Drive system and method for controlling a drive system
By presetting and adjusting the operating parameters of the speed controller in the elevator drive system, the problem of difficult trade-off between the response time of the speed controller and the driving comfort in high-speed elevators is solved, and higher driving accuracy and comfort are achieved.
Patent Information
- Application Number
- CN201980103418.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-12-05
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2039-12-05
Smart Images
Figure CN114929607B_ABST
Abstract
Description
Technical Field
[0001] The present invention generally relates to the technical field of drive systems. In particular, the present invention relates to a drive system for driving an electric motor. Background Art
[0002] Typically, a conveyor (e.g., an elevator) includes a drive system for controlling the power supply to the electric motor of the conveyor in order to move a conveyed entity, such as an elevator car. In addition, the drive system controls the speed and torque of the electric motor. The drive system may include a drive control unit and a frequency converter. The drive control unit generates a speed reference and a torque reference to the frequency converter, and the frequency converter controls the speed of the electric motor according to the speed reference and controls the torque of the electric motor according to the torque reference. The frequency converter may include an internal speed controller, such as a proportional integral (PI) controller or a proportional integral differential (PID) controller. The speed controller may include adjustable operating parameters that may have an impact on the drive comfort experienced by passengers of the elevator car and / or the stopping accuracy of the elevator car.
[0003] In particular, in high-speed elevator embodiments, the speed controller should be able to respond fairly quickly to changes in the speed reference. At the same time, it is preferred that the speed controller responds substantially slowly when the speed reference is constant, i.e., when the electric motor has reached a constant speed, so as to achieve a smooth drive. Too slow a response time may cause poor conveyor operation due to speed differences. Conversely, too fast a response time may affect the drive comfort experienced by the conveyor passengers and / or may result in an increase in electric motor noise.
[0004] Typically, the operating parameters of the speed controller remain fixed and a compromise is made between the values of the operating parameters of the speed controller in order to simultaneously achieve a sufficiently fast response time and a sufficiently good driving comfort, i.e. a smooth drive. Typically, the monitored speed signal of the electric motor and / or the error signal of the speed controller may be filtered in order to prevent the speed controller from generating a high frequency reference which would normally generate noise at the electric motor and / or vibrations in the transport entity, e.g. an elevator car. Summary of the invention
[0005] A simplified overview is provided below to provide a basic understanding of some aspects of various embodiments of the present invention. This overview is not a broad overview of the present invention. It is neither intended to identify key or important elements of the present invention nor to describe the scope of the present invention. The following overview only presents some concepts of the present invention in a simplified form as a preface to a more detailed description of exemplary embodiments of the present invention.
[0006] The object of the present invention is to provide a drive system for driving an electric motor and a method for controlling the drive system. Another object of the present invention is to provide a drive system for driving an electric motor and a method for controlling the drive system to improve the driving accuracy and / or driving comfort of the electric motor.
[0007] The objects of the invention are achieved by a system and a method as defined by the respective independent claims.
[0008] According to a first aspect, a drive system for driving an electric motor is provided, wherein the drive system comprises a drive control unit and a frequency converter comprising a speed controller, wherein the drive control unit is configured to: define a speed reference of the electric motor, wherein the speed reference represents the speed of the electric motor as a function of time; before starting to drive the electric motor according to the speed reference, preset operating parameters of the speed controller of the frequency converter to provide a first response time of the speed controller; after the speed of the electric motor reaches a constant speed according to the speed reference, adjust at least one operating parameter of the speed controller of the frequency converter to provide a second response time of the speed controller, wherein the second response time of the speed controller is slower than the first response time of the speed controller; and before starting to decelerate from the constant speed according to the speed reference, readjust at least one operating parameter of the speed controller of the frequency converter to provide the first response time of the speed controller.
[0009] The speed controller may be a proportional-integral-derivative controller, PID controller, which includes at least the following operating parameters: proportional gain, integral time, and derivative time.
[0010] Alternatively, the speed controller may be a proportional-integral controller, PI controller, comprising at least the following operating parameters: proportional gain, integral time.
[0011] The at least one operating parameter of the speed controller may further include a filtering time of the speed of the electric motor and / or a filtering time of the error value of the speed controller.
[0012] The drive control unit may further be configured to apply a time delay after reaching the constant speed and before adjusting at least one operating parameter of the speed controller of the frequency converter.
[0013] Alternatively or additionally, the drive control unit may also be configured to readjust at least one operating parameter of a speed controller of the frequency converter using the time advance applied before starting the deceleration from the constant speed.
