CN111830309A

CN111830309A - Method for checking measured values of the current intensity of a current supplied by a six-phase current transformer to at least one electric machine

Info

Publication number: CN111830309A
Application number: CN202010293749.5A
Authority: CN
Inventors: P.梅林格
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-04-16
Filing date: 2020-04-15
Publication date: 2020-10-27
Also published as: DE102019205471A1

Abstract

The invention relates to a method for checking measured values of the current intensity of a current supplied by a six-phase current transformer to at least one electric machine, wherein the current intensity of the total current and the current intensity of the respective phase current between a high-side switch and a first current transformer terminal are detected during at least one current measurement of each of the six phases, respectively, wherein a check is performed on the basis of the detected current intensities: whether the sum of the detected current strengths of the phase currents of the phases of the at least one electric machine results in a value of zero at least substantially and/or whether the sum of the detected current strengths of the phase currents of the phases whose high-side switches are closed corresponds at least substantially to the detected current strength of the total current and/or whether the sum of the detected current strengths of the phase currents of the phases whose low-side switches are closed corresponds at least substantially to the negative value of the detected current strength of the total current, and wherein it is determined on the basis of the checking result whether all the detected current strengths are correct or whether at least one of the detected current strengths is incorrect.

Description

Method for checking measured values of the current intensity of a current supplied by a six-phase current transformer to at least one electric machine

Technical Field

The invention relates to a method for checking measured values of the current intensity of a current supplied by a six-phase current transformer to at least one electric machine, to a computing unit and to a computer program for carrying out the method.

Background

For controlling or regulating an electric machine, such as an electric machine in a motor vehicle, which can be operated as an engine or as a generator, it is expedient to detect the phase currents of the individual phases of the electric machine in a measurement-related manner. Faulty measurement of the phase currents can negatively influence the control of the electric machine and for example cause errors in the torque regulation. It is therefore sensible to be able to detect whether the current intensity of the phase current has been detected in error.

US 2018/0102719 a1 shows the following possibilities: an error of a current sensor for measuring phase currents in a three-phase alternating current motor can be identified.

Disclosure of Invention

According to the invention, a method for checking measured values of the current intensity of the current supplied by a six-phase current transformer to at least one electric machine, a computing unit and a computer program for carrying out the method are proposed with the features of the independent claims. Advantageous embodiments are the subject matter of the dependent claims and the following description.

The invention provides the possibility of checking the current supplied by the six-phase current transformer to the at least one electric machine with as few sensors as possible.

For example, a six-phase converter can be connected to a six-phase machine, which has, for example, six windings, or, for example, also to two respective three-phase machines. Such an embodiment is used in particular when a plurality of electric machines are to be operated by means of only one electronic device, for example in an electric drive. The at least one electric machine thus has a total of six phase or six phase terminals. Each of the six phases of the at least one electric machine is connected to a high-side switch and a low-side switch of the converter. For this purpose, in particular one phase connection of the respective phase is connected to a center tap of the half bridge of the converter. The high-side switch is connected to the first converter terminal, in particular via a common electrical connection or a common bus or bus line. The first converter terminal may be, in particular, a positive potential terminal, a first consumer terminal or a first vehicle electrical system terminal, which may also be connected to a consumer and/or an energy source to be supplied, for example, a vehicle electrical system of a motor vehicle. Accordingly, the low-side switch of the converter is connected to the second converter terminal, in particular also via a second common electrical connection, such as a second bus or bus line. The second terminal is in particular a negative potential terminal, a second electrical load terminal or a second vehicle electrical system terminal for a further connection to an electrical load or an energy source to be supplied, for example a vehicle electrical system. Suitably, the second terminal may be a ground terminal.

In the context of the method, the current intensity of the total current and the current intensity of the respective phase current between the high-side switch and the first converter terminal are detected during the current measurement of each of the six phases. Each current measurement thus comprises determining seven measurement values. The current strengths of the phase currents are each detected in particular between a respective phase connection of a respective phase of the at least one electric machine and a respective center tap between a respective high-side and low-side switch of the converter. The total current or the current intensity of the bus current is detected in particular in the common connecting line or the bus line. As long as the intermediate circuit capacitor is connected in parallel between the first and second converter terminals, the current strength of the total current is suitably detected upstream of the intermediate circuit capacitor on the converter side. The respective current intensity can in particular be detected by means of suitable current sensors, for example by means of hall sensors.

In connection with the current strengths detected during the at least one current measurement, a check is carried out, in particular a check whether the detected current strengths satisfy a predetermined or desired relationship with respect to one another. In dependence on the result of the check, it is determined whether all detected current strengths are correct or whether at least one detected current strength is erroneous.

