Method and system for calibrating a control device of an electric machine

Abstract

The invention discloses a method and a system for calibrating a control device (1) of an electric motor (2), in particular an inverter control device, the method comprising the following operating steps: operating the electric motor (2) as part of a force flow; performing (102) a force measurement by means of piezoelectric elements (11a, 11b, 11c), the piezoelectric elements being arranged in the force flow such that the force flow is in particular only applied to the piezoelectric elements (11a, 11b, 11c); and calibrating the torque component (ΔM) based on at least one force component derived from the force measurement, in particular a change in at least one force component, and / or at least one torque component derived from the force measurement, in particular a change in the torque component. x , ΔM y , ΔF z ), adjust the control characteristic curve (5) of the control device (1).

Description

Technical Field

[0001] The present invention relates to a method for calibrating a control device of an electric motor, in particular an AC motor, in particular an inverter control device, in which the electric motor is operated as part of a force flow and force measurement is performed using a piezoelectric element, wherein the piezoelectric element is arranged in the force flow such that the force flow is exerted, in particular, only on the piezoelectric element. Furthermore, the present invention relates to a method for regulating an electric motor, in particular an AC motor, in which the electric motor is operated as part of a force flow and force measurement is performed using a piezoelectric element, which is arranged in the force flow such that the force flow is exerted, in particular, only on the piezoelectric element. Furthermore, the present invention relates to a system for performing the method. Background Art

[0002] From the prior art it is known to operate electric machines using power supply units which can generate a variable voltage system such as direct current, alternating current or three-phase alternating current from a constant voltage system such as the mains or a battery.

[0003] In particular, for three-phase motors, it is necessary to convert the DC voltage from the power supply into an AC voltage suitable for the power requirement. Therefore, so-called inverter controllers are usually used to control the motors.

[0004] Furthermore, the prior art discloses measuring forces or torques on a shaft using a measuring flange with a piezoelectric element, or determining the forces or torques on the shaft from reaction forces acting between a shaft bearing and a support device for the bearing, wherein the bearing is typically formed by an electric motor. This is described, for example, in WO 2019 / 144172 A1. Furthermore, WO 2019 / 144171 A1 discloses determining torque components based on a system of equations for force measurement using various piezoelectric elements. Summary of the Invention

[0005] Based on this prior art, the object of the present invention is to provide an improved method and system for calibrating a control device of an electric machine and an improved method and system for regulating an electric machine.

[0006] This object is achieved by the method and system according to the independent claims. Advantageous embodiments are defined in the dependent claims.

[0007] A first aspect of the present invention relates to a method for calibrating a control device of an electric machine, in particular an inverter control device, comprising the following operating steps:

[0008] running a motor as part of a force flow;

[0009] The force measurement is performed by means of a piezoelectric element, which is placed in the force flow in such a way that the force flow is exerted, in particular, only on the piezoelectric element; and

[0010] A control characteristic curve of the control device is adjusted based on at least one force component derived from the force measurement, in particular a change in at least one force component, and / or at least one torque component derived from the force measurement, in particular a change in the torque component.

[0011] The electric motor preferably has a shaft or cooperates with this shaft, which transmits a force flow from the electric motor or transmits a force flow to the electric motor. In addition, the method is preferably computer-assisted.

[0012] A second aspect of the present invention relates to a method for regulating an electric machine, in particular a three-phase electric machine, comprising the following steps:

[0013] running a motor as part of a force flow;

[0014] The force measurement is performed by means of a piezoelectric element, which is arranged in the force flow such that the force flow is exerted, in particular, only on the piezoelectric element; and

[0015] At least one control parameter of the electric machine is set based on at least one force component derived from the force measurement, in particular a change in at least one force component, and / or at least one torque component derived from the force measurement, in particular a change in the torque component.

[0016] The electric motor preferably has a shaft or cooperates with a shaft which transmits a force flow from the electric motor or transmits a force flow to the electric motor. Furthermore, the method is preferably computer-assisted.

[0017] A third aspect of the present invention relates to a system for calibrating a control device, in particular an inverter control device, of an electric machine, in particular a three-phase electric machine, which is part of a power flow. The system preferably comprises:

[0018] a piezoelectric element for performing force measurement, wherein the piezoelectric element is arranged in the force flow such that the force flow is exerted, in particular, only on the piezoelectric element;

[0019] an evaluation device configured to evaluate, from the force measurement, at least one force component, in particular a change in the at least one force component, and / or at least one torque component, in particular a change in the at least one torque component; and

[0020] Means are provided for adapting a control characteristic curve of a control device based on at least one force component derived from a force measurement and / or at least one torque component derived from a force measurement.

[0021] The electric motor preferably has a shaft or cooperates with a shaft which transmits a force flow from the electric motor or transmits a force flow to the electric motor.

[0022] A fourth aspect of the invention relates to a system for regulating an electric machine, in particular a three-phase electric machine, which is part of a power flow, comprising:

[0023] a piezoelectric element provided for carrying out a force measurement, wherein the piezoelectric element is arranged in the force flow such that the force flow is in particular only applied to the piezoelectric element;

[0024] evaluation means, which are provided for deriving at least one force component, in particular a change in the at least one force component, and / or at least one torque component, in particular a change in the at least one torque component, from the force measurement; and

[0025] A control device is provided for setting at least one control parameter of the electric machine based on at least one force component derived from the force measurement and / or at least one torque component derived from the force measurement.

