Method for calibrating current sensors, control device for an electric drive system, and electric drive system

Abstract

The invention relates to recalibration or correction of the parameterization of current sensors in an electric drive system. For this purpose, provision is made for harmonics of a variable for controlling the electric machine to be minimized and new correction values for the current sensors to be determined on the basis of the parameterization required for the minimization.

Description

[0001] Description

[0002] title

[0003] Method for calibrating current sensors, control device for an electric drive system and electric drive system

[0004] The present invention relates to a method for calibrating current sensors, in particular for calibrating current sensors in an electric drive system. The present invention further relates to a control device for an electric drive system and an electric drive system with such a control device. The present invention particularly relates to the determination of correction parameters for current sensors for detecting phase currents in an electric drive system.

[0005] background

[0006] The document DE 10 2017 203 691 A1, for example, describes a control device for an electrical machine and electrical drive system, whereby a disturbance variable can be compensated and a setpoint value can be set simultaneously.

[0007] For the operation of an electrical machine, such as a multi-phase permanently excited synchronous machine (PSM), a phase current can be adjusted as a setpoint. This phase current is preferably adjusted as a sinusoidal fundamental wave. Such a phase current results in the output of a uniform average torque during operation of the electrical machine. For this type of phase current control, the electrical currents in the phase lines of the electrical machine must be recorded by sensors. Current sensors are provided for this purpose, each of which outputs a sensor signal corresponding to an electrical current in a phase line. For reliable operation, the correct calibration of the sensors, for example the correct setting of the offset and gain factor of the sensors, is of crucial importance.

[0008] Disclosure of the invention

[0009] The present invention provides a method for calibrating current sensors in an electric drive system, a control device for an electric drive system, and an electric drive system having the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

[0010] Accordingly, it is provided:

[0011] A method for calibrating current sensors, in particular current sensors in an electrical drive system, such as an electrical drive system with a permanently excited synchronous machine (PSM). The method comprises a step for generating a first controlled variable for controlling an electrical machine in the electrical drive system. The first controlled variable can, for example, specify an electrical voltage to be set. The first controlled variable can be generated using sensor values ​​from current sensors, in particular from current sensors in the phase lines of the electrical machine. Furthermore, the first controlled variable can be generated using a setpoint to be set, for example a torque to be set, a speed to be set, or the like.The method further comprises a step for detecting harmonics in a variable for controlling the electrical machine. Such an electrical variable can be, for example, the sensor values ​​from the current sensors. Furthermore, the electrical variable can be, for example, an output variable from a controller, in particular a controller for setting an electrical voltage. The harmonics to be detected can be, in particular, the first harmonic and / or the second harmonic of the fundamental wave for controlling the electrical machine. The method further comprises a step for determining correction parameters for the sensor values ​​from the current sensors. The correction parameters can, for example, comprise a correction value for an offset and / or a correction value for a gain factor of the respective current sensors.The correction values ​​for the current sensors can be determined, for example, in a control loop in which the correction values ​​for the current sensors are adjusted depending on the detected harmonics. The goal of the control system for adjusting the correction values ​​for the current sensors is to minimize the harmonics in size for controlling the electrical machine. In other words, such a control loop directly adjusts the correction values ​​for the current sensors depending on the harmonics. Additionally or alternatively, it is also possible to first generate a second controlled variable. This second controlled variable is used to generate compensating harmonics. Such compensating harmonics are suitable for at least partially compensating the detected harmonics.In other words, the compensating harmonics are preferably complementary to the detected harmonics. By superimposing the first controlled variable and the second controlled variable, currents with or without reduced harmonics can be achieved in the phase lines of the electrical machine. The correction values ​​for the current sensors can then be determined using control parameters for generating the second controlled variable, i.e., the controlled variable for generating compensating harmonics. For this purpose, suitable modeling can be used, for example, from which the relationships between the control parameters for generating the second controlled variable and the required correction parameters for the current sensors can be derived.

