DE102019205471A1 - Method for checking measured values of current intensities of currents which are provided by a six-phase converter to at least one electrical machine - Google Patents

Abstract

The invention relates to a method for checking measured values of current strengths of currents which are provided by a six-phase converter to at least one electrical machine (E1, E2), with each of the six phases (u, v, w, x, y, z) the at least one electrical machine (E1, E2) each with a high-side switch (M1, M3, M5, M7, M9, M11) and a low-side switch (M2, M4, M6, M8, M10, M12) of the converter is connected, the high-side switches (M1, M3, M5, M7, M9, M11) of the converter being connected to a first converter connection (B +) and the low-side switches (M2, M4, M6, M8, M10 , M12) of the converter are connected to a second converter connection (B-), in the course of at least one current measurement for each of the six phases (u, v, w, x, y, z) one current intensity of the corresponding phase current and one Amperage of a total current between the highside switches (M1, M3, M5, M7, M9, M11) and the first current line ter connection (B +) are detected, with a check being carried out as a function of the detected current levels as to whether the sum of the detected current levels of the phase currents of the phases (u, v, w, x, y, z) of the at least one electrical machine ( E1, E2) results in the value zero or at least essentially the value zero and / or whether the sum of the recorded currents of the phase currents of those phases whose highside switches (M1, M3, M5, M7, M9, M11) are closed, the detected current intensity of the total current corresponds or at least substantially corresponds to and / or whether the sum of the recorded currents of the phase currents of those phases whose low-side switches (M2, M4, M6, M8, M10, M12) are closed, the negative value of the recorded current intensity corresponds to or at least substantially corresponds to the total current and, depending on a result of the check, it is determined whether all the recorded current intensities are correct or whether at least one of the recorded th currents is incorrect.

Description

The present invention relates to a method for checking measured values of current strengths of currents which are provided by a six-phase converter to at least one electrical machine, as well as a computing unit and a computer program for its implementation.

State of the art

To control or regulate electrical machines, such as electrical machines in motor vehicles that can be operated as a motor or generator, for example, it is important to measure the phase currents of the individual phases of the electrical machine. Incorrect measurements of the phase currents can negatively affect the control of the electrical machine and, for example, lead to errors in the torque position. It is therefore important to be able to recognize whether the strengths of phase currents were incorrectly recorded.

The US 2018/0102719 A1 shows a way of detecting faults in current sensors for measuring phase currents in a three-phase AC motor.

Disclosure of the invention

According to the invention, a method for checking measured values of current strengths of currents that are provided by a six-phase converter to at least one electrical machine, as well as a computing unit and a computer program for its implementation with the features of the independent claims are proposed. Advantageous configurations are the subject of the subclaims and the description below.

The invention provides a possibility of checking currents provided by a six-phase converter to at least one electrical machine with as few sensors as possible.

For example, the six-phase converter can be connected to a six-phase electrical machine, which e.g. has six windings, or, for example, with two each three-phase electrical machines. Such designs are used in particular when several machines are to be operated using just one electronics unit, for example in the case of electric travel drives. The at least one electrical machine thus has a total of six phases or six phase connections. Each of the six phases of the at least one electrical machine is connected to a high-side switch and to a low-side switch of the converter. For this purpose, one phase connection of the respective phase is in particular connected to a center tap of a half-bridge of the converter. The highside switches are connected to a first converter connection, in particular via a common electrical connection or a common sum line or bus line. This first converter connection can in particular be a positive potential connection, a first consumer connection or a first on-board network connection, with which a consumer to be supplied and / or an energy source can also be connected, for example an on-board network of a motor vehicle. Correspondingly, the low-side switches of the converter are connected to a second converter connection, in particular also via a second common electrical connection such as a second sum or bus line. The second connection is in particular a negative potential connection, a second consumer connection or a second vehicle electrical system connection for further connection to the consumer to be supplied or the energy source, for example the vehicle electrical system. The second connection can expediently be a ground connection.

In the context of the present method, in the course of a current measurement, a current strength of the corresponding phase current and a current strength of a total current between the highside switches and the first converter connection are recorded for each of the six phases. Each current measurement thus includes the determination of seven measured values. The current strengths of the phase current are in each case detected in particular between the respective phase connection of the corresponding phase of the at least one electrical machine and the respective center tap between the corresponding high-side and low-side switches of the converter. The current strength of the total current or bus current is recorded in particular in the common connecting line or the bus line. If an intermediate circuit capacitor is connected in parallel between the first and second converter connection, the current intensity of the total current is expediently detected on the converter side in front of this intermediate circuit capacitor. The single ones Current strengths can in each case be detected in particular by means of an appropriate current sensor, for example in each case by means of a Hall sensor.

Depending on the current intensities detected in the course of the at least one current measurement, a check is carried out, in particular a check as to whether the detected current intensities fulfill predetermined or expected relationships to one another. As a function of a result of this check, it is determined whether all the recorded current levels are correct or whether at least one of the recorded current levels is faulty.

As a predetermined relationship, it is checked whether the sum of the recorded current intensities of the phase currents of the phases of the at least one electrical machine, in particular the total current of all phases belonging to an electrical machine, results in zero or at least essentially the value zero. In particular, for this purpose it is checked whether the amount of this sum is below a predetermined threshold value. This threshold value can, for example, be at most 20% of a nominal phase current and, for example, have the value 70 A (for phase currents up to 400 A). Without restricting the generality, this predetermined relationship will be referred to below as the first relationship.