[0026] The electric motor preferably has a shaft or cooperates with a shaft which transmits a force flow from the electric motor or transmits a force flow to the electric motor.

[0027] A fifth aspect of the invention relates to a test bench for an electric motor, wherein the test bench has a support device and a device for applying a load, in particular a dynamometer, and the electric motor can be arranged in the force flow between the support device and the load of the test bench, wherein the test bench also has a system for calibrating the control device of the electric motor.

[0028] According to the present invention, a force flow is preferably the path of a force and / or torque in a mechanical system from its point of action, in particular the location of introduction, to one or more locations at which the force and / or torque is absorbed by a reaction force and / or reaction moment. The force flow preferably consists of forces, in particular transverse forces relative to the direction of rotation of the shaft, and / or torques, in particular about the axis of rotation.

[0029] According to the invention, a power flow is preferably the path by which power is transmitted in a mechanical system from the point where it is introduced to one or more points at which the power is reduced.

[0030] According to the invention, the piezoelectric element is preferably a measuring element, which is provided for measuring a force acting via two surfaces resting against the piezoelectric element. The piezoelectric element is preferably formed from a piezoelectric crystal and a charge discharge structure or circuit.

[0031] According to the invention, the electric machine is preferably an electromechanical energy converter which preferably converts kinetic energy, in particular rotation, into electrical energy or vice versa.

[0032] According to the invention, calibration preferably involves loading the control device with control data. Calibration is preferably used when coordinating and / or optimizing the control of the electric machine.

[0033] According to the present invention, the device can be constructed using hardware and / or software technology and can in particular comprise a processing unit, in particular a microprocessor unit (CPU), and / or one or more programs or program modules, preferably with a data or signal connection to a storage system and / or a bus system. The CPU can be designed to process instructions implemented as a program stored in the storage system, detect input signals of a data bus, and / or output output signals to the data bus. The storage system can have one or more, in particular different, storage media, in particular optical, magnetic, solid-state, and / or other non-volatile media. The program can be created such that it embodies or is capable of implementing the method described herein, so that the CPU can carry out the steps of this method and thus, in particular, calibrate or control the motor.

[0034] According to the present invention, a control characteristic curve preferably represents how a control device controls or regulates an electric motor. The control characteristic curve is preferably determined by a computer program stored in a data memory of the control device and implementing an assignment rule. The assignment rule can be stored as an assignment function or as a table. Furthermore, the control characteristic curve is preferably influenced by a controller of the controlled system.

[0035] Most inverter controls for electric motors automatically calibrate the inverter control by measuring current and voltage after initial installation. This method is simple, but often yields unsatisfactory results. Manual calibration improves efficiency by 10 to 20%, particularly under specific conditions, such as a low battery charge.

[0036] In conventional manual calibration, the effective or efficient torque is measured at multiple operating points under specific marginal conditions, and the control characteristic is adjusted. The problem with this is that these manual calibration methods can take a long time, up to several weeks, to complete. Furthermore, the only measured effect of the changed inverter control settings is the effective torque. Dynamic torque patterns, in particular those responsible for efficiency losses, cannot be determined.

[0037] The present invention follows the practical approach of improving the calibration and therefore also the control of an electric motor by taking into account the force measurement performed by means of a piezoelectric element when creating or adjusting a control characteristic or even when setting control parameters.

[0038] By measuring force using a piezoelectric element, the dynamics of the force or torque components can be determined. Torque ripple and / or so-called cogging torque can be determined in this way and taken into account in the control characteristic curve of the control device or directly when regulating the electric motor via the control device.

[0039] By arranging the piezoelectric element directly in the force flow between the motor and the device for applying the load, in particular a dynamometer or its holding device, the measurement is no longer restricted to a specific operating point. Rather, force measurements can be performed at all operating points during the entire operation of the motor. The calibration and control methods are also not limited to test bench applications. More specifically, the piezoelectric element used to perform force measurement can also be arranged directly in the drive train, for example, in a vehicle, in which the motor is installed. This allows the force measurement to be used continuously for motor control.

[0040] In particular, the method according to the present invention allows for automated calibration and optimization of the control system of an electric motor. This allows for highly accurate dynamic response and vibration measurements. Furthermore, optimization based on these two criteria can significantly improve the control of the electric motor. In particular, torque fluctuations and energy losses, such as those caused by waste heat, can be reduced, in particular to a minimum, which can be achieved by adjustments to the controller without hardware adjustments.

[0041] The features and advantages of the advantageous embodiments described below with reference to the methods of the first and second aspects of the present invention also apply correspondingly to the other aspects of the present invention, and vice versa.

[0042] In an advantageous embodiment of the method, the electric motor is a three-phase synchronous motor or a three-phase asynchronous motor, and the control characteristic is determined by a P component and / or an I component of a PI controller or a PID controller of at least one control variable.

[0043] In another advantageous embodiment of the method, the electric machine is a three-phase synchronous machine, and the at least one control variable is the salient-pole rotor current, in particular its longitudinal and transverse components in a complex vector diagram. This is particularly advantageous because the transverse component of the salient-pole rotor current is particularly responsible for torque generation. Torque fluctuations or cogging torques generated by the electric machine can be compensated in this manner.

