in the time domain. To this end, by adapting the first and / or second dead time caused by the modulation signal, the minimum value of the noise signal can be shifted in the frequency domain so that at least one minimum value is consistent with the operating bandwidth as described above.

[0030] Preferably, the operating bandwidth of the electromagnetic wave receiving device is in the kHz or MHz range. These frequency ranges are typical for receiving devices included in, for example, a radio device. Such a radio device is part of a vehicle, which itself also includes an inverter and a motor. Based on the above method, the signal-to-noise ratio of such a radio device can be improved. Therefore, the comfort of the user is improved.

[0031] Optionally, the control device is further configured to execute the method as described above.

[0032] In some embodiments, the method as described above may be specifically performed in a computer-implemented manner.

[0033] According to another aspect, there is also provided a computer program product comprising instructions, which, when executed by a data processing device, cause the data processing device to perform the method as described above. The data processing circuit may be, for example, part of a control device of an inverter.

[0034] Furthermore, according to another aspect, a data storage medium comprising the computer program product as described above is also provided, so that when executed by a data processing device, it causes the data processing device to perform the method as described above.

[0035] According to another aspect, there is also provided an inverter for an electric motor, comprising the control device as described above.

[0036] According to yet another aspect, there is also provided an assembly comprising an electric motor as described above and an inverter. The assembly can be used, for example, in a vehicle or in different devices. Essentially, the assembly can be used in all devices that require or include some motorized mechanism.

[0037] According to yet another aspect, there is also provided a vehicle comprising the assembly as described above.

[0038] All features and embodiments disclosed with respect to any aspect of the present disclosure may be combined alone or in combination (sub-combination) with any remaining aspect of the present disclosure (including each preferred embodiment thereof), as long as the resulting combination of features is reasonable to a person skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The foregoing aspects and further advantages of the claimed subject matter will become more readily understood and better appreciated when reference is made to the following detailed description in conjunction with the accompanying drawings.

[0040] - Figure 1 is a schematic diagram of an assembly including a control device, an inverter and an electric motor according to an embodiment of the present invention,

[0041] - Figure 2 is a schematic diagram of a vehicle including an assembly having an inverter for an electric motor, an electric motor, and an electromagnetic wave receiving device according to an embodiment of the present invention,

[0042] - Figure 3 is a schematic diagram of a method for operating an inverter for an electric motor according to an embodiment of the present invention,

[0043] - Figure 4 is an equivalent electrical schematic describing the stray capacitance in an electric motor, and

[0044] - Figure 5 is a schematic diagram of a noise signal in the frequency domain. DETAILED DESCRIPTION

[0045] The detailed description set forth below in conjunction with the accompanying drawings, in which the same numerals refer to the same elements, is intended to be a description of various embodiments of the disclosed subject matter, and is not intended to represent the only embodiment. Each embodiment described in the present disclosure is provided only as an example or explanation, and should not be interpreted as being superior to or better than other embodiments. The illustrative examples provided herein are not intended to be exhaustive or limit the claimed subject matter to the disclosed precise form. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments. Therefore, the described embodiments are not limited to the embodiments shown, but conform to the widest range consistent with the principles and features disclosed herein.

[0046] All features disclosed below with respect to the exemplary embodiments and / or figures may be combined with features of various aspects of the present disclosure, including features of its preferred embodiments, alone or in any subcombination, as long as the resulting feature combination is reasonable for a person skilled in the art.

[0047] For purposes of this disclosure, for example, the phrase "at least one of A, B, and C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when more than three elements are listed. In other words, the term "at least one of A and B" generally refers to "A and / or B," i.e., "A" alone, "B" alone, or "A and B."

[0048] Figure 1 is a schematic diagram of an inverter 10 for a device, such as an electric motor 12 in the embodiment shown.

[0049] In the illustrated embodiment, the inverter 10 comprises a B6 bridge 14 having three switching arms 16. The following functionality is illustrated for only one switching arm 16, but will apply to all switching arms 16 of the B6 bridge 14 accordingly.

[0050] Each switching leg 16 includes a first power switch 18 serving as a high-side power switch and a second power switch 20 serving as a low-side power switch.

[0051] Each power switch 18, 20 of the switching arm 16 is preferably a controllable semiconductor switch, for example a switch based on a transistor such as a field effect transistor. As an alternative, the power switches 18, 20 of the switching arm 16 may be metal oxide semiconductor field effect transistors (MOSFETs), for example based on silicon (SI-MOSFET) or silicon carbide (SiC-MOSFET), or insulated gate bipolar transistors (IGBTs) or even gallium nitride field effect transistors (GaN FETs).

[0052] Between the first power switch 18 and the second power switch 20 , each switching leg 16 includes a central node 22 for providing an AC signal, in this case L2 , to the electric motor 12 .

