Method for commissioning an electric drive system

Abstract

The invention relates to a method for commissioning an electric drive system (100) with at least one controller (1, 2, 3) to be parameterised, comprising the steps: - determining a frequency response of a controlled system (4) on which the controller (3) acts, - selecting a parameterisable model of the controlled system (4) and carrying out a parameter fitting of the selected parameterisable model of the controlled system (4) depending on the determined frequency response of the controlled system (4), and - selecting a parameterisable controller type and setting controller parameters of the selected parameterisable controller type depending on the result of the selection and the parameter fitting of the selected parameterisable model of the controlled system (4).

Description

[0001] Procedure for commissioning an electric drive system

[0002] The invention is based on the object of providing a method for commissioning an electric drive system which enables the electric drive system to be commissioned as simply and safely as possible.

[0003] The method according to the invention is used to commission an electric drive system with at least one controller to be parameterized.

[0004] The method comprises the following steps: A frequency response of a controlled system on which the controller acts or of which the controller is a component is recorded. Next, a parameterizable model of the controlled system is selected based on the determined frequency response of the controlled system. Furthermore, a parameter fitting of the selected parameterizable model of the controlled system is performed based on the determined frequency response of the controlled system. Finally, based on the result of selecting the parameterizable model of the controlled system and the result of the parameter fitting, a parameterizable controller type is selected, and controller parameters of the selected parameterizable controller type are set.

[0005] In one embodiment, a frequency response of the selected and parameterized model of the controlled system is visualized or displayed.

[0006] In one embodiment, the selection of the parameterizable controller type and the setting of the controller parameters of the selected parameterizable controller type are further carried out depending on signal propagation times that occur when determining the frequency response of the controlled system.

[0007] In one embodiment, the controller is selected from the following set of controller types: P controllers, PI controllers, PID controllers, and state-space controllers.

[0008] In one embodiment, a filter, in particular a notch filter, is connected downstream of the at least one controller.

[0009] In one embodiment, nonlinearities of the controlled system are detected when determining the frequency response of the controlled system, particularly in the form of lags. In one embodiment, any detected nonlinearities are taken into account when activating the controlled system.

[0010] In one embodiment, in addition to a control by means of the selected controller type, a feedforward control and / or vibration damping is carried out.

[0011] In one embodiment, parameters of the feedforward control and / or vibration damping are set as a function of natural frequencies and / or damping and / or a friction characteristic of the controlled system.

[0012] In one embodiment, after selecting the parameterizable controller type and setting the controller parameters of the selected parameterizable controller type, a time-varying setpoint curve is specified to the controller and it is detected whether instabilities arise.

[0013] To commission an electrical drive system or machine, controllers must be configured or parameterized. Apart from a current controller, which only needs to be adapted to a generally known control loop, i.e., the motor's electrical parameters, speed and position controllers must be adapted to the specific machine in use. Since their parameters and properties are not always known, or only partially known, this is often done experimentally. Should machine properties change due to wear or repair, this step must also be performed outside of commissioning.

[0014] Adjusting and adapting requires expert knowledge and, usually, measurements. For time-domain measurements, parameterization programs typically provide an oscilloscope function. This is helpful for adjusting control loops, but does not always reveal the properties of the controlled system to which the controller needs to be adapted.

[0015] The invention enables a user to determine the frequency response of the controlled system or the frequency response of the closed control loop. From the frequency response information, a controller setting can be derived by specifying a few predefined boundary conditions. Such a procedure can, for example, include the following steps: 1) Determining the frequency response of the controlled system by measurement.

[0016] 2) Adaptation of a plant model to the measured frequency response by means of parameter fitting against various physical models, if necessary with automatic determination of the model order.

[0017] 3) Visualize the frequency response of the plant model (result of parameter fitting).

[0018] 4) Using the information from the fitted system model and taking signal propagation times into account, determine suitable controller parameters for a P(ID) / PID cascade control or a state-space control. The control may also include filtering (e.g., notch filter) or a higher-order controller, generally with any number of poles and zeros.

[0019] 5) Detection of nonlinearities in the measurement results, for example in the form of lots.

[0020] 6) Based on the steps described above, derive countermeasures, for example measuring backlash only with counter torque.

[0021] 7) Avoid excitation of non-linearities during further measurements, for example, in the case of backlashes, ensure the necessary counter torque by moving the machine.

[0022] 8) Determination of parameters that are relevant for feedforward control or vibration damping, for example in the form of natural frequencies, damping, friction characteristics, etc.

