Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66B—ELEVATORS; ESCALATORS OR MOVING WALKWAYS
  • B66B1/00—Control systems of elevators in general
  • B66B1/24—Control systems with regulation, i.e. with retroactive action, for influencing travelling speed, acceleration, or deceleration
  • B66B1/28—Control systems with regulation, i.e. with retroactive action, for influencing travelling speed, acceleration, or deceleration electrical
  • B66B1/32—Control systems with regulation, i.e. with retroactive action, for influencing travelling speed, acceleration, or deceleration electrical effective on braking devices, e.g. acting on electrically controlled brakes

Definitions

• the present invention is directed to a method for controlling an elevator drive device for operating an elevator car in an elevator system, providing a control circuit for controlling an elevator drive device adapted to operate an elevator car, and providing a pre-torque signal to the control circuit, the pre- torque signal adapted as a control signal for holding the elevator car still after a brake for holding the car is released. Further, the invention is directed to a related operation device for an elevator system comprising a control circuit for controlling an elevator drive device for operating an elevator car of the elevator system, and comprising a pre-torque generating circuit for providing a pre- torque signal to the control circuit.
• the elevator car for hoisting passengers between different landings of a building is counterweighted by means of a counterweight connected to a rope which is connected to the elevator car.
• the weight of the counterweight is approximately equal to the weight of the empty car plus an overbalance weight.
• a pre-torque signal is provided to a control circuit for controlling an elevator drive device which is adapted to operate the elevator car.
• the provided pre-torque signal may result in a corresponding torque current which is adapted to keep the elevator drive motor still at standstill when the brake is released prior to a run.
• the object is solved by a method for controlling an elevator drive device according to claim 1 and by a related operation device for an elevator system according to claim 10.
• the method according to the invention comprises the steps of providing a control circuit for controlling an elevator drive device adapted to operate an elevator car, providing a pre-torque signal to the control circuit which is adapted as a control signal for holding the elevator car still after a brake for holding the car is released. Further, a tracking error signal is provided derived from a difference between a command speed signal and a detected speed signal of the elevator drive device after the brake for holding the elevator car is released. Furthermore, a load weight signal of a load associated with the elevator car is provided.
• At least two tracking error signals and at least two related load weight signals are monitored over at least two operating runs of the elevator car, wherein the monitored tracking error signals and the related load weight signals are provided as input signals for controlling and adjusting the pre-torque signal.
• the related operation device for an elevator system comprises a pre-torque generating circuit for providing a pre-torque signal to the control circuit, and a load sensor device providing a load weight signal of a load associated with the elevator car.
• the control circuit for controlling the elevator drive device comprises a terminal for providing a tracking error signal derived from a difference between a command speed signal and a detected speed signal of the elevator drive device after the brake for holding the elevator car is released.
• An observer circuit is connected to the terminal of the control circuit for receiving the tracking error signal, and is connected to the load sensor device for receiving the load weight signal.
• the observer circuit is adapted to monitor at least two received tracking error signals and at least two related load weight signals over at least two operating runs of the elevator car, the observer circuit providing an output signal trans- mitted to the pre-torque generating circuit for controlling and adjusting the pre- torque signal.
• the start behaviour of the elevator car at the start of a normal run after the brake for holding the elevator car is released can be monitored by means of monitoring the tracking error signals and the related load weight signals over different operating runs of the elevator car.
• elevator roll back and roll forward behaviour prior to the start of a normal run may be monitored, wherein the load weighing system setup, i.e. the controlling and adjusting of the pre-torque signal for controlling the elevator drive device may be effected automatically.
• the control and adjustment of the pre-start settings of the elevator system operate without the need of special calibration or reference weights placed in the elevator car during a reference operating run of the elevator car for tuning the system.
• the method according to the invention may record the load loo conditions during normal operation of the elevator car, wherein the pre-torque signal may be adjusted to the instant load conditions within the elevator system.
• the pre-torque signal may be adjusted to the instant load conditions within the elevator system.
• another at least two tracking error signals and at least two related load weight signals are monitored over another at least two operating runs of the elevator car.
• the pre-torque signal which operates the control circuit based on the previously adjusted pre- 110 torque signal value is controlled and readjusted based on the another at least two tracking error signals and the related load weight signals which are provided as input signals for controlling and readjusting the pre-torque signal.
• the pre-torque signal may be re-adjusted a second time based on yet another respective tracking error signals and related load weight signals 115 monitored over yet another at least two operating runs.
• the load weighing system for providing the pre-torque signal may be adjusted in a self-learning manner and automatically during operation of the elevator car by means of continuously monitoring respective tracking error signals and related load weight signals monitored over respective operating 120 runs of the elevator car.
• a load weight offset value is calculated which defines a load weight value in a balanced load operating state of the elevator car.