[0053] The three corresponding AC signals L1 , L2 and L3 are applied to the electric motor 12 via the three switching arms 16. However, other topologies are also possible, such as a six-phase electric motor, which would require corresponding modifications of the inverter 10.

[0054] The respective switching arms 16 are coupled to a busbar structure 24 of the inverter 10. The inverter 10 is coupled to a DC power source 26. The DC power source 26 comprises connection terminals 28, 30 between which a high voltage HV is provided, being a voltage greater than 100V.

[0055] Thus, during operation, between opposite nodes of the busbar structure 24 , a DC link voltage 33 is applied.

[0056] Furthermore, the inverter 10 includes a DC link capacitor 34 , which serves as a smoothing element between the DC power source 26 and the electric motor 12 .

[0057] In order to control the switching states of the power switches 18 , 20 , the inverter 10 includes (or is coupled to) a control device 36 , which includes at least one data processing circuit 38 .

[0058] The control device 36 is configured to provide corresponding gate signals G1, G2 as switching signals for the power switches 18, 20, thereby influencing the switching position of the power switches 18, 20 based on these signals. The gate signals G1, G2 depend on a modulation signal 40 determined by the data processing circuit 38.

[0059] The control device 36 is configured to apply the modulation signal 40 to alternately place the switching arm 16 in a high configuration, in which the high side power switch 18 is closed and the low side power switch 20 is open, and a low configuration, in which the high side power switch 18 is open and the low side power switch 20 is closed.

[0060] In order to prevent the high voltage short circuit between the terminals 28, 30, the two power switches 18, 20 of the switch arm 16 cannot be turned on at the same time at any time. Therefore, the modulation signal 40 is designed so that the first dead time between the opening of the high-side power switch and the closing of the low-side power switch and the second dead time between the opening of the low-side power switch and the closing of the high-side power switch are used to ensure that the two power switches 18, 20 are not turned on at the same time.

[0061] The control device 36 is also typically connected to other components of the circuit, such as the electric motor 12 or the DC power supply 26 or corresponding sensors. The control device 36 can then output corresponding gate signals G1, G2, for example, depending on the relative position of the rotor of the electric motor 12 relative to the stator of the electric motor 12, so that as a result, the windings of the electric motor 12 are controlled as required.

[0062] In the illustrated embodiment, the control device 36 is also coupled directly or via a communication network to an electromagnetic wave receiving device 42. The electromagnetic wave receiving device 42 includes an antenna element 44 by which electromagnetic waves can be received if the electromagnetic waves match an operating bandwidth 46 of the electromagnetic wave receiving device 42 in the frequency domain.

[0063] Figure 2 is a schematic diagram of a vehicle 48 including an assembly 50 having an inverter 10 for an electric motor 12 and an electromagnetic wave receiving device 42 .

[0064] The vehicle 48 includes front axle wheels 52 and rear axle wheels 54. The front axle wheels 52 are driven by the shaft of the motor 12 of the assembly 50. The motor 12 is supplied with current using the inverter 10 of the assembly 50. As shown, the inverter 10 is coupled to the magnetic wave receiving device 42, which may be part of the radio equipment of the vehicle 48.

[0065] Although the assembly 50 is described here as being used in a vehicle 48, the assembly 50 is not limited thereto. Other applications of the assembly 50 are also within the scope of the present invention. For example, the assembly 50 can be used in a windmill.

[0066] Additionally, the vehicle 48 may also include a second component for driving rear axle wheels 54 .

[0067] Figure 3 is a schematic diagram of a method 56 of operating an inverter 10 for an electric motor 12. Optional steps are represented by dashed lines.

[0068] In step 58, the modulation signal 40 is adjusted from the first modulation sequence to the second modulation sequence so that the minimum amplitude of the noise signal is consistent with the operating bandwidth of the electromagnetic wave receiving device 42. The first modulation sequence is different from the second modulation sequence.

[0069] This means that, although the first modulation sequence defines the first sequence of gate signal portions G1, G2 according to a predefined manner, the sequence is changed to a second modulation sequence so that the noise signal is appropriately shifted in the frequency domain. In particular, the noise signal is shifted so that the operating bandwidth of the electromagnetic wave receiving device coincides with the minimum amplitude of the noise signal.

[0070] In order to adjust the modulation signal 40 , the signal part of the modulation signal 40 can be changed, so that, for example, the resulting first dead time and / or the resulting second dead time are adapted.

[0071] Here, the control device 36 applies a PWM algorithm to create the modulation signal 40. In particular, a remote state switching modulation algorithm is applied in this respect. However, other PWM algorithms can also be used.