If the at least one electrical machine has two groups of three phases each, e.g. If the converter is connected to two three-phase electrical machines, it can be checked in particular as a first predetermined indicator whether the sum of the detected currents of the phase currents of the first group of phases results in zero or at least essentially zero, and in particular checked as a second predetermined relationship whether the sum of the current intensities of the phase currents of the second group of phases results in zero or at least essentially zero.

Alternatively or additionally, it is checked as a predetermined relationship whether the sum of the recorded currents of the phase currents of those phases of the at least one electrical machine whose high-side switches are closed corresponds to or at least substantially corresponds to the recorded current of the total current. This relationship is referred to below as the third predetermined relationship without loss of generality. In particular, it is thus checked whether the sum of the phase currents whose high-side switches are closed corresponds at least essentially to the recorded sum or bus current. It can expediently be checked whether this sum minus the current intensity of the total current is below a predetermined threshold value of, for example, at most 20% of a nominal phase current.

Alternatively or additionally, it is checked as a predetermined relationship whether the sum of the recorded currents of the phase currents of those phases of the at least one electrical machine whose low-side switches are closed corresponds or at least substantially corresponds to the negative value of the recorded amperage of the total current. This relationship is expediently referred to below as the fourth predetermined relationship without restricting the generality. In contrast to the third predetermined relationship, in the course of this fourth predetermined relationship it is checked whether the sum of the phase currents whose low-side switches are closed corresponds at least essentially to the negative value of the recorded sum or bus current. In particular, for this purpose it can be checked whether this sum plus the current strength of the total current is below a predetermined threshold value of, for example, at most 20% of a nominal phase current.

In particular, it can also be checked as a predetermined relationship whether the sum of the recorded currents of the phase currents of those phases whose high-side switches are closed corresponds or at least to the negative value of the sum of the recorded currents of the phase currents of those phases whose low-side switches are closed essentially corresponds.

The present method thus provides a possibility for a six-phase converter in addition to the six current intensities of the six phase currents to detect only one further current intensity of a further current and to be able to recognize by means of predetermined relationships whether one or more of these seven current intensities were detected incorrectly.

To control or regulate the electrical machines, it is important that the current strengths of the phase currents of the individual phases are correctly recorded, since incorrectly recorded current strengths of the phase currents have a negative impact on the control of the electrical machine and can lead to errors in the torque position, for example. In the context of the present method, it can be recognized in a cost-effective and effective manner whether current strengths of phase currents were incorrectly recorded and, if so If this is the case, the control of the electrical machine can react accordingly to this incorrect detection.

The at least one current measurement is advantageously carried out at least at one point in time after a switching state of one of the high-side switches and one of the low-side switches that are connected to the same phase has changed. Such a point in time at which a current measurement is carried out lies in particular in a time interval between a first switching point in time, at which the switching state of the respective high-side and low-side switch changes, and a second switching point in time, at which a switching state of one changes the next time Highside switch and / or a low side switch changes.

In particular, the current measurements are thus carried out after the switching states of both switches of a half-bridge of the converter that are connected to the same phase of the at least one electrical machine have changed. In this context, the change in the switching state is to be understood in particular as meaning that the corresponding switch was previously closed and then opened or, vice versa, was previously opened and then closed.

In particular, the current switching states of the half-bridges or the individual high-side and low-side switches at the time of the current measurement are taken into account as parameters or boundary conditions in the checking of the predetermined relationships. Carrying out and evaluating the current measurements at times after the switching state of exactly one half-bridge has changed in each case is a particularly effective way of being able to draw precise conclusions about incorrect measurements based on the predetermined relationships.

According to an advantageous embodiment, a first current measurement is carried out at a first point in time after a switching state of a first high-side switch and a first low-side switch, which are connected to a first phase of the six phases of the at least one electrical machine, have changed. The designation of the “first” high-side switch, the “first” low-side switch, the “first” phase, etc. should be understood in the context of the present description without restricting the generality and should not express any relevance or evaluation of these individual elements . Rather, the nomenclature of these “first” elements should only serve to distinguish them from the other elements. In particular, each of these switches, phases, etc. can expediently be selected as these “first” elements. Likewise, in the following, when "second", "third", "fourth" etc. elements are mentioned, these terms should also be understood without restricting the generality.

• Entweder wird vorzugsweise bestimmt, dass alle im Zuge der ersten Strommessung erfassten Stromstärken korrekt sind. Sofern alle sieben Strommessungen korrekt sind, kann dies im Rahmen des vorliegenden Verfahrens mit nur einer einzigen Strommessung zu einem einzigen Zeitpunkt bereits erkannt werden. Insbesondere wird dies bestimmt, wenn die Summe der erfassten Stromstärken der Phasenströme der wenigstens einen elektrischen Maschine Null oder zumindest im Wesentlichen den Wert Null ergibt, wenn also die erste Beziehung bzw. die erste und die zweite Beziehung erfüllt sind.

Depending on the current strengths detected in the course of the first current measurement, one of the following four cases can advantageously be recognized in the course of the check:

• Either it is preferably determined that all current intensities detected in the course of the first current measurement are correct. If all seven current measurements are correct, this can already be recognized within the scope of the present method with just a single current measurement at a single point in time. In particular, this is determined when the sum of the recorded current intensities of the phase currents of the at least one electrical machine results in zero or at least essentially the value zero, that is to say when the first relationship or the first and second relationships are fulfilled.