[0014] The adjustment and / or re-adjustment of at least one operating parameter of the speed controller may result in an adaptation of one or more of the following behavioral characteristics of the speed controller: noise immunity, overshoot, settling time.
[0015] The drive system may be used to drive an electric motor of a conveyor, wherein the conveyor is an elevator, an escalator or a moving walkway.
[0016] According to a second aspect, a method for controlling a drive system for driving an electric motor is provided, wherein the drive system includes a drive control unit and a frequency converter including a speed controller, wherein the method includes: defining a speed reference of the electric motor, wherein the speed reference represents the speed of the electric motor as a function of time; before starting to drive the electric motor according to the speed reference, presetting operating parameters of the speed controller of the frequency converter to provide a first response time of the speed controller; when the speed of the electric motor reaches a constant speed according to the speed reference, adjusting at least one operating parameter of the speed controller of the frequency converter to provide a second response time of the speed controller, wherein the second response time of the speed controller is slower than the first response time of the speed controller; and before starting to decelerate from the constant speed of the electric motor according to the speed reference, re-adjusting at least one operating parameter of the speed controller of the frequency converter to provide the first response time of the speed controller.
[0017] The speed controller may be a proportional-integral-derivative controller, PID controller, which includes at least the following operating parameters: proportional gain, integral time, and derivative time.
[0018] Alternatively, the speed controller may be a proportional-integral controller, PI controller, comprising at least the following operating parameters: proportional gain, integral time.
[0019] The at least one operating parameter of the speed controller may further include a filtering time of the speed of the electric motor and / or a filtering time of the error value of the speed controller.
[0020] The method may further comprise applying a time delay after reaching a constant speed and before adjusting at least one operating parameter of a speed controller of the frequency converter.
[0021] Alternatively or additionally, the method may further comprise re-adjusting at least one operating parameter of a speed controller of the frequency converter using the time advance applied before starting the deceleration from the constant speed.
[0022] The adjustment and / or re-adjustment of at least one operating parameter of the speed controller may result in an adaptation of one or more of the following behavioral characteristics of the speed controller: noise immunity, overshoot, settling time.
[0023] The method may be implemented for driving an electric motor for a conveyor, wherein the conveyor is an elevator, an escalator or a moving walkway.
[0024] Various exemplary and non-limiting embodiments of the invention, both as to constructions and methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplary and non-limiting embodiments when read in connection with the accompanying drawings.
[0025] The verbs "comprise" and "include" are used in this document as open limitations that neither exclude nor require the presence of unrecited features. The features recited in the dependent claims are mutually freely combinable unless expressly stated otherwise. Furthermore, it should be understood that the use of "a" or "an" throughout this document, i.e. the singular, does not exclude a plurality. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In the drawings, embodiments of the invention are shown by way of example and not by way of limitation.
[0027] Figure 1 A simple example of a drive system according to the invention is schematically shown.
[0028] Figure 2 An example of a state-based adaptive regulation function of a frequency converter according to the invention is shown.
[0029] Figure 3 Another example of a state-based adaptive regulation function of a frequency converter according to the present invention is shown.
[0030] Figure 4 An example of a method according to the invention is schematically shown.
[0031] Figure 5 An illustrative example of a drive control unit according to the present invention is disclosed. DETAILED DESCRIPTION
[0032] Figure 1 A simple example of a drive system 100 according to the present invention is schematically shown. The drive system 100 according to the present invention can be used to drive an electric motor 110 in a circulation application, such as a lift, winch, crane, pump, blower, etc. Preferably, the drive system 100 according to the present invention can be used to drive an electric motor 110 of a conveyor (e.g., a people conveyor). Examples of people conveyors can be elevators, escalators and / or moving walkways. The conveyor includes a drive machine, which includes an electric motor 110 for generating a driving force, which is used to move a conveying entity of the conveyor, such as an elevator car. The drive system 100 is configured to control the power supply to the electric motor 110 so as to move the conveying entity of the conveyor. In addition, the drive system 100 is configured to control the speed and / or torque of the electric motor 110.
[0033] According to an exemplary embodiment of the present invention, the drive system 100 can be implemented in an elevator. The elevator can include at least one elevator car as a transport entity, and at least one elevator car is arranged to travel between landings along the elevator shaft for transporting people and / or loads. The drive machine of the elevator system can be an elevator hoist including an electric motor 110 to move the elevator car along the elevator shaft.