• the load weight offset value may be provided for load calibration purposes of the elevator system.
• the load weight offset value may be calculated by interpolating the monitored tracking error signals in relation to the load weight, thereby deriving a parametric equation for the tracking error signal in relation to the load weight.
• the load weight offset value defines the load weight value corresponding to a tracking error of approximately zero.
• This load weight offset value may be refer- 135 enced to the installed overbalance of the elevator system of, e.g., 45% of the nominal load, and may further be used to define certain overload thresholds provided to the control circuit of the elevator drive device.
• the control circuit comprises a first control loop for providing a drive command value to the elevator drive device which is derived from the pre- torque signal and from the difference between the command speed signal and the detected speed signal.
• the first control loop is adapted to control the operation of the elevator car using the feedback of the detected speed signal us which is, e.g., derived from the rotational frequency of the drive motor.
• control circuit the observer circuit and the pre-torque generating circuit are connected to constitute a second control loop for controlling and adjusting the pre-torque signal.
• a closed loop feedback of the start behaviour of the elevator car is provided to the control circuit via the second
• Fig. 1 shows a schematic block diagram of an embodiment of an
• Figs. 2 to 4 show exemplified diagrams of a respective command velocity signal and a detected velocity signal, and the respective resulting tracking error signal recording the start behaviour of a respective 165 operating run of an elevator car
• Fig. 5 shows an embodiment of an operation device for an elevator system according to the invention
• Figs. 6 to 8 show exemplified diagrams of the recorded tracking error signals in relation to the load weight according to a differently adjusted load weighing system.
• a schematic block diagram of a common 175 elevator system comprising a control circuit 2 for controlling an elevator drive device 3 adapted to operate an elevator car 10.
• the elevator drive device 3 comprises, e.g., a 3-phase synchronous motor (not shown) which is mechanically connected to a sheave 31 of a hoist, which is driven by the motor.
• a length of a traction rope 14 is trained over the sheave 31 and connected at both 180 ends to an elevator car 10 and to a counterweight 11 for balancing purposes of the elevator system.
• a load sensor device 5 is affixed to the elevator car 10 for providing a load weight signal of a load associated with the elevator car 10.
• the load sensor device 5 provides a load weight signal corresponding to a load which is placed inside 185 the elevator car 10, e.g. passengers who are to be hoisted between the different landings 12 and 13 inside a building.
• the counterweight 11 is equal to the weight of the empty car 10 plus an overbalance weight which is, e.g., approximately equal to 45% of the maximum load of the car 10.
• a brake 32 stops the car 10 when commanded by the control circuit 2.
• the speed of the motor or of the sheave 31, respectively, may be measured by a speed transducer (not shown)
• Such transducer feeds back a detected velocity signal which is compared to a command velocity signal.
• any other speed signal such as the rotational frequency may be used instead.
• the load sensor device 5 beneath the car 10 provides measured load of the car to the 200 control circuit 2.
• Figs. 2 to 4 exemplified diagrams of a respective command velocity of the control circuit 2 and a respective detected velocity detected in the drive device 3 are shown recording the start behaviour of a respective operating run 205 of the elevator car 10.
• Fig. 2 an operating run of the elevator car is shown, wherein the car is loaded with nominal load (full load), without using any mechanism for holding the elevator car still after the brake 32 for holding the car is released.
• nominal load full load
• 210 part of Fig. 2 shows a significant divergence between the command velocity signal 201 and the detected velocity signal 202 of the elevator drive device after the brake 32 for holding the elevator car 10 is released. After releasing the brake 32, elevator car rollback occurs until the control circuit 2 increases the motor torque accordingly to follow the reference velocity profile. In the lower
• the resulting tracking error signal 203 is shown which is derived from the difference between the command velocity signal 201 and the detected velocity signal 202, herein referred to as start tracking error (STE).
• start tracking error STE has a maximum value of 4.
• the STE value can be taken as a reference value for measuring the
• the pre-torque signal provided to the drive device for holding the elevator car still after the brake for holding the car is released is too small, thus resulting in elevator rollback. Due to 225 improperly set pre-torque, the control circuit starts a re-levelling dictation and increases the motor torque to follow the reference velocity profile. Thus, the car does not stay still after the brake is released which causes passenger discomfort.
• a start behaviour of an operating run of an elevator car is shown, wherein the pre-torque provided by the drive motor for holding the elevator car after the brake is released is too large, resulting in roll forward of the elevator car.
• a divergence of the command velocity signal 201 and the detected velocity signal 202 occurs in the other direction resulting in a negative start 235 tracking error STE which has the value of, e.g., -4.
• a similar situation as in Fig. 2 occurs in which the car does not stay still after the brake is released, thus causing passenger discomfort.
