DE102021206006A1 - Electrical machine with a stator and a rotor, in particular designed to be permanent magnets, having at least a first subsystem and a second subsystem, each with a plurality of phases for driving the electrical machine - Google Patents

Abstract

Electrical machine (10) with a stator (20) and a rotor (39) designed in particular to be permanent magnets, the electrical machine having at least (10) a first subsystem (11) and a second subsystem (12) each having a plurality of phases for driving the electrical Machine (10), wherein the second subsystem (12) is electrically separated from the first subsystem (11) and in particular is offset from the first subsystem (11), and wherein the electrical machine (10) is set up to the first subsystem (11) and the second subsystem (12) to be controlled symmetrically to one another, and wherein the electrical machine is set up to measure first phase currents (i1) of the first subsystem (11).
One aspect of the invention is that the electrical machine (10) is set up to determine second, estimated phase currents (is2) of the second subsystem (12) and/or their space vector parameters as a function of the first phase currents (i1).

Description

State of the art

The invention is based on an electrical machine with a stator and a rotor which is in particular designed to be permanent magnets, the electrical machine having at least a first subsystem and a second subsystem each having a plurality of phases for driving the electrical machine, the second subsystem being electrically isolated from the first subsystem , and in particular offset to the first subsystem, and wherein the electric machine is set up to control the first subsystem and the second subsystem symmetrically to one another, and wherein the electric machine is set up to measure first phase currents of the first subsystem.

Such an electrical machine is known to those skilled in the art. In this case, this electrical machine is typically set up to also measure the phase currents of the second subsystem in order to be able to correspondingly adjust the actuation of the electrical machine for the respective phases.

Disclosure of Invention

The invention is based on an electrical machine with a stator and a rotor which is in particular designed to be permanent magnets, the electrical machine having at least a first subsystem and a second subsystem each having a plurality of phases for driving the electrical machine, the second subsystem being electrically isolated from the first subsystem , and in particular offset to the first subsystem, and wherein the electric machine is set up to control the first subsystem and the second subsystem symmetrically to one another, and wherein the electric machine is set up to measure first phase currents of the first subsystem.

One aspect of the invention is that the electrical machine is set up to determine second, estimated phase currents of the second subsystem and/or their space vector parameters as a function of the first phase currents.

It is advantageous here that no additional sensors are required for detecting the second phase currents of the second subsystem, since these can be estimated as a function of the measured first phase currents. As a result, costs, effort and installation space of the electrical machine can be reduced.

An electrical machine is to be understood here as meaning a system which forms a drive motor, for example, by means of a stator and rotor, among other things. The electrical machine can be designed in particular as an electric motor. Such an electrical machine is particularly suitable for a motor vehicle, a hand-held power tool or an electric bicycle.

For example, the first subsystem and the second subsystem each include a B6 bridge and corresponding stator windings, the B6 bridges being controlled accordingly, for example by a common processing unit, thereby forming an electrical machine with 2×3 phases, for example.

In this case, the stator windings can in particular be arranged mechanically offset in such a way that when the stator windings of both subsystems are controlled identically, viewed electrically, there is a phase shift φ between the two subsystems. Due to their design, the two subsystems have a phase shift relative to one another. The phase of the first sub-system relative to the second sub-system is shifted by φ=30°, for example, due to the offset arrangement. However, it would also be conceivable for the subsystems to have a phase shift of 0° and accordingly not be offset, but arranged on an identical axis to one another.

The subsystems are controlled symmetrically in order in particular to take into account the mechanical offset of the stator windings of the corresponding subsystems. In this case, symmetrical control means that both subsystems are acted upon by the same voltage vector that is phase-shifted by φ, as a result of which phase-shifted currents of the same magnitude are set. If the subsystems are not offset from one another, both subsystems experience identical activation without a phase offset.