[0034] According to another exemplary embodiment of the present invention, the drive system 100 can be implemented in an escalator or a moving walkway, which can be used to transport people and / or loads by steps or pallets provided on an endless crawler as a transport entity. A drive machine including an electric motor 110 can be arranged to drive the endless crawler through a sprocket or corresponding means.
[0035] The drive system 100 according to the present invention comprises a drive control unit 120 and a frequency converter 130. The drive control unit 120 is configured to generate, i.e. define, a speed reference of the electric motor 110 and a torque reference of the electric motor 110. The speed reference represents the speed of the electric motor 110 as a function of time. The drive control unit is configured to provide the generated speed reference of the electric motor 110 and the generated torque reference of the electric motor 110 to the frequency converter 130. The frequency converter 130 is configured to control the speed of the electric motor 110 according to the speed reference, and to control the torque of the electric motor 110 according to the torque reference.
[0036] The frequency converter 130 includes an internal speed controller 140. The speed controller 140 may be any type of speed controller including one or more adjustable operating parameters. Preferably, the speed controller 140 may be a proportional integral (PI) controller. The adjustable operating parameters of the PI controller may include at least a proportional gain and an integral time. Alternatively, the speed controller 140 may preferably be a proportional integral derivative (PID) controller. The adjustable operating parameters of the PID controller may include at least a proportional gain, an integral time, and a derivative time.
[0037] The operation of the speed controller 140 can be implemented, for example, with a microcontroller with embedded software or with discrete analog electronic components. The speed controller 140 continuously defines the error value as the difference between the desired speed of the electric motor 110 according to the speed reference and the measured speed of the electric motor 110 (i.e., the actual speed of the monitored electric motor 110). The drive system 100 can obtain the measured speed of the electric motor 110 from one or more sensors inside or outside the drive system 100. Further, the speed controller 140 applies correction based on the operating parameters of the speed controller 140. In addition to the above-mentioned operating parameters of the PID controller and the PI controller, the operating parameters of the speed controller 140 can also include other operating parameters, such as the filtering time of the measured speed of the electric motor 110 and / or the filtering time of the error value signal. The measured speed of the electric motor 110 and / or the error value signal of the speed controller 140 can be filtered to prevent the speed controller 140 from generating a high-frequency reference, which may generate noise on the electric motor 110 and / or vibration in the transport entity (e.g., elevator car) moved by the electric motor 110. The operating parameters of the speed controller 140 may have an impact on the driving accuracy of the electric motor 110. Alternatively or additionally, when the drive system 100 according to the present invention is used to drive a conveyor for people, the operating parameters of the speed controller 140 may have an impact on the driving comfort experienced by the passengers of the conveyor. The goal is to provide a smooth drive without unexpected and transient movements of the conveyor entity (e.g., an elevator car) caused by unexpected and transient changes in the speed of the electric motor 110, so as to improve the comfort of the drive. The frequency converter 130 may also include other components for controlling the power supply to the electric motor 110.
[0038] The frequency converter 130 according to the invention comprises an adaptive regulation function in order to adapt at least one behavior characteristic of the speed controller 140, such as the response time of the speed controller 140, based on the speed reference in order to improve the driving comfort. The adaptive regulation function may be provided by regulating, i.e. changing, at least one operating parameter of the speed controller 140. For example, in order to reduce the response time of the speed controller 140, the proportional gain of the speed controller 140 may be increased, and in order to increase the response time of the speed controller 140, the proportional gain of the speed controller 140 may be reduced. Alternatively or additionally, in order to reduce the response time of the speed controller 140, the integral time of the speed controller 140 may be increased, and in order to increase the response time of the speed controller 140, the integral time of the speed controller 140 may be reduced. Alternatively or additionally, in order to reduce the response time of the speed controller 140, the derivative time of the speed controller 140 may be increased, and in order to increase the response time of the speed controller 140, the derivative time of the speed controller 140 may be reduced. Alternatively or additionally, the filtering time of the speed controller 140, such as the filtering time of the measured speed of the electric motor 110 and / or the filtering time of the error value signal, may be adjusted in order to adapt the response time of the speed controller 140. The filtering behavior of the filter and thus the effect of the adjustment of the filtering time on the response time of the speed controller 140 may depend on the type of filter used. For example, if the filter is of a low-pass type, in order to reduce the response time of the speed controller 140, the filtering time of the speed controller 140 may be increased, and in order to increase the response time of the speed controller 140, the filtering time of the speed controller 140 may be reduced. It is discussed above how the adjustment of each operating parameter of the speed controller 140 affects the response time of the speed controller 140 individually. However, if more than one operating parameter of the speed controller 140 is adjusted, the combined effect on the response time of the speed controller 140 may not be so direct, because it depends on the operating parameter to be adjusted and the adjustment of each operating parameter (e.g., the amount of adjustment, whether the adjustment is an increase or decrease, etc.).
