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
  • B66B1/285—Control systems with regulation, i.e. with retroactive action, for influencing travelling speed, acceleration, or deceleration electrical with the use of a speed pattern generator

Definitions

• the present invention relates to a control method implemented in a variable speed drive for controlling a lifting load such as an elevator.
• the invention also relates to a variable speed drive capable of implementing said method.
• the control profile of a lifting load such as an elevator that moves between floors generally comprises the following main steps: an acceleration to a first speed, the receipt of a deceleration order when the elevator has reached a certain level, this order being able to be given during the passage of the elevator in front of an external sensor, a first deceleration to a second speed lower than the first speed, the receipt of a stop command when the elevator is close to the arrival floor, this order can also be given during the passage of the elevator in front of a second sensor, a second deceleration to the stop.
• the profile may also comprise a step of maintaining the speed of the elevator at the first speed before the first speed. deceleration and a holding step at the second speed before the second deceleration.
• the first speed is set to be the maximum speed to be reached by the elevator when traveling between two stages separated by several levels. But when the elevator must make a shorter trip, for example between two separate floors of a single level, this maximum speed is often never reached. In such a situation the elevator is still controlled according to the control profile defined above. The elevator thus receives the deceleration order before reaching its maximum speed and therefore starts the first deceleration earlier according to the same speed profile than if the maximum speed had been reached. However, at the time of receipt of the deceleration order, the elevator has traveled a short distance. During all the distance remaining before receiving the stop command, the elevator moves at low speed. The time spent by the elevator at low speed is therefore very long.
• GB1560348 discloses a solution to overcome this problem.
• This document describes the application of a first speed profile to an elevator, this profile with acceleration to a maximum speed, followed by a first deceleration to a low speed landing before further deceleration to a stop.
• this document proposes the introduction of a second speed profile for shifting the beginning of the first deceleration. The new braking moment occurs at the intersection between the two velocity profiles.
• the goal is thus to recover the lost distance because of the too premature appearance of the deceleration order by continuing the acceleration to a new speed following the ramp of initial acceleration.
• the distance remaining to be covered will be respected but not the duration.
• Document EP0826621 describes a method for adjusting the low speed of an elevator car by applying a compensation frequency in the control.
• the object of the invention is to provide a control method for minimizing the time spent at low speed when the elevator performs a path such that it receives the deceleration order before reaching its maximum speed.
• a control method implemented in a variable speed drive for controlling a lifting load the control of the load being performed according to a first control profile which comprises the following main steps: acceleration of the load in view to reach a first speed, deceleration of the load following receipt of a deceleration order, stopping of the load, characterized in that when the load receives the deceleration order while it is at a lower current speed at the first speed, the method comprises: a step of determining a second speed lower than the first speed and greater than the current speed, said second speed having an optimum value for minimizing the travel time of the load up to the first speed; stopping, a step of generating and applying a second control profile replacing the first control profile and including a step of accelerating the load until the second speed is reached according to a nonlinear acceleration ramp taking into account the distance remaining to be traveled, followed by a deceleration step and a stopping step.
• the second control profile may comprise a step of maintaining the speed of the load at the
• the second control profile includes a step of maintaining the speed of the load at a third speed lower than the second speed.
• the second control profile comprises a step of receiving a stop command.
• the second control profile after receiving the stop command, comprises a deceleration step until it stops.
• the deceleration order or the stop command is sent by an external sensor capable of detecting the passage of the lifting load or can be sent by a PLC connected to the variable speed drive.
• the invention also relates to a variable speed drive for controlling the lifting load, the control of the load being performed according to a first control profile which comprises the following steps: acceleration of the load to reach a first speed, reception a deceleration order, deceleration of the load, stopping of the load, characterized in that, when the load receives the deceleration order at a current speed lower than the first speed, the variable speed drive implements: means for determining a second speed lower than the first speed and greater than the current speed, said second speed having an optimum value for minimizing the travel time of the load until it stops, means for generating and setting implementation of a second control profile replacing the first control profile and comprising a step of acceleration of the load until reached e of the second speed according to a nonlinear acceleration ramp taking into account the distance remaining to be traveled, followed by a deceleration step and a stopping step.
• a first control profile which comprises the following steps: acceleration of the load to reach a first speed, reception a deceleration order, deceleration of
• the variator comprises means for maintaining the speed of the load at the second speed for a determined duration.
• variable speed drive comprises means for maintaining the speed of the load at a third speed lower than the second speed.
• second control profile comprises a reception of a stop command.
• the second control profile comprises a deceleration to the stop following the reception of the stop command.
• the drive is connected to an external sensor capable of sending the deceleration command or the stop command when it detects the passage of the lifting load.
• the drive can be connected to a programmable controller able to send the deceleration order or the stop order.
• FIGS. 1A and 1B respectively represent a speed profile and its corresponding position profile followed by an elevator moving between two stages while reaching its maximum speed
• FIGS. 2A and 2B respectively represent a speed profile and its corresponding position profile followed by an elevator moving between two stages without reaching its speed
• 3A and 3B represent respectively a speed profile and its corresponding position profile followed by an elevator moving between two stages without reaching its maximum speed and with application of the method of the invention. control of the invention.