In such an electrical machine, the sub-systems can also be inductively coupled, which is to be understood as meaning that the magnetic fields generated by the sub-systems influence or superimpose one another. However, it would also be conceivable for the stator windings of each to be designed in such a way that there is no or almost no inductive coupling between the two subsystems.

A measurement of the phase currents can be implemented, for example, by appropriate current sensors that detect the respective phase currents of a subsystem. The current sensor ren can be designed, for example, by means of a measuring resistor or as Hall sensors. In order to be able to determine all phase currents of a subsystem, it is in principle sufficient to measure only all but one phase current, with this last phase current being able to be determined using Kirchhoff's law from the other phase currents of the subsystem.

In this context, space vector parameters are to be understood as meaning parameters which, starting from the phase currents, can be obtained by a corresponding space vector transformation of these phase currents.

The processing unit can be configured as a microcontroller, for example.

One embodiment of the invention provides that the electrical machine is set up to measure second phase currents of the second subsystem and to compare the second, estimated phase currents and/or their space vector parameters with the second phase currents and/or their space vector parameters and in Depending on the comparison to implement a reaction. It is advantageous here that a plausibility check of the second phase currents is possible as a result, without requiring redundant sensors for detecting the second phase currents. This in turn can save costs and installation space of the electrical machine.

Such a plausibility check is particularly necessary in safety-relevant applications, such as those found in the automotive sector, in which, for example, the existing torque is determined as a function of the phase currents and the electrical machine is controlled based on this. In this case, an incorrect input variable in the form of a corresponding phase current can lead to an incorrect torque calculation and correspondingly to an incorrect activation of the electric machine, which must be avoided at all costs.

In addition to errors in the measuring path, the plausibility check of the measured versus estimated phase currents can also, for example, enable the diagnosis of winding short circuits or short circuits to the housing in a subsystem.

A further embodiment of the invention provides that the electric machine is set up to generate a warning signal in response to a significant deviation of the second, estimated phase currents and/or their space vector parameters from the second phase currents and/or their space vector parameters.

It is advantageous here that the warning signal can be used to indicate a possible error in the corresponding subsystem. The warning signal can either be processed internally, for example to adjust the activation of the faulty subsystem accordingly, or it can be sent out using a wireless communication unit in particular, for example to inform a user of the electric machine about the possible fault.

A significant deviation is to be understood as a difference which represents a difference between measured and estimated phase currents or their space vector parameters, which is not solely due to measurement inaccuracies or calculation inaccuracies. The corresponding sizes should therefore differ from one another by at least a few percent.

According to one embodiment of the invention, it is provided that the electrical machine is set up to determine first, estimated phase currents of the first subsystem and/or their space vector parameters as a function of the second phase currents and to determine the first, estimated phase currents and/or their space vector Compare parameters with the first phase currents and / or their space vector parameters and implement a further reaction depending on the comparison.

The advantage here is that the phase currents of both subsystems can be checked for plausibility.

According to a further embodiment of the invention, it is provided that the electrical machine is set up to generate estimated phase currents and/or space vector parameters based on measured phase currents as a function of a space vector transformation, in particular a Clarke transformation or a Park transformation, and in To determine dependence on the symmetrical control of the first subsystem to the second subsystem.

The advantage here is that the dependence of the two subsystems can be mapped particularly easily in a corresponding space vector transformation due to their known structure with regard to symmetry and corresponding phase offset between the two subsystems, in order to then be able to derive corresponding conclusions about the phase currents of the other subsystem .

