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EP0826621A2 - Compensation adaptative de la charge pour un système d'ascenseur - Google Patents

Compensation adaptative de la charge pour un système d'ascenseur Download PDF

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Publication number
EP0826621A2
EP0826621A2 EP97114768A EP97114768A EP0826621A2 EP 0826621 A2 EP0826621 A2 EP 0826621A2 EP 97114768 A EP97114768 A EP 97114768A EP 97114768 A EP97114768 A EP 97114768A EP 0826621 A2 EP0826621 A2 EP 0826621A2
Authority
EP
European Patent Office
Prior art keywords
creep speed
elevator
compensation
speed
adjusting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97114768A
Other languages
German (de)
English (en)
Other versions
EP0826621A3 (fr
Inventor
Christoph M. Ernecke
Brukhard Braasch
Marvin Dehmlow
Jürgen Dieluweit
Thomas Gietzold
Alberto Vecchiotti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Otis Elevator Co
Original Assignee
Otis Elevator Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Otis Elevator Co filed Critical Otis Elevator Co
Publication of EP0826621A2 publication Critical patent/EP0826621A2/fr
Publication of EP0826621A3 publication Critical patent/EP0826621A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66B—ELEVATORS; ESCALATORS OR MOVING WALKWAYS
    • B66B1/00—Control systems of elevators in general
    • B66B1/34—Details, e.g. call counting devices, data transmission from car to control system, devices giving information to the control system
    • B66B1/36—Means for stopping the cars, cages, or skips at predetermined levels
    • B66B1/44—Means for stopping the cars, cages, or skips at predetermined levels and for taking account of disturbance factors, e.g. variation of load weight