[0072] In optional step 60, the control device 36 receives a notification signal indicating the operating bandwidth of the electromagnetic wave receiving device 42 before step 58. This provides the possibility of customizing the noise signal by appropriately adjusting the modulation signal 40 according to the corresponding needs based on the corresponding operating bandwidth of the electromagnetic wave receiving device 42. In addition, it is conceivable that the operating bandwidth of the electromagnetic wave receiving device 42 can be changed from the first frequency range to the second frequency range. Then, the modulation signal 40 can be repeatedly adjusted.

[0073] Furthermore, for electric motors there are several stray capacitances, namely:

[0074] Cwr between stator winding and rotor,

[0075] Cwf between one stator winding and the housing of the motor,

[0076] Crf between the motor’s rotor and housing, and

[0077] Due to Cb of each roller bearing between the housing and the rotor,

[0078] This led to Figure 4 The equivalent circuit diagram is shown.

[0079] Due to these stray capacitances, a common mode voltage is generated and the shaft of the motor 12 radiates at its drive end, thereby generating electromagnetic interference, ie, noise signal 66 .

[0080] Figure 5 FIG64 is a simulation of an example of a noise signal 66 in the frequency domain (i.e., after applying a Fourier transform to transform the noise signal from the time domain to the frequency domain) when a remote state switching modulation algorithm in which the first dead time and the second dead time are set to the same value is applied by the control device 36 to create the modulation signal 40. In this figure, two representations of the noise signal 66 are shown, each corresponding to a different electromagnetic interference detector. However, it must be emphasized that the general characteristics of the noise signal 66 are the same.

[0081] Due to the influence of the first and second dead times in the modulator, the switching operations of the various switching arms are not completely synchronized with each other. As a result, periodically repeated high-frequency voltage pulses Vb having the first and second dead time widths appear between the terminals of the Cb stray capacitance. The resulting noise signal 66 in the frequency domain above a certain threshold frequency 68 (e.g., about 400kHz) shows a shape similar to a sin(x) / (x) function, where x represents the value of the first dead time and the second dead time of the modulation signal 40. Therefore, the noise signal 66 shows a sequence of multiple minimum values ​​70, where different minimum values ​​70 correspond to different orders of the specified function. By adjusting the modulation signal 40, for example, by adapting the first and second dead times, the minimum value 70 can be shifted in the frequency domain. Therefore, by appropriately adjusting the modulation signal 40, at least one minimum value 70 can be located so that a portion of the noise signal centered on the at least one minimum value 70 in the frequency domain contains the operating bandwidth of the electromagnetic wave receiving device 42. Therefore, a mechanism is established for directly and actively minimizing the noise signal amplitude in the frequency domain within the operating bandwidth of the electromagnetic wave receiving device 42, thereby improving its performance.

[0082] Certain embodiments disclosed herein, in particular various modules, utilize circuits (e.g., one or more circuits) to implement the standards, protocols, methods, or techniques disclosed herein, operably connect two or more components, generate information, process information, analyze information, generate signals, encode / decode signals, convert signals, send and / or receive signals, control other devices, etc. Any type of circuit may be used.

[0083] In one embodiment, the circuit includes, among other things, one or more computing devices, such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SoC), etc., or any combination thereof, and may include discrete digital or analog circuit elements or electronic devices, or a combination thereof. In one embodiment, the circuit includes a hardware circuit implementation (e.g., an analog circuit implementation, a digital circuit implementation, etc., and a combination thereof).

[0084] In one embodiment, the circuit includes a combination of circuits and a computer program product having software or firmware instructions stored on one or more computer readable memories that work together to cause the device to perform one or more protocols, methods, or techniques described herein. In one embodiment, the circuit includes circuits that require software, firmware, etc. to operate, such as a microprocessor or portion of a microprocessor. In one embodiment, the circuit includes one or more processors or portions thereof and accompanying software, firmware, hardware, etc.

[0085] The present application may quote quantities and numbers. Unless otherwise specified, these quantities and numbers should not be considered as limiting, but examples of possible quantities or numbers related to the present application. Also in this regard, the present application may use the term "plurality" to refer to quantities or numbers. In this regard, the term "plurality" refers to any number greater than 1, such as 2, 3, 4, 5, etc. The terms "approximately", "approximately", "close to", etc. represent plus or minus 5% of the value.

[0086] Although the present disclosure has been shown and described with respect to one or more embodiments, equivalent changes and modifications will occur to other skilled persons in the art after reading and understanding this specification and the accompanying drawings. In addition, although a particular feature of the present disclosure may be disclosed for only one of several embodiments, such a feature may be combined with one or more other features of other embodiments, which may be desirable and advantageous for any given or specific application.