[0044] In another advantageous embodiment, the electric motor is a three-phase asynchronous motor and at least one controlled variable is the stator voltage and / or the standing frequency, or at least one controlled variable is the stator current and / or the stator frequency. This also makes it possible to compensate particularly well for adverse effects caused by the design of the electric motor, such as torque ripple and / or cogging torque.

[0045] In a further advantageous embodiment, the at least one criterion for adapting the control characteristic or for setting the at least one control parameter is selected from the following group:

[0046] the intensity of the resonance of the torque and / or force variations; and / or

[0047] Integration of the intensity of the oscillation of the torque and / or force change over a predetermined frequency spectrum.

[0048] These criteria for frequency-resolved vibration analysis make it possible to describe the vibration behavior of individual frequency ranges or broad frequencies. Within the scope of optimization, the intensity of individual vibrations and / or the overall vibration is reduced. This analysis is preferably performed during stationary operation of the motor.

[0049] In a further advantageous embodiment of the method, at least one criterion for adapting the control characteristic or for setting at least one control parameter is selected from the following group:

[0050] The duration of the torque ramp-up from 10% of the torque request to 90% of the torque request;

[0051] The delay from the time of the torque request to the time of the torque increase; and / or

[0052] Overshoot intensity for a value of 100% of the torque request.

[0053] These criteria for the dynamic vibration profile make it possible to describe the drive train's response to a torque request, in particular its vibration behavior. Within the scope of optimization, the overshoot intensity, the duration of the delay time, and / or the duration of the torque rise are reduced.

[0054] In another advantageous embodiment of the method, the force and torque components are determined based on the measurement signals of the individual piezoelectric elements using a system of equations. The measurement signals of the individual piezoelectric elements are preferably decomposed into several parts that contribute to the corresponding force and / or torque components to be derived. In addition, preferably, all contributions of the individual piezoelectric measuring elements to the corresponding force and / or torque components to be determined are taken into account. By using a system of equations that is solved according to the force and / or torque components to be determined, measurements using a large number of piezoelectric elements can be taken into account. In addition, all measurements of a multi-component sensor or piezoelectric element can be proportionally taken into account in the force and / or torque components to be determined. This makes it possible to reduce or even avoid force diversion through piezoelectric elements that are not involved in the measurement.

[0055] In another advantageous embodiment of the method, an electric motor is operated together with a shaft that transmits a force flow from the electric motor or to the electric motor, wherein a piezoelectric element is arranged between a first part of the shaft and a second part of the shaft such that forces, in particular shear forces, in the first and second parts can be measured by means of the piezoelectric element. A particularly simple measurement arrangement can be achieved by measuring directly in or on the shaft.

[0056] In another advantageous embodiment of the method, a piezoelectric element measures forces, particularly shear forces, between the motor and a support device for supporting the motor. In this embodiment, the piezoelectric element is positioned between the motor and the support device. Thus, in this embodiment, force measurements are performed relative to a spatially fixed reference system, namely, the powertrain test bench or its base plate, or the vehicle. Depending on how the motor is mounted on the support device, piezoelectric elements with transverse, longitudinal, or shear effects can be used. This arrangement of the force sensor essentially leaves the rotating mass of the shaft unchanged. In particular, the reaction torque to the torque applied to the shaft is measured.

[0057] In another advantageous embodiment of the method, the motor is operated together with a shaft which transmits a force flow from the motor or transmits a force flow to the motor, wherein the measuring system formed by the piezoelectric element does not change the rotating mass of the shaft and / or the rotating mass of the integrated rotating part formed by the shaft and the motor.

[0058] The method is preferably implemented on a computer. Further aspects of the invention therefore relate to: a computer program comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method; and a computer-readable medium on which the computer program is stored. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Further features and advantages will be apparent from the following description with reference to the accompanying drawings, in which:

[0060] Figure 1 An embodiment of a system for calibrating a control device of an electric machine is shown, at least in part, schematically;

[0061] Figure 2 An embodiment of a method for calibrating a control device of an electric machine is shown, at least in part, schematically;

[0062] Figure 3 An embodiment of a system for regulating an electric machine is shown, at least in part, schematically;

[0063] Figure 4 An embodiment of a method for regulating an electric machine is shown, at least in part, schematically;

[0064] Figure 5 A first measuring arrangement with a piezoelectric element is shown, at least partially schematically, of an exemplary embodiment of a system for calibrating a control device or a system for regulating an electric motor;

[0065] Figure 6 A second measuring arrangement with a piezoelectric element is shown, at least partially schematically, of an exemplary embodiment of a system for calibrating a control device or a system for regulating an electric motor;

[0066] Figure 7 A third measuring arrangement with a piezoelectric element is shown, at least partially schematically, of an exemplary embodiment of a system for calibrating a control device or a system for regulating an electric motor;

[0067] Figure 8 An at least partially schematic illustration of a vibration spectrogram of an electric machine, which is determined by means of a method for calibrating a control device or a method for regulating an electric machine;

[0068] Figure 9 shows, at least partially schematically, another frequency spectrum diagram determined using the method for calibrating a control device or the method for regulating an electric machine; and

[0069] Figure 10 The time curve of the torque is shown at least partially schematically. DETAILED DESCRIPTION

[0070] Figure 1 An overall structure consisting of an embodiment of a system 10 for calibrating an inverter control device 1 of an electric machine 2 and the inverter controller 1 to be calibrated and the electric machine 2 to be controlled is shown.