In this case, it is checked as a predetermined relationship whether the sum of the detected current strengths of the phase currents of the phases of at least one electric machine, in particular the sum of the currents of all phases belonging to the electric machine, results in zero or at least substantially in the value zero. In particular, it is checked for this purpose whether the absolute value of the sum falls below a predetermined threshold value. The threshold value may be, for example, at most 20% of the rated phase current and may have, for example, a value of 70A (with phase currents of up to 400A). Without limiting the generality, the predetermined relationship shall also be referred to as first relationship in the following.

If at least one electric machine has two sets of three phases each, for example if a converter is connected to two three-phase machines, it can be checked as a first predetermined relationship, in particular, whether the sum of the detected current strengths of the phase currents of the phases of the first set results in zero or at least substantially zero, and as a second predetermined relationship, in particular, whether the sum of the current strengths of the phase currents of the phases of the second set results in zero or at least substantially zero.

Alternatively or additionally, it is checked as a predetermined relationship whether the sum of the detected current strengths of the phase currents of the phases of the at least one electric machine whose high-side switch is closed corresponds or at least substantially corresponds to the detected current strength of the total current. The relationship is referred to hereinafter without limiting the generality as a third predetermined relationship. In particular, it is therefore checked whether the sum of the phase currents whose high-side switches are closed corresponds at least substantially to the detected total current or bus current. It can be suitably checked whether the sum minus the current intensity of the total current is lower in absolute value than a preset threshold value, for example, of the highest 20% of the phase rated current.

Alternatively or additionally, it is checked as a predetermined relationship whether the sum of the detected current strengths of the phase currents of those phases of the at least one electric machine whose low-side switch is closed corresponds or at least substantially corresponds to the negative value of the detected current strength of the total current. Suitably, said relationship is referred to hereinafter without limitation in generality as a fourth predetermined relationship. In contrast to the third predetermined relationship, it is therefore checked in the fourth predetermined relationship whether the sum of the phase currents whose low-side switches are closed corresponds at least substantially to the negative value of the detected total current or bus current. In particular, for this purpose, it can be checked whether the sum minus the current intensity of the total current is below a predetermined threshold value, for example, of up to 20% of the rated current of the phase, in absolute terms.

In particular, it can also be checked as a predetermined relationship whether the sum of the detected current strengths of the phase currents of the phases whose high-side switch is closed corresponds or at least substantially corresponds to the negative value of the sum of the detected current strengths of the phase currents of the phases whose low-side switch is closed.

The method therefore offers the possibility of detecting only the further current intensity of the further current in addition to the six current intensities of the six phase currents in the six-phase current transformer, and by means of a predetermined relationship it can be recognized whether one or more of these seven current intensities were detected incorrectly.

For controlling or regulating the electric machine, it is expedient to correctly detect the current strengths of the phase currents of the individual phases, since a current strength of a phase current which is detected in error negatively affects the control of the electric machine and can, for example, cause errors in the torque regulation. In the context of the method, it can be recognized in a cost-effective and efficient manner whether the current intensity of the phase current is detected incorrectly, and if this is the case, this incorrect detection can be responded to accordingly during the control of the electric machine.

Advantageously, the at least one current measurement is performed at least one time after a change of switching state of one of the high-side switches and one of the low-side switches connected to the same phase. Such a time instant at which the current measurement is carried out lies in particular in a time interval between a first switching time instant at which the switching state of the respective high-side and low-side switch changes and a second switching time instant at which the switching state of the high-side switch and/or the low-side switch changes next.

In particular, the current measurement is carried out after a change in the switching state of two switches of a half bridge of the converter, which are connected to the same phase of the at least one electric machine. A change of the switch state is understood in this context in particular to mean that the respective switch is previously closed and subsequently opened or conversely is previously opened and subsequently closed.

In particular, the respective current switching state of the half-bridges or of the individual high-side and low-side switches at the time of the current measurement is taken into account as a parameter or boundary condition when checking the predetermined relationship. Performing and evaluating the current measurement at a time immediately after the change of the respective switching state of the exactly one half bridge is a particularly effective way, so that faulty measurements can be accurately inferred from a predetermined relationship.

According to one advantageous embodiment, a first current measurement is carried out at a first time after a change in the switching state of a first high-side switch and a first low-side switch connected to a first of the six phases of the at least one electric machine. The terms "first" high-side switch "," first "low-side switch", "first" and the like are in particular to be understood in the scope of the present description without limiting the generality and without expressing the importance or value of the individual elements in question. Rather, the designation of "first" element is used only to distinguish the remaining elements. In particular, each of the switches, equivalents, described herein may be suitably selected as the "first" element. Likewise, in the following, if reference is made to "second", "third", "fourth", etc. elements, these terms should not be construed as limiting the generality either.

In connection with the current intensity detected during the first current measurement, one of the following four cases can advantageously be identified during the examination.

