Method for determining a pre-torque of a lift system

Abstract

A method for determining a lead torque of an elevator system (100) comprises the steps of: generating control commands for actuating an electric motor (110) such that an elevator car (104) which is coupled to the counterweight carries out at least one first, second, third, and fourth test run, wherein the elevator car is moved from a first position into a second position in each of the first and third test runs and from the second position into the first position in each of the second and fourth test runs, and the elevator car is loaded with a weight (126) in the third and fourth test runs and is not loaded with the weight in the first and second test runs; receiving current-measurement data, which indicates the current flowing through the electric motor, said current being measured by a current-measuring device (124) during the movement of the elevator car, and height measurement data, which indicates the height of the elevator car relative to the first and / or second position, said height being measured by a height measuring device (122) during the movement of the elevator car, in multiple successive time steps in each test run; calculating at least one parameter of a calibration function, which defines a relationship between the current, the height, and the weight, using the current-measurement data and the height measurement data received in different test runs in order to obtain at least one calibration value; and calculating an adaptation value using the at least one calibration value in order to adapt the counterweight so that the counterweight is in equilibrium with the elevator car (104).

Description

[0001] The present invention relates to a method for determining the holding torque of an elevator system. The invention further relates to a control device, a computer program, and a computer-readable medium for executing such a method. The invention also relates to an elevator system equipped with such a control device.

[0002] An elevator system, such as a passenger or freight elevator, typically includes a counterweight that is connected to a car via suitable lifting means and serves to reduce the forces required to raise or lower the car.

[0003] US 2013 / 0018639 A1 discloses a control device for an elevator intended to operate with a speed pattern that is changed based on the elevator's load, wherein a control parameter is automatically adjusted within a short period of time, so that the capability of a drive device is appropriately provided regardless of the magnitudes of the travel resistance and mechanical loss, which vary for each elevator, and consequently the elevator is operated with high efficiency, wherein the control device comprises: a travel model used to calculate the elevator's setpoint speed; and means for automatically adjusting a parameter of the travel model based on travel data during an elevator journey when the elevator is installed and adjusted.

[0004] The counterweight and the car should be in equilibrium when the car is loaded with a specific weight. To achieve this equilibrium, the loaded car can be gradually weighted or lightened with counterweights until it is balanced with the counterweight, meaning it no longer moves when the car brake is released. The counterweight can then be adjusted according to the added or removed counterweights. Such a gradual approach to finding the correct counterweight can be very time-consuming. Furthermore, the result can be inaccurate due to varying friction conditions when raising and lowering the car. The actual state of equilibrium influences the stopping torque. To achieve a high level of ride quality, it must be taken into account when determining the stopping torque.

[0005] Therefore, there may be a need for a simplified method for determining a holding torque that takes into account the actual equilibrium state. Furthermore, there may be a need for a control device, a computer program, and a computer-readable medium for executing such a method, as well as for an elevator system equipped with such a control device.

[0006] Such a need can be met by the subject matter of one of the independent claims. Advantageous embodiments are defined in the dependent claims and in the following description.

[0007] A first aspect of the invention relates to a method for determining a holding torque. The elevator system comprises an elevator shaft, a car which is movable along the elevator shaft at least between a first position and a second position and is coupled to the counterweight via load-bearing elements, and an electric motor for driving the car. The method comprises at least the following steps: generating control commands for controlling the electric motor so that the car performs at least one first, second, third, and fourth test run, wherein in the first and third test runs the car is moved from the first position to the second position, and in the second and fourth test runs from the second position to the first position, wherein in the third and fourth test runs the car is loaded with a weight, and in the first and second test runs it is not loaded with the weight;Receiving current measurement data, indicating a current flowing through the electric motor as measured by a current measuring device during the movement of the car, and height measurement data, indicating a height of the car relative to the first and / or second position as measured by a height measuring device during the movement of the car, in several successive time steps in each test run; calculating at least one parameter of a calibration function that defines a relationship between the current, the height, and the weight, using the current measurement data and the height measurement data received in different test runs to obtain at least one calibration value;Calculate a first weight difference, representative of the weight difference between the mass of the elevator system on one side of the electric motor's drive sheave and the mass of the elevator system on the other side of the drive sheave when the car is in the first position; calculate a second weight difference, representative of the weight difference between the mass of the elevator system on one side of the electric motor's drive sheave and the mass of the elevator system on the other side of the drive sheave when the car is in the second position, the first and second weight differences being calculated using the calibration function and at least one calibration value; and determine a holding torque for applying to the electric motor before the car is moved, depending on the first and second weight differences.

[0008] The process can, for example, be carried out automatically by a processor in the elevator system's control device.

[0009] The first and second positions can refer to different heights of the elevator car within the shaft. For example, the first position could be the highest position of the car and the second position the lowest position, or vice versa.

[0010] To calculate at least one parameter of the calibration function, only those current measurement data and / or only those height measurement data can be used that were generated and / or received during a period in which the speed of the elevator car is recognized as constant. This can be the case, for example, if, by evaluating the height measurement data, it is recognized that the elevator car is moving within a certain height range between the first and second positions.

[0011] The electric motor can be controlled, for example, so that the elevator car moves from the first to the second position or from the second to the first position during each test run, following a predetermined speed profile without stopping. This speed profile can include, for example, a continuously increasing section, a constant section, and a continuously decreasing section. The constant section can transition directly into the continuously increasing section, and vice versa.