[0071] The present invention will be described below with reference to such an inverter control device 1 for a three-phase synchronous motor or a three-phase asynchronous motor 2, wherein the salient pole rotor current I d , Iq Or stator voltage U S , stator frequency f S and stator current I S However, the described system and method can also be used with reference to other control devices 1 and motors 2 .

[0072] A control characteristic curve 5 is stored in the inverter control device 1 shown. With the aid of this control characteristic curve 5, the control device 1 controls the inverter based on the input variables IN1 and IN2 using the control parameter I d , I q , I S 、f S 、U S Control the motor.

[0073] The input variables IN1 , IN2 are, for example, a torque request, a speed request or also a braking torque request.

[0074] The system 10 for calibrating an inverter control preferably comprises piezoelectric elements 11 a , 11 b , 11 c , an evaluation device 12 and a device 13 provided for adjusting the control characteristic 5 .

[0075] The piezoelectric elements 11a, 11b, 11c are arranged or mounted in the force flow including the motor 2 in such a way that they can measure a change in the force or torque acting on or exerted by the motor 2. Based on these measurements of the different piezoelectric elements 11a, 11b and 11c, the evaluation device 12 can calculate at least one force component and / or torque component ΔM. X , ΔM Y , ΔF Z ; ΔF X , ΔF Y , ΔM Z In the present description and the accompanying drawings, the present invention is referred to purely by way of example ascertaining the two torque components ΔM X , ΔM Y and a force component ΔF Z As another example, alternatively, in particular, two force components ΔF can also be determined. X , ΔF Y and a torque component ΔM Z changes.

[0076] The means 13 for adjusting the control characteristic curve 5 can calibrate the control characteristic curve 5 based on various criteria, such as NVH-related criteria or dynamics-related criteria. Optimization can be performed with reference to these criteria, or the control characteristic curve can also be adapted, for example, to a specific inverter control device 1 .

[0077] Figure 2A block diagram of a method for calibrating a control device 100 is shown. This method can be used in particular with the aid of Figure 1 The illustrated embodiment of a system 10 for calibrating a control device preferably comprises components or modules implemented in hardware or software.

[0078] In a first operating step 101, the motor is operated as part of the power flow. The motor 2 is controlled by means of the inverter control device 1. For this purpose, the inverter control device 1 generates a control parameter I based on the input parameters IN1 and IN2. d , I q ;I S 、f S 、U S The input parameter reflects the driver's wish or a request by the vehicle (not shown). Force measurement 102 is performed with the aid of piezoelectric elements 11a, 11b, 11c. From this force measurement, individual force components and / or torque components ΔM can be derived. X , ΔM Y , ΔF Z or their temporal variations. Such temporal variations contain information about torque ripple and / or cogging torque.

[0079] In order to compensate for this torque fluctuation or cogging torque, in a further operating step 103 the control characteristic 5 stored in the inverter control is adjusted or modified 103 .

[0080] Figure 1 System 10 is preferably used on a test bench for electric drive trains. Evaluation device 12 and device 13 for adjusting the control characteristic curve can be part of the test bench. The data signal is recorded at a defined storage rate, preferably 100 kHz, and subjected to a fast Fourier transform analysis to identify the vibration intensity based on the rotor's rotational frequency.

[0081] The use of the piezoelectric elements 11a, 11b, 11c as dynamic force or torque sensors is particularly important. Piezoelectric elements provide sufficient time resolution for such dynamic measurements.

[0082] The control characteristic curves 5 or their variable parameters, in particular the I part of the PI controller stored there, are preferably changed in such a way that the criteria are optimized. In the case of NVH-related and dynamics-related criteria as optimization targets, it is usually necessary to find the best compromise here because these criteria conflict with each other.

[0083] Preferably, so-called model-based calibration or optimization methods are used in the calibration method and, if appropriate, in the optimization.

[0084] A model is designed that reflects the relationship between the changing parameters and the standard values ​​of the control characteristic curve 5. This model can be used, for example, in test bench tests to specifically target areas where optimal results or compromises between optimal results are particularly expected.

[0085] The control characteristic curve is preferably optimized as follows: firstly a parameter for the change of the inverter control device, in particular the control parameter I is created. d , I q ;U S , I S 、f S The experimental plan of changing the parameters of the P part or I part of the PI regulator is as follows. Based on this setting of the changing parameters, Figure 1 The tests are carried out using the overall arrangement shown. The operating progress or individual operating points reached during the tests are evaluated using the criteria. Based on this evaluation, the control characteristic curve is adjusted.

[0086] These standards can be fundamentally divided into NVH-related standards and dynamics-related standards.

[0087] In NVH-related standards, in particular the amplitude analysis of different resonances and of the fast Fourier transformed torque signal, in particular its integral, is particularly suitable.