It can also advantageously be recognized whether the amperage of the total current detected in the course of the first current measurement is incorrect. An incorrectly detected total current or bus current can thus also be recognized with a single current measurement at a single point in time. This is the case in particular if the first relationship explained above is fulfilled during the first current measurement and the third relationship is not fulfilled.

It can preferably also be determined whether the amperage of the phase current of the first phase detected in the course of the first current measurement is incorrect. This is especially the case when the first Relationship is not fulfilled and if the third relationship is also not fulfilled, or if the first relationship is not fulfilled and if the fourth relationship is on the other hand fulfilled. It can thus be recognized in particular whether the amperage of the phase current of that phase was incorrectly detected whose high-side and low-side switches have changed their switching state.

Alternatively, it is preferably determined whether one of the current strengths of the phase currents of the remaining five phases detected in the course of the first current measurement is faulty. This is particularly the case if the first relationship is not fulfilled and if, on the other hand, the third relationship is fulfilled, or if the first relationship and the third relationship are each not fulfilled. In particular, at least one further current measurement is required for a precise differentiation as to which current intensity is faulty.

In the latter case, if it is determined that one of the current strengths of the phase currents of the remaining five phases detected in the course of the first current measurement is faulty, at least one further current measurement is advantageously carried out at at least one further point in time after a switching state of a highside switch and of a low-side switch, which are connected to the same of the remaining five phases. Depending on the current strengths detected in the course of the at least one further current measurement, it is advantageously determined in the course of the check which current strength of the phase currents of the remaining five phases is faulty.

The six phases of the at least one electrical machine preferably have a first group of three phases and a second group of three phases. For example, each of the two groups of phases can represent a three-phase electrical machine.

The first phase is preferably a phase of the first group. In the course of the check, it is advantageously determined in this case whether one of the current intensities of the phase currents of a second phase and a third phase of the first group of three phases detected in the course of the first current measurement is faulty. This is determined in particular when the first relationship is not fulfilled and when the third relationship, on the other hand, is fulfilled, or when the first relationship and the fourth relationship are each not fulfilled. For a precise distinction as to which current intensity of this second and third phase is faulty, a second current measurement is required in particular at a second point in time after the switching states of the high-side and low-side switch of one of these two phases have changed.

Alternatively, it can preferably be recognized whether at least one of the current strengths of the phase currents of the phases of the second group of three phases detected in the course of the first current measurement is faulty. For a precise differentiation which phase current of these three phases of the second group was detected incorrectly, a further current measurement is expediently required at a further point in time after the switching states of the switches of these phases have changed.

If it is determined that one of the detected current intensities of the phase currents of the second phase and the third phase of the first group of three phases is faulty, according to an advantageous embodiment, a second current measurement is carried out at a second point in time. At this second point in time, a switching state of a second high-side switch and a second low-side switch, which are connected to the second phase of the first group, has changed. The second point in time is advantageously after the first point in time. As explained above, the nomenclature of the “second” high-side switch, the “second” low-side switch, the “second” phase, etc. should be understood without restricting the generality.

Depending on the amperages detected in the course of the second current measurement, it is advantageously determined in the course of the check whether the amperage of the phase current of the second phase of the first group detected in the course of the second current measurement is incorrect or whether the amperage of the phase current detected in the course of the second current measurement the third phase of the first group is faulty. In particular, it is determined that the current intensity of the second phase is incorrect when the third relationship is not met or when the fourth relationship is met. On the other hand, when the third relationship is satisfied or when the fourth relationship is not satisfied, it is specifically determined that the current of the third phase is faulty. If a phase current of a phase of the first group is detected incorrectly, it can be determined at the latest with two current measurements at two different points in time which phase current is incorrectly detected.

If it is determined that at least one of the current intensities of the phase currents of the phases of the second group of three phases detected in the course of the first current measurement is faulty, a third current measurement is advantageously carried out at a third point in time. This third point in time is advantageously after the first point in time. Furthermore, the third point in time is in particular after the second point in time. If it is not determined at the first point in time that the current intensities of the second or third phase of the first group were recorded incorrectly, the above-explained second current measurement can in particular also be omitted and a further current measurement can expediently only be carried out at the third point in time.

At the third point in time, a switching state of a third high-side switch and a third low-side switch, which are connected to a first phase of the second group (overall the fourth phase), has advantageously changed. Thus, at the third point in time, switching states of switches of the second group of phases are changed in order to determine which phase current of this second group is incorrectly detected. Depending on the current strengths detected in the course of the third current measurement, one of the following two cases is advantageously recognized in the course of the check.

It is either determined that the amperage of the phase current of the first phase of the second group detected in the course of the third current measurement is incorrect. Thus, in particular, immediately after the third current measurement, it can be recognized whether the amperage of the phase current was incorrectly detected in that phase whose high-side and low-side switches changed their switching state at the third point in time.

Alternatively, it is determined that one of the current intensities of the phase currents of a second phase of the second group (fifth phase) and a third phase of the second group (sixth phase) detected in the course of the third current measurement is faulty. In order to determine precisely whether the second or the third phase of the second group was detected incorrectly, a further current measurement is expediently required.

In the latter case, if it is determined that one of the current intensities of the phase currents of the second phase and the third phase of the second group detected in the course of the third current measurement is faulty, a fourth current measurement is advantageously carried out at a fourth point in time. This fourth point in time is preferably after the third point in time. At the fourth point in time, a switching state of a fourth high-side switch and a fourth low-side switch, which are connected to the second phase of the second group, have changed. Depending on the amperages detected in the course of the fourth current measurement, it is determined in the course of the check whether the amperage of the phase current of the second phase of the second group detected in the course of the fourth current measurement is incorrect or whether the amperage of the phase current detected in the course of the fourth current measurement third phase of the second group is faulty. If one of the six phase currents is not correctly detected, in the context of the present method it can thus be determined precisely after four current measurements at four different times at the latest which of the six phase currents cannot be correctly detected.