[0012] It is possible that the current measuring device generates current measurement data in several consecutive time steps during each test run and sends it to the control device. Similarly, it is possible that the altitude measuring device generates altitude measurement data in several consecutive time steps during each test run and sends it to the control device. The current measurement data and the altitude measurement data can be temporally correlated. For example, the same timestamp can be assigned to the temporally correlated current measurement data and the altitude measurement data.

[0013] The current measuring device can, for example, be a component of a current controller for regulating the current flow through the electric motor. The controller can be configured to operate the power switches of an inverter, which is connected at its output to the terminals of the electric motor, using the current measurement data.

[0014] The height measuring device can, for example, include a position sensor in the form of an absolute encoder or an incremental encoder. Additionally or alternatively, the height measuring device can include a barometer. Alternatively or additionally to such a direct measurement, the height of the elevator car can also be determined from the acceleration of the car, its rotational speed, or the rotational angle of the electric motor.

[0015] A "calibration function" can be understood as a mathematical function, such as a linear function or a second-degree or higher polynomial. The parameter(s) of the calibration function can be calculated, for example, by processing the current and height measurement data using a regression procedure. This can involve processing the current and height measurement data generated and / or received during all four test runs. As mentioned previously, only those current and / or height measurement data from each test run that were generated and / or received during a specific period in which the speed of the elevator car was determined to be constant can be processed.

[0016] For example, the current can be a dependent variable of the calibration function, while the height and weight can be independent variables of the calibration function.

[0017] The term "current" can also refer to a current component, for example a d- or q-component of the current.

[0018] The term "calibration value" can be understood as a parameter value assigned to a single parameter of the calibration function.

[0019] The "weight difference" (also called "unbalance" and expressed in kg) refers to an imbalance within the elevator system relative to the center point formed by the traction sheave. In other words, the weight difference is the difference between the weight of the elevator system (e.g., the first section of the suspension system plus the counterweight) on one side of the traction sheave and the weight of the elevator system (total suspension system minus the first section of the suspension system plus the car) on the other side of the traction sheave. For example, when the car is on the top floor (first position), the suspension system may be located almost exclusively on the counterweight side of the traction sheave. In this case, the amount of the weight difference is the difference between the weight of the counterweight plus almost the total weight of the suspension system minus the weight of the car.

[0020] The "first weight difference" (unbalance_top) corresponds to the aforementioned weight difference in the first position (that is, when the cabin is on the top floor). The "second weight difference" (unbalance_bot) corresponds to the aforementioned weight difference in the second position (that is, when the cabin is on the bottom floor).

[0021] The "pre-torque" (also called "holding torque") refers to the torque that must be applied to the electric motor of the elevator system to keep the car in the stopping position after the brake is released. Applying this holding torque to the electric motor prevents the car from moving downwards or upwards after the brake is released. This is particularly important for ride quality. The more precisely the holding torque can be determined, the better the ride quality.

[0022] In short, the method described here and below allows for a significantly simpler and more accurate determination of the holding torque compared to conventional methods. Accurate determination of the holding torque prevents unwanted car movements when releasing the car brake.

[0023] This allows measurement inaccuracies due to friction fluctuations to be reduced to a minimum. This can be achieved, for example, by appropriately averaging measurement results from measurements taken during a phase in which the elevator car travels at a (nearly) constant speed, thereby effectively filtering out measurement noise and deviations due to friction fluctuations as a function of the travel distance.

[0024] A second aspect of the invention relates to a control device with a processor configured to execute the method according to an embodiment of the first aspect of the invention. The control device may comprise hardware and / or software modules. In addition to the processor, the control device may include memory and data communication interfaces for data communication with peripheral devices. Features of the method according to an embodiment of the first aspect of the invention may also be features of the control device, and vice versa.

[0025] A third aspect of the invention relates to an elevator system, for example a freight or passenger elevator. The elevator system comprises an elevator shaft, a car that is movable along the elevator shaft at least between a first position and a second position, a counterweight that is coupled to the car via load-bearing means, an electric motor for driving the car, a current measuring device for measuring a current flowing through the electric motor, a height measuring device for measuring a height of the car relative to the first and / or second position, and a control device according to an embodiment of the second aspect of the invention.

[0026] A fourth aspect of the invention relates to a computer program comprising instructions that, when the computer program is executed by the processor, cause the processor to execute the method according to an embodiment of the first aspect of the invention.

[0027] A fifth aspect of the invention relates to a computer-readable medium on which the computer program is stored according to an embodiment of the fourth aspect of the invention. The computer-readable medium can be a volatile or non-volatile data storage medium. For example, the computer-readable medium can be a hard drive, a USB storage device, RAM, ROM, EPROM, or flash memory. The computer-readable medium can also be a data communication network that enables the download of program code, such as the internet or a cloud.

[0028] Features of the method according to an embodiment of the first aspect of the invention may also be features of the computer program and / or the computer-readable medium and vice versa.

[0029] Possible features and advantages of embodiments of the invention can be considered, among other things and without limiting the invention, as being based on the ideas and findings described below.

[0030] According to one embodiment, a height reference value can be calculated by halving the height difference between the first and second positions. Additionally or alternatively, a weight reference value can be calculated by multiplying a permissible weight mass by a predetermined weight factor. Furthermore, the lead torque can be calculated using the height reference value, the weight reference value, or a combination of both.