[0088] Among the dynamics-related criteria, the so-called T90 / T10 rise time is particularly important. This is the time required for the torque to change from 10% to 90% of the requested torque when the torque request is reached. Another possible criterion is the delay time T D and overshoot intensity I D , as referenced Figure 10 As explained below.

[0089] Force component F x (t) and F y (t) and torque component M z (t) and the force component F x (t) and the torque component M x (t) and M y (t) can be determined in a manner known per se by means of a targeted arrangement of the preferred directions of the individual piezoelectric elements 11 a , 11 b , 11 c and the addition of the individual measurement signals S1 , S2 , S3 .

[0090] Other methods can also be used to determine these parameters, for example the measurement signals of the individual piezoelectric elements 11a, 11b, 11c or derived from the measurement signals, that is, the measured forces F1, . . . , F i decomposition, especially orthogonal decomposition.

[0091] Here, the parameter M to be determined Z 、F X 、F Y For example, the solution to the system of equations is:

[0092] S1=a 11 ·M z +a 12 ·Fx+a 13 ·Fy

[0093] S2=a 32 ·M z +a 22 ·Fx+a 23 ·Fy

[0094] S3=a 31 ·M z +a 32 ·Fx+a 33 ·Fy

[0095]

[0096] SN=a N1 ·M z ...

[0097] Here, S1, S2, ... Si, ... SN are the measurement signals of the respective piezoelectric elements 11a, 11b, 11c, ... 11i, ... 11N. Each coefficient a depends on a number of factors, such as the respective position of the measuring elements 11a, 11b, 11c, ... 11i, ... 11N and the orientation of the respective preferred direction in the reference system, the sensitivity of the respective measuring elements 11a, 11b, 11c, ... 11i, ... 11N, and possible signal losses due to force diversion through the fixing means.

[0098] In order to solve the torque M Z , the first lateral force component F X and the second lateral force component F Y This system of equations requires the measurement signals of at least three piezoelectric elements 11a, 11b, 11c, whose preferred directions are oriented parallel to or in a plane. Furthermore, at least two of the preferred directions should be oriented neither parallel nor antiparallel.

[0099] For the general case described with N=3, that is, with three piezoelectric elements 11a, 11b, 11c, the solution of the equation system shown above is unambiguous. If further measuring elements are added to the measuring system 1, then with three parameters M to be determined z 、Fx 、F y The system of equations is then overdetermined, but the measurement accuracy can be improved again.

[0100] When N=4, four different equation groups can be listed: F(S1, S2, S3), F(S1, S2, S4), F(S1, S3, S4), and F(S2, S3, S4). z 、F x 、F y The determined values ​​can then be added and averaged, ie, divided by 4 for four piezoelectric elements 11a, 11b, 11c, ... 11i, ... 11N. The overdetermined system of equations F(S1, S2, ..., SN) can be formulated in a similar manner and solved using a minimization task.

[0101] If the general solution of the equations is found, then the parameter M to be determined can be z 、F x 、F y The calculation of simplifies to a matrix multiplication. This matrix multiplication has three rows and as many columns as the measurement signals S1, S2, S2, ... SN available. The matrix elements or coefficients map the respective contributions of the individual sensors to the parameters M to be determined. z 、F x 、F y .

[0102]

[0103] In order to decompose the measurement signals S1, S2, ... Si, ... SN into the corresponding parameters M to be determined, z 、F x 、F y The components of , require knowing the position and preferred orientation of the piezoelectric elements 11a, 11b, 11c, ... 11i, ... 11N.

[0104] The geometrical parameters can be determined from the structural design drawings of the powertrain test bench and knowledge of the preferred orientations of the piezoelectric elements 11a, 11b, 11c, ... 11i, ... 11N.

[0105] However, the preferred orientation of piezoelectric elements 11a, 11b, 11c, ..., 11i, ..., 11N can also be determined by determining the preferred orientation using calibration measurements. For this purpose, piezoelectric elements 11a, 11b, 11c, ..., 11i, ..., 11N are preferably clamped between two flat plates. In the next step, an external lateral force of known direction is applied. The preferred orientation of piezoelectric elements 11a, 11b, 11c, ..., 11i, ..., 11N in the plane spanned by the preferred orientation of piezoelectric elements 11a, 11b, 11c, ..., 11i, ..., 11N can be determined by comparing the magnitude and direction of the introduced lateral force with the magnitude of the individual measurement signals S1, S2, ..., Si, ..., SN.

[0106] When the preferred orientation of the individual piezoelectric elements 11a, 11b, 11c, ... 11i, ... 11N is known, the piezoelectric element 11a, 11b, 11c, ... 11i, ... 11N can be controlled in a similar manner by applying a defined torque M. z The distances of the piezoelectric elements 11 a , 11 b , 11 c , 11 i , 11 N from the axis of rotation D are determined by measuring the individual measurement signals S1 , S2 , . . . Si, . . SN.

[0107] Figure 3 An exemplary embodiment of a system 20 for regulating an electric machine 2 , which is part of a power flow, is shown.

[0108] and Figure 1 The system 10 shown differs in that the force and / or torque components ΔM derived from the force measurement by means of the piezoelectric elements 21a, 21b, 21c are taken into account directly in the control means 23, which is in particular a control device. x , ΔM y , ΔF z These are therefore preferably stored as input parameters in Figure 3 This is taken into account accordingly in the control characteristic 5 shown and in the characteristic map and the control function.