[0012] Furthermore, it is planned:

[0013] A control device for an electric drive system with a plurality of current sensors, a first control device, and a calibration device. The plurality of current sensors can, in particular, comprise a current sensor for each phase line of the electric machine. The current sensors are each designed to detect an electric current in a phase line of the electric machine in the electric drive system and to provide a sensor signal corresponding to the detected electric current. The first control device is designed to generate a first controlled variable for controlling the electric machine in the electric drive system. The first controlled variable can, in particular, be generated using sensor values ​​from the current sensors.Furthermore, to generate the first controlled variable, another setpoint value, such as a torque to be set, a speed to be set, or the like, can also be taken into account. The calibration device is designed to detect harmonics in a quantity for controlling the electrical machine. Furthermore, the calibration device is designed to determine correction parameters for the sensor values ​​from the current sensors using the detected harmonics. In particular, the calibration device can comprise a control loop which, by adjusting the correction values ​​for the current sensors, minimizes the harmonics in the quantity for controlling the electrical machine. Additionally or alternatively, the calibration device can be designed to generate a second controlled variable for generating compensating harmonics.The compensating harmonics are suitable for compensating the detected harmonics completely or at least partially. In this case, the calibration device is further designed to determine one or more correction values ​​for the current sensors using at least one control parameter for generating the second controlled variable. For this purpose, the calibration device can, for example, use a model or a modeling process that yields a relationship between the control parameters of the second controlled variable or the second controlled variable itself and the required correction parameters for the sensor values.

[0014] Finally, it is planned:

[0015] An electric drive system comprising an electric machine, an electric power converter, and a control device according to the invention. The electric power converter is designed to control the electric machine using the first controlled variable or a combination of the first controlled variable and the second controlled variable.

[0016] Advantages of the invention

[0017] The present invention is based on the finding that the accuracy of current sensors is of crucial importance for current control of an electrical machine. However, the accuracy of the current sensors can decrease over time, for example due to aging effects or similar. Furthermore, the present invention is based on the finding that sensor errors in the current sensors of an electrical drive system can cause harmonic oscillations to occur. For example, an offset error in a current sensor can lead to a first-order harmonic oscillation. Furthermore, an error in the gain factor, for example, can lead to a second-order harmonic oscillation. Thus, such harmonic oscillations can be used to draw conclusions about possible calibration errors or changes due to aging of the current sensors.

[0018] Therefore, one idea of ​​the present invention is to take this finding into account and create a concept for recalibration, in particular for determining suitable correction factors for current sensors. In particular, the present invention enables the determination of suitable correction parameters for current sensors, which can be performed during operation of the electric drive system. For this purpose, no special hardware is required for determining the correction factors and the associated recalibration, which would have to be installed during the calibration process.

[0019] According to the invention, the occurrence of harmonics attributable to sensor errors is minimized by suitable control and the appropriate correction parameters for the current sensors are derived from the operating parameters with minimized or eliminated harmonics. Since an operating state with minimal harmonics, i.e., minimal ripple current, is set for such operation to determine the correction parameters for the current sensors, such minimized or eliminated ripple current has no significant influence that could negatively impact the determination of the correction parameters for the current sensors.

[0020] For analyzing the occurring harmonics and, if necessary, generating a second controlled variable to compensate for the occurring harmonics, a control algorithm such as Harmonic Current Injection (HCl) or Current Shaping can be used. This algorithm allows additional harmonic currents to be impressed onto the fundamental current of the electrical machine. Such functionalities or algorithms are already implemented in numerous control components for electrical machines, so no additional components are required.

[0021] According to one embodiment, the control bandwidth for generating the first controlled variable can be limited during the calibration of the current sensors, i.e., during the determination of the correction values. In particular, the bandwidth for generating this first controlled variable can be set so low that no or only minimal compensation of harmonics in the variable for controlling the electric machine occurs. In this way, it can be ensured that the harmonics due to sensor errors in the current sensors are available as completely as possible for determining the correction values. For this purpose, the control bandwidth for generating the first controlled variable can be adjusted or limited.Additionally or alternatively, it is also possible to select an operating point for determining the correction values ​​from the current sensors in the electric drive system at which the operating parameters, such as the speed of the electric machine, are in a range in which no or no significant compensation of harmonics occurs by determining the first controlled variable.

[0022] According to one embodiment, determining the correction values ​​for the current sensors comprises determining at least one offset value for a current sensor. Such an offset value for a current sensor can be determined, in particular, using the first harmonic of the variable for controlling the electric machine.

[0023] Additionally or alternatively, the determination of the correction values ​​for the

[0024] Current sensors determine at least one correction value for a

[0025] The correction value for a current sensor's gain factor can be determined, in particular, using the second harmonic in the magnitude for controlling the electric machine. Thus, both the offset and gain factor of the current sensors can be adjusted from the first and second harmonics.