At least one of the current intensities of the phase currents and the total current is preferably detected in the course of the at least one current measurement with the aid of a Hall sensor. All of these current intensities are preferably recorded with the aid of a Hall sensor. Due to stray fields, Hall sensors can be susceptible to incorrect current measurements. The present method is therefore particularly advantageous for checking current strengths detected in a six-phase electrical machine for errors with the aid of Hall sensors.

A ripple current or a current ripple load of a capacitor element or intermediate circuit capacitor connected in parallel between the first and second converter connection is preferably determined as a function of the amperage of the total current detected in the course of the at least one current measurement. A ripple current or so-called superimposed alternating current is to be understood in particular as an alternating current that is superimposed on a direct current. Such a ripple current can in particular be generated by the pulsating direct current generated by the converter in the capacitor element or intermediate circuit capacitor connected in parallel.

The at least one current measurement and the plausibility check are preferably carried out in the course of a test phase, in the course of which the switching states of the individual high-side switches and the individual low-side switches are changed. In particular, these switching states are continuously changed, i.e. The switching states of the various high-side and low-side switches of the individual half-bridges are expediently changed continuously. If the converter is connected to two three-phase electrical machines, one of these electrical machines can expediently be deactivated or switched off for the test phase.

A computing unit according to the invention, e.g. a control unit of a motor vehicle is set up, in particular in terms of programming, to carry out a method according to the invention.

The implementation of a method according to the invention in the form of a computer program or computer program product with program code for performing all method steps is advantageous, since this causes particularly low costs, in particular if an executing control device is also used for other tasks and is therefore available anyway. Suitable data carriers for providing the Computer programs are, in particular, magnetic, optical and electrical memories, such as hard drives, flash memories, EEPROMs, DVDs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and configurations of the invention emerge from the description and the accompanying drawing.

The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing.

Figure list

• 1 shows schematically a preferred embodiment of an arrangement with a converter and two electrical machines, which can be the basis of a preferred embodiment of a method according to the invention.
• 2 shows schematically a preferred embodiment of a method according to the invention as a block diagram.

Embodiment (s) of the invention

In 1 a preferred embodiment of an arrangement with a converter and two electrical machines E1, E2 is shown schematically and denoted by 100. The order 100 is expediently provided in a motor vehicle and can be operated as a generator, for example, in order to generate electrical energy to supply consumers in an on-board network of the vehicle, or motor-driven to use electrical energy stored in the on-board network to drive the vehicle.

The arrangement has six phases or phase connections. In the example of 1 instructs the arrangement 100 two three-phase electrical machines E1 and E2. It is also conceivable that a six-phase electrical machine with six windings is provided.

A first electrical machine E1 has a first group 101 from three phases u , v , w on. A second electrical machine E2 has a second group 102 from three phases x , y , z on.

For the first machine E1 or the first group 101 of phases u , v , w is a first part 110 a converter with high-side switches M1, M3, M5 and with low-side switches M2, M4, M6. The same applies to the second machine E2 or the second group 102 of phases x , y , z a second part 120 of the converter with high-side switches M7, M9, M11 and low-side switches M8, M10, M12. The individual high-side and low-side switches can each be designed as a semiconductor switching element, for example each as a MOSFET.

Each of the six phases u , v , w , x , y , z is connected to a high-side switch and a low-side switch. In particular, each of the phases u , v , w , x , y , z with a center tap 111 , 112 , 113 , 121 , 122 , 123 connected between the respective high-side switch and low-side switch.

The high-side switches M1, M3, M5 or M7, M9, M11 are also jointly connected to a first converter connection or vehicle electrical system connection B +. The low-side switches M2, M4, M6 or M8, M10 and M12 are jointly connected to a second converter connection or on-board network connection B-. Electrical consumers and energy sources in a motor vehicle electrical system can also be connected to these connections B + and B-. In 1 is an example of an electrical resistance R1 shown as such a consumer, which can represent a rear window heater, for example. In addition, there is an intermediate circuit capacitor in parallel with the vehicle electrical system connections B + and B- C1 intended.

A control unit 140 is also provided to the arrangement 100 to control and for this purpose in particular the switches of the converter 110 , 120 head for. This control is expediently dependent on the current phase currents of the individual phases u , v , w , x , y , z carried out. To measure the current strengths of these phase currents is per phase u , v , w , x , y , z one current sensor each 131 , 132 , 133 , 134 , 135 or. 136 intended. For example, these current sensors 131 , 132 , 133 , 134 , 135 , 136 each be designed as a Hall sensor.

Furthermore, there is a current sensor in the common connection or bus line between the high-side switches M1, M3, M5 or M7, M9, M11 and the first converter connection B + 137 provided in order to detect the amperage of a sum current or bus current. This current sensor too 137 can be designed as a Hall sensor. The current sensor 137 is before the capacity on the converter side C1 arranged.

Due to stray fields, however, such Hall sensors can be susceptible to incorrect current measurements. Incorrect measurements of the phase currents can affect the control of the electrical machine 100 but negatively influence and lead, for example, to errors in the moment position.