[0039] Alternatively or additionally, in order to adjust the response time of the speed controller 140, adjusting (i.e., changing) at least one operating parameter of the speed controller 140 may result in adjusting one or more other behavioral characteristics of the speed controller 140. In other words, by adjusting at least one operating parameter of the speed controller 140, different one or more other behavioral characteristics of the speed controller 140 may be provided. The one or more other behavioral characteristics of the speed controller 140 may include noise immunity, overshoot, and / or settling time.
[0040] According to an example embodiment of the present invention, at least one operating parameter of the speed controller 140 may be adjusted according to the state of the electric motor 110. The different states of the electric motor 110 may be stationary, accelerating, constant speed, and decelerating. One or more states of the electric motor 110 may further include one or more sub-states, such as increasing acceleration, decreasing acceleration, constant acceleration, increasing deceleration, decreasing deceleration, constant deceleration, etc. Figure 2 An example of a state-based adaptive regulation function of the frequency converter 130 according to the invention is shown, wherein a proportional gain of the speed controller 140 is adjusted depending on the state of the electric motor 110. In this example, the proportional gain of the speed controller 140 is adjusted, but alternatively or additionally any other operating parameter of the speed controller 140 may be adjusted depending on the state of the electric motor 110. The speed reference of the electric motor 110 as a function of time is shown with a dashed line 210. Figure 2 The example of FIG. 2 only shows one example of a speed reference 110 of the electric motor 110, and the present invention is not limited thereto. Furthermore, in the context of the present invention, any other type of speed reference including one or more constant speed segments may be used. The solid line 220 shows the proportional gain of the speed controller 140 as a function of time.
[0041] Before starting the driving of the electric motor 110, i.e. when the state of the electric motor 110 is stationary, the drive control unit 120 is configured to define a speed reference of the electric motor 110. Furthermore, the drive control unit 120 is configured to define a moment at which the state of the electric motor 110 changes based on the defined speed reference. Figure 2 In the example of FIG. 1 , at time t0, the speed of the electric motor 110 begins to increase, so that the state of the electric motor 110 changes from static to accelerated at time t0. The acceleration can be as follows: Figure 2 As shown, it increases between time t0 and time t1, as Figure 2 is shown to be constant between time t1 and time t2, or as Figure 2 As shown, the speed of the electric motor 110 decreases between time t2 and time t3. At time t3, the speed of the electric motor 110 reaches a constant speed, so that the state of the electric motor 110 changes from acceleration to constant at time t3. At time t4, the speed of the electric motor 110 begins to decrease from the constant speed, so that the state of the electric motor 110 changes from constant speed to deceleration at time t4. The deceleration can be as follows: Figure 2 As shown, it increases between time t4 and time t5, as Figure 2 As shown, it remains constant between time t5 and time t6, or as shown Figure 2 The speed of the electric motor 110 decreases between time t6 and time t7. At time t7, the driving of the electric motor 110 stops, that is, the speed of the electric motor 110 at time t7 is zero, resulting in the state of the electric motor 110 changing from deceleration to rest again at time t7.
[0042] Furthermore, before starting the driving of the electric motor 110 , the driving control unit 120 is configured to preset operating parameters of the speed controller 140 of the frequency converter 130 to provide a first response time of the speed controller 140 .