It is preferably determined that all the current intensities detected during the first current measurement are correct. As long as all seven current measurements are correct, this can already be recognized within the scope of the method by means of only a single current measurement at a single time. In particular, this is determined in the following cases: the sum of the detected current strengths of the phase currents of the at least one electric machine yields zero or at least substantially zero, i.e. the first relation or the first and second relations are fulfilled.

It can also be advantageously recognized whether the current intensity of the total current detected during the first current detection is erroneous. The total current or bus current detected in error can therefore already be identified by means of a current measurement which is unique at a single time. This is especially the case: the first relationship described above is satisfied and the third relationship is not satisfied in the first current measurement.

It can also be determined, preferably, whether the current strength of the phase current of the first phase detected during the first current measurement is incorrect. This is especially the case: the first relationship is not satisfied and the third relationship is also not satisfied, or the first relationship is not satisfied and the fourth relationship is satisfied. In particular, it can thus be recognized whether the current strength of the phase current of the phase whose high-side switch and low-side switch have changed their switching state has been erroneously detected.

Alternatively, it is preferably determined whether the current intensities of the phase currents of the remaining five phases detected during the first current measurement are incorrect. This is especially the case: the first relationship is not satisfied and the third relationship is satisfied, or the first relationship and the third relationship are not satisfied, respectively. In order to distinguish exactly which current intensity is faulty, at least one further current measurement is allowed in particular.

In the latter case, if it is determined that the current intensity of the phase currents of the remaining five phases detected during the first current measurement is faulty, then advantageously at least one further current measurement is carried out at least one further point in time after a respective change in the switching state of the high-side switch and the low-side switch which are connected to the same phase in the remaining five phases. In connection with the current strengths detected during the at least one further current measurement, it is advantageously determined during the examination which of the remaining five-phase current strengths is faulty.

Preferably, the six phases of the at least one electric machine have a first set of three phases and a second set of three phases. For example, each of the two sets of phases may represent a three-phase motor.

The first phase is preferably a phase of the first group. During the test, it is advantageously determined in this case whether the current intensities of the phase currents of the second phase and of the third phase of the three phases of the first group detected during the first current measurement are incorrect. This is determined in particular in the following cases: the first relationship is not satisfied and the third relationship is satisfied, or the first relationship and the fourth relationship are not satisfied, respectively. In order to distinguish exactly which current strength of the second and third phases is faulty, a second current measurement is allowed at a second time, in particular after a change in the switching state of the high-side and low-side switches of one of the two phases.

Alternatively, it can preferably be detected whether at least one of the phase currents of the phases of the three phases of the second group has an error in the current intensity detected during the first current measurement. In order to precisely distinguish which phase current in the three phases of the second group was erroneously detected, additional current measurements are suitably allowed at additional times after a change in the switching state of the switches of these phases.

If it is determined that one of the detected current strengths of the phase currents of the second phase and the third phase of the three phases of the first group is faulty, a second current measurement is carried out at a second point in time, according to an advantageous embodiment. At the second instant, the switching states of a second high-side switch and a second low-side switch connected to a second phase of the first group change. The second time advantageously follows the first time in time. As mentioned above, the designations "second" high-side switch, "second" low-side switch, "second" and the like are not to be construed in a limiting sense.

In connection with the current strength detected during the second current measurement, it is advantageously determined during the check whether the current strength of the phase current of the second phase of the first set detected in the second current measurement is faulty or whether the current strength of the phase current of the third phase of the first set detected during the second current measurement is faulty. The current strength of the second phase is determined in error, in particular in the following cases: the third relationship is not satisfied or the fourth relationship is satisfied. If the third relationship or the fourth relationship is not satisfied, it is in particular determined that the current strength of the third phase is faulty. If the phase current of one phase of the first group is detected incorrectly, it can be determined at the latest by means of two current measurements at two different times, which phase current was detected incorrectly.

If it is determined that the current intensity of the phase currents of the phases of the three phases of the second group detected during the first current measurement is faulty, a third current measurement is advantageously carried out at a third point in time. The third time advantageously follows the first time in time. Furthermore, the third time is located in particular after the second time. In particular, the second current measurement described above can also be omitted and a further current measurement can be carried out only at the third point in time, if the current strength of the second or third phase of the first group is detected incorrectly at the first point in time.

At the third point in time, the switching states of the third high-side switch and the third low-side switch connected to the first phase of the second group (fourth phase overall) have advantageously changed. The switching state of the switches of the phases of the second group is therefore changed at the third time in order to determine which phase current of the second group was detected in error. In connection with the current intensity detected during the third current measurement, one of the two following cases is advantageously identified during the examination.

It is determined that the current intensity detected during the third current detection of the phase current of the first phase of the second group is erroneous. In particular, it can thus be recognized immediately after the third current measurement whether the current strength of the phase current of the phase whose high-side switch and low-side switch change their switching state at the third instant has been erroneously detected.