[0026] According to one embodiment, the electric machine can be controlled using a combination of the first controlled variable and the second controlled variable. By superimposing the first controlled variable with the second controlled variable in this way, harmonics in the variable for controlling the electric machine can be minimized. In this case, the correction values ​​for the current sensors can be calculated using control parameters for generating the second controlled variable. Additionally or alternatively, the correction values ​​can also be calculated using the second controlled variable itself. The basis for this is an operating point at which the harmonics, in particular the first and / or second harmonic, are minimal, preferably zero, due to the second controlled variable.

[0027] According to an alternative embodiment, the electric machine is controlled using only the first controlled variable, without the second controlled variable. In this case, the correction values ​​for the current sensors can be adjusted using the second controlled variable or control parameters for the second controlled variable. In other words, although a second controlled variable is generated that is suitable for minimizing or eliminating harmonics, this second controlled variable is not overlaid by the first controlled variable, but is used solely to determine the correction parameters for the current sensors.

[0028] According to one embodiment, the method can be carried out multiple times.

[0029] In this case, correction values ​​can be determined for a subset of all current sensors. Thus, for example, mathematical approaches can be used to determine the correction values, which assume at least one sensor value as correct and only determine correction values ​​for the remaining sensor values. After correction values ​​have been determined for some of the sensors in this way, a different sensor can be assumed to be correct in a subsequent step in order to then determine correction values ​​for the remaining sensors. Using such an approach, correct correction values ​​can be determined iteratively and gradually for all sensors, even if the underlying approach requires one or more sensors to be considered correct at a time.

[0030] According to one embodiment, the method can be executed until a predetermined termination condition is met. Such a predetermined termination condition can, for example, comprise a threshold value for the detected harmonics falling below. Since the detected harmonics and, in particular, their amplitudes can correspond to the inaccuracy of the sensor values, the method can be executed in this way until the correction values ​​for the sensors are sufficiently accurate. If necessary, further termination conditions, such as a maximum number of repetitions, a maximum time period, leaving a predefined operating range, or the like, can also be provided.

[0031] According to one embodiment, the first controlled variable can also be generated using a sensor signal from a position sensor of the electric machine. By means of such a position sensor (e.g. resolver), a current angle of rotation of the electric machine can be determined. In this case, the output signals of such a position sensor can also be subject to interference, in particular harmonics. In such a configuration, the correction values ​​can be determined once using the sensor signal from the position sensor in order to determine a first set of correction values. Furthermore, the correction values ​​can be determined once using an alternative method for determining the rotor position in order to determine a second set of correction values.Subsequently, at least one correction value for the sensor data of the position sensor can be determined using a comparison of the first set of correction values ​​and the second set of correction values. In particular, by comparing the correction values ​​from the first set and the second set, a separation of the correction values ​​for the sensor data from the current sensors and for the sensor data from the position sensor can be performed. This allows not only correction values ​​for the current sensors to be determined that are decoupled from the influences of the position sensor, but also correction values ​​for the position sensor.

[0032] According to one embodiment, the calibration of the current sensors is carried out if a predetermined activation condition is met. Such an activation condition can, for example, include reaching or exceeding a predeterminable period of time since a previous calibration. Furthermore, the activation condition can, for example, include exceeding a threshold value for a current ripple, i.e., an amplitude in the harmonics. Furthermore, the activation condition can, for example, include exceeding or falling below an operating parameter, such as a temperature, a current value, or an electrical power. In particular, operating parameters that could potentially lead to premature aging due to overload or thermal stress can be taken into account.

[0033] The above embodiments and further developments can be combined with one another as desired, where appropriate. Further embodiments, further developments, and implementations of the invention also include combinations of features of the invention not explicitly mentioned above or described below with respect to the exemplary embodiments. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

[0034] Short description of the drawings

[0035] Further features and advantages of the invention are explained below with reference to the figures. These show:

[0036] Fig. 1 : a schematic representation of a block diagram of an electric drive system with a control device according to an embodiment;

[0037] Fig. 2: a current-time diagram illustrating an oscillation in the case of an offset error;

[0038] Fig. 3: a current-time diagram illustrating an oscillation in the event of a gain error;

[0039] Fig. 4: a schematic representation of a block diagram of an electric drive system with a control device according to a further embodiment;

[0040] Fig. 5: a schematic representation of a block diagram of an electric drive system with a control device according to yet another embodiment; Fig. 6: a schematic representation of a block diagram of an electric drive system with a control device according to another embodiment;

[0041] Fig. 7: a schematic representation of a block diagram of an electric drive system with a control device according to a further embodiment; and

[0042] Fig. 8: a flowchart of how a method for calibrating current sensors according to an embodiment may be based.