• a conventional control profile applied in a variable speed drive for controlling a lifting load such as an elevator using an electric motor comprises the following main steps: receiving a starting order to move the elevator from one stage to another, acceleration along an acceleration ramp RA to a maximum speed ⁇ R , receiving a deceleration order (FLG1) for example with the aid of a first external sensor placed on the path of the elevator, deceleration according to a deceleration ramp RD until a low speed is reached ⁇ L , reception of a stop command (FLG2) for example with the aid of a second external sensor placed on the elevator path, deceleration along an RS stop ramp until the elevator stops at the desired floor.
• a deceleration order FLG1
• FLG2 stop command
• Each external sensor is disposed on the elevator path at a distance before the desired arrival stage to meet the deceleration and stopping distances.
• each ramp acceleration, deceleration, stop
• the pulses or rounded jerk in English
• the control profile defined above is ideal when the elevator moves several levels because the elevator then has a sufficient time to reach its maximum speed ⁇ R before receiving the deceleration order (FLG1).
• the deceleration order (FLG1) can be received before the elevator has had time to reach its stage. maximum speed ⁇ R.
• the variator determines a second speed C 0 R 0pt lower than the speed C O R and greater than its current speed, this second speed being an optimum speed up to which the elevator can continue to accelerate to minimize the time of travel to a stop while respecting stopping distances (see Figures 3A and 3B).
• the principle of the invention therefore consists in seeking a function of time such that:
• ⁇ is designated as the current speed of the load
• ⁇ the current position of the load
• ⁇ represents the acceleration of the load
• j represents the pulse ("jerk") of the load.
• ( ⁇ o , ⁇ o ) represents the trajectory point at the moment of reception of the deceleration order
• ( ⁇ L , ⁇ ) represents the point to reach of the trajectory
• ⁇ Dd the distance to be traveled during the deceleration movement , between the maximum speed and the low speed.
• t D represents the deceleration time
• the pair ( ⁇ o , ⁇ o ) is obtained by the current position of the trajectory.
• the distance ⁇ Dd is known because it is the distance traveled during the first deceleration. If this distance ⁇ Dd is respected by the control profile, the stopping distance constraints will also be respected.
• the resolution consists of starting from all the known data ( ⁇ o , ⁇ o , ⁇ Dd , T R ) to calculate an optimal maximum speed ⁇ R opt to achieve which minimizes the total time of movement.
• the first example is to determine the optimal speed ⁇ R opt , considering for example the following control profile, piecewise linear acceleration (see Figure 1 B): acceleration ⁇ A during the time Ta following an acceleration ramp RA, holding at the speed ⁇ R during a bearing time Tp, acceleration ⁇ D during the time Td following a deceleration ramp RD, holding at the low speed CO L during a time T L to travel the remaining distance to the stop.
• the calculation of the optimal speed ⁇ R opt is done in respect of the magnitudes of accelerations and impulses to maintain a level of comfort. It may be that the calculation of the optimal speed changes the acceleration and momentum quantities compared to the initial trajectory.
• the acceleration ramp to reach the optimal speed C0 R ⁇ pt calculated is the acceleration ramp RA of the initially planned control profile and that the deceleration ramp applied after reaching the optimal speed ⁇ R opt is also the deceleration ramp RD of the initially planned control profile.
• T R The variation of T R is determined from its derivative:
• ⁇ R is greater than ⁇ L , it follows that the function T R is monotonically decreasing on its definition space, that is to say ⁇ R in [ ⁇ L , ⁇ R opt ].
• the speed ramps are calculated from a polynomial of order 6, a function of time.
• speed follows a continuous and non-linear profile.
• the acceleration ramp to reach the optimal speed ⁇ R opt calculated is also the acceleration ramp RA of the initially planned control profile and that the deceleration ramp applied after reaches the optimum speed C0 R ⁇ pt is also the deceleration ramp RD of the initially planned control profile.
• ( ⁇ o , ⁇ o ) represents the trajectory point at the moment of reception of the deceleration order
• ( ⁇ L , ⁇ ) represents the point to reach of the trajectory
• ⁇ Dd the distance to be traveled during the movement of deceleration, between the maximum speed and the low speed.
• t D represents the deceleration time
• the pair ( ⁇ o , ⁇ o ) is obtained by the current position of the trajectory.
• the distance ⁇ Dd is known because it is the distance traveled during the first deceleration. If this distance ⁇ Dd is respected by the control profile, the stopping distance constraints will also be respected.
• the optimum speed calculated by the first or second example is inserted in a new control profile determined by the drive when the deceleration command (FLG1) is received while the maximum speed ⁇ R provided in the initial control profile has not been set. not been reached.
• This second control profile is determined by taking into account the new optimum speed calculated ⁇ R opt , by respecting the two previously defined principles related to the accelerations and pulses to be applied in order to guarantee an optimal comfort to the user and taking into account the distance remaining to go.
• This new control profile therefore comprises, after reception of the deceleration order (FLG1), the following steps: acceleration to the optimum speed ⁇ R opt calculated according to a new acceleration ramp RA opt taking into account in particular the remaining distance to be traveled, deceleration according to a new deceleration ramp RD opt , taking also into account the distance remaining to be traveled, until reaching the low speed COL, receiving the stop command (FLG2) for example at the using the second external sensor placed on the path of the elevator, deceleration along the stop ramp RS until the complete stop of the elevator to the desired floor.
• the new ramps RA opt , RD opt calculated are of course non-linear to respect the constraints of comfort. According to the invention, in certain cases, the initial ramps RA and RD can no longer be respected and it is necessary to determine new ramps to respect the imposed distance. For example, if the distance to travel is too great to reach the optimal speed ⁇ R opt when applying the initial acceleration ramp
• This new control profile can include in particular a step of maintaining the speed of the load at the optimum speed ⁇ R opt to create a step at this speed for a determined duration, between zero and several seconds, and a step of maintaining the speed of the load at low speed COL for a certain duration, ranging from zero to several seconds, before receiving the stop command (FLG2).

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• Engineering & Computer Science (AREA)
• Automation & Control Theory (AREA)
• Elevator Control (AREA)

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• 2008
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