[0043] The drive control unit 120 may be configured to adjust at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide a second response time of the speed controller 140 after the speed of the electric motor 110 reaches a constant speed according to the speed reference. In other words, after the state of the electric motor 110 changes from the acceleration state to the constant speed state, the drive control unit 120 is configured to adjust at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide a second response time of the speed controller 140. The adjustment value of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be predefined before the driving of the electric motor 110, or dynamically defined during the driving of the electric motor 110. The adjustment of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided immediately after the state of the electric motor 110 changes according to the speed response, i.e., at the earliest at this time. Alternatively, the adjustment of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided after a time delay applied after the state of the electric motor 110 changes according to the speed response, which will be discussed later in this application. When the speed of the electric motor 110 is constant, the second response time of the speed controller 140 is slower than the first response time of the speed controller 140 so as to be able to respond to the change of the error value slowly enough, which in turn improves the smoothness of the electric motor driving. Figure 2 In the example of , the drive control unit 120 is configured to adjust, i.e. reduce, the proportional gain of the speed controller 140 to provide a second response time after time t3, at which the state of the electric motor 110 changes from the acceleration state to the constant speed state. Alternatively or additionally, the drive control unit 120 may be configured to adjust the integral time, the differential time and / or the filter time of the speed controller 140 to provide the second response time. Depending on the operating parameter to be adjusted, the adjustment may be a decrease or an increase, as long as the provided second response time is slower than the first response time. The adjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may preferably be abrupt, such as Figure 2 As described above, in addition to the adjustment of the response time of the speed controller 140, the adjustment of at least one operating parameter of the speed controller 140 may result in the adjustment of one or more other behavioral characteristics of the speed controller 140, such as noise immunity, overshoot, and / or settling time. The one or more other behavioral characteristics may be increased or decreased depending on the operating parameter to be adjusted.
[0044] The drive control unit 120 may also be configured to readjust at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide the first response time of the speed controller 140 again before the speed of the electric motor 110 starts to decrease from the constant speed according to the speed reference. In other words, before the state of the electric motor 110 changes from the constant speed state to the deceleration state, the drive control unit 120 is configured to readjust at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide the first response time of the speed controller 140 again. The readjustment of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided just before the state of the electric motor 110 changes according to the speed response, i.e., at the latest at this time. Alternatively, the readjustment of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided a period of time in advance before the state of the electric motor 110 changes from the constant speed state to the deceleration state, which will be discussed later in this application. Figure 2 In the example of , the drive control unit 120 is configured to readjust (i.e. increase) the proportional gain of the speed controller 140 before time t4 to provide the first response time again, at which time t4 the state of the electric motor 110 changes from the constant speed state to the deceleration state. Alternatively or additionally, the drive control unit 120 may be configured to readjust the integral time, the differential time and / or the filter time of the speed controller 140 to provide the first response time again. Depending on the operating parameter to be readjusted, the readjustment may be a decrease or an increase, as long as the provided first response time is faster than the second response time. The readjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may preferably be abrupt, such as Figure 2 As described above, in addition to the adjustment of the response time of the speed controller 140, the re-adjustment of at least one operating parameter of the speed controller 140 may result in the adjustment of one or more other behavioral characteristics of the speed controller 140, such as noise immunity, overshoot, and / or settling time. The one or more other behavioral characteristics may be increased or decreased depending on the operating parameter to be re-adjusted.
[0045] The state-based adaptive adjustment function of the speed controller 140 enables at least one operating parameter of the speed controller 140 to be predictably adjusted and re-adjusted so that the response to the change of the error value is sufficiently fast when the speed reference of the electric motor 110 changes, i.e., during the acceleration state and the deceleration state of the speed of the electric motor 110. In addition, when the speed of the electric motor 110 is constant, the state-based adaptive adjustment function of the speed controller 140 enables the response to the change of the error value to be sufficiently slow so as to provide a smooth drive of the electric motor 110. The state-based adaptive adjustment function of the speed controller 140 is particularly preferred for longer drives including a speed reference with one or more constant speed states (i.e., sections). For example, in high-rise elevator embodiments, where the drive time with a constant speed may be quite long, for example, between 10 and 40 seconds, or even longer in super high-rise elevators, the state-based adaptive adjustment function of the speed controller 140 is preferred.
[0046] According to an example embodiment, the drive control unit 120 may be configured to apply the time delay 330 before adjusting at least one operating parameter of the speed controller 140 of the frequency converter 130 after the state of the electric motor 110 changes from the acceleration state to the constant speed state. In other words, the drive control unit 120 may be configured to adjust at least one operating parameter of the speed controller 140 of the frequency converter 130 after applying the time delay 330 after reaching the constant speed. Alternatively or additionally, the drive control unit 120 may be configured to re-adjust at least one operating parameter of the speed controller 140 of the frequency converter 130 using the time advance 330 applied before the state of the electric motor 110 changes from the constant to the deceleration. In other words, the drive control unit 120 may be configured to apply the time advance 340 when re-adjusting at least one operating parameter of the speed controller 140 before starting to decelerate from the constant speed.