Claims

1. A method (56) of operating an inverter (10) for an electric motor (12), the inverter (10) comprising at least one switching arm (16) comprising a high-side power switch (18) and a low-side power switch (20) connected to a central node for providing an AC signal to the electric motor (12), and a control device (36) configured to apply a modulation signal (40) that alternately places the switching arm in a high configuration, in which the high-side power switch is closed and the low-side power switch is open, and in a low configuration, in which the high-side power switch is open and the low-side power switch is closed, wherein interference is induced during operation of the inverter (10) resulting in a noise signal (66), the method (56) comprising at least the following steps: The modulation signal (40) is adjusted from a first modulation sequence to a second modulation sequence so that the amplitude minimum value of the noise signal (66) in the frequency domain is located within the operating bandwidth of the electromagnetic wave receiving device (42), and the first modulation sequence is different from the second modulation sequence.

2. The method (56) of claim 1, wherein: The modulation signal (40) is adjusted to adapt a first dead time between the opening of the high-side power switch and the closing of the low-side power switch and / or a second dead time between the opening of the low-side power switch and the closing of the high-side power switch caused by the modulation signal (40).

3. The method (56) according to claim 1 or 2, wherein: Before adjusting the modulation signal (40), the control device (36) receives a notification signal indicating an operating bandwidth of the electromagnetic wave receiving device (42).

4. The method (56) according to any one of the preceding claims, wherein: The modulation signal (40) is adjusted so that the minimum value of the noise signal (66) in the frequency domain is included in the operating bandwidth of the electromagnetic wave receiving device (42).

5. The method (56) of claim 4, wherein: The modulation signal is adjusted so that a portion of the noise signal centered around a minimum value of the noise signal in the frequency domain includes an operating bandwidth of the electromagnetic wave receiving device.

6. The method (56) according to any one of the preceding claims, wherein: The modulation signal (40) is based on a pulse width modulation algorithm.

7. The method (56) according to any one of the preceding claims, wherein: The modulation signal (40) is based on a remote state switching modulation algorithm.

8. The method (56) according to any one of the preceding claims, wherein: The noise signal (66) comprises a partial sin(x) / x waveform in the frequency domain, and wherein x corresponds to the first dead time and / or the second dead time.

9. The method (56) according to any one of the preceding claims, wherein: The operating bandwidth of the electromagnetic wave receiving device (42) is in the kHz or MHz range.

10. The method (56) according to any one of the preceding claims, wherein: The noise signal is generated by the voltage variation between the terminals of at least one of the following stray capacitances: The capacitance between the stator winding and the rotor of the motor (Cwr), The capacitance between the stator winding and the housing of the motor (Cwf), The capacitance between the motor’s rotor and housing (Crf), and Capacitance (Cb) for the roller bearing between the housing and the rotor.

11. A control device (36) for an inverter (10) for an electric motor (12), the control device (36) comprising a data processing circuit (38), the inverter (10) comprising at least one switching arm (16), the switching arm comprising a high-side power switch (18) and a low-side power switch (20) connected to a central node for providing an AC signal to the electric motor (12), the control device (36) being configured to: applying a modulation signal (40) that alternately places the switch arms in a high configuration, in which the high-side power switch is closed and the low-side power switch is open, and a low configuration, in which the high-side power switch is open and the low-side power switch is closed, wherein interference is caused during operation of the inverter (10), resulting in a noise signal (66), The modulation signal (40) is adjusted from a first modulation sequence to a second modulation sequence so that the amplitude minimum value of the noise signal (66) in the frequency domain is located within the operating bandwidth of the electromagnetic wave receiving device (42), and the first modulation sequence is different from the second modulation sequence.

12. The control device (36) according to claim 11, wherein: The modulation signal (40) is adjusted to adapt a first dead time between the opening of the high-side power switch and the closing of the low-side power switch and / or a second dead time between the opening of the low-side power switch and the closing of the high-side power switch caused by the modulation signal (40).

13. The control device (36) according to claim 11 or 12, wherein: The control device (36) is further configured to receive a notification signal indicating an operating bandwidth of the electromagnetic wave receiving device (42) before adjusting the modulation signal.

14. The control device (36) according to any one of claims 11 to 13, wherein: The control device (36) is configured to adjust the modulation signal (40) so that a minimum value of the noise signal (66) in the frequency domain is included in an operation bandwidth of the electromagnetic wave receiving device (42).

15. The control device (36) according to any one of claims 11 to 14, wherein: The control device (36) is further configured to perform a method (56) according to any one of claims 1 to 9.

16. An inverter (10) for an electric motor (12), comprising a control device (36) according to any one of claims 11 to 15.

17. An assembly (50) comprising an electric motor (12) and an inverter (10) according to claim 16 assigned thereto.

18. A vehicle (48) comprising an assembly (50) according to claim 17.

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