Alternatively, it is determined that one of the current strengths detected during the third current measurement of the phase currents of the second phase (fifth phase) of the second group and of the third phase (sixth phase) of the second group is faulty. In order to determine precisely whether the second phase or the third phase of the second group is detected incorrectly, it is appropriate to allow further current measurements.

In the latter case, if it is determined that one of the current strengths detected during the third current measurement of the phase currents of the second and third phases of the second group is faulty, a fourth current measurement is advantageously carried out at a fourth instant. The fourth time is preferably located after the third time in time. At a fourth time, the switching states of a fourth high side switch and a fourth low side switch connected to the second phase of the second group have changed. In connection with the current strength detected during the fourth current measurement, it is determined during the check whether the current strength detected during the fourth current measurement of the phase currents of the second phase of the second set is faulty or whether the current strength detected during the fourth current measurement of the phase currents of the third phase of the second set is faulty. In the context of the method, it can therefore be precisely determined, particularly at the latest, after four current measurements at four different times, which of the six phase currents may be incorrectly detected, if one of the six phase currents is incorrectly detected.

Preferably, the total current and at least one current intensity of the phase current are detected by means of a hall sensor during at least one current measurement. Preferably, all these current levels are detected by means of hall sensors. Due to the fringe field, the hall sensor may easily result in erroneous current measurements. The method therefore provides particularly advantageously for error checking the current strength detected by means of the hall sensor in a six-phase motor.

Preferably, the ripple current or the current ripple load of the capacitor element or the intermediate circuit capacitor connected in parallel between the first and second converter terminals is determined as a function of the current intensity of the total current detected during the at least one current measurement. An alternating current is understood to mean, in particular, a ripple current or a so-called superimposed alternating current, which is superimposed on a direct current. Such ripple currents can be generated in particular by pulsating direct currents generated by the converter in parallel-connected capacitor elements or intermediate circuit capacitors.

Preferably, the at least one current measurement and the reliability test are performed during a test phase during which the switching state of the respective high-side switch and the respective low-side switch changes. In particular, the switching states are changed continuously in this case, i.e. the switching states of the different high-side and low-side switches of the respective half-bridge are suitably changed continuously. If the converter is connected to two respective three-phase motors, one of the motors can be deactivated or switched off for the test phase, as appropriate.

The computing unit according to the invention, for example a control device of a motor vehicle, is designed in particular in terms of program technology for carrying out the method according to the invention.

The implementation of the method according to the invention in the form of a computer program or a computer program product with program code for carrying out all method steps is also advantageous, since this results in particularly low costs, in particular when the implemented control device is also used for other tasks and is therefore always present. Suitable data carriers for supplying the computer program are, in particular, magnetic, optical and electrical memories, such as a hard disk, flash memory, EEPROM, DVD, etc. It is also possible to download the program via a computer network (internet, ethernet, etc.).

Further advantages and embodiments of the invention emerge from the description and the drawing.

Drawings

The invention is schematically illustrated in the drawings and will be described hereinafter with reference to the drawings according to embodiments.

Fig. 1 schematically shows a preferred embodiment of a device with a converter and two electric machines, which can be based on a preferred embodiment of the method according to the invention.

Fig. 2 shows a preferred embodiment of the method according to the invention schematically as a block diagram.

Detailed Description

Fig. 1 schematically shows an advantageous embodiment of a device with a converter and two electric machines E1, E2, and designated by 100. The device 100 is suitably arranged in a motor vehicle and can be operated, for example, in the manner of a generator in order to generate electrical energy for supplying consumers in the on-board electrical system of the vehicle or in the manner of an engine in order to use the electrical energy stored in the on-board electrical system for driving the vehicle.

The device has six phases or phase terminals. In the example of fig. 1, the device 100 has two three-phase motors E1 and E2. It is likewise conceivable to provide a six-phase machine with six windings.

The first electric machine E1 has a first group 101 of three phases u, v, w. The second motor E2 has a second group 102 of three phases x, y, z.

For the phases u, v, w of the first machine E1 or of the first group 101, there is a first part 110 of the converter with high-side switches M1, M3, M5 and low-side switches M2, M4, M6. Correspondingly, for the phases x, y, z of the second machine E2 or of the second group 102, there is provided a second part 120 of the converter with high-side switches M7, M9, M11 and low-side switches M8, M10, M12. The high-side and low-side switches can each be in the form of a semiconductor switching element, for example in the form of 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 is connected with an

intermediate tap

111, 112, 113, 121, 122, 123 between the respective high-side switch and low-side switch.