[0023] 9) The location where the step chain described above is executed can be either the controller itself or a parameterization program.

[0024] 10) The parameter settings found are automatically checked against a measurement, for example by means of a reference run with the determined controller settings, during which any instability is detected.

[0025] According to the invention, all steps necessary for controller parameterization can be combined, namely measurement data acquisition, measurement data combination, parameter determination, controller design, protective measures against nonlinearities, and plausibility checks. In one embodiment, the controlled system is a speed control system, with a frequency response and / or a characteristic of the open speed control system being determined. The characteristic here specifically indicates whether the speed control system is a single-mass system, a dual-mass system, etc.

[0026] In one embodiment, a frequency response of the closed speed control loop is additionally determined.

[0027] In one embodiment, the electric drive system has at least three cascaded control loops, wherein an innermost control loop is a current control loop, a further outer or inner control loop is the speed control loop and an outer control loop is a position control loop, wherein a frequency response of the closed current control loop is additionally determined.

[0028] In one embodiment, a frequency response of the closed position control loop is additionally determined.

[0029] In one embodiment, a higher-order system, in particular a third-order system, is selected as the parameterizable model of the controlled system(s).

[0030] In one embodiment, parameter fitting is performed based on a least-square method.

[0031] In one embodiment, the selected controller type, the set controller parameters and the result of the parameter fitting are stored non-volatilely in a cloud storage.

[0032] According to the invention, frequency responses of controlled systems or control loops are measured / recorded. These frequency responses can be approximately described by mathematical equations of the transfer functions. Approximately because not all physically present properties are also relevant for control engineering. To design a controller or characterize a control loop—that is, to answer the question "does the control loop have the desired properties?"—it is helpful to determine the parameters of the assumed equations.

[0033] In the context of drive technology, the following elements and their equations are of interest: a) the transfer function of the open speed control loop, i.e. the current control loop and the mechanical system, b) the transfer function of the closed current control loop, c) the transfer function of the closed speed control loop and d) the transfer function of the closed position control loop.

[0034] In the open speed control loop, the properties of the mechanical system can be identified. Typically, one is confronted with the following variants: a) a "rigid system," in which the motor and load can be described by a common moment of inertia; b) a "two-mass system," in which the motor and load are connected via elastic elements; and c) a "friction system," in which damping due to friction dominates the behavior.

[0035] Systems with even higher orders can usually be successfully approximated by the systems mentioned, so that the explicit consideration of systems with higher orders is typically not necessary.

[0036] The closed control loops can usually be simulated with sufficient accuracy by third-order systems (case d)):

[0037] It is therefore expedient to provide a so-called “parameter fitting” only for the systems a) to c) mentioned above and for the closed control loop d) and, if necessary, to anchor it in a computer-supported expert system or tool.

[0038] The parameter determination or parameter fitting can be carried out using a least-square algorithm for the defined elements "closed control loop", "open control loop single-mass system", "open control loop two-mass system" and "open control loop frictional system".

[0039] A good agreement between the measured frequency response and the theoretical frequency response creates the basis for a digital twin. If the parameters and information of the used transfer function are stored in a data system, for example, in the cloud, a functional description of the transmission path (digital twin) is available with good accuracy. At the same time, the data required to describe the system is reduced to a minimum. In one embodiment, to determine the frequency response of the controlled system and / or to determine the frequency response of the closed control loop, the controlled system and / or the control loop is / are excited at different frequencies using at least two different methods.

[0040] Frequency responses can be measured, for example, by specifically stimulating the device under test, such as the speed control loop or the closed control loop. Signals such as PRBS or MFE signals (PRBS = Pseudo Random Binary Sequence, MFE = Multi Frequency Excitation) are used for this purpose. These signals can theoretically be designed to cover an identical frequency range. However, this is generally not possible in practice. The signals then have to be recorded using limited resources, and different standards may be applied to recording duration and speed. This results in a situation where different methods cover different frequency ranges, and the relevant range of the frequency response is not adequately captured.This can lead to problems if one wants to determine the parameters of the transfer function using a measurement in the form of a frequency response. To determine the parameters of a controlled system, measurements across the entire relevant frequency range are submitted to the parameter estimation. To this end, measurement results from different methods and in different quantities are offset against each other. Consequently, parameter determination is improved by combining measurement records that, in total, describe a larger frequency range and, when overlapping, reduce the measurement error.

[0041] In one embodiment, setting the controller parameters of the selected parameterizable controller type comprises the steps of: automated calculation of first controller parameters using a first method, automated calculation of second controller parameters using a second method different from the first method, and using the first controller parameters, the second controller parameters or a combination of the first controller parameters and the second controller parameters only if the first controller parameters and the second controller parameters differ from each other by less than a predeterminable amount.