[0047] Figure 3 Another example of a state-based adaptive regulation function of the frequency converter 130 according to the present invention is shown, in which the proportional gain of the speed controller 140 is adjusted. In addition to applying the time delay 330 and the time advance 340, Figure 3 The example is otherwise similar to Figure 2 In this example, the proportional gain of the speed controller 140 is adjusted, but alternatively or additionally, any other operating parameter of the speed controller 140 may be adjusted depending on the state of the electric motor 110. The adjustment and / or readjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may preferably be abrupt, such as Figure 3The drive control unit 120 is configured to apply a time delay 330 before adjusting (i.e. reducing) the proportional gain of the speed controller 140 after the state of the electric motor 110 changes from the acceleration state to the constant speed state, i.e. after time t3. In addition, the drive control unit 120 is configured to readjust at least one operating parameter of the speed controller 140 with a time advance 340 before the state of the electric motor 110 changes from the constant speed state to the deceleration state, i.e. before time t4.
[0048] The time delay 330 and the time advance 340 may be significantly shorter than the constant speed segment, i.e. the time period during which the speed of the electric motor 110 is constant, so as to be able to change from the first response time to the second response time during the constant speed segment, and vice versa. The time delay 330 may at least allow the speed of the electric motor 110 to have reached and stabilized to the rated speed, i.e. the time delay 330 may preferably be at least as long as the stabilization time of the speed controller 140. The time advance 340 may preferably be long enough so that the speed controller 140 has enough time to adjust the operating parameters of the speed controller 140 before the deceleration begins. The time advance may preferably be about 10 control cycles, for example between 8 and 12 control cycles. Applying the time delay 330 and / or the time advance 340 in the state-based adaptive regulation function of the speed controller 140 ensures that the response to the change of the error value is fast enough when the speed reference of the electric motor 110 changes, i.e. during the acceleration state and the deceleration state of the electric motor 110.
[0049] The present invention has been described above with respect to the drive system 100 according to the present invention. Figure 4 An example of a method for controlling a drive system according to the present invention is described, Figure 4 The present invention is schematically shown as a flow chart. In step 410, the drive control unit 120 defines a speed reference of the electric motor 110 before starting the drive of the electric motor 110, i.e. when the state of the electric motor 110 is stationary. In addition, the drive control unit 120 is configured to define the moment of the state change of the electric motor 110 based on the defined speed reference. The different states of the electric motor 110 may be stationary, acceleration, constant speed and deceleration. One or more states of the electric motor 110 may also include one or more sub-states, such as increasing acceleration, decreasing acceleration, constant acceleration, increasing deceleration, decreasing deceleration, constant deceleration, etc. The moments of these state changes may be defined before the drive of the electric motor 110 is started, i.e. when the state of the electric motor 110 is stationary, so as to enable predictable adjustment and readjustment of at least one operating parameter of the speed controller 140.
[0050] In step 420, before starting the driving of the electric motor 110, the driving control unit 120 presets the operating parameters of the speed controller 140 of the frequency converter 130 to provide a first response time of the speed controller 140. Steps 410 and 420 may also be performed in reverse order. After steps 410 and 420, the driving of the electric motor 110 may be started.
[0051] At step 430, after the speed of the electric motor 110 reaches a constant speed according to the speed reference, the drive control unit 120 adjusts at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide a second response time of the speed controller 140. In other words, after the speed state of the electric motor 110 changes from the acceleration state to the constant speed state, the drive control unit 120 adjusts at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide a second response time of the speed controller 140. The adjustment value of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be predefined before the driving of the electric motor 110, or dynamically defined during the driving of the electric motor 110. The adjustment of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided immediately after the state of the electric motor 110 changes according to the speed response, i.e., at the earliest. Alternatively, the adjustment of the at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided after a time delay is applied after the state of the electric motor 110 changes according to the speed response (i.e., after the speed of the electric motor 110 reaches a constant speed according to the speed reference). When the speed of the electric motor 110 is constant, the second response time of the speed controller 140 is slower than the first response time of the speed controller 140 so as to be able to respond to the change of the error value slowly enough, which in turn improves the smoothness of the driving of the electric motor 110. After the state of the electric motor 110 changes from the acceleration state to the constant speed state, the drive control unit 120 may adjust the proportional gain, the integral time, the differential time and / or the filter time of the speed controller 140 to provide the second response time. Depending on the operating parameter to be adjusted, the adjustment may be a decrease or an increase, as long as the provided second response time is slower than the first response time. The adjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may preferably be abrupt.
