A motor system having a switched motor

Abstract

The invention relates to an electric machine system having an electric machine and a switching device for exciting the electric machine, wherein the electric machine system comprises at least one disturbing vibration (1) having a corresponding disturbing frequency (f E ). The switching device can excite the electric machine at a switching time point (4) which depends on an adjustable switching frequency (f S ), wherein the switching frequency (f S ) of the switching device is adjusted in accordance with the power requirements to be achieved by the electric machine. The time point (4) of the switching device is also adjusted in accordance with at least one disturbing frequency (f E ) of the electric machine system.

Description

TECHNICAL FIELD

[0001] The invention relates to an electric machine system. The electric machine system has a switching electric machine and a switching device for exciting the electric machine. The electric machine system further comprises at least one disturbing vibration having a corresponding disturbing frequency, wherein the switching device can excite the electric machine at switching time points, which are dependent on an adjustable switching frequency. The switching frequency of the switching device is adjusted in accordance with a power requirement to be fulfilled by the electric machine. BACKGROUND

[0002] Electric machines of the above-mentioned type can be used both as electric motors, in particular reluctance electric machines, and as internal combustion engines. The excitation of the electric machines, in particular, takes place in batches at switching time points. Here, the switching time points are usually time-spaced on a switching frequency, wherein the switching frequency is dependent on the power requirement of the electric machine or the power requirement imposed on the electric machine. Usually, the switching time points are adapted here only to the switching frequency and the power requirement imposed on the electric machine, so that the electric machine is excited in accordance with the power.

[0003] The invention relates in particular to electric machine systems, which are used in the field of domestic technology, for example for stationary, hand-held or autonomous kitchen devices or cleaning devices, for example vacuum cleaners.

[0004] In these electric machine systems, disturbing vibrations often occur. At least one vibration is in particular a self-vibration of the electric machine. In addition, disturbing vibrations having a disturbing frequency can also be transmitted to the electric machine from external sources. Such externally generated vibrations are in particular from a second electric machine system, for example an autonomous vacuum cleaner (vacuum cleaner robot) has more than one electric machine for vacuuming and moving, or a device with a refrigeration device, for example a cooling fan. The disturbing vibrations in particular cause an increased material load and a greater noise emission, which should be avoided, as they can affect the service life and the comfort of use.

[0005] In order to reduce the noise emission and the material load, there are many strategies in the prior art for reducing the noise of electric machines. They are mainly passive and active solutions. Passive solutions are mainly vibration damper elements. Active solutions in particular include active counter-sound measures, for example "active noise cancellation" (ANC) measures.

[0006] Passive solutions have the disadvantage that they have high requirements for installation space and in particular limit the operation and use of the electric machine system. Active solutions also have the disadvantage that they are very expensive, require additional installation space and often also additional sensors. SUMMARY

[0007] It is the task of the invention to improve electric machine systems of the known type in such a way that they have a long service life and a high comfort of use, in particular by reducing the noise emission and the material load.

[0008] According to the application, this task is solved by the features of claim 1. By adjusting the switching point in time of the switching device in accordance with at least one disturbance frequency of the electric machine system, it is advantageously possible to influence the disturbance vibrations in the electric machine system systematically using the switching point in time or the electric machine excitation. In particular, the switching point in time can be slightly offset from the power-dependent switching frequency, such that the switching point in time is adapted to at least one disturbance frequency, in particular to at least the own frequency of the electric machine. Preferably, the achieved electric machine power is not influenced or is only slightly influenced, in particular to the extent that is not relevant for the respective use of the electric machine system. A particularly advantageous compromise between quiet operation, noise emission, material loading and power is thereby achieved.