For example, the measured phase currents can be converted into a space vector in the alpha-beta coordinate system by means of a Clarke transformation (T _αβ,1 , T _αβ,2 ), also called alpha-beta transformation. It should be noted here that in the transformation there is a rotation of, for example, φ=30°, which is due to the offset arrangement of the two subsystems in relation to one another. If there is no offset, the phase angle is assumed to be φ=0°.

$${\text{T}}_{\mathrm{\alpha \beta }\mathrm{,1}}=\frac{2}{3}\left(\begin{array}{ccc}\text{cos}\left(\mathrm{+\phi }\right)& \text{cos}\left(-\frac{2}{3}\mathrm{\pi +\phi }\right)& \text{cos}\left(-\frac{4}{3}\mathrm{\pi +\phi }\right)\\ -\text{sin}\left(\mathrm{+\phi }\right)& -\text{sin}\left(-\frac{2}{3}\mathrm{\pi +\phi }\right)& -\text{sin}\left(-\frac{4}{3}\mathrm{\pi +\phi }\right)\\ \frac{1}{2}& \frac{1}{2}& \frac{1}{2}\end{array}\right)$$

$$t_{\alpha \beta \mathrm{,2}}=T_{\alpha \beta \mathrm{,1}}\cdot i1$$

$$t_{\alpha \beta \mathrm{,1}}=T_{\alpha \beta \mathrm{,2}}\cdot i2$$

T _αβ,1 establishes the reference to the second subsystem with a rotation around + φ. T _αβ,2 establishes the reference to the first subsystem with a rotation around - φ. The following equations are applied accordingly: $$T_{a\beta \mathrm{,2}}=\frac{2}{3}\left(\begin{array}{ccc}\text{cos}\left(-\mathrm{\phi }\right)& \text{cos}\left(-\frac{2}{3}\mathrm{\pi }-\mathrm{\phi }\right)& \text{cos}\left(-\frac{4}{3}\mathrm{\pi }-\mathrm{\phi }\right)\\ -\text{sin}\left(-\mathrm{\phi }\right)& -\text{sin}\left(-\frac{2}{3}\mathrm{\pi }-\mathrm{\phi }\right)& -\text{sin}\left(-\frac{4}{3}\mathrm{\pi }-\mathrm{\phi }\right)\\ \frac{1}{2}& \frac{1}{2}& \frac{1}{2}\end{array}\right)$$

$${\text{T}}_{\mathrm{\alpha \beta }\mathrm{,1}}=\frac{2}{3}\left(\begin{array}{ccc}\text{cos}\left(\mathrm{+\phi }\right)& \text{cos}\left(-\frac{2}{3}\mathrm{\pi +\phi }\right)& \text{cos}\left(-\frac{4}{3}\mathrm{\pi +\phi }\right)\\ -\text{sin}\left(\mathrm{+\phi }\right)& -\text{sin}\left(-\frac{2}{3}\mathrm{\pi +\phi }\right)& -\text{sin}\left(-\frac{4}{3}\mathrm{\pi +\phi }\right)\\ \frac{1}{2}& \frac{1}{2}& \frac{1}{2}\end{array}\right)$$

$$t_{a\beta \mathrm{,2}}=T_{a\beta \mathrm{,1}}\cdot i1$$

$$t_{a\beta \mathrm{,1}}=T_{a\beta \mathrm{,2}}\cdot i2$$

$$is1=T_{\alpha \beta ,inv1}\cdot t_{\alpha \beta \mathrm{,1}}$$

$$is2=T_{\alpha \beta ,inv2}\cdot i_{\alpha \beta \mathrm{,2}}$$

Then, for example, the previously determined space vectors can be converted into the estimated phase currents using an inverse Clarke transformation: $$T_{a\beta ,inv1}=T_{a\beta ,inv2}=\left(\begin{array}{ccc}\text{cos}\left(0\right)& -\text{sin}\left(-\frac{2}{3}\mathrm{\pi }\right)& 1\\ \text{cos}\left(-\frac{2}{3}\mathrm{\pi }\right)& -\text{sin}\left(-\frac{2}{3}\mathrm{\pi }\right)& 1\\ \text{cos}\left(-\frac{4}{3}\mathrm{\pi }\right)& -\text{sin}\left(-\frac{2}{3}\mathrm{\pi }\right)& 1\end{array}\right)$$

$$is1=T_{a\beta ,inv1}\cdot t_{a\beta \mathrm{,1}}$$

$$is2=T_{a\beta ,inv2}\cdot i_{a\beta \mathrm{,2}}$$

Then i1 can be compared with is1 or also i2 with is2 for plausibility checking.