The high-side switches M1, M3, M5 or M7, M9, M11 are also connected in common to the first converter terminal or the vehicle electrical system terminal B +. The low-side switches M2, M4, M6 or M8, M10 and M12 are connected in common to a second converter terminal or a vehicle electrical system terminal B-. The terminals B + and B-can also be connected to energy sources and consumers in the onboard network of the motor vehicle. As such an electrical load, a resistor R1 is shown by way of example in fig. 1, which may be, for example, a rear window heater. Furthermore, an intermediate circuit capacitor C1 is provided in parallel with the vehicle electrical system terminals B + and B-.

The control device 140 is also provided for controlling the apparatus 100 and for this purpose, in particular, for actuating the switches of the

converters

110, 120. The control is suitably carried out in relation to the current phase current of the respective phase u, v, w, x, y, z. In order to measure the current intensity of the phase current, a

current sensor

131, 132, 133, 134, 135 or 136 is provided for each phase u, v, w, x, y, z. For example, the

current sensors

131, 132, 133, 134, 135, 136 may each be configured as hall sensors.

Furthermore, a current sensor 137 is provided in the common connecting line or bus line between the high-side switch M1, M3, M5 or M7, M9, M11 and the first converter terminal B +, in order to detect the current intensity of the total current or bus current. The current sensor 137 may also be configured as a hall sensor. The current sensor 137 is arranged upstream of the capacitor C1 on the converter side.

However, such hall sensors may easily result in erroneous current measurements due to stray fields. However, faulty measurement of the phase currents can negatively affect the control of the electric machine 100 and for example cause errors in the torque regulation.

In order to be able to detect whether the respective current intensity is detected correctly or in error by means of the

hall sensors

131, 132, 133, 134, 135, 136, 137, the control device 140 is designed, in particular in terms of programming, to carry out a preferred embodiment of the method according to the invention, which is illustrated schematically as a block diagram in fig. 2 and which is subsequently described with reference to fig. 1 and 2.

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

During this current measurement, the current intensity I of the respective phase current is determined for each of the six phases u, v, w, x, y or z by means of the

hall sensors

131, 132, 133, 134, 135, 136_U、I_V、I_W、I_X、I_YOr I_ZAnd the current intensity I of the total current is detected by means of the hall sensor 137_G。

In connection with the predetermined relationship between the detected current intensity and the current intensity, the following check or plausibility test is carried out, all detected current intensities I_U、I_V、I_W、I_X、I_Y、I_ZAnd I_GWhether it is correct or whether at least one of the detected current intensities is erroneous.

For the predetermined relationship, for example, a digital function is defined for each phase or for each pair of high-side and low-side switches, respectively, which digital function can assume the value 0 or 1, respectively, and thus characterizes the switching state of the two corresponding switches of the phase.

Thus, for example, a digital function U is defined for the high-side switch M5 and the low-side switch M6 of phase U. If the 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 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.

Accordingly, a digital function V, W, X, Y or Z is also defined for the remaining phases v, w, x, y, Z, respectively, wherein a value 1 of the function indicates that the respective high-side switch of the respective phase is closed and the respective low-side switch is open, respectively, and wherein a value 0 of the digital function indicates that the respective high-side switch is open and the respective low-side switch is closed, respectively.

The following table is an exemplary control diagram for continuously changing the switching states of the individual high-side and low-side switches, wherein the switching states of the switch pairs respectively change at successively following times t1 to t6 respectively.

In the following, it is now explained with reference to fig. 2 how, within the scope of a preferred embodiment of the method according to the invention, it is checked whether the respective current strength is correctly detected.

In step 201 a first current measurement is performed at a first time instant. Without limiting generality, examples are observed hereinafter: at the time t1, which is the first time according to the above table, after the switching state of the high-side switch M3 and the low-side switch M4 of the phase V has changed, the high-side switch M3 is closed and the low-side switch M4 is opened and the digital function V assumes the value 1 at this first time t 1. The digital function U, W, X, Y, Z of the remaining phases u, w, x, y, z is, at this first time t1, for example, each a value 0, i.e., the remaining high-side switches are open and the remaining low-side switches are closed.

In step 202, the currents of the phase currents of the three phases u, v, w of the first group 101 which are detected during the first current measurement are checked as a first predetermined relationship (1)Strength I_U、I_V、I_WWhether the sum of (a) yields the value zero or at least substantially the value zero:

in order to allow a certain measurement accuracy, the first predetermined relationship (1') can also be checked as an alternative, in particular, whether the sum at least substantially yields a value of zero or whether the absolute value of the sum falls below a predetermined threshold value I, for example, of up to 20% of the rated phase current_thE.g., 70A (in the case of phase current of 400A):

in particular, it can also be checked in step 202 as a second predetermined relationship (2) that the current intensity I of the phase currents of the three phases x, y, z of the second group 102, which were detected during the first current measurement, is present_X、I_Y、I_ZWhether the sum of (a) yields the value zero or at least substantially the value zero:

in order to also allow a certain measurement accuracy in this case, as an alternative a second predetermined relationship (2') can be checked whether the sum at least substantially results in a value of zero or whether the absolute value of the sum is less than a predetermined threshold value I_th：

If the first predetermined relationship (1) or (1') is fulfilled, it is determined in step 203 that the detected current strength I of the phases u, v, w_U、I_V、I_WIs correct. If, in addition, the predetermined relationship (2) or (2') is also satisfied, step 203 also includesDetermining the detected current intensity I of the phases x, y, z_X、I_Y、I_ZIt is also correct so that all phase currents are correctly detected.