[0009] It is known that the disturbance vibrations within an electric machine system are influenced as soon as the electric machine is excited by the switching device. The influence corresponds to an amplitude excitation of the disturbance vibrations and is measurable on the electric machine system. Measurements on the electric machine system show that the excitation of the disturbance vibrations is sometimes not, weakly or particularly strong; the switching point in time in the electric machine system is adjusted only in dependence on the power, i.e. in the switching frequency, and independently of the disturbance frequencies of the electric machine. The reason for this is that the electric machine is excited in the same direction at each excitation. If the disturbance vibrations vibrate in the same direction as the excitation at the switching point in time, a beneficial vibration interference occurs, in the opposite case a negative vibration interference. Correspondingly, the disturbance vibrations are either intensified or weakened at the excitation.

[0010] The disturbance vibrations are in particular the own vibrations of the electric machine. The own vibrations are in particular started by the first excitation of the electric machine by the switching device. Since the electric machine preferably vibrates at its own frequency, in this case the type of interference is in particular determined by the switching point in time or the switching point in time of the respective excitation.

[0011] A beneficial interference occurs and the amplitude of the disturbance vibrations is significantly increased as soon as the switching point in time is an integer multiple of the disturbance frequency of the electric machine system. In the opposite case, when the switching point in time is a half-integer multiple of the disturbance frequency, a negative interference occurs and the amplitude of the disturbance vibrations is significantly reduced.

[0012] According to the application, therefore, the switching point in time is adjusted not only in dependence on the power-related switching frequency of the motor system, but also in dependence on the disturbance frequency of the motor system, so that the power requirements imposed on the motor are substantially met. The disturbance vibrations can be both self-vibrations of the motor and also external vibrations. In motor systems, in particular, a plurality of disturbance vibrations occur, for example both self-vibrations of the motor and also vibrations generated by a second motor system, which are transmitted to the motor of the first motor system. In this case, the switching point in time can advantageously be optimized for the specific disturbance vibration. Furthermore, in the case of a plurality of disturbance vibrations, the switching point in time can be coordinated with each disturbance vibration in a compromise, in such a way that only the release region over time or the release point for a defined time interval allows the switching point in time or the excitation.

[0013] In an advantageous embodiment of the application, the switching device has a time measuring device. The time measuring device, in particular, starts a time measurement at each switching point in time and compares the measured time with the time points which are an integer multiple and / or a half-integer multiple of the at least one disturbance frequency.

[0014] In particular, when the at least one disturbance frequency is known, the current phase information of the respective disturbance vibration can be determined by means of the time measurement. The switching point in time can thus be adapted to the disturbance frequency in dependence on the determined phase information. This embodiment is particularly advantageous if the disturbance vibration to be influenced is a self-vibration of the motor, since the self-vibration of the motor starts with the first excitation of the motor.

[0015] The time measuring device is here either present in the motor system already available and can easily be adapted to the requirements of the motor system according to the application, or it can advantageously be installed in the motor system already present or to be completed without major constructive changes.

[0016] In particular, the disturbance vibration can also be determined in such a way that the switching device has a vibration measuring device which detects the current disturbance vibration and determines its current disturbance frequency and / or amplitude and / or phase information. This vibration measuring device is particularly advantageous in the case of vibrations which are transmitted to the motor from an external source and for which the phase information can thus be determined non-mathematically or by means of time measurement.

[0017] The self-frequency of the motor is in particular generated by the mechanical construction and is substantially the same for all motors of a series-produced machine type. If relevant deviations occur in a series, the self-frequency can also be determined once in production. This is then determined, for example, by simple mechanical excitation according to the principle of the tuning fork case.

[0018] The electric machine of the electric machine system is in particular a switched electric machine, in particular a reluctance electric machine. Advantageously, in order to excite the electric machine, a current is injected into the electric machine at an adjusted switching point in time. The electric machine has in particular advantages for the electric machine system according to the invention, because it has a fast and stable excitation behavior and thus can easily be coordinated or determined with the own frequency of the electric machine.