[0042] According to the invention, frequency responses of controlled systems and / or control loops are measured or recorded, for example, using a computer-aided expert system or tool, and these are used to design controllers. Therefore, there is a potential risk that measurement errors could cause incorrect parameterization. To prevent or detect this before the parameters determined in this way are used for the first time, the invention performs a plausibility check using an independent method.

[0043] Such an independent plausibility check procedure is described, for example, in the publication by K.J. Aström and T. Hägglund. PID controllers: theory, design, and tuning. Instrument Society of America, Research Triangle Park, NC, 2nd edition, 1995. Here, controller parameters for a PID controller are determined using a simple test. Since these results are determined using a different methodology, these results can be used to check the plausibility of the other results. If both results lie within a defined window, the confidence in the found controller parameters is significantly increased.

[0044] The invention is described in detail below with reference to the drawings.

[0045] Fig. 1 is a schematic block diagram of an electric drive system and

[0046] Fig. 2 a display menu of a computer-based expert system showing a measured frequency response and a frequency response derived from it by parameter fitting.

[0047] Fig. 1 shows a block diagram of an electric drive system 100. The drive system 100 has three cascaded control loops 9, 10, and 11. An innermost control loop in the form of a current control loop 10 with a current controller 3 and a (current) control system 4, a central control loop in the form of a speed control loop 9 with a speed controller 2 and a (speed) control system 8, and an outer control loop in the form of a position control loop 11 with a position controller 1 and a (position) control system 13.

[0048] In general, a controlled system or the controlled systems 4, 8 and 13 comprise all elements that lie between the associated controller output, ie the output of controllers 1, 2 and 3, respectively, and the corresponding controlled variable, ie usually the negative input of the respective summation point.

[0049] The electric drive system 100 further comprises a notch filter 6, which is connected upstream of the current regulator 3. The electric drive system 100 further comprises, in the illustrated topology, a mechanical path 14 and a differentiating element 15.

[0050] Furthermore, with regard to the basic structure of such an electric drive system 100, reference is also made to the relevant specialist literature.

[0051] The commissioning of the electric drive system 100 is described below, initially based on the parameterization of the current controller 3. The remaining controllers 2 and 3 can be parameterized accordingly.

[0052] First, a frequency response 5, see Fig. 2, of the current control system 4, on which the current controller 3 acts, is automatically determined.

[0053] Then, a parameterizable model of the current control system 4 is selected based on the frequency response. The selected parameterizable model is mathematically described, for example, by a second-order model as follows:

[0054] The parameterizable model has the parameters T1 and T2, which are determined by means of a parameter fitting depending on the determined frequency response 5 of the controlled system 4. The parameter fitting can be carried out, for example, based on a least-square method. Depending on the result of the selection and parameter fitting, a parameterizable controller type of the current controller is selected, in this case, for example, a PI-type controller 3 with a parameterizable or adjustable P parameter and a parameterizable or adjustable I parameter. Finally, the adjustable P and I parameters are set depending on the result of the parameter fitting.

[0055] The selection of the parameterizable controller type and the setting of the controller parameters of the selected parameterizable controller type can be performed depending on the signal propagation times that occur when determining the frequency response of the controlled system 4. When determining the frequency response of the controlled system 4, nonlinearities of the controlled system 4 can be detected, particularly in the form of lags. The determined nonlinearities can be taken into account when activating the controlled system 4.

[0056] In addition to closed-loop control using the selected controller type, feedforward control and / or vibration damping can be implemented. The feedforward control and / or vibration damping parameters can be adjusted depending on the natural frequencies, damping, and / or friction characteristics of the controlled system 4.

[0057] After selecting the parameterizable controller type and setting the controller parameters of the selected parameterizable controller type, a time-varying setpoint curve can be specified for controller 3 and then it can be detected whether instabilities arise.

[0058] Fig. 2 shows an example of a display menu of a computer-based expert system 7, which displays the measured frequency response 5 and a frequency response 16 derived from it by parameter fitting. The diagram below also shows the measured phase and the phase derived by parameter fitting, so that the display forms a so-called Bode diagram.

[0059] Access to the computer-aided expert system 7 can be secured by means of activation information or a password.

[0060] Furthermore, a frequency response of the open speed control loop 8 can be determined. Additionally, a frequency response of the closed speed control loop 9 can be determined. Additionally, a frequency response of the closed current control loop 10 can be determined. Additionally, a frequency response of the closed position control loop 11 can be determined. All of the aforementioned measurement results can be used to parameterize controllers 1, 2, and 3.