If the second relationship (2) or (2') is not satisfied, this means that at least one of the current strengths I of the phases x, y, z of the second group 102_X、I_Y、I_ZIs faulty. In this case, at least one additional current measurement is allowed and step 221 is carried out at a later time, as shall also be explained further below.

However, first consider the case where the first theoretical relationship (1) or (1') examined in step 202 is satisfied and the current intensity I of the phases u, v, w of the first group 101_U、I_V、I_WIs correct. In this case, it is checked in step 204 as a third predetermined relationship (3) whether the sum of the detected current strengths of the phase currents of the phases whose high-side switches are closed corresponds to the detected current strength of the total current. The predetermined relationship (3) can be mathematically expressed by means of a numerical function U, V, W, X, Y, Z as follows:

in order to take the inaccuracies into account, an alternative third predetermined relationship (3') can be checked whether the sum substantially corresponds to the total current intensity I_G：

If the check in step 204 results in that the third predetermined relationship (3) or (3') is fulfilled, then it is determined in step 205 that the total current is also correctly detected. If, however, the third predetermined relationship (3) or (3') is not satisfied, then in step 206 it is determined that the detected current intensity I of the total current is present_GIs faulty.

However, if the check in step 202 yields, the first advanceDetermining that the relation (1) or (1') is not fulfilled, this then means that at least one of the current strengths I of the phases u, v, w of the first group 101_U、I_V、I_WIs detected with errors. In this case, it is likewise checked in step 207 whether a third predetermined relationship (3) or (3') is satisfied.

If the third predetermined relationship (3) or (3') is not satisfied in this case, it is determined in step 209 that the current intensity I_VIs erroneous, i.e. the current strength of the phase v of 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 instant t1 is erroneous.

And if the third relation (3) or (3') is satisfied, it is determined in step 210 that the current intensity I_UOr current intensity I_WIs erroneous, i.e. one of the current strengths of the two other phases u, w of the first set 101 is erroneous. In this case, a further current measurement is allowed in order to determine which of the two current levels is_UOr I_WIs faulty.

Alternatively or additionally to the check of the third predetermined relationship (3), (3 ') in step 207, it can also be checked as a fourth predetermined relationship (4) or (4') in step 208 whether the sum of the detected current strengths of the phase currents of the phases whose low-side switch is closed corresponds or at least substantially corresponds to the negative value of the detected current strength of the total current:

if said fourth predetermined relationship (4) or (4') is fulfilled, it is also determined in step 209 that the current intensity I_VIs faulty. If the fourth predetermined relationship (4) or (4') is not satisfied, again as determined in step 210, the current level I_UOr current intensity I_WIs faulty.

In the case of step 210, a second time is executed in step 211 at a second instantA current measurement from which it can be determined that I is now_UOr I_WWhether it is faulty or not.

Without limiting generality, before said second time t2, the switching states of the high-side switch M5 and the low-side switch M6 of phase u, for example, have changed in particular such that the high-side switch M5 is closed and the low-side switch M6 is open. Digital function U at a second time t₂And thus has a value of 1.

In step 212, it is checked whether the current intensity detected during the second current measurement satisfies a third predetermined relationship (3) or (3'). If the third predetermined relationship (3) or (3') is satisfied, the current strength I of the phase w is determined in step 214_WIs faulty. And if the third predetermined relationship (3) or (3') is not satisfied, the current intensity I of the phase u is determined in step 215_UIs faulty.

Alternatively or additionally to step 212, it may also be checked in step 213 whether the current intensity detected during the second current measurement satisfies a fourth predetermined relationship (4) or (4'). If the fourth predetermined relationship (4) or (4') is fulfilled in this case, it is determined in step 215 that the current strength I of the phase u_UIs faulty. And if the fourth predetermined relationship (4) or (4') is not satisfied, the current intensity I of the phase w is determined in step 214_WIs faulty.

As long as in the check in step 202 the second predetermined relationship (2) or (2') is not satisfied, this is expressed as explained above, and the current strengths I of the phases x, y, z of the second group 102_X、I_Y、I_ZIs faulty.

In this case, a third current measurement is performed at a third instant in step 221. After the high-side switch M7 of phase X is closed and the low-side switch M8 of phase X is open so that the digital function X assumes the value 1, the third time may be, for example, the time indicated by t4 in the above table.