[0052] At step 440, the drive control unit 120 may further re-adjust at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide the first response time of the speed controller 140 again before the speed of the electric motor 110 starts to decrease from the constant speed according to the speed reference. In other words, before the state of the electric motor 110 changes from the constant speed state to the deceleration state, the drive control unit 120 re-adjusts at least one operating parameter of the speed controller 140 of the frequency converter 130 to provide the first response time of the speed controller 140 again. The re-adjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided just before the state of the electric motor 110 changes according to the speed response, i.e., at the latest at this time. Alternatively, the re-adjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may be provided with a time advance, which is applied before the state of the electric motor 110 changes from the constant speed state to the deceleration state, i.e., before deceleration from the constant speed starts according to the speed reference. Before the state of the electric motor 110 changes from the constant speed state to the deceleration state, the drive control unit 120 may readjust the proportional gain, the integral time, the derivative time and / or the filter time of the speed controller 140 to provide a first response time. Depending on the operating parameter to be adjusted, the readjustment may be a decrease or an increase, as long as the provided first response time is faster than the second response time. The readjustment of at least one operating parameter of the speed controller 140 of the frequency converter 130 may preferably be abrupt. As described above, in addition to adjusting the response time of the speed controller 140, the adjustment and / or readjustment of at least one operating parameter of the speed controller 140 may result in the adjustment of one or more other behavioral characteristics of the speed controller 140, such as noise immunity, overshoot and / or settling time. One or more other behavioral characteristics may be increased or decreased depending on the operating parameter to be adjusted and / or readjusted.
[0053] Figure 5An illustrative example of a drive control unit 120 according to the present invention is disclosed. The drive control unit 120 may be a separate unit, or may be included in or as part of other units, such as a frequency converter 130, and / or in an elevator embodiment, the drive control unit 120 may be included in or as part of an elevator control unit. The drive control unit 120 may also be arranged in more than two locations or more than two units in a distributed manner. The drive control unit 120 may include one or more processors 510, one or more memories 520, volatile or non-volatile, for storing portions of a computer program code 525 and any data values, one or more communication interface units 530, and possibly one or more user interface units 540. The mentioned elements may be communicatively coupled to each other via, for example, an internal bus. The processor may be configured to execute at least some portions of the computer program code 525 stored in the memory 520, so that the processor 510 and therefore the drive control unit 120 performs the desired tasks, such as the operation of the drive control unit 120 and / or at least some of the above-mentioned method steps. Therefore, the processor 510 may be arranged to access the memory 520 and retrieve any information therefrom and store any information therein. For the sake of clarity, the processor here refers to any unit suitable for processing information and controlling the operation of the drive control unit and other tasks. It is also possible to use a microcontroller solution with embedded software to implement the operation. Similarly, the memory 520 is not limited to a certain type of memory, but any memory type suitable for storing the described information can be applied to the context of the present invention. The communication interface unit 530 provides an interface for communicating with any external unit. The communication interface unit can be based on one or more known wired or wireless communication technologies to exchange information. One or more user interface units 540 may include one or more input / output (I / O) devices for receiving input and output information, such as buttons, keyboards, touch screens, microphones, loudspeakers, displays, etc.
[0054] The term "constant speed" of the electric motor 110 used throughout this application may preferably be the rated speed of the electric motor 110. Alternatively, at least in some embodiments, it may be desirable to drive the electric motor 110 at one or more different constant speeds, which are not necessarily the rated speed of the electric motor 110. For example, an elevator may include a high-rise elevator shaft, which may be divided into at least two different sections, such as into a shuttle section and one or more destination floor sections. Thus, the electric motor 110 may be configured to use the rated constant speed of the electric motor 110 for the shuttle section, and to use a lower constant speed when operating in other sections.
[0055] As described above, the present invention can be implemented in cyclic applications. The adaptive regulation function of the speed controller 140 discussed above is particularly beneficial for driving an electric motor 110 having a working cycle (i.e., a load cycle) that includes a constant speed section in its cyclic speed reference mode. The drive system 100 and the method for controlling the drive system 100 according to the present invention enable the drive accuracy and / or drive comfort of the electric motor 110 to be improved without additional costs.
[0056] The specific examples provided in the description given above should not be construed as limiting the applicability and / or interpretation of the appended claims.The lists and groups of examples provided in the description given above are not exhaustive unless expressly stated otherwise.