[0109] according to Figure 3 System 20 compared to Figure 1 The system 10 accordingly also has no means for adjusting the control characteristic 5 itself, ie for fundamentally changing the control characteristic 5 .

[0110] The system 20 is implemented in hardware or software and is configured to implement Figure 4 Components or modules of the method 200 for regulating an electric machine 2 are shown in FIG.

[0111] The electric machine 2 is operated 201 as part of a power flow, in particular in a motor vehicle. During this operation, a force measurement is again performed 202 by means of the piezoelectric elements 21a, 21b, 21c.

[0112] Here, too, the piezoelectric elements 21 a , 21 b , 21 c are arranged in a force flow also acting on the electric motor 2 in such a way that the force flow is in particular only acting on the piezoelectric elements 21 a , 21 b , 21 c .

[0113] Based on the control characteristic curve 5 stored in the control means or control device 23, in particular stored as a characteristic curve or control function, the control parameters I of the electric motor 2 are set 203. d , I q ;U S , I S 、f S , wherein, in addition to the other input variables IN1 , IN2 , the force component and / or torque component ΔM calculated by the evaluation device 22 based on the force measurement is also taken into account x , ΔM y , ΔF z or changes as input parameters.

[0114] Figures 5 to 7 Different measuring arrangements are shown for determining the force and / or torque applied to the electric machine 2. Such measuring arrangements can be used both in the system 10 for calibrating the inverter control device 1, for example Figure 1 In the embodiment shown, it can also be used in a system 20 for regulating an electric motor 2, for example Figure 3 In the embodiment shown.

[0115] Figures 5 to 7 A section or part of a drive train is shown in each case, wherein the electric motor 2 is supported by a support device 6, in particular a base plate. The electric motor 2 drives a shaft 3, 3a, for example, or is driven by the shaft.

[0116] The shafts 3 , 3 a , 3 b each rotate here about an axis of rotation D, the extension of which is shown as a dashed line in all three figures.

[0117] exist Figure 5 In FIG. 3 , three piezoelectric elements 11 a , 11 b , 11 c are arranged between a flange of a first shaft portion 3 a and a flange of a second shaft portion 3 b .

[0118] The piezoelectric elements 11a, 11b, 11c are preferably held at the end faces between the flanges in a force-fitting or friction-fitting manner, so that all force action occurs via the end faces of the piezoelectric elements 11a, 11b, 11c. The piezoelectric elements 11a, 11b, 11c preferably form the main force flow, which is the reference force flow. Furthermore, it is preferred that there is minimal or even no force shunt.

[0119] The first shaft part 3a is or can be connected in a rotationally fixed manner to a rotor (not shown) of an electric machine. The second shaft part 3b is or can be connected in a rotationally fixed manner to a load 4. The load 4 can be formed, for example, by one or more dynamometers on a test bench.

[0120] The force flow extends from the motor 2 via the first shaft portion 3 a , the piezoelectric elements 11 a , 11 b , 11 c , the second shaft portion 3 b to the load 4 , or vice versa.

[0121] The force and / or torque components determined by force measurement at the piezoelectric elements 11 a , 11 b , 11 c correspond at least substantially to the force and / or torque components also exerted at the electric motor 2 via the first shaft portion 3 a .

[0122] In press Figure 6 In the measuring arrangement of , the piezoelectric elements 11a, 11b, 11c are arranged between the motor 2 and the support device 6, which serves as a support device or bearing 6 for the motor 2. Figure 6 In the measuring arrangement shown, the force flow therefore extends from the support 6 , formed, for example, by a base plate, via the piezoelectric elements 11 a , 11 b , 11 c , the motor 2 , the shaft 3 to the load 4 , formed, in particular, by one or more dynamometers.

[0123] Even in this measuring arrangement, the force and / or torque is preferably introduced into the piezoelectric elements 11a, 11b, 11c only via their end faces, and the piezoelectric elements 11a, 11b, 11c are preferably fixed in a force-fitting, in particular friction-fitting, manner between the motor 2 and the support device 6. Even in this measuring arrangement, this main force flow occurs via the piezoelectric elements 11a, 11b, 11c, with only a small or no force diversion occurring via other elements.

[0124] However, when pressing Figure 6 In the measurement arrangement, the force component and / or torque component applied to the motor 2 is not measured directly, but is indirectly measured via the reaction force or reaction torque provided to the motor 2 by the support device 6 as a support. Figure 5 The advantage of the measuring arrangement is that the piezoelectric elements 11a, 11b, 11c or the measuring device (of which they are part) do not influence the rotational mass or the shaft's moment of inertia of the shaft 3 and therefore do not affect the force measurement. Furthermore, due to the measuring arrangement of the piezoelectric elements 11a, 11b, 11c and the additional mass in the shaft, the quality of the measurement signal is not affected by elasticity in the case of a direct connection to the stator and is therefore particularly direct and rigid.

[0125] according to Figure 7 The measurement arrangement basically corresponds to Figure 6 In this measuring arrangement, the force measurement of the reaction force is also performed.