Definitions

  • the present invention relates to generally to elevators and, in particular, relates to elevator load compensation.
  • Modern elevator systems utilize sophisticated software and controllers which control most aspects of the elevators operation.
  • the controllers gather information from various sources in the elevator system and use that information to efficiently operate the elevator.
  • elevator speed, starting, stopping, dispatching, floor positioning or leveling, and the like are all governed by the controller.
  • each of these functions are affected by an elevator load. For example, an increase in the load can cause a decrease in elevator speed.
  • Load information is especially useful in providing accurate stopping at the various landings in the building.
  • a method of adjusting an elevator creep speed comprising the steps of: determining an actual creep speed; determining a difference between a dictated creep speed and the actual creep speed; determining a compensation frequency for minimizing the difference between the dictated creep speed and the actual creep speed, the compensation frequency being determined in accordance with a load compensation characteristic; and adjusting the elevator creep speed in response to the compensation frequency.
  • an elevator system 10 employing a preferred embodiment of the present invention is shown.
  • the elevator system 10 is disposed in a building having a plurality of floors.
  • the building includes a hoistway 12 with a plurality of landings 14 that correspond to the plurality of floors.
  • An elevator car 16 is disposed in the hoistway 12 such that the elevator car 16 may travel along the elevator guide rails 18 disposed vertically in the hoistway 12.
  • a pair of leveling sensors 11, including a first leveling sensor and a second leveling sensor, is attached to the elevator car 16 so that the sensors 11 detect magnets 15 disposed in the hoistway 12 as the elevator car 16 travels in the hoistway 12.
  • the first leveling sensor and the second leveling sensor are spaced apart with respect to each other by a predetermined fixed distance and are normally used for facilitating leveling the elevator car 16 at the plurality of landings 14.
  • An elevator controller 20 disposed in a machine room 22, monitors and provides system control of the elevator system 10.
  • the elevator controller 20 provides a control signal to a motive apparatus 24 for controlling the movements of the elevator car 16 within the hoistway 12 as is explained herein below.
  • the controller 20 includes a processor 21 and a memory 23.
  • the processor 21 is a commercially available microcontroller such as an Intel 80C196 and the memory 23 is a commercially available memory such as a NEC ⁇ PD43256AGU-85L (32K x 8 bit static CMOS RAM).
  • the processor 21 executes commands which are stored in the memory 23.
  • One such set of commands enables the controller 20 to control the operation of an elevator drive 25 and thus the speed of a motor 26.
  • Another set of commands enables the controller 20 to respond to various load conditions as is explained herein below.
  • the motive apparatus 24 provides a means to move the elevator car 16 in the hoistway 12 and is responsive to the controller 20 such that the elevator car moves in the hoistway at a dictated speed according to the control signal.
  • the motive apparatus 24 includes the drive 25, the motor 26, a drive sheave 28, a counterweight 30 and hoist ropes 32.
  • the motor 26 is drivenly associated with the drive sheave 28 such that a rotational output of the motor 26 is transferred to the drive sheave 28.
  • the rotational output of the motor 26 is transmitted to the elevator car 16 by the hoist ropes 32 guided around the drive sheave 28; the elevator car 16 being at one end of the hoist ropes 32 and the counterweight 30 at the other.
  • a traveling cable 34 is used to provide an electrical connection between the elevator controller 20 and electrical equipment in the elevator car 16.
  • the drive 25 is electrically connected to the motor 26 such that the drive 25 dictates the motor speed in response to the control signal as is explained below.
  • the present invention can be used in conjunction with other elevator systems including hydraulic and linear motor systems, among others.
  • the drive 25 is described illustratively in the context of a preferred embodiment of a pulse width modulated motor drive.
  • the motor 26 is supplied with alternating currents i u , i v , i w from a pulse width modulating voltage source inverter ("PWMVSI") connected to a voltage DC source 36 through a DC-Link comprising terminals of opposite polarities P, N and a capacitor bank 38.
  • PWMVSI pulse width modulating voltage source inverter
  • the DC source 36 in general is achieved with a rectifier, or an AC/DC converter, supplied with an AC power from supply lines RST.
  • the PWMVSI in one embodiment, comprises a plurality of switches S1-S6, such as IGBTs. Connected across each switch S1-S6 is a free-wheeling diode D1-D6 for providing a path for reactive current flow. Actuation of the switches S1-S6 in the PWMVSI occurs in accordance with one of many pulse width modulation schemes well known in the art. Accordingly, the motor currents i u , i v , i w are controlled by a pulse width modulator PWM which provides a plurality of switching signals in response to the control signal provided by the controller 20. A frequency f CNTR of the control signal is representative of a desired speed of the motor 26 for achieving the dictated speed of the elevator car 16.
  • the switching signals are provided to the inverter switches S1-S6 so that the output current signals i u , i v , i w of the PWMVSI correspond to the desired speed of the motor 26.
  • control of the motor speed, motor acceleration and motor deceleration is achieved.
  • the present invention may be implemented with other schemes for controlling the switching, whether of the pulse width modulation variety or some other, without departing from the spirit or scope of the present invention.
  • a sensor 39 is used in accordance with the principles of the present invention to detect a DC-Link current i DC between the DC source and the PWMVSI.
  • the sensor 39 provides a DC-Link signal, which is representative of a value of the DC-Link current i DC , in response to the DC-Link current i DC .
  • a shunt resistor R shunt is placed in the DC-Link between the DC source and the PWMVSI such that the DC-Link current i DC flows through the shunt resistor R shunt .
  • the shunt resistor R shunt is used to obtain the information from the DC-Link current i DC by connecting a conventional voltage sensor 39 across the shunt resistor R shunt .
  • Other sensor arrangements may be used without departing from the spirit and scope of the present invention.
  • an elevator car speed profile 40 is shown as a function of time.
  • dashed line 42 an increase in the load can cause a reduction in the speed of the elevator car 16; this becomes important in a creep speed region 44 because it affects the elevator system's ability to properly level at the landings 14.
  • the present invention provides a compensation signal having a compensation frequency f COMP which is based, in part, on the DC-Link signal as is described below.
  • the present invention is predicated, in part, on the discovery that the DC-Link current i DC is substantially proportional to the load of the elevator car during a constant speed region 45 of the elevator car 16.
  • the present inventors have discovered that during a constant speed region 45 the value of the DC-Link current i DC increases proportionately to increases in the load. Accordingly, a method for calibrating the controller 20 to provide the compensation signal in response to the varying loads is described below.
  • the controller 20 operates in accordance with the principles of the present invention as is explained herein.
  • an empty elevator car is moved in a first direction in step 46.
  • the controller 20 may move the elevator car 16 in the up direction which, as a result of the counterweight 30, represents an almost empty load.
  • the elevator car 16 After the elevator car 16 leaves an acceleration region 47, the elevator car 16 enters a constant speed region 45 where the speed of the elevator car 16 remains substantially constant therein.