[0043] Description of embodiments

[0044] Figure 1 shows a schematic representation of a block diagram of an electric drive system according to one embodiment. The electric drive system comprises an electric machine 22 and a power converter 21. The power converter 21 can generate an alternating electrical voltage, in particular a multi-phase alternating electrical voltage, for example a three-phase alternating electrical voltage, from a provided input voltage, for example a direct current input voltage, which is suitable for driving the electric machine 22. For this purpose, a suitable controlled variable can be provided to the electric power converter 21 by a control device 1. The power converter 21 and the electric machine 22 can be implemented in a common drive module 2.

[0045] The electrical machine 22 can, for example, be a permanently excited synchronous machine (PSM). In the example shown here, it is a three-phase electrical machine 22. In principle, however, the present invention is not limited to three-phase electrical machines. To monitor the electrical currents from the power converter 21 to the electrical machine 22, a current sensor 23 is provided for each phase of the electrical machine 22. This current sensor 23 can provide a sensor signal corresponding to an electrical current. Furthermore, a position sensor 24 (resolver) can be provided, for example. This position sensor 24 can provide a sensor signal corresponding to a current rotor position of the electrical machine 22.

[0046] The sensor values, in particular the sensor values ​​from the current sensors 23 and the sensor value from the position sensor 24, can be provided to a control device 1. Furthermore, the control device 1 can receive, for example, a setpoint value S, such as a specification for a torque to be set, a desired speed, or the like. The control device 1 can comprise a first control device 11. This first control device 11 can generate a first controlled variable R1 for controlling the power converter 21 based on the setpoint value S, the sensor values ​​from the current sensors 23, and optionally further parameters. The first controlled variable R1 generated by the first control device 11 generally relates to the fundamental frequency, which corresponds to the rotation rate of the electric machine 22.

[0047] For processing within the control device 1, the electrical currents from the current sensors 23 can be converted, for example, into a rotor-fixed d / q system by means of a suitable transformation. Accordingly, the controlled variable generated in the control device 1 can be converted in reverse form from the rotor-fixed system to the stator-fixed system by means of a suitable transformation before the controlled variable is output to the power converter 21.

[0048] For precise control of the electric drive system, the phase currents of the electric machine 22 must be known very precisely. This requires precise calibration of the current sensors 23 to compensate for possible deviations due to an offset and / or in the gain. For example, an offset error in a current sensor 23 can lead to an oscillation in the current value with the first harmonic. Such an oscillation in the current value due to an offset error is shown, for example, in Figure 2 in the rotor-fixed d / q system. T denotes the period of the fundamental frequency for controlling the electric machine 22.

[0049] Furthermore, for example, a deviation in the gain factor for a current sensor 23 can lead to an oscillation with the second harmonic, as shown by way of example in Figure 3.

[0050] If sensor errors occur over time which need to be corrected and which require a recalibration of the sensors 23 or if an initial calibration of the sensors 23 is to be carried out, this can be achieved, for example, on the basis of the harmonics which occur in the case of sensor errors.

[0051] As shown by way of example in Figure 1, a calibration device 12 can be provided for this purpose in the control device 1. This calibration device 12 can, for example, comprise a module 13 with a control algorithm for Harmonic Current Injection (HCl) or Current Shaping. For example, this module 13, referred to below as the HCI module 13, can process the sensor signals from the current sensors 23 in order to detect harmonics in the current waveforms. Furthermore, the HCI module 13 can generate a second controlled variable R2. This second controlled variable R2 can be formed such that the detected harmonics in the current waveforms from the current sensors 23 are minimized or compensated as completely as possible by this second controlled variable R2. In particular, the HCI module 13 can compensate the first and second harmonics as far as possible.For example, after the harmonics occurring due to sensor errors have been compensated as completely as possible by a suitable control loop by superimposing the second controlled variable R2, suitable correction values ​​for the sensors 23 can be determined based on this control. For this purpose, a suitable model can be used, for example, from which the relationship for a control system to compensate for the harmonics and the sensor errors can be derived. In principle, any suitable mathematical model is possible for this purpose.