[0126] However, the support device 6 in this case is not a base plate or a bottom plate, but a device for applying a load, in particular a dynamometer or a gear, which runs through the shaft 3 and is supported on the motor housing or structure 7. The element 7 is, for example, a gear housing.

[0127] The force flow in this case extends from the device 6 via the gear housing 7, the piezoelectric elements 11a, 11b, 11c, the motor 2 and the shaft 3 back to the device 6. In the illustrated case, the device 6 is formed by a gear which is preferably in turn connected in a rotationally fixed manner to a dynamometer or dynamometers.

[0128] Figure 8 A frequency analysis diagram is shown, which illustrates a fast Fourier transform analysis of the amplitude of the torque variation or torque oscillation during operation of the electric machine 2. The torque variation is determined using the methods 100, 200 and systems 10, 20 described above.

[0129] The dependence of the amplitude of the torque oscillation in Newton meters on the corresponding rotational speed of the rotor of the electric machine 2 in Hertz is indicated here.

[0130] The motor 2 used in the measurement is a three-phase synchronous motor with 48 slots or grooves and 4 pole pairs. Using the previously described measuring systems 10, 20 and methods 100, 200, it can be confirmed that peaks of the torque ripple occur particularly at frequencies of 48 or multiples of 4.

[0131] Figure 9 This is again a diagram of a fast Fourier transform analysis, in which the amplitude of the torque oscillation amplitude of the rotor of the electric machine 2 is plotted against a frequency spectrum from 0 to 220 Hz. Two calibration states are plotted here: a basic calibration BC and a calibration OC optimized using the method 100 for calibration.

[0132] In this case, in particular the intensities of the 4th, 8th, 24th and 48th resonances of the vibration system of the electric machine 2 and the integrated value of the frequency-dependent intensities serve as criteria for optimizing the control characteristic 5 .

[0133] Compared to the basic calibration BC, the optimized calibration has a significantly smaller amplitude than the corresponding vibration mode.

[0134] Figure 10 The time profile of the torque at the shaft is shown as a function of time: At time t=0, a torque request is made, the rotational speed of the shaft remaining constant.

[0135] The new set value M of the torque request can be referred to S It can be seen that the delay time T from torque request to torque rise D, from 10% of the torque request value to the torque request value M S 90% increase time T R . M A The actual value torque curve is shown.

[0136] It should be noted that the described embodiments are merely examples and are not intended to limit the scope of protection, application, or structure. Rather, the foregoing description provides guidance to those skilled in the art for implementing at least one embodiment, wherein various modifications may be made to the functions and arrangements of the described components without departing from the scope of protection defined by the claims and their equivalent feature combinations. The various embodiments may be combined with one another.

[0137] Reference Signs List

[0138] 1 Control device

[0139] Axes 3, 3a, and 3b

[0140] 4 Load

[0141] 5 Control characteristic curve

[0142] 6 Support device

[0143] 10 Systems for calibration

[0144] 11a, 11b, 11c Piezoelectric elements

[0145] 12 Evaluation Devices

[0146] 13 Devices for Adjustment

[0147] 20 Systems for regulation

[0148] 21a, 21b, 21c Piezoelectric elements

[0149] 22 Evaluation Devices

[0150] 23 Control devices

[0151] D Rotation axis

[0152] IN1, IN2 input parameters

[0153] I d Longitudinal component of salient pole rotor current

[0154] I q Transverse component of salient pole rotor current

[0155] U S stator voltage

[0156] f S stator frequency

[0157] I S stator current

[0158] T D Delay time

[0159] T R Rise time

[0160] ΔI Overshoot intensity

[0161] M S Torque request

Claims

1. A method (100) for calibrating a control device (1) of an electric machine (2), comprising the following steps: - Step 101: operating the motor (2) as part of the power flow; - Step 102: performing a force measurement with the aid of a piezoelectric element (11a, 11b, 11c), said piezoelectric element being arranged in the force flow such that the force flow acts on said piezoelectric element (11a, 11b, 11c); as well as - step 103: adjusting a control characteristic curve (5) of the control device (1) based on at least one force component derived from the force measurement and / or at least one torque component derived from the force measurement, in, Select at least one criterion for adjusting the control characteristic from the following groups: The duration of the torque ramp-up from 10% of the torque request to 90% of the torque request; Delay time from the time of torque request to the time of torque rise; and / or The intensity of the overshoot at a value of 100% of the torque request.

2. The method according to claim 1, wherein The control device (1) is an inverter control device.

3. A method (200) for regulating an electric machine (2), comprising the following steps: - Step 201: operating the motor (2) as part of the power flow; - step 202: performing a force measurement by means of a piezoelectric element (21a, 21b, 21c), said piezoelectric element being arranged in the force flow such that the force flow acts on the piezoelectric element (21a, 21b, 21c); and - step 203: setting at least one control parameter of the electric machine (2) based on at least one force component derived from the force measurement and / or at least one torque component derived from the force measurement, The at least one criterion for adjusting the at least one control parameter is selected from the following group: The duration of the torque ramp-up from 10% of the torque request to 90% of the torque request; The delay from the time of the torque request to the time of the torque increase; and / or The intensity of the overshoot at a value of 100% of the torque request.