• Fig. 4 the start behaviour of an operating run of an elevator car with a 240 properly adjusted pre-torque is shown. Accordingly, the reference profile of the command velocity signal 201 is followed by the detected velocity signal 202, resulting in a start tracking error STE of approximately zero. Hence, according to Figs. 2 to 4, the start tracking error STE correlates with the amount of unbalanced load associated with the elevator car. In case of a balanced load 245 condition, the STE value is approximately zero as the reference profile is being followed closely.
• FIG. 5 an embodiment of an operation device 1 for an elevator system according to the invention is shown.
• the elevator drive device
• the drive device 3 may include typical components such as a power source, a transformer, and/or inverting or rectifying means (such as a PWM-inverter) for supplying a respective current to a PWM-inverter
• the drive device 3 acts as a variable frequency propulsion system.
• the operation device comprises a control circuit 2 for controlling the elevator drive device 3, the control circuit 2 comprising, in the present embodiment, a subtracter 21, a velocity regulator 22, a summarizing circuit 23 and a feedback loop 24.
• 260 components constitute a first control loop for providing a drive command value 205 to the elevator drive device 3 derived from a pre-torque signal 401 and a command torque signal 204.
• the command torque signal 204 is provided through the velocity regulator 22 which receives a tracking error signal 203 derived from a difference between the command velocity signal 201 and the 265 detected velocity signal 202, the tracking error signal 203 provided at terminal 25.
• the first control loop of the control circuit 2 starts the velocity profile dictation as shown and controls the drive command value 205 in a time sequential manner in order to cause the drive device 3 to follow the reference profile dictated by the command velocity signal 201.
• the operation device of the invention comprises a pre- torque generating circuit 4 for providing the pre-torque signal 401 to the control circuit 2, i.e. the summarizing circuit 23, wherein the pre-torque signal 401 is adapted as a control signal causing the drive device 3 for holding the elevator 275 car still after the brake for holding the car is released.
• a load sensor device 5 is connected to the pre-torque generating circuit 4 and provides a load weight signal 501 of a load associated with the elevator car.
• An observer circuit 6 receives the tracking error signal 203, which corre-
• the observer circuit 6 is connected to the load sensor device 5 for receiving the load weight signal 501.
• the observer circuit 6 comprises, in the present embodiment, of a computing circuit 61, an arithmetic logic circuit
• control circuit 2 the observer circuit 6 and the pre-torque generating circuit 4 are connected to constitute a second control loop for controlling and adjusting the pre-torque signal 401, as explained in greater detail below.
• the pre-torque generating circuit 4 is adapted to generate the pre-torque signal 401
• the computing circuit 61 of the observer circuit 6 is adapted and programmed to monitor multiple received tracking error signals and related
• At least two tracking error signals 203 which represent the difference between the command velocity signal 201 and the detected velocity signal 202, and at least two related load weight signals 501 are monitored over at least two operating runs of the elevator car with different associated load amount.
• respective data pairs consisting of a respective load weight signal 501 and a respective related tracking error signal 203 (STE value) are denoted as 610 to 613.
• the monitored tracking error signals denoted with the data pairs 610 to 613 are interpolated in relation to the load weight LW, which represents the x-axis, in order to derive a parametric
• An operating run according to the invention may be a run between two
• an operating run is understood as a run between two stops of the elevator car. Such operating run may be executed during a reference operating state or during the setting-up operation of the elevator system, e.g. on the occasion when building workers use the newly installed elevator system.
• operating run may also be executed during a normal operating state of the elevator system, in particular when readjusting the pre-torque signal in order to eliminate deviations resulting from a long operation period of the elevator system.
• the computing circuit 61 determines at least a minimum and a maximum value min, max of the parametric equation within a defined load weight range, i.e. between 0 and 100% of the nominal load weight, thereby obtaining a tracking error signal range STER.
• the STER value is 340 approximately 10.
• the STER value is provided as a signal 601 to subtraction circuit 62 having an input for receiving the STER value and having an input for receiving a preset target value 603 which has, in the present case, a value of 0.
• the output of subtraction circuit 62 is connected to the tuning regulator 63 which provides a load weight gain signal 604 to the pre- 345 torque generating circuit 4 as a result of the output signal of subtraction circuit 62.
• a valid STER value transmitted with signal 601 is compared with the reference target value 603, which is set to the 0 value, for referencing to a
• the tuning regulator 63 after a valid STER value calculation, increases the load weight gain signal 604 fed to the pre-torque generating circuit 4.
• This load weight gain signal 604 based on the monitored signals according to Fig. 6, controls and adjusts, dependent on the load weight signal 501, a certain
• pre-torque signal 401 which causes the elevator drive device 3 to apply a corresponding amount of pre-torque current when the brake is released.