To be able to recognize whether the individual current strengths with the help of the Hall sensors 131 , 132 , 133 , 134 , 135 , 136 , 137 correctly or incorrectly recorded, is the control unit 140 , in particular in terms of programming, set up to carry out a preferred embodiment of a method according to the invention, which is implemented in 2 is shown schematically as a block diagram and below with reference to FIG 1 and 2 should be explained.

Within the scope of a preferred embodiment of the present method, at least one current measurement is carried out at least at one point in time after a switching state of one of the high-side switches and one of the low-side switches that are connected to the same phase change.

In the course of such a current measurement, the Hall sensors 131 , 132 , 133 , 134 , 135 , 136 for each of the six phases u , v , w , x , y , or. z a current intensity lu, Iv, Iw, Ix, I _Y or Iz of the corresponding phase current is determined and with the help of the Hall sensor 137 a current intensity I _{G of} the total current is recorded.

As a function of the recorded currents and of predetermined relationships between the currents, a check or plausibility check is carried out to determine whether all recorded currents I _U , I _V , I _W , I _X , I _Y , I _Z and I _{G are} correct or at least one of the recorded currents is incorrect.

For these predetermined relationships, a digital function is defined for each phase or for each pair of high-side switches and low-side switches, for example, which can take either the value and 0 or 1, which characterizes the switching states of the two respective switches of the phase will.

For example, a digital function U for the high-side switch M5 and the low-side switch M6 is the phase u Are defined. If this digital function U assumes the value 1, this means that the high-side switch M5 is closed and the low-side switch M6 is open. If, on the other hand, the digital function U assumes the value 0, this means that the high-side switch M5 is open and the low-side switch M6 is closed.

The same applies to the remaining phases v , w , x , y , z each defines a digital function V, W, X, Y or Z, where the value 1 of these functions means that the corresponding high-side switch of the respective phase is closed and the respective low-side switch is open, and the value 0 of these digital functions each means that the corresponding highside switch is open and the respective lowside switch is closed.

The following table shows an exemplary control scheme for continuously changing the switching states of the individual high-side and low-side switches, the switching state of a switch pair having changed at successive times t ₁ to t ₆ . t U V W. X Y Z t ₀ 0 0 0 0 0 0 t ₁ 0 1 0 0 0 0 t ₂ 1 1 0 0 0 0 t ₃ 1 1 1 0 0 0 t ₄ 1 1 1 1 0 0 t ₅ 1 1 1 1 1 0 t ₆ 1 1 1 1 1 1

The following now uses 2 explains how, in the context of a preferred embodiment of the method according to the invention, it is checked whether the individual current intensities are correctly detected.

In step 201 a first current measurement is carried out at a first point in time. Without restricting the generality, the following example considers that time t ₁ according to the table above represents this first time after the switching state of high-side switch M3 and low-side switch M4 have changed phase v has changed in such a way that the high-side switch M3 has been closed and the low-side switch M4 has been opened and that the digital function V has assumed the value 1 at this first point in time t ₁ . The digital functions U, W, X, Y, Z of the remaining phases u , w , x , y , z at this first point in time t _{1 are,} for example, the value 0, ie the remaining high-side switches are open and the remaining low-side switches are closed.

In step 202 it is checked as a first predetermined relationship (1) whether the sum of the current intensities I _U , I _V , I _{W of} the phase currents of the three phases detected in the course of the first current measurement u , v , w the first group 101 the value zero or at least essentially the value zero results: $${\text{I.}}_{\text{U}}+{\text{I.}}_{\text{V}}+{\text{I.}}_{\text{W.}}=0$$

In order to allow a certain measurement inaccuracy, an alternative first predetermined relationship (1 ') can also be used to check whether this sum is at least essentially zero or whether the amount of this sum is below a predetermined threshold value I _th of, for example, at most 20% of a nominal phase current, e.g. 70 A (in the case of phase currents of 400 A): $$\left|{\text{I.}}_{\text{U}}+{\text{I.}}_{\text{V}}+{\text{I.}}_{\text{W.}}\right|<{\text{I.}}_{\text{th}}$$

In particular, in step 202 It is also checked as a second predetermined relationship (2) whether the sum of the current intensities I _X , I _Y , I _{Z of} the phase currents of the three phases detected in the course of the first current measurement x , y , z the second group 102 the value zero or at least essentially the value zero results: $${\text{I.}}_{\text{X}}+{\text{I.}}_{\text{Y}}+{\text{I.}}_{\text{Z}}=0$$

In order to allow a certain measurement inaccuracy in this case as well, it can be checked as an alternative second predetermined relationship (2 ') whether this sum at least essentially results in the value zero or whether the amount of this sum is below the specified threshold value I _th : $$\left|{\text{I.}}_{\text{X}}+{\text{I.}}_{\text{Y}}+{\text{I.}}_{\text{Z}}\right|<{\text{I.}}_{\text{th}}$$

If the first predetermined relationship (1) or (1 ') is satisfied, step 203 determines that the detected currents I _U , I _V , I _{W of} the phases u , v , w are correct. Furthermore, if the predetermined relationship (2) or (2 ') is also satisfied, step 203 furthermore determines that the recorded current intensities I _X , I _Y , I _{Z of} the phases x , y , z are correct and that all phase currents have thus been correctly recorded.

If the second relationship (2) or (2 ') is not fulfilled, this indicates that at least one of the currents I _X , I _Y , I _{Z of} the phases x , y , z the second group 102 is faulty. In this case, at least one additional current measurement is required and a step is carried out at a later point in time 221 as will be explained below.