[0052] To determine the suitable correction values ​​for the sensors 23, it may be necessary to use a model in which at least one of the sensors 23 must or should be assumed to be error-free. Accordingly, in a first step, a suitable correction can initially be carried out only for some of the plurality of sensors 23. The described method can then be carried out again if necessary, wherein in a subsequent step, an already corrected sensor value is used as the correct value and correction values ​​are determined for the sensor 23 that was assumed to be correct in the previous step. In this way, a correction of all sensor values ​​23 can also be carried out iteratively in several steps.

[0053] It is also possible, for example, to carry out the method for determining the correction values ​​for the sensors 23 recursively several times and in this way further increase the accuracy of the correction values. For example, a predetermined number of repetitions can be carried out for this purpose, or the method can be repeated several times until a predetermined termination condition is reached. For example, the method can be repeated until an amplitude of detected harmonics falls below a maximum threshold value. However, any other suitable termination conditions are also possible. In the embodiment shown in Figure 1, the correction values ​​are determined by a processing module 14a after a second controlled variable R2 has been set by the HCI module 13, which second controlled variable R2 leads to a minimization orElimination of the occurring harmonics, in particular the first and / or second harmonics. The determined correction values ​​can then be applied to the sensors 23.

[0054] Figure 4 shows a block diagram of an electric drive system with a control device 1 according to a further embodiment. In principle, all explanations already made in connection with Figure 1 apply to this embodiment, as well as to the embodiments described below. The embodiment according to Figure 4 differs from the previously described embodiment according to Figure 1, in particular in that the processing module 14b, together with the HCI module 13 and the sensors 23, forms a control loop. In this case, the processing module 14b continuously or regularly adjusts the correction values ​​for the offset and / or gain factor of the sensors 23 in accordance with the output from the HCI module 13, until the second controlled variable R2 output by the HCI module 13 no longer requires any further compensation for harmonics.

[0055] The calibration or correction process is thus completed when the correction values ​​for the current sensors 23 are adjusted by the processing module 14b in such a way that no first and / or second harmonic oscillation occurs anymore, which would have to be compensated by the HCI module 13.

[0056] Figure 5 shows a schematic representation of a block diagram for an electric drive system with a control device 1 according to another embodiment. The embodiment according to Figure 5 differs from the previously described embodiment according to Figure 4 in particular in that in this case, the second controlled variable R2 is not superimposed on the first controlled variable R1, but is merely fed to the processing module 14c.

[0057] In the described embodiments, the first control device 11 performs the control for the fundamental frequency according to the rotation rate of the electric machine 22. The first control device 11 generally has a relatively low bandwidth, i.e., a bandwidth so narrow that harmonics are not compensated for, or at least only compensated for to a very small extent. Otherwise, such compensation of harmonics could interfere with the determination of correction values ​​for the current sensors 23.Therefore, when implementing the described method for determining the correction values ​​for the current sensors 23, care must be taken to ensure that the control bandwidth of the first control device 11 is correspondingly low and / or that the fundamental frequency is sufficiently high, corresponding to the rotation rate of the electric machine 22, so that the harmonics are not affected, or not significantly affected, by the first control device 11. If necessary, the control bandwidth of the first control device 11 can also be temporarily adjusted, in particular reduced, for determining the correction factors.

[0058] If, however, the first controlled variable R1 has a high control bandwidth, which also allows for the compensation of harmonics, then, as shown in Figure 6, the generation of a second control component R2 by the HCI module 13 can be dispensed with. In this case, the control is carried out entirely by the first control device 11. In this case, the processing module 14d only receives information from the HCI module 13 about detected harmonics in order to determine the correction values ​​for the sensors 23 based on this information. Figure 7 shows a schematic representation of a block diagram for an electric drive system with a control device 1 according to a further embodiment.The embodiment according to Figure 7 differs from the previously described embodiments in particular in that, for detecting the harmonics, not the current signals themselves are used, but rather a first controlled variable R1 generated on the basis of these current signals. In such an embodiment, the first controlled variable R1 can be processed, for example, by an analysis module 15 to detect the harmonics, whereas in the previous embodiments, this detection is carried out by evaluating the currents in the HCI module 13. Here, too, the processing module 14e can then adjust the correction parameters for the current sensors 23 based on the detected harmonics in order to minimize the harmonics, in particular the first and / or second harmonic.