4. The method (100, 200) according to claim 1 or 3, wherein: The motor (2) is a three-phase motor.

5. The method (100, 200) according to claim 1 or 3, wherein: The piezoelectric elements (11a, 11b, 11c) are arranged in the force flow such that the force flow acts only on the piezoelectric elements (11a, 11b, 11c).

6. The method (100, 200) according to claim 1 or 3, wherein: Step 103: Adjusting the control characteristic curve (5) of the control device (1) or Step 103: Setting at least one control parameter of the motor (2) based on the change of at least one force component and / or the change of the torque component.

7. The method (100, 200) according to claim 1 or 3, wherein: The motor (2) is a three-phase synchronous motor and the at least one control parameter is a salient-pole rotor current.

8. The method (100, 200) according to claim 7, wherein: The at least one control parameter is the longitudinal component and the transverse component of the salient pole rotor current in the complex vector diagram.

9. The method (100, 200) according to claim 1 or 3, wherein: The motor (2) is a three-phase asynchronous motor and the at least one control parameter is a stator voltage and / or a stator frequency or the at least one control parameter is a stator current and / or a stator frequency.

10. The method (100, 200) according to claim 1 or 3, wherein: At least one criterion for adapting the control characteristic or for setting at least one control parameter is selected from the following group: the intensity of the resonance of the torque and / or force variations; and / or The integral of the intensity of the vibration of the torque and / or force variations over a predetermined frequency spectrum.

11. The method (100, 200) according to claim 1 or 3, wherein: Based on the measurement signals of the individual piezoelectric elements (11a, 11b, 11c; 21a, 21b, 21c), force components and torque components are determined with the aid of a system of equations.

12. The method (100, 200) according to claim 1 or 3, wherein: The measurement signals of the individual piezoelectric elements (11a, 11b, 11c; 21a, 21b, 21c) are decomposed into components which contribute to the respective force and / or torque components to be derived.

13. The method (100, 200) according to claim 1 or 3, wherein: Taking into account the individual piezoelectric elements contributes to the respective force and / or torque components to be derived.

14. The method (100, 200) according to claim 13, wherein: All of the individual piezoelectric elements are taken into account to contribute to the respective force and / or torque components to be derived.

15. The method (100, 200) according to claim 1 or 3, wherein: The motor (2) is operated together with a shaft (3a, 3b) which transmits a force flow to or from the motor (2), wherein the piezoelectric element (11a, 11b, 11c; 21a, 21b, 21c) is arranged between a first part (3a) and a second part (3b) of the shaft in such a way that the force between the first part (3a) and the second part (3b) can be measured by means of the piezoelectric element (11a, 11b, 11c; 21a, 21b, 21c).

16. The method (100, 200) according to claim 1 or 3, wherein: The piezoelectric element (11a, 11b, 11c; 21a, 21b, 21c) measures the force between the motor (2) and a support device (6) for supporting the motor (2).

17. The method (100, 200) according to claim 15, wherein: The force is a shear force.

18. The method (100, 200) according to claim 1 or 3, wherein: The motor (2) is operated together with a shaft (3) that transmits a force flow to or from the motor, wherein the measuring system formed by the piezoelectric elements (11a, 11b, 11c; 21a, 21b, 21c) does not change the rotating mass of the shaft (3) and / or the rotating mass of the integral rotating part formed by the shaft (3) and the motor (3).

19. A system (10) for calibrating a control device (1) of an electric machine (2) which is part of a power flow, the system comprising: - a piezoelectric element (11a, 11b, 11c) for performing force measurement, wherein The piezoelectric elements (21a, 21b, 21c) are arranged in a force flow such that the force flow acts on the piezoelectric elements; - an evaluation device (12) configured to derive at least one force component and / or at least one torque component from the force measurement; and - means (13) configured to adjust a control characteristic curve (5) of the control device (1) based on at least one force component derived from the force measurement and / or at least one torque component derived from the force measurement, In this case, at least one criterion for adjusting the control characteristic curve is selected from the following group: The duration of the torque ramp-up from 10% of the torque request to 90% of the torque request; Delay time from the time of torque request to the time of torque rise; and / or The intensity of the overshoot at a value of 100% of the torque request.

20. A system (20) for regulating an electric machine (2) which is part of a power flow, the system comprising: - a piezoelectric element (21a, 21b, 21c) provided for carrying out a force measurement, wherein The piezoelectric elements (21a, 21b, 21c) are arranged in the force flow so that the force flow acts on the piezoelectric elements; - an evaluation device (22) configured to derive at least one force component and / or at least one torque component from the force measurement; and - a control device (23) configured to set at least one control parameter of the electric machine (2) based on at least one force component derived from the force measurement and / or at least one torque component derived from the force measurement, The at least one criterion for adjusting the at least one control parameter is selected from the following group: The duration of the torque ramp-up from 10% of the torque request to 90% of the torque request; The delay from the time of the torque request to the time of the torque increase; and / or The intensity of the overshoot at a value of 100% of the torque request.

21. Test bench for electric motors, wherein: The test bench has at least one support device (6) for an electric motor and a load (4), and the electric motor can be arranged in a force flow between the support device (6) of the test bench and the load (4), wherein the test bench also has a system (10) according to claim 19.

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