  • the controller 20, in step 48, detects the DC-Link signal provided by the sensor 39 while the elevator car 16 is traveling in the constant speed region 45. In one embodiment, the elevator car travels in the constant speed region 45 for at least one second.
  • the controller 20 determines an actual creep speed; this is the speed of the elevator car 16 while it is traveling in the creep speed region 44.
  • the actual creep speed is determined by using the pair of leveling sensors 11 (shown in Fig. 1).
  • the pair of sensors 11 are conventionally used to detect magnets 15 (also shown in Fig. 1) for leveling purposes as is described above.
  • the sensors may be used to determine the actual creep speed as is described herein below.
  • the actual creep speed could be determined by other means without departing from the spirit or scope of the present invention.
  • speed distance / time .
  • the time between the activation of the first leveling sensor and the second leveling sensor is calculated by a timer built into the processor 21.
  • the first leveling sensor When the first leveling sensor is activated, in response to sensing the magnet 15, the first leveling sensor generates a first leveling signal.
  • the first leveling signal is used as an interrupt signal such that it causes a time measurement to be initiated and a value of the timer to be stored in the memory 23.
  • the second leveling sensor is activated, in response to detecting the magnet 15, the second leveling signal is generated which is also used as an interrupt signal.
  • the second leveling signal ends the time measurement and a value of the timer is again stored in the memory 23.
  • the difference between these two timer values multiplied by a constant is a time measurement value, i.e., the time required to cross the predetermined distance between the first and second leveling sensors.
  • the constant in one embodiment, is 1.6 ⁇ s per timer count, i.e., the timer is incremented every 1.6 ⁇ s by the processor 21 so that if we count 1000 counts then the elapsed time is 1.6 ms.
  • the counter is automatically incremented by the processor 21 and no software is required.
  • the timer may be implemented, for example, in software as would be understood by one skilled in the art in light of the present specification.
  • the actual creep speed of the elevator is determined by the processor 21 by dividing the predetermined distance by the time measurement value. For example, if the predetermined distance is 3 cm and the time measurement value is 270 ms then the actual creep speed is 11.1 cm/s.
  • the controller compares the actual creep speed to a dictated creep speed in step 52.
  • the dictated creep speed is the desired speed of the elevator car 16 while the car 16 is traveling in the creep speed region 44 and is determined by the controller 20.
  • the dictated creep speed is 10 cm/s.
  • varying loads may cause the elevator car 16 to travel at speeds other than the dictated creep speed in the creep speed region 44.
  • the empty car represents an almost empty car and may result in a speed faster than the dictated creep speed in the creep speed region 44.
  • the controller 20 determines the difference between the dictated creep speed and the actual creep speed.
  • the compensation frequency f COMP is derived directly from the difference between the dictated creep speed and the actual creep speed because the speed of the motor varies substantially proportionally with the frequency f CNTR of the control signal. For example, assuming we have no load, if a control signal frequency f CNTR of 25 Hz produces a creep speed of 5 cm/s then a control signal frequency f CNTR of 50 Hz will produce a creep speed of 10 cm/s. Therefore, if the dictated creep speed is 10 cm/s and a load causes the elevator car 16 to travel at only 5 cm/s then the compensation frequency f COMP is 50 Hz. Accordingly, a compensation signal having the compensation frequency f COMP of 50 Hz is added to the control signal having the frequency f CNTR of 50 Hz to adjust the actual creep speed to the dictated creep speed as is described herein below.
  • Step 46 through step 54 are repeated for a second direction in step 56 in order to determine a second compensation frequency f c2 .
  • the controller 20, in step 46 may move the elevator car 16 in the down direction which, as a result of the counterweight 30, represents an almost full load.
  • the controller 20 determines the second compensation frequency f c2 which is used to compensate for an almost full load in the elevator car 16.
  • the controller 20 creates a load compensation characteristic 62 by using the information obtained in steps 48 and 54.
  • the DC-Link signal i 1 detected during the first direction run and the compensation frequency f c1 corresponding thereto both define an empty load compensation point L 1 .
  • the DC-Link signal i 2 detected during the second direction run and the corresponding compensation frequency f c2 determined for this run both define a full load compensation point L 2 .
  • the load compensation characteristic 62 is created by using a known curve fitting technique to approximate the curve between the two load compensation Points L 1 , L 2 .
  • the load compensation characteristic has a top and bottom margin in order to prevent overcompensation in the event of a drive fault, such as a failure in the sensor 39.
  • the load compensation characteristic of the calibration method described above incorporates the individual characteristics of each elevator system to which it is applied. Accordingly, the present invention can be applied to a wide variety of elevator systems without the need to include speed encoder. Additionally, the calibration method may be applied during installation of the elevator system and again at a later time to provide adaptive fine tuning of the load compensation characteristic. For example, the calibration method may be applied periodically such as once every month.
  • step 64 the controller 20 detects the DC-Link signal during the constant speed region 45 in an elevator run.
  • step 66 the controller 20 uses the load compensation characteristic to determine the compensation frequency f COMP which corresponds to the detected DC-Link signal.
  • step 68 controls the elevator speed in accordance with the compensation signal having the compensation frequency f COMP .
  • the compensation signal is added to the control signal so that the speed of the elevator car 16 is controlled under load conditions in order to achieve the dictated speed of the elevator car.
  • the compensation signal is added to the control signal during the creep speed region 44 in order to achieve the dictated creep speed and improve the elevator system's ability to properly level the elevator car 16 at the landings 14.
  • the detection of the DC-Link signal in step 48 may be replaced by determining a travel time i.e., the time required for the elevator car 16 to travel a predetermined distance.
  • the travel time is used because it is a function of the load.
  • the travel time is determined under varying load conditions.
  • the first direction run represents one load condition and the second direction run represents another load condition as is explained above.
  • the time measurement value can be used as the travel time in step 48.
  • the time between the falling edges of the first and second leveling signals can be measured and used as the travel time.
  • the travel time is determined as the elevator car 16 is in the acceleration region 47 while departing from a landing 14. The remaining steps are as described above with the exception that the DC-Link current i DC in the load compensation characteristic 62 is replaced with the travel time.
  • the above mentioned alternative embodiment may be advantageous if the speed profile 40 does not include a constant speed region 45 sufficient to accurately detect the DC-Link signal.
  • the present invention provides the advantage of providing compensation for varying loads without the need for an encoder, or other closed loop device, which results in less complexity and lower costs. Costs are especially reduced in modernization efforts as a result of eliminating the high costs associated with configuring encoders to cooperate with a large number of different motor designs.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Elevator Control (AREA)
EP97114768A 1996-08-27 1997-08-26 Compensation adaptative de la charge pour un système d'ascenseur Withdrawn EP0826621A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US70813896A 1996-08-27 1996-08-27
US708138 1996-08-27