[0019] In a further advantageous embodiment of the electric machine system, the electric machine is an internal combustion engine and the switching point in time is a firing point in time of the internal combustion engine. Here, the firing point in time is advantageously aligned by an adjustable firing angle of the internal combustion engine. The internal combustion engine has the advantage in practice that the effect achieved by the embodiment of the invention is stronger. The internal combustion engine, for example, has in particular more oscillating mass than an electric machine, so that the oscillation amplitudes of the internal combustion engine are in general also greater than in comparable electric machines. BRIEF DESCRIPTION OF DRAWINGS

[0020] Further advantageous aspects of the invention result from the following description of the drawings and the associated dependent claims.

[0021] It is shown that:

[0022] Figure 1 The relationship between the switching frequency of the switching device and the own oscillation of the electric machine in the electric machine system is shown exemplarily.

[0023] In the different figures of the drawing pages, the same parts are always identified by the same reference signs. DETAILED DESCRIPTION

[0024] The following description requires that the invention is not limited to the embodiments and not limited to all or several features of the described feature combinations; rather, each individual sub-feature of the described / each embodiment can also be of essential significance for the subject matter of the invention itself, detached from all other associated described sub-features and in combination with any feature of another embodiment.

[0025] Figure 1 The relationship between the switching frequency of the switching device and the own oscillation of the electric machine in the electric machine system is shown. The electric machine system has an electric machine and a switching device for exciting the electric machine. The electric machine further comprises at least one oscillating disturbance 1 with an oscillation duration t E and an interference frequency f E . The interference frequency f E corresponds in particular to the reciprocal value 1 / t E of the oscillation duration t Figure 1 In the shown embodiment, the electric machine system has an oscillating disturbance 1, which corresponds to the own frequency of the electric machine.

[0026] The motor system vibrates with disturbance vibration 1, wherein the amplitude 3 of disturbance vibration 1 should preferably be kept low due to the noise generated by it and the material load.

[0027] The switching device can excite the motor in the motor system at switching time point 4, and the switching time point depends on the switching frequency f. S Adjustable vibration duration t E The switching frequency f S According to the frequency formula, the reciprocal of the vibration duration is 1 / t. S Especially, as in Figure 1 As shown, when the motor is excited, interference occurs between the excitation and the interference vibration 1 or the motor's own frequency.

[0028] According to the present invention, it is also based on the interference frequency f E Adjust the switching time of the switching device 4. Figure 1 This example illustrates possible design factors, based on which the standard switching time point 4 can be set to the interference frequency f. E Or the inherent frequency of the motor system, and how the switching time point 4 accordingly acts on the interference vibration 1 of the motor system, especially the amplitude 3 of the interference vibration 1.

[0029] Particularly advantageously, through embodiments of the invention, the switching time point 4 can be time-dependent on the switching frequency f. S Phase differentiation and based on at least one interference frequency f of the motor system E The adjustments were made to ensure that the power requirements for the motor remained essentially unchanged. The switching frequency f... S This is related to the power requirements to be achieved by the motor. At this switching time point 4, the corresponding disturbance vibration 1 of the motor system is also advantageously affected. The effect of at least one disturbance vibration 1 of the motor system can be used here to beneficially enhance or negatively reduce the corresponding amplitude 3 of the disturbance vibration 1 of the motor system.

[0030] for Figure 1 In an alternative embodiment, at least one interfering vibration 1 may be transmitted to the motor additionally or solely through external vibration. In this case, it is preferable to transmit the vibration according to the respective interfering frequency f. E At least one interfering vibration 1. Adjust the switching time point 4. In Figure 1 The example shown does not depict disturbance vibrations caused by external influences 1.

[0031] In a particular embodiment of the invention, the switching device has a frequency memory. To achieve the desired result, one or more interference frequencies f are stored in the frequency memory. E. In particular, at least one vibration curve of the disturbing vibration 1 is known in the electric machine system, so that a real-time measurement of the respective disturbing vibration 1 is not necessary. Thereby, the power requirements to be achieved by the electric machine, i.e. the switching frequency 1 / tS and the at least one disturbing frequency f E The switching time points 4 are adjusted or determined in time.