This transformation means that the sine and cosine functions of the transformation are only determined by constants and can therefore also be implemented using constants. This brings with it the following advantages. In this way, the determination can be implemented as simply as possible, as a result of which the computing time of the processing unit for determining the estimated phase currents and correspondingly also for the plausibility check can be reduced.

As an alternative, a Park transformation, also known as a d/q transformation, can be used.

According to a further embodiment of the invention, it is provided that the electrical machine is set up to determine alpha-beta components of the space vector of a Clarke transformation as space vector parameters and, in particular, to use them for comparison.

It is advantageous here that this represents a particularly simple possibility of carrying out the comparison between estimated and measured currents for the plausibility check of the respective phase currents.

According to a further embodiment of the invention, it is provided that the electrical machine is set up to determine space vector lengths as space vector parameters and, in particular, to use them for comparison. It is advantageous here that this represents a particularly simple possibility of carrying out the comparison between estimated and measured currents for the plausibility check of the respective phase currents.

According to a further embodiment of the invention, it is provided that the electrical machine is set up to determine an amount of the difference between transformed phase currents as a space vector parameter and, in particular, to use it for comparison.

It is advantageous here that this represents a particularly simple possibility of carrying out the comparison between estimated and measured currents for the plausibility check of the respective phase currents.

According to a further embodiment of the invention, it is provided that the electrical machine is set up to transfer the first phase currents and/or the second phase currents in each case to subject and/or to average a predetermined period of time to low-pass filtering.

It is advantageous here that the influence of harmonics can be reduced, as a result of which the determination of the phase currents of the other subsystem from the measured phase currents and also a subsequent plausibility check are less susceptible to interference.

character list

• 1 shows an embodiment of an electrical machine according to the invention with a stator and a rotor, in particular designed to be permanent magnets, the electrical machine having at least a first subsystem and a second subsystem, each with a plurality of phases for driving the electrical machine.

Description of exemplary embodiments

1 shows an embodiment of an electrical machine according to the invention with a stator and a rotor, in particular designed to be permanent magnets, the electrical machine having at least a first subsystem and a second subsystem, each with a plurality of phases for driving the electrical machine.

An electrical machine 10 is shown. The electrical machine 10 is designed in particular as an electrical drive and has a stator 20 and a permanent-magnetic rotor 30 . Furthermore, the electric machine 10 includes a first subsystem 11 and a second subsystem 12, shown in dashed lines, each with three phases for driving the electric machine 10. In particular, the first subsystem 11 and the second subsystem 12 each include a B6 bridge 40 and corresponding ones Stator windings 21, the B6 bridges 40 being controlled accordingly by a common processing unit 50. The control is symmetrical and takes into account the mechanical offset of the stator windings 21 of the corresponding subsystems 11, 12.

In this case, the second subsystem 12 is electrically separated from the first subsystem 11 , is offset from the first subsystem 11 and is inductively coupled to the first subsystem 11 .

Furthermore, the electrical machine is set up to measure first phase currents i1 of the first subsystem 11 and second phase currents i2 of the second subsystem in each case by means of current sensors 60 and make them available to the processing unit 50 .

In addition, the electric machine 10 is set up to determine second, estimated phase currents is2 of the second subsystem 12 and/or their space vector parameters as a function of the first phase currents i1 and first, estimated phase currents is1 of the first subsystem 11 and/or their space vector - to determine parameters depending on the second phase currents i2.

In particular, the electrical machine 10 is set up to, based on measured phase currents i1, i2 estimated phase currents is1, is2 and / or space vector parameters depending on a space vector transformation, in particular a Clarke transformation or a Park transformation, and depending on to determine the symmetrical control of the first subsystem 11 to the second subsystem 12.