In step 222, it is checked in accordance with step 207 whether a third predetermined condition (3) or (3') is fulfilled.

If the predetermined relationship (3) or (3') is not satisfied, it is determined in step 224 that the current strength I of the phase x of the second group 102 whose high-side and low-side switches M7 and M8 have changed their switching state before the third current measurement at instant t4_XIs faulty. However, if the third predetermined relationship (3) or (3') is satisfied, then in step 225 it is determined that the two other current strengths I of the further phases y, z of the second group 102_Y、I_ZOne is faulty.

Alternatively or additionally, according to step 223, a fourth predetermined relationship (4) or (4') may also be checked. If the relationship is satisfied, then it is also determined in step 224 that the current level I_XIs faulty. If the fourth predetermined relationship (4) or (4') is not satisfied, then the amperage I is determined according to step 225_YOr I_ZIs faulty.

In the case of step 225, a fourth current measurement is carried out in step 231 at a fourth time, for example at time t5 according to the above table, at which time the high-side switch M9 of phase y is closed and the low-side switch M10 is open.

In step 232, it is checked whether the current strength detected during the fourth current measurement satisfies a third relationship (3) or (3'). If this is the case, it is determined in step 234 that the current strength I of the phase z is_ZIs faulty. If the third predetermined relationship (3) or (3') is not satisfied, then in step 235 it is determined that the amperage I of phase y is_YIs faulty.

Alternatively or additionally, in step 233 it may be checked whether a fourth predetermined relationship (4) or (4') is fulfilled. If this is the case, it is determined in step 235 that the current strength I of phase y is_YIs faulty. If the fourth predetermined relationship (4) or (4') is not satisfied, the current strength I of the phase z is determined in accordance with step 234_ZIs faulty.

Claims

1. A method for checking measured values of the current intensity of an electric current supplied by a six-phase current transformer to at least one electric machine (E1, E2),

wherein each of the six phases (u, v, w, x, y, z) of the at least one electric machine (E1, E2) is connected to a high-side switch (M1, M3, M5, M7, M9, M11) and a low-side switch (M2, M4, M6, M8, M10, M12) of the converter,

wherein the high-side switches (M1, M3, M5, M7, M9, M11) of the converter are connected to a first converter terminal (B +) and wherein the low-side switches (M2, M4, M6, M8, M10, M12) of the converter are connected to a second converter terminal (B-),

wherein the current strength of the total current and the current strength of the respective phase current between the high-side switch (M1, M3, M5, M7, M9, M11) and the first converter terminal (B +) are detected (201, 211, 221, 231) during a current measurement for each of the six phases (u, v, w, x, y, z), respectively,

wherein the following check is performed in relation to the detected current strength,

-whether a sum of detected amperages of phase currents of phases (u, v, w, x, y, z) of the at least one electric machine (E1, E2) results in a value of zero or at least substantially in a value of zero (202), and/or

Whether the sum of the detected current strengths of the phase currents of the phases for which the high-side switch (M1, M3, M5, M7, M9, M11) is closed corresponds or at least substantially corresponds to the detected current strength (204, 207, 212, 222, 232) of the total current and/or

Whether the sum of the detected current strengths of the phase currents of those phases for which the low-side switch (M2, M4, M6, M8, M10, M12) is closed corresponds or at least substantially corresponds to the negative value (208, 213, 223, 233) of the detected current strength of the total current, and

wherein, depending on the result of the check, it is determined whether all detected current strengths are correct (205) or whether at least one detected current strength is faulty (206, 209, 210, 214, 215, 224, 225, 234, 235).

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein a current measurement is performed at a moment after a change of a switching state of one of the high-side switches (M1, M3, M5, M7, M9, M11) and one of the low-side switches (M2, M4, M6, M8, M10, M12) connected to a same phase (u, v, w, x, y, z) of the at least one electric machine (E1, E2).

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

wherein a first current measurement is performed (201) at a first time after a change of the switching state of a first high-side switch (M3) and a first low-side switch (M4) connected to a first phase (v) of six phases (u, w, x, y, z) of the at least one electric machine (E1, E2), wherein the first current measurement is determined during a check (202, 203, 207, 208) in relation to the current strength detected during the first current measurement,

-whether the current intensity detected during the first current measurement is correct throughout (203), or

-whether the current strength of the total current detected during the first current measurement is faulty (206), or

-whether the current strength of the phase current of the first phase (v) detected during the first current measurement is faulty (209), or

-whether one of the current strengths detected during the first current detection of the phase currents of the remaining five phases (u, w, x, y, z) is faulty.