[0031] The height difference may, for example, have been measured during a prior learning run of the car. The height difference may correspond to the actual length of a distance the car can travel at most when moving from the first position to the second position, or vice versa. In the balanced state, the car and the counterweight should remain at the same height, i.e., halfway between the first and second positions, when the car brake is released. The weight factor may indicate a predetermined ratio of the counterweight to the rated load, i.e., the permissible mass of the weight, in the balanced state.

[0032] According to one embodiment, a first average function, defining a first relationship between current and height under ideal friction conditions, can be determined using the current and height measurement data received during the first and second test runs. Additionally or alternatively, a second average function, defining a second relationship between current and height under ideal friction conditions, can be determined using the current and height measurement data received during the third and fourth test runs. At least one parameter of the calibration function can then be calculated using the first average function and / or the second average function. The term "ideal friction conditions" can be understood to mean identical friction conditions when the elevator car moves in both directions.The first average function and / or the second average function can, for example, be a linear function and / or a function obtained through linear regression. In this way, the parameter(s) of the calibration function can be calculated with minimal computational effort.

[0033] According to one embodiment, for each test run, an output function defining a linear relationship between current and altitude can be determined by processing the current and altitude measurement data received at different time steps during the respective test run. At least one parameter of the first average function can be calculated by averaging a parameter of the output function for the first test run and a parameter of the output function for the second test run. Additionally or alternatively, at least one parameter of the second average function can be calculated by averaging a parameter of the output function for the third test run and a parameter of the output function for the fourth test run. In this way, the computational effort required to calculate the parameter(s) of the calibration function can be further reduced.

[0034] The output function can, for example, include at least one first parameter and one second parameter.

[0035] In this case, it is possible to determine the first parameter of the first average function by calculating the average of the first parameter of the original function for the first test drive and the first parameter of the original function for the second test drive. Similarly, a second parameter of the first average function can be determined by calculating the average of the second parameter of the original function for the first test drive and the second parameter of the original function for the second test drive.

[0036] Additionally or alternatively, in this case, it is possible to determine the first parameter of the second average function by calculating the average of the first parameter of the original function for the third test drive and the first parameter of the original function for the fourth test drive. Similarly, a second parameter of the second average function can be determined by calculating the average of the second parameter of the original function for the third test drive and the second parameter of the original function for the fourth test drive.

[0037] According to one embodiment, a first current value can be calculated by inputting the height reference value into the first averaging function. Additionally or alternatively, a second current value can be calculated by inputting the height reference value into the second averaging function. In this process, at least one parameter of the calibration function can be calculated using the first and / or second current value. In this context, "current value" can be understood as an ideal value for the current flowing through the electric motor, or for a component of this current, for example, a d- or q-component, assuming ideal friction conditions during the movement of the elevator car.

[0038] According to one embodiment, an altitude-related parameter of the calibration function can be calculated to obtain an altitude calibration value as the calibration value. Additionally or alternatively, a weight-related parameter of the calibration function can be calculated to obtain a weight calibration value as the calibration value. Additionally or alternatively, a current-related parameter of the calibration function can be calculated to obtain a current calibration value as the calibration value. For example, the altitude calibration value can have the unit [ A / m ], the weight calibration value the unit [ A / kg ] and the current calibration value the unit [ A] have. However, other suitable units are also possible. In other words, the lead torque can be calculated using the height calibration value, the weight calibration value, the current calibration value, or a combination of at least two of the aforementioned calibration values. In this way, the lead torque can be calculated very accurately without having to load the car with weights of varying masses.

[0039] According to one embodiment, the altitude calibration value can be obtained by calculating an average of an altitude-related parameter of the first average function and an altitude-related parameter of the second average function. This further reduces the computational effort required to calculate the altitude calibration value.

[0040] According to one embodiment, the weight calibration value can be obtained by dividing the difference between the first current value and the second current value by a weight value indicating the current mass of the weight. Additionally or alternatively, the current calibration value can be obtained by subtracting the product of the altitude calibration value and the altitude reference value from the first current value. Alternatively or additionally, when determining the current calibration value, the product of the weight calibration value multiplied by the mass of the actual weight during the first test run can be subtracted. The current mass of the weight can, for example, be equal to a nominal mass of the counterweight or equal to a product of a permissible mass of the weight and a predetermined weight factor. In this way, the computational effort required to calculate the weight calibration value or the current calibration value can be further reduced.

[0041] According to one embodiment, it can be checked at each time step whether the elevator car is moving at a constant speed. For calculating the at least one parameter of the calibration function, only the current measurement data and / or only the height measurement data from those time steps in which it is detected that the elevator car is moving at a constant speed can be used. The constant speed of the elevator car can be detected by comparing the speed of the elevator car in a current time step with the speed of the elevator car in at least one time step preceding the current time step. It is also possible that the speed of the elevator car is detected as constant if it is detected that the elevator car is moving within a certain height range between the first and second positions.This height range can be calculated, for example, from known movement parameters of the elevator car, taking into account the known height difference between the first and second positions—that is, a simple distance between the first and second positions. Whether the elevator car is within this height range can be determined, for example, by appropriately evaluating the height measurement data. In this way, inaccuracies in the calculation of the stopping torque due to excessive speed changes can be avoided.