Publications (2)

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EP0826621A2 true EP0826621A2 (fr) 1998-03-04
EP0826621A3 EP0826621A3 (fr) 1998-08-19

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EP97114768A Withdrawn EP0826621A3 (fr) 1996-08-27 1997-08-26 Compensation adaptative de la charge pour un système d'ascenseur

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2937432A1 (fr) * 2008-10-22 2010-04-23 Schneider Toshiba Inverter Procede et dispositif de commande d'une charge de levage

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0200585A1 (fr) * 1985-03-25 1986-11-05 Societe Logilift S.A.R.L. Procédé de commande régulée du ralentissement d'un mobile et dispositif de commande régulée pour la mise en oeuvre du procédé
EP0335599A2 (fr) * 1988-03-30 1989-10-04 Otis Elevator Company Appareil de réglage de vitesse muni d'un inverseur
EP0575140A1 (fr) * 1992-06-15 1993-12-22 Otis Elevator Company Commande de moteur à induction à tension et fréquence variables sans capteur de vitesse

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0200585A1 (fr) * 1985-03-25 1986-11-05 Societe Logilift S.A.R.L. Procédé de commande régulée du ralentissement d'un mobile et dispositif de commande régulée pour la mise en oeuvre du procédé
EP0335599A2 (fr) * 1988-03-30 1989-10-04 Otis Elevator Company Appareil de réglage de vitesse muni d'un inverseur
EP0575140A1 (fr) * 1992-06-15 1993-12-22 Otis Elevator Company Commande de moteur à induction à tension et fréquence variables sans capteur de vitesse

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2937432A1 (fr) * 2008-10-22 2010-04-23 Schneider Toshiba Inverter Procede et dispositif de commande d'une charge de levage

Also Published As

Publication number Publication date
EP0826621A3 (fr) 1998-08-19

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