[0059] As already explained, a signal from a position sensor 24 can also be evaluated for controlling the electric machine 22 and, in particular, for controlling the electric power converter 21. However, it is possible that a sensor signal output by the position sensor 24 is not completely linear with respect to the current rotor angle of the electric machine 22. The sensor signal output by the position sensor 24 may also contain harmonics.

[0060] In such a case, it may also be possible to carry out a correction for possible sensor errors from the position sensor 24. For example, in one step, the method for determining the correction factors for the current sensors can be carried out using the sensor values ​​from the position sensor 24 in order to determine a first set of correction factors. In a further step, for example, the method for determining the correction factors for the current sensors can then be carried out a second time, wherein an alternative method for determining the rotor position, for example a sensorless position determination, is used instead of the sensor values ​​from the position sensor 24. This makes it possible to determine a second set of correction factors for the current sensors 23.Subsequently, using the difference between the two sets of correction factors—once based on the sensor data from the position sensor 24 and once based on an alternative method for determining the rotor position—the sensor technology of the position sensor 24 can also be adapted, for example, by separating the effects of the current sensors 23 from the effects of the position sensor 24. For example, suitable correction factors for the sensor data from the position sensor 24 can also be determined from the difference between the two sets of correction factors.

[0061] The described determination of correction values ​​for the current sensors 23 can be used, for example, to compensate for deviations due to aging effects or similar in the current sensors 23. For this purpose, the determination of the correction values ​​in the current sensors 23 can be activated based on any suitable concepts. For example, such a renewed determination of correction values ​​for the current sensors 23 can be carried out regularly, for example at predetermined time intervals. Additionally or alternatively, such a determination of correction values ​​can also be initiated or triggered by any other events. For example, if an event is detected that could lead to increased impairment or aging of a current sensor 23, a renewed determination of correction values ​​for the current sensors 23 can then be initiated.Such an event can be, for example, the exceeding of a certain temperature threshold, an overload, for example by exceeding a current threshold and / or a power threshold, or any other suitable event. Furthermore, manual triggering, for example by an external signal from a user or an external control device, is of course also possible in order to initiate the determination of new correction values ​​for the current sensors 23. Figure 8 shows a flowchart that may form the basis of a method for calibrating current sensors 23 in an electric drive system according to one embodiment. The method can, in principle, comprise any steps as previously described in connection with the electric drive system.Analogously, the previously described electric drive systems can also comprise any components that are suitable for carrying out the method steps described below.

[0062] In a step S1, a first controlled variable R1 is generated. This first controlled variable R1 is suitable for controlling an electrical machine 22 or an electrical power converter 21 for an electrical machine 22. The first controlled variable R1 can be generated using sensor values ​​from current sensors 23. Furthermore, a setpoint specification S and, if necessary, other parameters, such as sensor values ​​from a position sensor 24, can also be considered for generating the first controlled variable R1.

[0063] In step S2, harmonics are detected in the sensor values ​​from the current sensors 23. In particular, a first harmonic and / or a second harmonic can be detected in the sensor values ​​from the current sensors 23. Subsequently, in step S3, correction parameters for the sensor values ​​from the current sensors 23 are determined.

[0064] To determine the correction values ​​from the current sensors, the correction values ​​for the current sensors can, for example, be adjusted depending on the detected harmonics. For this purpose, a control loop can be provided, for example, to minimize the harmonics in the sensor values ​​from the current sensors 23. Additionally or alternatively, a second controlled variable R2 can be generated. This second controlled variable R2 can specify a controlled variable for generating compensating harmonics. Such compensating harmonics are suitable for completely or at least partially compensating the detected harmonics from the current sensors 23. Correction values ​​for the current sensors can then be determined. The correction values ​​can, in particular, be determined using a control parameter to generate the second controlled variable. In summary, the present invention relates to a recalibration orA correction of the parameterization of current sensors in an electric drive system. For this purpose, the harmonics are to be minimized in a quantity for controlling the electric machine and, based on the parameterization required for the minimization, new correction values ​​for the current sensors are to be determined.