Claims
1. A drive system (100) for driving an electric motor (110), the drive system (100) comprising a drive control unit (120) and a frequency converter (130) including a speed controller (140), wherein: The driving control unit (120) is configured to: defining a speed reference (210) for the electric motor (110), wherein the speed reference (210) represents the speed of the electric motor (110) as a function of time; Before starting driving of the electric motor (110) according to the speed reference (210), presetting operating parameters of a speed controller (140) of the frequency converter (130) to provide a first response time of the speed controller (140); adjusting at least one operating parameter of a speed controller (140) of the frequency converter (130) to provide a second response time of the speed controller (140) after the speed of the electric motor (110) reaches a constant speed according to the speed reference (210), wherein the second response time of the speed controller (140) is slower than the first response time of the speed controller (140); and Prior to initiating deceleration from the constant speed based on the speed reference (210), at least one operating parameter of a speed controller (140) of the frequency converter (130) is re-adjusted to provide a first response time of the speed controller (140).
2. The drive system (100) according to claim 1, wherein: The speed controller (140) is a proportional-integral-differential controller, PID controller, which includes at least the following operating parameters: proportional gain, integral time, and differential time.
3. The drive system (100) according to claim 1, wherein: The speed controller (140) is a proportional-integral controller, PI controller, and includes at least the following operating parameters: proportional gain, integral time.
4. The drive system (100) according to claim 2 or 3, wherein: The at least one operating parameter of the speed controller (140) further includes: a filtering time of the speed of the electric motor (110) and / or a filtering time of an error value of the speed controller (140).
5. The drive system (100) according to claim 1 or 2, wherein: The drive control unit (120) is configured to apply a time delay (330) after reaching the constant speed and before adjusting at least one operating parameter of a speed controller (140) of the frequency converter (130).
6. The drive system (100) according to claim 1 or 2, wherein: The drive control unit is configured to readjust at least one operating parameter of a speed controller (140) of the frequency converter (130) using a time advance (340) applied before starting deceleration from a constant speed.
7. The drive system (100) according to claim 1 or 2, wherein: Adjustment and / or re-adjustment of at least one operating parameter of the speed controller (140) results in adaptation of one or more of the following behavioral characteristics of the speed controller (140): noise immunity, overshoot, settling time.
8. The drive system (100) according to claim 1 or 2, wherein: The drive system (100) is used to drive an electric motor (110) of a conveyor, wherein the conveyor is an elevator, an escalator or a moving walkway.
9. A method for controlling a drive system (100) for driving an electric motor (110), the drive system (100) comprising a drive control unit (120) and a frequency converter (130) including a speed controller (140), wherein: The method comprises: defining (410) a speed reference (210) of the electric motor (110), wherein the speed reference (210) represents the speed of the electric motor (110) as a function of time; Before starting driving of the electric motor (110) according to the speed reference (210), presetting (420) operating parameters of a speed controller (140) of the frequency converter (130) to provide a first response time of the speed controller (140); When the speed of the electric motor (110) reaches a constant speed according to the speed reference (210), adjusting (430) at least one operating parameter of a speed controller (140) of the frequency converter (130) to provide a second response time of the speed controller (140), wherein the second response time of the speed controller (140) is slower than the first response time of the speed controller (140); and Prior to initiating deceleration from a constant speed of the electric motor (110) based on the speed reference (210), at least one operating parameter of a speed controller (140) of the frequency converter (130) is readjusted (440) to provide a first response time of the speed controller (140).
10. The method according to claim 9, wherein: The speed controller (140) is a proportional-integral-differential controller, PID controller, which includes at least the following operating parameters: proportional gain, integral time, and differential time.
11. The method according to claim 9, wherein: The speed controller (140) is a proportional-integral controller, PI controller, and includes at least the following operating parameters: proportional gain, integral time.
12. The method according to claim 10 or 11, wherein: The at least one operating parameter of the speed controller (140) further includes: a filtering time of the speed of the electric motor (110) and / or a filtering time of an error value of the speed controller (140).
13. The method according to claim 9 or 10, wherein: The method also includes applying a time delay (330) after the constant speed is reached and before adjusting at least one operating parameter of a speed controller (140) of the frequency converter (130).
14. The method according to claim 9 or 10, wherein: The method also includes re-adjusting at least one operating parameter of a speed controller (140) of the frequency converter (130) using a time advance (340) applied prior to initiating deceleration from a constant speed.
15. The method according to claim 9 or 10, wherein: Adjustment and / or re-adjustment of at least one operating parameter of the speed controller (140) results in adaptation of one or more of the following behavioral characteristics of the speed controller (140): noise immunity, overshoot, settling time.
16. The method according to claim 9 or 10, wherein: The method is implemented for driving an electric motor (110) of a conveyor, wherein the conveyor is an elevator, an escalator or a moving walkway.