[0042] According to one embodiment, the altitude calibration value can be multiplied by the altitude reference value, the resulting product added to the current calibration value, and the resulting sum divided by the weight calibration value and the permissible mass of the weight to obtain a negative actual equilibrium factor. This further reduces the computational effort required to calculate the lead value. According to another embodiment, the first and / or second weight difference is determined using the calibration function and the weight calibration value. Specifically, the first weight difference is determined by dividing the negative altitude calibration value by the weight calibration value and multiplying by the altitude reference value. Specifically, the second weight difference is determined by dividing the altitude calibration value by the weight calibration value and multiplying by the altitude reference value.In this way, the computational effort required to calculate the reserve value can be further reduced.

[0043] According to one embodiment, the lead torque is determined proportionally to the sum of the second weight difference; the current mass of the weight in the car; the negative actual equilibrium factor multiplied by the permissible mass of the weight; and the measured height divided by the height difference between the first and second positions multiplied by the difference between the first weight difference and the second weight difference. In this way, the computational effort required to calculate the lead torque can be further reduced.

[0044] For example, it is possible to recalculate the initial average function using additional current and altitude measurements to obtain an updated initial average function. The current calibration value can then be recalculated using this updated initial average function. Finally, the lead torque can be recalculated using this updated current calibration value, along with the altitude and weight calibration values.

[0045] Embodiments of the invention are described below with reference to the accompanying drawings, whereby neither the drawings nor the description are to be interpreted as limiting the invention. Fig. 1 Figure 1 shows an elevator system according to an embodiment of the invention. Fig. 2 shows a control device according to an embodiment of the invention. Fig. 3 shows a diagram illustrating different current and velocity profiles that occur when controlling the elevator system. Fig. 1 were measured or calculated. Fig. 4 shows a flowchart of a process according to an embodiment of the invention.

[0046] The figures are merely schematic and not to scale. Identical reference symbols in the different figures denote identical or equivalent features.

[0047] Fig. 1 Figure 1 shows an elevator system 100, such as a passenger or freight elevator in a building, comprising an elevator shaft 102, a car 104, a counterweight 106 which is coupled to the car 104 via support means 108, for example via one or more ropes, belts or straps, and an electric motor 110 for driving the support means 108, and thus the car 104 or the counterweight 106.

[0048] The elevator car 104 can travel along the elevator shaft 102 between a first position 112 and a second position 114. For example, in Fig. 1 The first position 112 refers to a stop for the elevator car 104 opposite a first shaft opening 116 on a top floor of the building, and the second position 114 refers to a stop for the elevator car 104 opposite a second shaft opening 118 on a bottom floor of the building. Additional stops for the elevator car 104 may be provided between the two positions 112 and 114.

[0049] Furthermore, the elevator system 100 includes a control device 120 for controlling the electric motor 110, as shown below with reference to Fig. 2 will be described in more detail.

[0050] An input of the control device 120 is connected to an output of a height measuring device 122, which is configured to measure the current height of the car 104 in the elevator shaft 102 relative to the first position 112 and / or the second position 114. The height measuring device 122 is shown by way of example in Fig. 1 Configured as an absolute encoder to measure the absolute position of the car 104 in the elevator shaft 102. However, it can also be configured as an incremental encoder or barometer.

[0051] The input of the control device 120 is further connected to an output of a current measuring device 124, which is configured to measure a current flowing through the electric motor 110. The current measuring device 124 can, for example, be implemented as a component of a controller for regulating the speed of the car 104 and / or as a component of a converter. Contrary to the Fig. 1 In the selected representation, the current measuring device 124 can also be implemented as a component of the control device 120.

[0052] The control device 120 is configured to control the electric motor 110 such that the car 104 performs a series of test runs between the two positions 112, 114 as part of a procedure described in more detail below. In some of the test runs, the car 104 can, as in Fig. 1 shown to be loaded with a weight of 126.

[0053] The individual steps of the procedure described below for determining a holding torque are detailed in the document in Fig. 4 The flowchart shown illustrates this.

[0054] According to the in Fig. 2 In the example shown, the control device 120 first generates control commands 200 (S10) that cause the electric motor 110 to raise or lower the car 104, so that the car 104 performs a first, second, third, and fourth test run. The test runs can be performed sequentially in the specified order. However, another suitable sequence of test runs is also possible. In this case, the car 104 is moved from the first position 112 to the second position 114 in the first and third test runs, and from the second position 114 to the first position 112 in the second and fourth test runs. Furthermore, the car 104 is loaded with weight 126 before the third test run, so that the car 104 performs the third and fourth test runs with weight 126. In contrast, the car 104 is unloaded in the first and second test runs.

[0055] In each of the aforementioned test runs, in a second step S20, current measurement data 202, which are generated and provided by the current measuring device 124 during the movement of the car 104 in several successive time steps, and height measurement data 204, which are generated and provided by the height measuring device 122 during the movement of the car 104 in several successive time steps, are received in the control device 120.

[0056] The current measurement data 202 and the height measurement data 204 are processed in a third step S30 to obtain at least one calibration value 206, which is assigned to a parameter 208 of a calibration function 210 that defines a linear relationship between the current flowing through the electric motor 110, the height of the car 104 and a mass of weight 126.

[0057] For this purpose, the current measurement data 202 and the altitude measurement data 204 are entered into a first module 212, which determines an output function 214 for each test run based on the current measurement data 202 and the altitude measurement data 204, which were received in different time steps during the respective test run. This output function defines a linear relationship between the current and the altitude (see also Fig. 3 ).