First, however, consider the case that in step 202 checked first theoretical relationship (1) or (1 ') is fulfilled and the currents I _U , I _V , I _{W of} the phases u , v , w the first group 101 are correct. In this case, step 204 as a third predetermined relationship (3) checks whether the sum of the detected current intensities of the phase currents of those phases whose high-side switches are closed, the detected current strength corresponds to the total current. This predetermined relationship (3) can be expressed mathematically using the digital functions U, V, W, X, Y, Z as follows: $$U\ast {\mathrm{I.}}_U+V\ast {\mathrm{I.}}_V+\mathrm{W.}\ast {\mathrm{I.}}_{\mathrm{W.}}+X\ast {\mathrm{I.}}_X+Y\ast {\mathrm{I.}}_Y+Z\ast {\mathrm{I.}}_Z={\mathrm{I.}}_G$$

In order to take into account an inaccuracy, it can be checked as an alternative third predetermined relationship (3 ') whether this sum corresponds at least essentially to the total current I _G : $$\left|\text{U}\ast {\text{I.}}_{\text{U}}+\text{V}\ast {\text{I.}}_{\text{V}}+\text{W.}\ast {\text{I.}}_{\text{W.}}+\text{X}\ast {\text{I.}}_{\text{X}}+\text{Y}\ast {\text{I.}}_{\text{Y}}+\text{Z}\ast {\text{I.}}_{\text{Z}}-{\text{I.}}_{\text{G}}\right|<{\text{I.}}_{\text{th}}$$

When checking in step 204 shows that the third predetermined relationship (3) or (3 ') is fulfilled, in step 205 determines that the total current was also recorded correctly. If, on the other hand, the third predetermined relationship (3) or (3 ') is not fulfilled, step 206 determines that the detected current intensity I _{G of} the total current is incorrect.

When checking in step 202 however, if the first predetermined relationship (1) or (1 ') is not fulfilled, this indicates that at least one current intensity I _U , I _V , I _{W of} the phases u , v , w the first group 101 was recorded incorrectly. In this case, step 207 also checks whether the third predetermined relationship (3) or (3 ') is fulfilled.

If the third predetermined relationship (3) or (3 ') is not satisfied in this case, step 209 determines that the current intensity I _{V is} incorrect, i.e. the current intensity of that phase v the first group 101 whose high-side and low-side switches M3 and M4 have changed their switching state before the first current measurement at the first time t ₁ .

If, however, the third relationship (3) or (3 ') is fulfilled, step 210 determines that either the current lu or the current I _{W is} incorrect, i.e. a current of the other two phases u , w the first group 101 . In this case, a further current measurement is required to determine which of these two current intensities lu or I _{W is} faulty.

$$\left|\left(1-\text{U}\right)\ast {\text{I}}_{\text{U}}+\left(1-\text{V}\right)\ast {\text{I}}_{\text{V}}+\left(1-\text{W}\right)\ast {\text{I}}_{\text{W}}+\left(1-\text{X}\right)\ast {\text{I}}_{\text{X}}+\left(1-\text{Y}\right)\ast {\text{I}}_{\text{Y}}+\left(1-\text{Z}\right)\ast {\text{I}}_{\text{Z}}+{\text{I}}_{\text{G}}\right|<{\text{I}}_{\text{th}}$$

Alternatively or in addition to the checking of the third predetermined relationship (3), (3 ') in step 207 can in step 208 It can also be checked as a fourth predetermined relationship (4) or (4 ') whether the sum of the recorded current strengths of the phase currents of those phases whose low-side switches are closed corresponds to the negative value of the recorded current strength of the total current or at least substantially corresponds to: $$\left(1-\text{U}\right)\ast {\text{I.}}_{\text{U}}+\left(1-\text{V}\right)\ast {\text{I.}}_{\text{V}}+\left(1-\text{W.}\right)\ast {\text{I.}}_{\text{W.}}+\left(1-\text{X}\right)\ast {\text{I.}}_{\text{X}}+\left(1-\text{Y}\right)\ast {\text{I.}}_{\text{Y}}+\left(1-\text{Z}\right)\ast {\text{I.}}_{\text{Z}}=-{\text{I.}}_{\text{G}}$$

$$\left|\left(1-\text{U}\right)\ast {\text{I.}}_{\text{U}}+\left(1-\text{V}\right)\ast {\text{I.}}_{\text{V}}+\left(1-\text{W.}\right)\ast {\text{I.}}_{\text{W.}}+\left(1-\text{X}\right)\ast {\text{I.}}_{\text{X}}+\left(1-\text{Y}\right)\ast {\text{I.}}_{\text{Y}}+\left(1-\text{Z}\right)\ast {\text{I.}}_{\text{Z}}+{\text{I.}}_{\text{G}}\right|<{\text{I.}}_{\text{th}}$$

If this fourth predetermined relationship (4) or (4 ') is satisfied, step 209 determines that the current Iv is incorrect. If the fourth predetermined relationship (4) or (4 ') is not fulfilled, step 210 determines that either the current lu or the current I _{W is} incorrect.

In the case of step 210 will be in step 211 A second current measurement is carried out at a second point in time, which can be used to determine whether I _U or I _W is now faulty.

Without loss of generality, before this second point in time t _2, for example, the switching state of the high-side switch M5 and the low-side switch M6 have changed phase u in particular changed so that the high-side switch M5 was closed and the low-side switch M6 was opened. The digital function U therefore has the value 1 at the second point in time t ₂ .

