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
  • B66B1/30—Control systems with regulation, i.e. with retroactive action, for influencing travelling speed, acceleration, or deceleration electrical effective on driving gear, e.g. acting on power electronics, on inverter or rectifier controlled motor

Definitions

• the present invention relates to the control of an elevator.
• the invention concerns a method for controlling an elevator that works without changing the torque direction, such as an elevator without counterweight, and a control system designed for applying said method.
• the control method of the invention is applicable for use e.g. in an elevator without counterweight having an alternating-current electric motor rotating at a relatively high speed and a gear system for adapting the speed for elevator operation.
• Elevator control systems nowadays typically comprise an elevator control section and a drive section controlling the electric motor (Fig. 1).
• the elevator control section comprises traffic control TRC, to which the calls issued from d ifferent floors are directed.
• T he drive section again typically comprises motion control MOC, speed control SPC, torque control TOC and a safety cir- cuit SAC.
• the drive control section receives feedback data giving the position of the elevator car for rriotion control, the speed for speed control, the motor current for torque control, and safety-related control data from safety contactors, by means of which the supply of current to the motor drive can be switched off to stop at a landing.
• present control systems between the control blocks a relatively large amount of data traffic, generally serial data traffic is needed for the transmission of signals (generally in serial form). Due to this, present control systems are relatively complex.
• speed control is relatively important especially in the case of elevators having a high capacity (high speed, height). By contrast, in slower elevators having a gear system with a large transmission ratio, speed control is not such a critical factor.
• the object of the present invention is to overcome the drawbacks of prior art and to achieve a new and very simple elevator control method and system especially for elevators without counterweight or corresponding elevators in which the torque direction does not change.
• a speed reference is computed in the elevator control section instead of in the motor drive section, and it is converted at an early stage into a position reference (position profile), which is thus a signal controlling the motor.
• the motor control signal need not be in serial form, which would require e.g. two microcontrollers transmitting and receiving complicated messages, but the motor control signal may be a pulse diagram wherein it is coded e.g. by PWM or frequency modulation, which is used to control the current or voltage signal to be fed into the motor.
• the mo- tor is typically a synchronous or asynchronous motor provided with permanent magnets.
• a nd torque control s ignals a re transmitted between the elevator control section and the motor drive.
• Fig. 1 presents a block diagram of a prior-art elevator control system
• Fig. 2 presents a block diagram of the elevator control system of the invention
• Figures 3a and 3b illustrate the implementation of a position-speed reference according to the invention
• Fig. 2 represents a control system according to the invention for the control of a relatively slow elevator without counterweight.
• the elevator has an elevator motor M1 , e.g. a discoid permanent-magnet alternating-current electric motor mounted in the elevator shaft, and its control system, which is also disposed in the elevator shaft.
• the control system comprises a drive section DRIVE 1 integrated in conjunction with the e levator motor M1 and, disposed separately from the control section, an elevator control section ECO1 , including the control of safety switches SASW1.
• the position reference (Fig. 3a and 3b), which is obtained from motion control, is used directly to control the current or voltage signal to be fed into the motor M1.
• the position reference is a pulse diagram SPEED1 , either fre- quency-coded (Fig. 3a) or PWM-coded (Fig. 3b), which is passed to a so-called look-up table block TABLE1 , either directly (Fig.
• the essential feature of the invention is the use of the position reference as a channel interrupting the motion. Without the position reference, the voltage vector cannot rotate, and consequently the elevator cannot move (and will not cause a danger situation). Motion control becomes simpler, and no speed profile is needed any more. Instead, the system utilizes a position profile, which may form part of very simple traffic control. Each pulse in the position profile moves the elevator through a certain distance.
• torque control it can be stated that, when a permanent magnet synchronous motor is used in an elevator without counterweight, there is no need to use torque control based on weighing of the load.
• the motion profile rotates the magnetic field of the motor, and the torque is generated automatically on the basis of the load-induced variation of the electrical angle of the motor.
• the e levator control s ection must g ive s ome s ort of torque refer- ence because the torque varies i n e levators of different s izes.
• the reference may be based on the elevator size or on the properties of the wire ropes and motor. In addition, the reference can be adjusted based on elevator car position feedback.
• One method of controlling the torque is to generate a simple V/f conversion based on the position profile.
• another channel is used between the traffic control and the motor drive (e.g. a PWM signal).
• the safety of the motor drive is based on two channels between the traffic control and the motor drive: the position profile and the torque reference. If either of these is absent, the elevator cannot move.
• the control system of the invention requires no operating parameters on the motor drive side.
• the motor is controlled by only two signals: position and torque.
• Some sort of diagnostics is needed on the motor drive side as well. In this invention, diagnosing can be carried out while the elevator is stationary.
• the above-mentioned two channels can be used if they are bi-directional. It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the example described above, but that they may be varied within the scope of the claims presented below.

Landscapes

• Engineering & Computer Science (AREA)
• Automation & Control Theory (AREA)
• Elevator Control (AREA)
• Control Of Ac Motors In General (AREA)
• Lift-Guide Devices, And Elevator Ropes And Cables (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)
• Valve Device For Special Equipments (AREA)
• Lifting Devices For Agricultural Implements (AREA)
• Indicating And Signalling Devices For Elevators (AREA)

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• 2003
  • 2003-09-10 FI FI20031295A patent/FI113754B/fi active
• 2004
  • 2004-05-11 JP JP2006525844A patent/JP4733038B2/ja not_active Expired - Fee Related
  • 2004-05-11 DE DE602004007671T patent/DE602004007671T2/de not_active Expired - Lifetime
  • 2004-05-11 EP EP04732126A patent/EP1663836B1/en not_active Expired - Lifetime
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  • 2004-05-11 WO PCT/FI2004/000279 patent/WO2005023695A1/en active IP Right Grant
  • 2004-05-11 CN CN2004800261561A patent/CN1849256B/zh not_active Expired - Fee Related
• 2006
  • 2006-02-16 US US11/355,099 patent/US7314120B2/en not_active Expired - Fee Related
  • 2006-12-01 HK HK06113257.5A patent/HK1092447A1/xx not_active IP Right Cessation

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