[0032] One possible disturbing frequency f E , in particular the own frequency of the electric machine, is generated in particular by the mechanical construction and is essentially the same for all electric machines or devices of a series. Thus, the own frequency of the electric machine can be determined once for a series of devices or alternatively for each device and / or each device type. In this regard, the own frequency can be determined, for example, according to the tuning fork principle by simple mechanical excitation.

[0033] In a particular embodiment of the electric machine system, the switching device has a time measuring device. The time measuring device, in particular, starts a time measurement at each switching time point 4. It is purposeful to compare the measured time and the time points which are an integer multiple of and / or a half-integer multiple of the at least one disturbing frequency f E by the time measuring device.

[0034] In particular, amplitude maxima of the respective disturbing vibration 1 occur at integer multiples of the disturbing frequency f E , wherein amplitude minima of the respective disturbing vibration 1 occur at half-integer multiples of the disturbing frequency f E .

[0035] In particular, when the at least one disturbing frequency f E is known and there is at least one phase information relating to it, the current phase information can be determined by the time measuring device. This embodiment is in particular advantageous if the at least one disturbing frequency f E is the own vibration of the electric machine, since the electric machine starts to vibrate with its own frequency for the first time.

[0036] The time measuring device is here in particular either present in the already available electric machine system and can easily be adapted to the requirements of the electric machine system according to the invention, or it can advantageously be installed in the already existing or to be completed electric machine system without large constructive changes.

[0037] In an advantageous embodiment of the invention, the switching time points 4 are adjusted in such a way that the switching device compares the at least one disturbing frequency f E and the switching frequency f S and determines the switching time points 4 in dependence on the relationship of the respective disturbing frequency f E and the switching frequency f S and / or the respective disturbing frequency f EThe phase information is adjusted.

[0038] In particular, when it is not possible to mathematically determine phase information and / or interference frequency f through time measurements and other means... E When the amplitude 3 of the interfering vibration 1 is disturbed, an advantageous embodiment of the invention is provided herein, wherein the switching device has a vibration measuring device. Accordingly, the vibration measuring device detects the current interfering vibration 1 and determines its current interfering frequency f. E And / or amplitude 3 and / or phase information.

[0039] exist Figure 1 In the diagram, the T-axis shows the time curve, and the A-axis shows the degree of excitation 6 of the disturbance vibration 1 of the motor system. Figure 1 It can be seen that the interference frequency f E Or its own frequency and switching frequency f S There is no mutual phase shift because the excitation 6 determines the curve of the disturbance vibration 1 or the motor's own vibration through the switching time point 4.

[0040] Based on the existing conditions and the power requirements of the motor, a switching time point of 4 should be adopted. This leads to different advantageous application scenarios and design schemes for the motor system. Here, the switching time point 4 should be positioned as close as possible to the power-dependent switching frequency f. S This achieves an optimal trade-off between increased power, material load, quiet operation, and comfort.

[0041] Especially in Figure 1 As shown in paragraphs 2.8 and 3.9, the switching time point 4 is adjusted in such a way that it is not equal to the interference frequency f. E The motor is excited by an integer multiple of or its own frequency. In particular, the switching device delays the next switching time point 4 to a value not equal to the corresponding interference frequency f. E The time point is an integer multiple of the corresponding switching time point, or the corresponding next switching time point 4 is advanced to a time not equal to the corresponding interference frequency f. E The time points that are integer multiples of each other.

[0042] This design effectively reduces the maximum peak amplitude of the corresponding disturbance vibration 1 in the motor system. This minimum requirement can also be expressed as the minimum amplitude at one or more disturbance frequencies f. E Motor excitation is prohibited when the frequency is an integer multiple of the interference frequency f. This is especially true at the corresponding interference frequency f. E This embodiment is used when the excitation cannot be directly adjusted at time points that are half-integer multiples of the motor system. This is especially true when the power loss will be less than the power required by the motor system. When the corresponding interference frequency f E Below the switching frequency f SThis embodiment is particularly useful when the value is 150%. When the number of interfering vibrations 1 and their corresponding interfering frequency f... E It is impossible to directly excite the selected interference frequency f E When the excitation is an integer multiple of 1, and other disturbing vibrations are not amplified beyond the permissible range by the excitation, this embodiment is also used to produce an advantageous compromise.