[0058] Each output function 214 here includes a first parameter 216 related to the height and a second parameter 218.

[0059] In a second module 220, by combining the four obtained initial functions 214 accordingly, a first average function 222 and a second average function 224 are determined, which are also linear functions with each having a further first parameter 226 related to the height and a further second parameter 228.

[0060] The further first parameter 226 for the first average function 222 is calculated by taking the mean of the first parameters 216 of the two output functions 214 resulting from the first and second test runs. The further second parameter 228 for the first average function 222 is calculated by taking the mean of the second parameters 218 of the two output functions 214 resulting from the first and second test runs.

[0061] The further first parameter 226 for the second average function 224 is calculated by taking the mean of the first parameters 216 of the two original functions 214 resulting from the third and fourth test runs. Similarly, the further second parameter 228 for the second average function 222 is calculated by taking the mean of the second parameters 218 of the two original functions 214 resulting from the third and fourth test runs.

[0062] The second module 220 is further configured to calculate a first current value 232 by entering an altitude reference value 230 into the first average function 222 and a second current value 234 by entering the altitude reference value 230 into the second average function 224.

[0063] The altitude reference value of 230 was calculated, for example, by halving the altitude difference measured during a previous learning run between the first position 112 and the second position 114. However, other calculation methods for the altitude reference value 230 are also possible.

[0064] The calibration value 206 is calculated in a third module 236.

[0065] In this example, the third module 236 calculates an altitude-related parameter 208a of the calibration function 210 to obtain an altitude calibration value 206a, a weight-related parameter 208b of the calibration function 210 to obtain a weight calibration value 206b, and a current-related parameter 208c of the calibration function 210 to obtain a current calibration value 206c.

[0066] The altitude calibration value 206a is calculated, for example, by forming a mean value from the two further first parameters 226 of the first average function 222 and the second average function 224.

[0067] The weight calibration value 206b, for example, is calculated from the two current values ​​232, 234 and a weight value 238, which indicates a mass of weight 126, by subtracting the first current value 232 from the second current value 234 and dividing the resulting difference by the weight value 238.

[0068] The current calibration value 206c, for example, is calculated from the altitude calibration value 206a, the altitude reference value 230 and the first current value 232 by multiplying the altitude calibration value 206a by the altitude reference value 230 and subtracting the resulting product from the first current value 232.

[0069] Finally, in a fourth step S40 in a fourth module 240, using the calibration value 206 or the calibration values ​​206a, 206b, 206c, a holding torque 242 is calculated, which indicates the torque with which the electric motor 110 must be applied in order to prevent the car from moving when the car brake is released.

[0070] For this purpose, for example, in a first block 244 a negative actual equilibrium factor 246 is calculated by multiplying the altitude calibration value 206a with the altitude reference value 230, adding the resulting product to the current calibration value 206c, and dividing the resulting sum by the weight calibration value 206b and the permissible mass of the weight (126, not shown).

[0071] Subsequently, for example in a second block 248, the holding torque 242 is calculated by adding the negative actual equilibrium factor 246 multiplied by the permissible mass of the weight (126) to a value 250.

[0072] The value 250 corresponds, for example, to the sum of the second weight difference (unbalanced_bot); the current mass of the weight (126) in the elevator car; and the measured height divided by the height difference between the first position (112) and the second position (114) multiplied by the difference between the first weight difference (unbalanced_top) minus the second weight difference (unbalanced_bot).

[0073] The control device 120 can be configured to generate further control commands 252 in an optional step S50, for example during a regular inspection, after the initial calculation of the calibration value 206 or the calibration values ​​206a, 206b, 206c, by which the electric motor 110 is controlled in such a way that the car 104 performs further test runs, whereby in these further test runs the car 104 is moved, for example, from the first position 112 to the second position 114 and in the opposite direction.

[0074] Analogous to step S20 described above, in an optional step S60 the control device 120 receives further current measurement data 254 from the current measurement device 124 and further altitude measurement data 256 from the altitude measurement device 122 in several successive time steps in the further test runs.

[0075] The additional measurement data 254, 256 are used by the control device 120 in an optional step S70 to update at least one of the calibration values ​​206, 206a, 206b, 206c. The additional measurement data 254, 256 can be processed analogously to the method described above for step S30. For example, in this case, only the current calibration value 206c can be updated, while the altitude calibration value 206a and the weight calibration value 206b remain unchanged.

[0076] The adjustment value 242 is then recalculated in an optional step S80 by processing the updated calibration value(s) together with the unupdated calibration value(s).

[0077] Fig. 3 Figure 1 shows, as an example, a first velocity profile 300, which indicates the velocity of the elevator car 104 in [m / s] during the first test run, a second velocity profile 302, which indicates the velocity of the elevator car 104 in [m / s] during the second test run, a first current profile 304 of the measured current ISQ associated with the first velocity profile 300, and a second current profile 306 of the measured current ISQ associated with the second velocity profile 302. In addition, the output functions 214 resulting from the first and second test runs are shown: a first output function 214a resulting from the first test run and a second output function 214b resulting from the second test run.