[0061] The selected controller type(s), the set controller parameters and the result of the parameter fitting can be stored non-volatilely in a cloud memory 12.

[0062] To determine the frequency response of the controlled system 4 and / or to determine the frequency response of the closed control loop 10, the controlled system 4 and / or the control loop 10 can be excited at different frequencies using at least two different methods. The controller parameters calculated as described above can be checked for plausibility using a second method different from the first method.

Claims

Patent claims 1. A method for commissioning an electric drive system (100) with at least one controller (1, 2, 3) to be parameterized, comprising the steps: Determining a frequency response (5) of a controlled system (4) on which the controller (3) acts, selecting a parameterizable model of the controlled system (4) and carrying out a parameter fitting of the selected parameterizable model of the controlled system (4) depending on the determined frequency response (5) of the controlled system (4), and selecting a parameterizable controller type and setting controller parameters of the selected parameterizable controller type depending on the result of the selection and the parameter fitting of the selected parameterizable model of the controlled system (4).

2. Method according to claim 1, characterized in that a frequency response (5) of the selected and parameterized model of the controlled system (4) is displayed.

3. Method according to one of the preceding claims, characterized in that the selection of the parameterizable controller type and the setting of the controller parameters of the selected parameterizable controller type are further carried out as a function of signal propagation times which occur when determining the frequency response of the controlled system (4).

4. Method according to one of the preceding claims, characterized in that the following set of controller types is selected: P-controllers, PI controllers, PID controllers, and State space controllers.

5. Method according to one of the preceding claims, characterized in that a filter (6), in particular a notch filter, is connected downstream of the at least one controller (1, 2, 3).

6. Method according to one of the preceding claims, characterized in that when determining the frequency response of the controlled system (4), non-linearities of the controlled system (4) are detected, in particular in the form of losses.

7. Method according to claim 6, characterized in that any non-linearities determined are taken into account when exciting the controlled system (4).

8. Method according to one of the preceding claims, characterized in that in addition to a control by means of the selected controller type, a pre-control and / or vibration damping is carried out.

9. Method according to claim 8, characterized in that Parameters of the feedforward control and / or the vibration damping are set as a function of natural frequencies and / or damping and / or a friction characteristic of the controlled system (4).

10. Method according to one of the preceding claims, characterized in that after selecting the parameterizable controller type and setting the controller parameters of the selected parameterizable controller type, a time-varying setpoint curve is specified to the controller (3) and it is detected whether instabilities arise.

11. Method according to one of the preceding claims, characterized in that the method runs at least partially on a computer-aided expert system (7).

12. Method according to claim 11, characterized in that access to the computer-aided expert system (7) is only possible after activation information has been entered.

13. Method according to one of the preceding claims, characterized in that the control system is a speed control system (8), wherein a frequency response and / or a character of the open speed control system (8) is determined.

14. Method according to claim 13, characterized in that a frequency response of the closed speed control loop (9) is additionally determined.

15. Method according to claim 13 or 14, characterized in that the electric drive system (100) has at least three cascaded control loops, wherein an innermost control loop is a current control loop (10), a further outer control loop is the speed control loop (9) and an outer control loop is a position control loop (11), wherein a frequency response of the closed current control loop (10) is additionally determined.

16. Method according to claim 15, characterized in that a frequency response of the closed position control loop (11) is additionally determined.

17. Method according to one of the preceding claims, characterized in that a higher-order system, in particular a third-order system, is selected as the parameterizable model of the controlled system or systems.

18. Method according to one of the preceding claims, characterized in that the parameter fitting is carried out based on a least-square method.

19. Method according to one of the preceding claims, characterized in that the selected controller type, the set controller parameters and the result of the parameter fitting are stored non-volatilely in a cloud memory (12).

20. Method according to one of the preceding claims, characterized in that in order to determine the frequency response of the controlled system (4) and / or in order to determine the frequency response of the closed control loop (10), the controlled system (4) and / or the control loop (10) is / are excited at different frequencies using at least two different methods.

21. Method according to one of the preceding claims, characterized in that setting the controller parameters of the selected parameterizable controller type comprises the steps: Calculating first controller parameters using a first method, Calculating second controller parameters using a second method different from the first method, and Using the first controller parameters, the second controller parameters, or a combination of the first controller parameters and the second controller parameters if the first controller parameters and the second controller parameters differ from each other by less than a predefined amount. -

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