Furthermore, the electric machine 10 is set up to compare the second, estimated phase currents is2 and/or their space vector parameters with the second phase currents i2 and/or their space vector parameters and to implement a reaction depending on the comparison and the first To compare estimated phase currents is1 and/or their space vector parameters with the first phase currents i1 and/or their space vector parameters and to implement a further reaction depending on the comparison.

In particular, if the second, estimated phase currents is2 and/or their space vector parameters deviate significantly from the second phase currents i2 and/or their space vector parameters, a warning signal can be generated as a reaction, which can be sent, for example, by means of a communication unit (not shown) or processed further internally can be. A corresponding reaction can take place for the further reaction when comparing the first, estimated phase currents is1 and/or their space vector parameters with the first phase currents i1 and/or their space vector parameters.

In the comparison, for example, the space vector of a Clarke transformation can be used as a space vector parameter based on alpha-beta components, or space vector lengths can be used as space vector parameters, or an absolute value of the difference between transformed phase currents can be used as space vector parameters.

Furthermore, the electrical machine 10 can be set up to subject the first phase currents i1 and/or the second phase currents i2 to low-pass filtering and/or to average them over a predetermined period of time.

Claims (9)

Electrical machine (10) with a stator (20) and a rotor (39) designed in particular to be permanent magnets, the electrical machine having at least (10) a first subsystem (11) and a second subsystem (12) each having a plurality of phases for driving the electrical Machine (10), wherein the second subsystem (12) is electrically separated from the first subsystem (11) and in particular is offset from the first subsystem (11), and wherein the electrical machine (10) is set up to the first subsystem (11) and the second subsystem (12) symmetrically to each other, and wherein the electrical machine is set up to measure first phase currents (i1) of the first subsystem (11), characterized in that the electrical machine (10) is set up to do so to determine second, estimated phase currents (is2) of the second subsystem (12) and/or their space vector parameters as a function of the first phase currents (i1). Electrical machine (10) after claim 1 , characterized in that the electrical machine (10) is set up to measure second phase currents (i2) of the second subsystem (12) and the second, estimated phase currents (is2) and / or their space vector parameters with the second phase currents (i2 ) and/or to compare their space vector parameters and to implement a reaction depending on the comparison. Electrical machine (10) after claim 2 , characterized in that the electrical machine (10) is set up to respond to a significant deviation of the second, estimated phase currents (is2) and / or their space vector parameters compared to the second phase currents (i2) and / or their space vector parameters generate a warning signal. Electrical machine (10) after a claims 2 until 3 , characterized in that the electrical machine (10) is set up to determine first, estimated phase currents (is1) of the first subsystem (11) and / or their space vector parameters as a function of the second phase currents (i2) and the first, to compare estimated phase currents (is1) and/or their space vector parameters with the first phase currents (i1) and/or their space vector parameters and to implement a further reaction depending on the comparison. Electrical machine (10) according to one of the preceding claims, characterized in that the electrical machine (10) is set up based on measured phase currents (i1, i2) estimated phase currents (is1, is2) and / or space vector parameters depending on a space vector transformation, in particular a Clarke transformation or a Park transformation, and depending on the symmetrical control of the first subsystem (11) to the second subsystem (12). Electrical machine (10) after claim 5 , characterized in that the electrical machine (10) is set up to determine alpha-beta components of the space vector of a Clarke transformation as a space vector parameter and in particular to use for comparison. Electrical machine (10) after claim 5 or 6 , characterized in that the electrical machine (10) is set up to determine space vector lengths as space vector parameters and in particular to use them for comparison. Electrical machine (10) according to one of Claims 5 until 7 , characterized in that the electrical machine (10) is set up to determine an amount of the difference between transformed phase currents as a space vector parameter and in particular to use for comparison. Electrical machine (10) according to one of the preceding claims, characterized in that the electrical machine (10) is set up to subject the first phase currents (i1) and/or the second phase currents (i2) to low-pass filtering over a predetermined period of time and /or to average.

Images