• this amount of pre-torque may not be sufficiently dimensioned in order to get a balanced load situation when starting a new operating run of the elevator car with different associated load.
• control circuit 2 of Fig. 5 is operated based on the controlled and adjusted pre-torque signal 401, as described with reference to Fig. 6 hereinabove, wherein another at least two tracking error signals and at least two related load weight signals
• the tuning regulator 63 now sets a corresponding increase of the load weight gain signal 604 during the next cycle of the second control loop for controlling and readjusting the pre-torque signal 401.
• a smooth and stable control loop operation characteristic could be obtained.
• pre-torque signal 401 is readjusted by pre-torque generating circuit 4 which may result in a balanced start behaviour of an operating run of the elevator car independent of the load weight associated with the elevator car.
• the pre-torque signal 401 may be readjusted a second time based on yet another respective tracking error signals and related load weight signals monitored over yet another multiple operating runs of the elevator car with different associated load amount. Again, the next valid STER value feedback is given when again at
• the pre-torque signal 401 provided by the pre-torque generating circuit 4 is iteratively readjusted based on another operating runs of the elevator car with differently associated load amount, wherein the outer control loop for
• 405 tolerance may be set in calculation circuit 61 in such that, if the STER value gets greater than a preset limit over a certain operation period, the second control loop for readjusting the pre-torque signal 401 is activated again to operate as described above in order to reduce the STER value.
• a load weight offset value is calculated in addition to the STER value and the load weight gain signal 604.
• the load weight offset value defines a load weight value in a balanced load operating state of the elevator car and may be provided for load calibration purposes of the elevator system.
• the load weight offset value 605 defines a load weight value corresponding to a tracking error of approximately 0, which represents the case of a balanced load with a start tracking error close to 0.
• the load weight offset value 605 falls within the crossing point of
• the load weight offset value 605 which is calculated in computing circuit 61 of observer circuit 6, is provided to the pre-torque generating circuit 4 which acts, in this case, also as a calibration circuit for load calibration purposes of the elevator system.
• the load weight signal provided by the load sensor device may be calibrated to an absolute load weight value, amounting e.g. in kg.
• the measurement point of the balanced load could be referenced to the installed 430 overbalance of the counterweight of the elevator system, e.g. 45% of the rated load.
• a run with an empty elevator car could be initiated by the control system, e.g. after having identified no door operation within a predefined observation period, e.g. 30 minutes without door operation.
• Such calibrated load weight signal could be used to define, e.g., an overload threshold which defines the 435 maximum amount of load associated with the elevator car which is allowed to be operated within the elevator system.
• operating functions such as "load non-stop (LNS)" or “ANS” may be provided with a calibrated load sensor signal.
• LNS defines the functionality for controlling the elevator car operation, wherein, for example, the elevator car does not stop at any intermediate 440 landing when more than 70% of the nominal load are associated with the elevator car.
• the ANS functionality controls the elevator car operation in such that the elevator car accepts only one landing command signal set by the user when the load associated with the elevator car, for example, falls below 10% of the nominal load.
• a landing recordation signal is provided, denoted as signal 701 in Fig. 5, which is received by the observer circuit 6 and which serves to record a respective landing in which the elevator car resides.
• signal 701 in Fig. 5 is received by the observer circuit 6 and which serves to record a respective landing in which the elevator car resides.
• the landing recordation signal 701 may be used as an input signal for controlling and adjusting the pre-torque signal 401 adapted to compensate for an unbalanced hoisting system.
• the traction rope 14 has a length 15 which is not compensated by counter-weight 11.
• traction cable 14 is different dependent on whether the elevator car 10 resides in landing 12 or in landing 13.
• the method as described with reference to Figs. 5 to 8 could further be used to identify the gain characteristics at upper and lower landing to derive the appropriate input parameters for a rope compensation pre-torque algorithm.
• the main benefit of the invention is that it is capable to compensate for drift in the performance of the load weighing circuitry, for example, as a result of aging and temperature changes, or deviated spring forces, drift of the load cell, etc.

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• Engineering & Computer Science (AREA)
• Automation & Control Theory (AREA)
• Elevator Control (AREA)
• Types And Forms Of Lifts (AREA)
• Lift-Guide Devices, And Elevator Ropes And Cables (AREA)

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• 2005
  • 2005-05-09 DE DE602005016466T patent/DE602005016466D1/de active Active
  • 2005-05-09 WO PCT/EP2005/005006 patent/WO2006119787A1/en not_active Application Discontinuation
  • 2005-05-09 EP EP05740265A patent/EP1885640B1/de not_active Not-in-force
  • 2005-05-09 AT AT05740265T patent/ATE441618T1/de not_active IP Right Cessation

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