[0043] Especially when the corresponding interference frequency f of the motor system E and the required switching frequency f for power requirements S When they are of the same order of magnitude, it is preferable to follow the order of magnitude. Figure 1 The third segment 9 shows the advance switching time point 4. The third segment 9 illustrates the interference frequency f of the motor system. E What is the effect of switching time point 4, which is a half-integer multiple of the time, on the disturbance vibration 1 of the motor system? Although advancing the switching time point 4 cannot eliminate the beneficial excitation 6 to the amplitude 3 of the corresponding disturbance vibration 1, it has a certain effect on the disturbance vibration 1. Figure 1 Compared to the situation shown in the first paragraph 7, this would result in favorable suppression. Figure 1 The first paragraph 7 shows that when the switching time point 4 is at the corresponding interference frequency f E When the excitation is an integer multiple of the excitation, what effect does the excitation 6 have on the disturbance vibration 1?

[0044] Particularly advantageous is that when the switching time point 4 is adjusted in this way, it is only at the interference frequency f E When the motor is excited by a half-integer multiple or the motor's own frequency, at least one negative excitation 6 of the disturbance vibration 1 can be applied, such as... Figure 1 As shown in section 8 of the second paragraph. When the motor's interference frequency f E Comparison of switching frequency f S When the frequency is much higher, preferably when the interference frequency f of the motor is much higher. E It is the switching frequency f S This design is particularly possible when the frequency is at least twice that of the interference frequency. Preferably, the switching device delays the next switching time point 4 to the corresponding interference frequency f. E The time points that are half-integer multiples of the following time.

[0045] In a suitable embodiment of the invention, the switching device delays the corresponding next switching time point 4 to the corresponding interference frequency f. E The most recent half-integer multiple of the time point or the corresponding next switching time point 4 is advanced to the most recent half-integer multiple of the time point. When the interference frequency is at the switching frequency f S In particular, when using this embodiment, the switching time point 4 is adjusted to the nearest half-integer multiple within the range of 150% to 200%. This allows for an advantageous shift of the switching time point from the power-dependent switching frequency f. Sto the next minimum of the amplitude of the corresponding disturbing vibration 1, whereby the corresponding disturbing vibration 1 is advantageously suppressed and at the same time the power loss is kept low compared to the switching point in time 4 S .

[0046] Especially when the shifting of the switching point in time as described above leads to a power loss, which influences the corresponding power requirement of the electric machine beyond the permissible range, in an alternative embodiment the switching device can delay or advance the corresponding next switching point in time 4 to a point in time which is a half-integer multiple of the next harmonic of the corresponding disturbing frequency f E .

[0047] The electric machine of the electric machine system is especially a switched electric machine. Figure 1 The application is shown in a particularly preferred embodiment, according to which the electric machine is a reluctance electric machine. Advantageously, in order to excite the electric machine, a current is injected into the electric machine at the adjusted switching point in time 4. In order to facilitate the observation, the injected current is depicted in Figure 1 by the mechanical response of the electric machine system, namely the disturbing vibration 1, especially the self-vibration of the electric machine.

[0048] The electric machine has particular advantages for the electric machine system of the application, because it has a fast and stable excitation behavior and thus can easily be coordinated with the switching frequency f S and the disturbing frequency f E of the electric machine system.

[0049] In a further advantageous embodiment of the electric machine system, the electric machine is an internal combustion engine and the switching point in time is the ignition point in time of the internal combustion engine. Here, the ignition point in time is advantageously adjusted and aligned by an adjustable ignition angle of the internal combustion engine. The internal combustion engine, for example, has more oscillating mass than the electric machine, so that the amplitude 3 of the disturbing vibration 1 of the internal combustion engine is generally also greater than in comparable electric machines. The effect of the switching point in time 4 is thus also greater in the internal combustion engine, which is specifically coordinated with the disturbing vibration 1 of the electric machine system.