In step 212 it is then checked whether the current strengths detected in the course of the second current measurement satisfy the third predetermined relationship (3) or (3 '). If the third predetermined relationship (3) or (3 ') is satisfied, step 214 determines that the current I _{W of} the phase w is faulty. If, on the other hand, the third predetermined relationship (3) or (3 ') is not fulfilled, step 215 determines that the current lu of the phase u is faulty.

Alternatively or in addition to step 212 can also be in step 213 it can be checked whether the current intensities detected in the course of the second current measurement satisfy the fourth predetermined relationship (4) or (4 '). If the fourth predetermined relationship (4) or (4 ') is satisfied in this case, step 215 determines that the current I _{U of} the phase u is faulty. If, on the other hand, the fourth predetermined relationship (4) or (4 ') is not satisfied, step 214 determines that the current I _{W of} the phase w is faulty.

Unless in the review in step 202 it is recognized that the second predetermined relationship (2) or (2 ') is not fulfilled, this indicates, as explained above, that at least one of the current intensities I _X , I _Y , I _{Z of} the phases x , y , z the second group 102 is faulty.

In this case, step 221 a third current measurement is carried out at a third point in time. For example, this third point in time can be the point in time denoted by t ₄ in the table above, after the high-side switch M7 of the phase x closed and the low-side switch M8 of the phase x has been opened and thus the digital function X has assumed the value 1.

In step 222 will then step accordingly 207 checks whether the third predetermined relationship (3) or (3 ') is fulfilled.

If this predetermined relationship (3) or (3 ') is not fulfilled, step 224 determines that the current Ix of that phase x the second group 102 is faulty whose high-side and low-side switches M7 and M8 have changed their switching state before the third current measurement at the third time t ₄ . However, if the third predetermined relationship (3) or (3 ') is satisfied, step 225 determines that one of the other two currents I _Y , I _{Z of} the other phases y , z of the second group 102 is faulty.

Alternatively or additionally, according to step 223 the fourth predetermined relationship (4) or (4 ') can also be checked. If this is fulfilled, step is also used 224 determines that the current Ix is incorrect. If the fourth predetermined relationship (4) or (4 ') is not fulfilled, according to step 225 determines that one of the currents I _Y or Iz is faulty.

In the case of step 225 will be in step 231 a fourth current measurement is carried out at a fourth point in time, for example at point in time t ₅ according to the table above, at which the high-side switch M9 of the phase y closed and the low-side switch M10 was opened.

In step 232 it is then checked whether the current intensities recorded in the course of the fourth current measurement satisfy the third relationship (3) or (3 '). If so, step in 234 determines that the current I _{Z of} the phase z is faulty. If the third predetermined relationship (3) or (3 ') is not fulfilled, step 235 determines that the current I _{Y of} the phase y is faulty.

Alternatively or additionally, in step 233 be checked whether the fourth predetermined relationship (4) or (4 ') is met. If this is the case, step 235 determines that the current I _{Y of} the phase y is faulty. If the fourth predetermined relationship (4) or (4 ') is not fulfilled, according to step 234 determines that the current I _{Z of} the phase z is faulty.

QUOTES INCLUDED IN THE DESCRIPTION

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Patent literature cited

• US 2018/0102719 A1 [0003]

Claims (14)