[0078] A constant section of the speed profiles 300, 302 corresponds to a height range within which the speed of the car 104 is considered or recognized as constant. The height range (HQ_const_speed) is calculated, for example, from the height difference (HG) between the two positions 112, 114, a nominal speed (VKN), a nominal acceleration (AK), and a nominal jerk (JK) of the car 104 as follows: HQ_const_speed = HQ − VKN 2 AK − VKN ⋅ AK JK + AK 2 JK 2 .

[0079] If HQ_const_speed ≥ 60% * HQ, then a test speed (v4) at which the car 104 is to be moved during the test runs is set equal to the nominal speed. Otherwise, the test speed is calculated, for example, using: v 4 = AK 2 2 ⋅ JK ⋅ 5 + 4 ⋅ 1 − 0 , 6 ⋅ HQ ⋅ JK 2 AK 3 − 1 , sodass HQ_const_speed = 60 % * HQ .

[0080] Fig. 3 shows typical results for HQ_const_speed ≥ 60% * HQ.

[0081] The following describes an exemplary procedure for determining the holding torque. GQT represents the current mass of weight 126 in [kg]. Accordingly: GQT = 0 kg when the car 104 is unloaded; GQT = GQ when the current mass of weight 126 is equal to the permissible mass GQ of weight 126. Furthermore: HQT = 0 m when the car 104 is in the second position 114, i.e., on the lowest floor; HQT = HQ when the car 104 is in the first position 112, i.e., on the top floor.

[0082] First, the weight value 238 is entered via a user interface, so for the first and second test drive GQT _test1 = 0 and for the third and fourth test drive, for example GQT _test2 = GQ or GQT_test2 ≈ GQ.

[0083] The control device 120 then requests a current converter current iq from the converter, which is communicated to the control device 120 regularly at specific time intervals, for example every 10 ms, during the further course of the process.

[0084] The test drive then starts according to the selected test speed.

[0085] As soon as it is detected that the elevator car 104 is moving in the height range HQ_const_speed, a linear regression is started based on the current measurement data 202 or 254 and the height measurement data 204 or 256, whereby the results of the linear regression are updated in each time step, for example every 10 ms.

[0086] As soon as it is detected that the elevator car 104 is no longer moving within the height range HQ_const_speed, the linear regression is interrupted.

[0087] From the regression results obtained up to the time of the interruption, the first parameter 216 and the second parameter 218 of the respective output function 214 are calculated at the end of the test drive.

[0088] The following four output functions 214 result from the first to fourth test runs: for the first test drive: ISQ_test 1 _down HQT , GQT = GQT_test 1 = a_test 1 _down * HQT + b_test 1 _down ; for the second test drive: ISQ_test 1 _up HQT , GQT = GQT_test 1 = a_test 1 _up * HQT + b_test 1 _up ; for the third test drive: ISQ_test 2 _down HQT , GQT = GQT_test 2 = a_test 2 _down * HQT + b_test 2 _down ; for the fourth test drive: ISQ_test 2 _up HQT , GQT = GQT_test 1 = a_test 2 _up * HQT + b_test 2 _up .

[0089] In this context, a_test1_down, a_test1_up, a_test2_down and a_test2_up each denote the first parameter 216 and b_testl_down, b_test1_up, b_test2_down and b_test2_up each denote the second parameter 218 of the respective output function 214.

[0090] From these results, the control device 120 calculates the three calibration values ​​a_HQT, b_GQT and ISQ0 and stores them permanently. a_HQT denotes the altitude calibration value 206a, b_GQT the weight calibration value 206b and ISQ0 the current calibration value 206c.

[0091] It is assumed that the same, i.e., ideal, friction conditions apply to both directions of movement of the car 104. Under this assumption, the current, more precisely a q-component of the current (ISQ_no_friction) used to control a torque of the electric motor 110, can be calculated as follows: using the first average function 222: ISQ_no_friction_test 1 HQT , GQT = GQT_test 1 = a_test 1 * HQT + b_test 1 ; using the second average function 224: ISQ_no_friction_test 2 HQT , GQT = GQT_test 2 = a_test 2 * HQT + b_test 2 .

[0092] The following applies: a_test 1 = a_test 1 _down + a_test 1 _up / 2 ; b_test 1 = b_test 1 _down + b_test 1 _up / 2 ; a_test 2 = a_test 2 _down + a_test 2 _up / 2 ; b_test 2 = b_test 2 _down + b_test 2 _up / 2 .

[0093] Here, a_test1 and a_test2 denote the further first parameters 226 and b_test1 and b_test2 denote the further second parameters 228.

[0094] Ideally, a_test1 and a_test2 are identical and depend only on HQT, while b_test1 and b_test2 do not depend on HQT, but only on GQT.

[0095] The calibration function 210 is accordingly: ISQ_no_friction HQT GQT = a_HQT * HQT + b_GQT * GQT + ISQ 0 , with a_HQT in [A / m], b_GQT in [A / kg] and ISQ0 in [A].

[0096] a_HQT is independent of GQT. Since a_test1 and a_test2 are based on independent measurements, a_HQT can be easily calculated using: a_HQT = a_test 1 + a_test 2 / 2 .

[0097] b_HQT and ISQ0 can be calculated using the following system of equations:

[0098] b_GQT results in: b_GQT = ISQ_no_friction_test 2 HQT = HQ / 2 , GQT = GQT_test 2 − ISQ_no_friction_test 1 HQT = HQ / 2 , GQT = GQT_test 1 / GQT_test 2 − GQT_test 1 .