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein if it is determined that one of the current strengths detected during the first current detection of the phase currents of the remaining five phases (u, w, x, y, z) is faulty, at least one further current measurement is performed (211, 221, 231) at least one further moment after the switching state of the high-side switch and the low-side switch, respectively, connected to one of the remaining five phases (u, w, x, y, z) has changed, and wherein it is determined during the examination (212, 213, 222, 223, 232, 233) which current strength of the phase currents of the remaining five phases (u, w, x, y, z) is faulty in relation to the current strength detected during the at least one further current measurement.

5. The method according to claim 3 or 4,

wherein the six phases (u, v, w, x, y, z) of the at least one electric machine (E1, E2) have a first set (101) of three phases (u, v, w) and a second set (102) of three phases (x, y, z), and wherein the first phase (v) is a first set (101) of phases, wherein it is determined during the examination (202, 203, 207, 208),

-whether one of the current intensities detected during the first current measurement of the phase currents of the second phase (u) and the third phase (w) of the three phases (u, v, w) of the first set (101) is faulty (210), or

-whether at least one of the current strengths of the phase currents of the phases (x, y, z) of the three phases (x, y, z) of the second set (102) detected during the first current measurement is faulty.

6. The method of claim 5, wherein the first and second light sources are selected from the group consisting of,

wherein a second current measurement is performed (211) at a second time instant after a change of the switching state of a second high-side switch (M5) and a second low-side switch (M6) connected to the second phase (u) of the three phases (u, v, w) of the first group (101) if it is determined that one of the detected current strengths of the phase currents of the second phase (u) and the third phase (w) of the three phases (u, v, w) of the first group (101) is faulty,

wherein the second time instant is temporally subsequent to the first time instant,

wherein the current intensity detected during the second current measurement is determined during the checking (212, 213),

whether the current strength of the phase current of the second phase (u) of the first set (101) of three phases (u, v, w) is faulty (215) or whether the current strength of the phase current of the third phase (w) of the first set (101) of three phases (u, v, w) is faulty (214) during the second current measurement.

7. The method according to claim 5 or 6,

wherein if it is determined that at least one of the current intensities detected during the first current measurement of the phase currents of the three phases (x, y, z) of the second set (102) is faulty, a third current measurement is performed (221) at a third time after a change of the switching state of a third high-side switch (M7) and a third low-side switch (M8) connected to the first phase (x) of the three phases (x, y, z) of the second set (102),

wherein the third time instant is subsequent in time to the second time instant,

wherein the current intensity detected during the third current measurement is determined during the examination (222, 223),

whether the current intensity of the phase current of the first phase (x) of the second set (102) of three phases (x, y, z) detected during the third current measurement is faulty (224), or

Whether one of the current strengths detected during the third current measurement of the phase currents of the second phase (y) of the second group (102) of three phases (x, y, z) and of the third phase (z) of the second group (102) of three phases (x, y, z) is faulty (225).

8. The method of claim 7, wherein the first and second light sources are selected from the group consisting of,

wherein if it is determined that one of the current strengths detected during the third current measurement of the phase currents of the second phase (y) of the three phases (x, y, z) of the second group (102) and of the third phase (z) of the three phases (x, y, z) of the second group (102) is faulty (225), a fourth current measurement is performed (231) at a fourth time instant after a change of the switching state of a fourth high-side switch (M9) and a fourth low-side switch (M10) connected to the second phase (y) of the three phases (x, y, z) of the second group (102),

wherein the fourth time instant is subsequent in time to the third time instant,

wherein the current intensity detected during the fourth current measurement is determined during the checking (232, 233),

-whether the current intensity of the phase current of the second phase (y) of the second set (102) of three phases (x, y, z) detected during the fourth current measurement is faulty (235), or

-whether the current intensity of the phase current of the third phase (z) of the second set (102) of three phases (x, y, z) detected during the fourth current measurement is faulty (234).

9. The method according to any one of the preceding claims,

wherein at least one current intensity of the total current and of the phase currents is detected during at least one current measurement by means of a Hall sensor (131, 132, 133, 134, 135, 136, 137), respectively.

10. The method according to any one of the preceding claims,

wherein a ripple current of a capacitor element (C1) connected in parallel between the first converter terminal (B +) and the second converter terminal (B-) is determined in relation to a current intensity of a total current detected during at least one current measurement.

11. The method according to any one of the preceding claims,

wherein at least one current measurement and confidence test is performed during a test phase during which the switching state of the respective high-side switch (M1, M3, M5, M7, M9, M11) and the respective low-side switch (M2, M4, M6, M8, M10, M12) is changed.

12. An arrangement (100) consisting of a six-phase current transformer, at least one electric machine (E1, E2) and a computing unit (140), which is designed to carry out all the method steps of the method according to any one of the preceding claims.

13. A computer program that facilitates an apparatus (100) according to claim 12, when the computer program is implemented on the computing unit (140), to perform all method steps of the method according to any one of claims 1 to 12.

14. A machine-readable storage medium having stored thereon a computer program according to claim 13.