Method for checking measured values of current strengths of currents which are provided by a six-phase converter to at least one electrical machine (E1, E2), each of the six phases (u, v, w, x, y, z) of the at least one electrical machine (E1, E2) each with a highside switch (M1, M3, M5, M7, M9, M11) and with one Lowside switch (M2, M4, M6, M8, M10, M12) of the converter is connected, where the high-side switches (M1, M3, M5, M7, M9, M11) of the converter are connected to a first converter connection (B +) and the low-side switches (M2, M4, M6, M8, M10, M12) of the converter are connected to a second converter connection (B-), whereby in the course of a current measurement for each of the six phases (u, v, w, x, y, z) a current strength of the corresponding phase current and a current strength of a total current between the highside switches (M1, M3, M5, M7, M9, M11) and the first converter connection (B +) are recorded (201, 211, 221, 231), whereby a check is carried out as a function of the recorded currents, - whether the sum of the recorded current intensities of the phase currents of the phases (u, v, w, x, y, z) of the at least one electrical machine (E1, E2) results in the value zero or at least essentially the value zero (202) and / or - whether the sum of the recorded amperages of the phase currents of those phases whose high-side switches (M1, M3, M5, M7, M9, M11) are closed corresponds or at least essentially corresponds to the recorded amperage of the total current (204, 207, 212, 222, 232) and / or - whether the sum of the recorded current strengths of the phase currents of those phases whose low-side switches (M2, M4, M6, M8, M10, M12) are closed corresponds to the negative value of the recorded current strength of the total current or at least essentially corresponds (208, 213 , 223, 233) and wherein, as a function of a result of the check, it is determined whether all detected current intensities are correct (205) or whether at least one of the detected current intensities is incorrect (206, 209, 210, 214, 215, 224, 225, 234, 235). Procedure according to Claim 1 , the current measurement being carried out at a point in time after a switching state of one of the highside switches (M1, M3, M5, M7, M9, M11) and of one of the lowside switches (M2, M4, M6, M8, M10 , M12) that are connected to the same phase (u, v, w, x, y, z) of the at least one electrical machine (E1, E2). Procedure according to Claim 2 , wherein a first current measurement is carried out at a first point in time (201) after a switching state of a first high-side switch (M3) and a first low-side switch (M4) has changed, which with a first phase (v) of the six phases (u, w, x, y, z) of the at least one electrical machine (E1, E2) are connected, being determined as a function of the current strengths detected in the course of the first current measurement in the course of the check (202, 203, 207, 208) - whether all the amperages detected in the course of the first current measurement are correct (203) or - whether the amperage of the total current detected in the course of the first current measurement is incorrect (206) or - whether the amperage of the phase current detected in the course of the first current measurement of the first Phase (v) is faulty (209) or - whether one of the current intensities of the phase currents of the remaining five phases (u, w, x, y, z) detected in the course of the first current measurement is faulty. Procedure according to Claim 3 , wherein if it is determined that one of the current intensities of the phase currents of the remaining five phases (u, w, x, y, z) detected in the course of the first current measurement is faulty, at least one further current measurement is carried out at at least one further point in time (211 , 221, 231) after a switching state of a high-side switch and a low-side switch that are connected to one of the remaining five phases (u, w, x, y, z) have changed, and depending on the In the course of the at least one further current measurement, it is determined in the course of the check (212, 213, 222, 223, 232, 233) which amperage of the phase currents of the remaining five phases (u, w, x, y, z) is faulty . Procedure according to Claim 3 or 4th , wherein the six phases (u, v, w, x, y, z) of the at least one electrical machine (E1, E2) have a first group (101) of three phases (u, v, w) and a second group (102 ) of three phases (x, y, z) and wherein the first phase (v) is a phase of the first group (101), wherein in the course of the check (202, 203, 207, 208) it is determined whether a the current strengths of the phase currents of a second phase (u) and a third phase (w) of the first group (101) of three phases (u, v, w) detected in the course of the first current measurement is faulty (210), or - whether at least one of the current intensities of the phase currents of the phases (x, y, z) of the second group (102) of three phases (x, y, z) detected in the course of the first current measurement is faulty. Procedure according to Claim 5 wherein, if it is determined that one of the detected current intensities of the phase currents of the second phase (u) and the third phase (w) of the first group (101) of three phases (u, v, w) is faulty (210), a second current measurement is carried out at a second point in time (211) after a switching state of a second high-side switch (M5) and a second low-side switch (M6) has changed, which with the second phase (u) of the first group (101) of three phases (u, v, w) are connected, the second point in time being after the first point in time, wherein it is determined in the course of the check (212, 213) whether the in the course of the second current measurement detected amperage of the phase current of the second phase (u) of the first group (101) of three phases (u, v, w) is faulty (215) or whether the amperage of the phase current detected in the course of the second current measurement of the third Phase (w) of the first group e (101) of three phases (u, v, w) is faulty (214). Procedure according to Claim 5 or 6 wherein, if it is determined that at least one of the current intensities of the phase currents of the second group (102) of three phases (x, y, z) detected in the course of the first current measurement is faulty, a third current measurement is carried out at a third point in time (221 ) after a switching state of a third high-side switch (M7) and a third low-side switch (M8) has changed, which is associated with a first phase (x) of the second group (102) of three phases (x, y, z) are connected, wherein the third point in time is after the first point in time, it being determined as a function of the current strengths detected in the course of the third current measurement in the course of the check (222, 223) whether the current strength of the phase current detected in the course of the third current measurement is first phase (x) of the second group (102) of three phases (x, y, z) is faulty (224) or whether one of the amperages of the phase currents of a second phase (y) of the second group detected in the course of the third current measurement ppe (102) of three phases (x, y, z) and a third phase (z) of the second group (102) of three phases (x, y, z) is defective (225). Procedure according to Claim 7 , wherein, if it is determined that one of the current intensities of the phase currents of the second phase (y) of the second group (102) of three phases (x, y, z) and the third phase (z) of the second group, detected in the course of the third current measurement Group (102) of three phases (x, y, z) is faulty (225), a fourth current measurement is carried out at a fourth point in time (231) after a switching state of a fourth high-side switch (M9) and a fourth low-side switch Switch (M10) has changed which are connected to the second phase (y) of the second group (102) of three phases (x, y, z), the fourth point in time occurring after the third point in time, depending on the Amperages detected in the course of the fourth current measurement are determined in the course of the check (232, 233), - whether the amperage detected in the course of the fourth current measurement of the phase current of the second (y) phase of the second group (102) of three phases (x, y , z) is incorrect (235) or - whether in the course of the four The amperage of the phase current of the third phase (z) of the second group (102) of three phases (x, y, z) detected is faulty (234). Method according to one of the preceding claims, wherein at least one of the current strengths of the phase currents and the total current is detected in the course of the at least one current measurement with the aid of a Hall sensor (131, 132, 133, 134, 135, 136, 137). Method according to one of the preceding claims, wherein, depending on the amperage of the total current detected in the course of the at least one current measurement, a ripple current of a capacitor element (C1) connected in parallel between the first converter connection (B +) and the second converter connection (B-) is determined. Method according to one of the preceding claims, wherein the at least one current measurement and the plausibility check are carried out in the course of a test phase, in the course of which the switching states of the individual high-side switches (M1, M3, M5, M7, M9, M11) and the individual low-side switches (M2, M4, M6, M8, M10, M12) can be changed. Arrangement (100) comprising a six-phase converter, at least one electrical machine (E1, E2) and a computing unit (140) which is set up to carry out all method steps of a method according to one of the preceding claims. Computer program that an arrangement (100) according to Claim 12 prompted all procedural steps of a method according to one of the Claims 1 to 12 to be carried out when it is executed on the computing unit (140). Machine-readable storage medium with a computer program stored thereon Claim 13 .

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