Claims

Claims 1. A method for calibrating current sensors (23) in an electric drive system, comprising the steps: Generating (S1) a first controlled variable (R1) for controlling an electric machine (22) in the electric drive system; wherein the first controlled variable (R1) is generated using sensor values ​​from the current sensors (23); Detecting (S2) harmonics in a quantity for controlling the electrical machine (22); and Determining (S3) correction parameters for the sensor values ​​from the current sensors (23), wherein determining (S3) the correction values ​​for the current sensors (23) comprises: Adjusting the correction values ​​for the current sensors (23) depending on the detected harmonics in order to minimize the harmonics; and / or Generating a second controlled variable (R2) for generating compensating harmonics, wherein the compensating harmonics are suitable for at least partially compensating the detected harmonics; and determining correction values ​​for the current sensors (23) using the second controlled variable (R2) and / or at least one control parameter for the Generation of the second controlled variable (R2) to generate compensating harmonics.

2. Method according to claim 1, comprising a step of limiting the control bandwidth for generating the first controlled variable (R1).

3. The method according to claim 1 or 2, wherein determining (S3) the correction values ​​for the current sensors (23) comprises determining at least one offset value using the first harmonic harmonics.

4. The method according to any one of claims 1 to 3, wherein determining (S3) the correction values ​​for the current sensors (23) comprises determining at least one correction value for the gain factors of the current sensors (23) using the second harmonic.

5. The method according to any one of claims 1 to 4, wherein the electrical machine (22) is controlled using a combination of the first controlled variable (R1) and the second controlled variable (R2) in order to minimize harmonics in the variable for controlling the electrical machine (22); and wherein the calculation of the correction values ​​for the current sensors (23) is carried out using control parameters for generating the second controlled variable (R2) for which the harmonics in the variable for controlling the electrical machine (22) are minimal.

6. The method according to any one of claims 1 to 4, wherein the electric machine (22) is controlled using the first controlled variable (R1) without the second controlled variable (R2); and wherein the correction values ​​for the current sensors (23) are set using the second controlled variable (R2) and / or control parameters for the second controlled variable (R2).

7. Method according to one of claims 1 to 6, wherein the method is carried out several times, and wherein in each step correction values ​​are determined for a subset of all current sensors (23).

8. The method according to any one of claims 1 to 7, wherein the method is executed until a predetermined termination condition is met, and wherein the predetermined termination condition comprises a threshold value for the detected harmonics falling below.

9. The method according to any one of claims 1 to 8, wherein the generation (S1) of the first controlled variable (R1) is further carried out using a sensor signal from a position sensor (24) of the electric machine (22), wherein the determination (S3) of the correction values ​​is carried out using the sensor signal from the position sensor (24) in order to determine a first set of correction values, and the determination (S3) of the correction values ​​is further carried out using an alternative method for determining the rotor position in order to determine a second set of correction values, and wherein at least one correction value for the sensor data of the position sensor (24) is determined using a comparison of the first set of correction values ​​and the second set of correction values.

10. The method according to any one of claims 1 to 9, wherein the method is carried out if a predetermined activation condition is met, and wherein the activation condition comprises a predeterminable period of time since a previous calibration, an exceeding of a threshold value for a Amplitude of the harmonic harmonics and / or an exceeding or falling below of an operating parameter, in particular a temperature, a current value and / or an electrical power.

11. Control device (1) for an electric drive system, comprising: a plurality of current sensors (23), each designed to detect an electric current in a phase line of an electric machine (22) in the electric drive system and to provide a sensor signal corresponding to the detected current; a first control device (11) designed to generate a first controlled variable (R1) for controlling the electric machine (22) in the electric drive system, wherein the first controlled variable (R1) is generated using sensor values ​​from the current sensors (23); a calibration device (12) designed to detect harmonics in a variable for controlling the electric machine (22) and to determine correction parameters for the sensor values ​​from the current sensors (23);wherein the calibration device (12) is designed to minimize harmonics in the magnitude for controlling the electrical machine (22) by adjusting the correction values ​​for the current sensors (23); and / or wherein the calibration device (12) is designed to generate a second controlled variable (R2) for generating compensating harmonics, wherein the compensating harmonics are suitable for at least partially compensating the detected harmonics, and wherein the calibration device (12) is designed to generate correction values ​​for the current sensors (23) using at least one; control parameter for generating the second controlled variable (R2) to generate compensating harmonics.

12. An electric drive system, comprising: an electric machine (22); an electric power converter (21); and a control device according to claim 11, wherein the electric power converter (21) is designed to control the electric machine (22) using the first controlled variable (R1) or a combination of the first controlled variable (R1) and the second controlled variable (R2).

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