[0050] The application is not limited to the embodiments shown and described, but includes all embodiments which have the same effect in the sense of the application. It is expressly emphasized that the embodiments are not limited to the combination of all features; rather, each individual sub-feature can also have inventive significance in itself, detached from all other sub-features. Furthermore, the application is also not limited to the combination of features defined in claims 1 and 8, but can also be defined by any other combination of certain features of all the individual features disclosed. This means that in principle each individual feature of claims 1 and 8 can be omitted or replaced by at least one individual feature disclosed elsewhere in this application.

Claims

1. An electric machine system having an electric machine and a switching device for exciting the electric machine, wherein the electric machine system comprises at least one disturbing vibration (1) having a corresponding disturbing frequency (f E ), wherein the switching device excites the electric machine at a switching time point (4) which depends on an adjustable switching frequency (f S ), wherein the switching frequency (f S ) of the switching device is adjusted in accordance with a power requirement to be achieved by the electric machine. characterized in that The time point (4) of the switching device is also adjusted in accordance with at least one disturbance frequency (f E ) of the electric machine system, wherein the switching device has a time measuring device which starts a time measurement at each switching time point (4) and compares the time measured by the time measuring device with the time points of the amplitude maxima which are integer multiples of the time of the disturbance frequency (f E ) or the amplitude minima which are half integer multiples of the time of the disturbance frequency (f E ) following on, The switching device delays or advances the respective next switching time point (4) to a time point which is the nearest half-integer multiple of the respective disturbing frequency (f E ) or to a time point which is not an integer multiple of the respective disturbing frequency (f E ) based on the time measured by the time measuring device.

2. The electric machine system according to claim 1, characterized in that at least one disturbing vibration (1) is a self vibration of the electric machine or is transmitted to the electric machine by an external vibration.

3. The electric machine system according to claim 1 or 2, characterized in that The switching device has a frequency memory in which one or more interference frequencies (f E ) are stored.

4. The electric machine system according to claim 1, characterized in that The switching device compares at least one interference frequency (f E ) and a switching frequency (f S ) and adjusts the switching point in time (4) depending on the relationship of the respective interference frequency (f E ) and the switching frequency (f S ) and the phase information of the respective interference frequency (f E ).

5. The electric machine system according to claim 1, characterized in that The switching device compares at least one interference frequency (f E ) and a switching frequency (f S ) and adjusts the switching point in time (4) depending on the relationship of the respective interference frequency (f E ) and the switching frequency (f S ) or phase information of the respective interference frequency (f E ).

6. The electric machine system according to claim 1, characterized in that The switch device has a vibration measuring device which detects the current interference vibration (1) and determines its current interference frequency (f E ) and amplitude (3) and phase information.

7. The electric machine system according to claim 1, characterized in that The switch device has a vibration measuring device which detects the current interference vibration (1) and determines its current interference frequency (f E ) or amplitude (3) or phase information.

8. The electric machine system according to claim 1, characterized in that The switching device delays the respective next switching time point (4) to a time point which is a half-integer multiple of time behind the respective disturbance frequency (f E ).

9. The electric machine system according to claim 1, characterized in that The switching device delays or advances the respective next switching time point (4) to a time point which is a next half-integer multiple of a harmonic of the respective disturbance frequency (f E ).

10. The electric machine system according to claim 1, characterized in that the electric machine is a switched electric machine and a current for exciting the electric machine is injected at the adjusted switching time point (4).

11. The electric machine system according to claim 10, characterized in that the electric machine is a switched reluctance electric machine.

12. The electric machine system according to claim 1, characterized in that the electric machine is an internal combustion engine and the switching time point (4) is a firing time point of the internal combustion engine, wherein the firing time point is adjusted and aligned by an adjustable firing angle of the internal combustion engine.

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