[0099] ISQ0 results in:

[0100] The values ​​a_HQT, b_GQT and ISQ0 are stored permanently.

[0101] The following applies to the calculations described below: KG_act: existing balancing factor (0 < KG_act < 1).

[0102] The elevator system 100 can be considered balanced if the following applies: ISQ_no_friction HQT = HQ / 2 , GQT = 0 .

[0103] It follows: GQT_balanced = − a_HQT * HQ / 2 + ISQ 0 / b_GQT .

[0104] The existing adjustment factor is calculated as follows: KG_act = GQT_balanced / GQ = − 100 * a_HQT * HQ / 2 + ISQ 0 / b_GQT / GQ . The weight difference can be defined as unbalance (HQT, GQT)= ISO_no_friction(HQT,GQT) / b_GQT.

[0105] The first weight difference is the additional weight required to compensate for the load at the first position (top floor), whereby such a weight difference arises from an unsuitable balancing of the system and / or from the load-bearing element. The first weight difference is unblance_top[kg]=unbalance(HQT=HQ,GQT)-unbalance(HQT=HQ / 2,GQT) = + ISQ_no_friction HQT = HQ , GQT / b_GQT − ISQ_no_friction HQT = HQ / 2 , GQT / b_GQT = + a_HQT * HQ + b_GQT * GQT + ISQ 0 / b_GQT − a_HQT * HQ / 2 + b_GQT * GQT + ISQ 0 / b_GQT = + a _ HQT * HQ − a _ HQT * HQ / 2 / b _ GQT unbalanced_bot= + a HQT / b_GQT * HQ / 2, where this is independent of GQT.

[0106] The second weight difference is the additional weight required to compensate for the load at the second position (lowest floor), whereby such a weight difference arises from an unsuitable balancing of the system and / or from the load-bearing element. The second weight difference is unbalance_bot[kg]=unbalance(HQT=0,GQT)-unbalance(HQT=HQ / 2,GQT) = + ISQ _ no _ friction HQT = 0 , GQT / b _ GQT − ISQ _ no _ friction HQT = HQ / 2 , GQT / b _ GQT = + a _ HQT * 0 + b _ GQT * GQT + ISQ 0 / b _ GQT − a _ HQT * HQ / 2 + b _ GQT * GQT + ISQ 0 / b _ GQT = + a _ HQT * 0 − a _ HQT * HQ / 2 / b _ GQT Unbalance_top=- a_HQT / b_GQT * HQ / 2, where this is independent of GQT.

[0107] The elevator control system sends the "Load" value (unit = [kg]) to the frequency converter. The frequency converter calculates the value of the holding torque as a proportional factor from the "Load" value.

[0108] The "Load" value is calculated by the elevator control system as follows:

[0109] Finally, it should be noted that terms such as "comprising," "encompassing," etc., do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps from other embodiments described above. Reference numerals in the claims are not to be considered as limitations.

Claims

1. A method for determining a pre-torque of an elevator system (100), wherein the elevator system (100) comprises an elevator shaft (102), an elevator car (104), which is movable along the elevator shaft (102) at least between a first position (112) and a second position (114) and is coupled to the counterweight (106) via suspension means (108), and an electric motor (110), which drives the suspension means by means of a drive pulley and thus moves the elevator car (104), wherein the method comprises: generating control commands (200) for controlling the electric motor (110) so that the elevator car (104) performs at least a first, second, third and fourth test run, wherein the elevator car (104) is moved from the first position (112) into the second position (114) during each of the first and third test runs and is moved from the second position (114) to the first position (112) in each of the second and fourth test runs, wherein the elevator car (104) is loaded with a weight (126) in the third and fourth test runs and is not loaded with the weight (126) in the first and second test runs; receiving current measurement data (202), which indicate a current measured by means of a current measuring device (124) during the movement of the elevator car (104), which current flows through the electric motor (110), and height measurement data (204), which indicate a height of the elevator car (104) relating to the first (112) and / or second position (114) measured by means of a height measuring device (122) during the movement of the elevator car (104) in a plurality of successive time steps in each test run; calculating at least one parameter (208, 208a, 208b, 208c) of a calibration function (210) that defines a relationship between the current, the height and the weight (126) using the current measurement data (202) and the height measurement data (204), which were received in different test runs, to obtain at least one calibration value (206, 206a, 206b, 206c); and calculating a first weight difference (unbalance_top), which is representative of a weight difference between the mass of the elevator system (100) on one side of the traction sheave of the electric motor (110) and the mass of the elevator system on the other side of the traction sheave when the elevator car (104) is in the first position (112); calculating a second weight difference (unbalance_top), which is representative of a weight difference between the mass of the elevator system (100) on one side of the traction sheave of the electric motor (110) and the mass of the elevator system (100) on the other side of the traction sheave when the elevator car is in the second position (114); wherein the first weight difference and the second weight difference (unbalance_top) are calculated using the calibration function (210) and the at least one calibration value (206, 206a, 206b, 206c); and determining a pre-torque for applying to the electric motor (110) before the elevator car (104) is moved in response to the first and second weight differences (unbalance_top, unbalance_bot).

2. The method according to claim 1, wherein a height reference value (230) is calculated by halving a height difference between the first position (112) and the second position (114); and / or wherein a weight reference value (250) is calculated by multiplying a permitted mass of the weight (126) by a predetermined weighting factor.

3. The method according to any of the preceding claims, wherein a first average function (222) that defines a first relationship between the current and the height, while assuming ideal frictional conditions, is determined using the current measurement data (202) and the height measurement data (204) received in the first and second test runs; and / or wherein a second average function (224) that defines a second relationship between the current and the height, while assuming ideal frictional conditions, is determined using the current measurement data (202) and the height measurement data (204) received in the third and fourth test runs; wherein the at least one parameter (208, 208a, 208b, 208c) of the calibration function (210) is calculated using the first average function (222) and / or the second average function (224).

4. The method according to claim 3, wherein for each of the four test runs, an output function (214) defining a linear relationship between the current and the height is determined by processing the current measurement data (202) and the height measurement data (204) that were received in different time steps in the relevant test run; wherein at least one parameter (226, 228) of the first average function (222) is calculated by forming a mean value from a parameter (216, 218) of the output function (214, 214a) for the first test run and a parameter (216, 218) of the output function (214, 214b) for the second test run; and / or wherein at least one parameter (226, 228) of the second average function (224) is calculated by forming a mean value from a parameter (216, 218) of the output function (214) for the third test run and a parameter (216, 218) of the output function (214) for the fourth test run.

5. A method according to claim 3 or 4, as dependent on claim 2, wherein a first current value (232) is calculated by inputting the height reference value (230) into the first average function (222); and / or wherein a second current value (234) is calculated by inputting the height reference value (230) into the second average function (224); wherein the at least one parameter (208, 208a, 208b, 208c) of the calibration function (210) is calculated using the first current value (232) and / or the second current value (234).

6. The method according to any of the preceding claims, wherein a height-related parameter (208, 208a) of the calibration function (210) is calculated to obtain a height calibration value (206, 206a) as the calibration value (206); and / or wherein a parameter (208, 208b) of the calibration function (210) relating to the weight (126) is calculated to obtain a weight calibration value (206, 206b) as the calibration value (206); and / or wherein a current-related parameter (208, 208c) of the calibration function (210) is calculated to obtain a current calibration value (206, 206c) as the calibration value (206).

7. The method according to claim 6, as dependent on one of claims 3 to 5, wherein the height calibration value (206, 206a) is obtained by forming a mean value from a height-related parameter (226) of the first average function (222) and a height-related parameter (226) of the second average function (224).

8. The method according to claim 6 or 7, as dependent on claim 5, wherein the weight calibration value (206, 206b) is obtained by dividing a difference between the first current value (232) and the second current value (234) by a weight value (238) indicating a current mass of the weight (126); and / or wherein the current calibration value (206, 206c) is obtained by subtracting a product from the height calibration value (206, 206a) and the height reference value (230) and / or from the product of the weight calibration value (206, 206b) multiplied by the mass of the actual weight at the first test run (GQT_test1) from the first current value (232).

9. The method according to any of the preceding claims, wherein, in each time step, a check is made to see whether the elevator car (104) is moving at constant speed; wherein, for calculating the at least one parameter (208, 208a, 208b, 208c) of the calibration function (210), only the current measurement data (202) and / or only the height measurement data (204) from the time steps in which the elevator car (104) is identified as moving at a constant speed are used.

10. The method according to any of claims 6 to 9, as dependent on claim 2 or 5, wherein the height calibration value (206, 206a) is multiplied by the height reference value (230), the resulting product is added to the current calibration value (206, 206c) and the resulting sum is divided by the weight calibration value (206, 206b) and the permissible mass of the weight (126) to obtain a negative actual balance factor (246).

11. The method according to any of claims 6 to 10, wherein the first and / or the second weight difference (unbalance_top, unbalance_bot) is determined on the basis of the calibration function (210) and the weight calibration value (206, 206a), wherein the first weight difference (unbalance_top) is determined in particular from the negative height calibration value (206, 206a) divided by the weight calibration value (206, 206b) multiplied by the height reference value (230), wherein the second weight difference (unbalance_bot) is determined in particular from the height calibration value (206, 206a) divided by the weight calibration value (206, 206b) multiplied by the height reference value (230).

12. The method according to claims 10 and 11, wherein the pre-torque is defined as proportional to the sum of the second weight difference (unbalance_bot); the current mass of the weight (126) in the elevator car; the negative actual balance factor (246) multiplied by the permissible mass of the weight (126); and the measured height divided by the height difference between the first position (112) and the second position (114) multiplied by the difference between the first weight difference (unbalance_top) minus the second weight difference (unbalance_bot).

13. A control device (120) for an elevator system (100), wherein the control device (120) comprises a processor configured to carry out the method according to any of the preceding claims.

14. An elevator system (100), comprising: an elevator shaft (102); an elevator car (104) that is movable along the elevator shaft (102) at least between a first position (112) and a second position (114); a counterweight (106) that is coupled to the elevator car (104) via suspension means (108); an electric motor (110) for driving the elevator car (104); a current measuring device (124) for measuring a current flowing through the electric motor (110); a height measuring device (122) for measuring a height of the elevator car (104) relating to the first position (112) and / or the second position (114); and a control device (120) according to claim 13.

15. A computer program comprising commands that cause the elevator system according to claim 14 to carry out the method steps according to any one of claims 1 to 12.

16. A computer-readable medium on which the computer program according to claim 15 is stored.

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