EP2337758A1

EP2337758A1 - Method and device for controlling a wash load

Info

Publication number: EP2337758A1
Application number: EP09821619A
Authority: EP
Inventors: François Malrait; Stéfan Capitaneanu
Original assignee: Schneider Toshiba Inverter Europe SAS
Current assignee: Schneider Toshiba Inverter Europe SAS
Priority date: 2008-10-22
Filing date: 2009-10-13
Publication date: 2011-06-29
Anticipated expiration: 2029-10-13
Also published as: CN102196982B; US20110166697A1; ES2640763T3; WO2010046275A1; FR2937432A1; US8584808B2; EP2337758B1; JP2012506352A; FR2937432B1; CN102196982A

Abstract

The invention relates to a control method implemented in a variable speed drive for controlling a wash load, the load control being carried out according to a first control profile that comprises the following main steps: accelerating the load with a view to reaching a first speed (?R), decelerating the load upon receiving a deceleration order (FLG1), stopping the load. When the load receives a deceleration order (FLG1) when it is at a current speed lower than the first speed (?R), the method comprises a step of determining a second speed (?R opt) lower than the first speed (?R) and higher than the current speed, said second speed (?R opt) having an optimal value for minimising the load running time until stopping.

Description

Method and device for controlling a lifting load

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.

Depending on the duration to reach the first speed following the acceleration and the duration to reach the second speed following the first deceleration, 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. When the braking command that controls the first deceleration occurs while the maximum speed has not been reached, 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. In this document of the state of the art, 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. However, by keeping the initial acceleration ramp to reach the new speed, 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.

This object is achieved by 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. According to one particularity of the invention, the second control profile may comprise a step of maintaining the speed of the load at the second speed for a determined duration.

According to another feature, between the deceleration step and the stop step, the second control profile includes a step of maintaining the speed of the load at a third speed lower than the second speed.

According to another feature, at the end of the deceleration step, the second control profile comprises a step of receiving a stop command.

According to another particular feature, after receiving the stop command, the second control profile comprises a deceleration step until it stops.

According to another particularity, 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.

According to one particularity of the invention, the variator comprises means for maintaining the speed of the load at the second speed for a determined duration.

According to another feature, the variable speed drive comprises means for maintaining the speed of the load at a third speed lower than the second speed. According to another particularity, the second control profile comprises a reception of a stop command.

According to another particularity, the second control profile comprises a deceleration to the stop following the reception of the stop command.

According to another feature, 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. Alternatively, the drive can be connected to a programmable controller able to send the deceleration order or the stop order.

Other features and advantages will appear in the detailed description which follows with reference to an embodiment given by way of example and represented by the appended drawings in which: 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.

As already described above, with reference to FIG. 1B, 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 ω _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 ω _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.

Each external sensor is disposed on the elevator path at a distance before the desired arrival stage to meet the deceleration and stopping distances.

This type of control profile is implemented taking into account constraints related to user comfort. Indeed, this control profile must be applied in a comfortable manner for the user which implies the application of nonlinear ramps. For this, two principles are generally applied: each ramp (acceleration, deceleration, stop) must be applied following a low acceleration, at most equal to 0.5 m / s ² , the pulses or rounded (jerk in English) at the beginning and at the end of each ramp must be limited, for example to a value between 0.2 and

0.5 m / s ³ .

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 ω _R before receiving the deceleration order (FLG1). On the other hand, when the elevator makes a short path between two stages, for example separated by a single level, the deceleration order (FLG1) can be received before the elevator has had time to reach its stage. maximum speed ω _R. In this case, if the elevator continues to accelerate after receiving the deceleration order (FLG1), the stopping distances at the desired floor can not be met or if the elevator is decelerated according to the control profile defined above, the low speed ω _L will be reached very early and the elevator will therefore have to move very slowly at this low speed CÛ _L to reach the desired floor as shown in Figures 2A and 2B .

According to the invention, when the speed controller receives the deceleration order (FLG1) while the elevator is at a current speed lower than its maximum speed CO _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:

In which ω is designated as the current speed of the load, θ the current position of the load, γ represents the acceleration of the load and j represents the pulse ("jerk") of the load.

This function f must respect the following constraints

0 = f (0) θ _Dd = f (t _D ) ω _o = f '(θ) ω _L = f' (t _D ). . γ _o = f '(θ) O = f' (t _D ) T <T ^MAX J <J ^MAX

(ω _o , γ _o ) represents the trajectory point at the moment of reception of the deceleration order, (ω _L , θ) represents the point to reach of the trajectory and θ _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 (ω _o , γ _o ) is obtained by the current position of the trajectory.

The distance θ _Dd is known because it is the distance traveled during the first deceleration. If this distance θ _Dd is respected by the control profile, the stopping distance constraints will also be respected.

If we add a known time parameter T _R corresponding to a dwell time at the maximum speed reached by the elevator, the resolution consists of starting from all the known data (ω _o , γ _o , θ _Dd , T _R ) to calculate an optimal maximum speed ω _R ^opt to achieve which minimizes the total time of movement.

By definition, the optimal maximum velocity is defined by ω _R ^opt = f '(t _R ), where t _R is such that f "(t _R ) = O.

Two examples are discussed below to model the function f defined above. The first example is to determine the optimal speed ω _R ^opt , considering for example the following control profile, piecewise linear acceleration (see Figure 1 B): acceleration γ _A during the time Ta following an acceleration ramp RA, holding at the speed ω _R during a bearing time Tp, acceleration γ _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 ω _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.

In this first example, we consider that the acceleration ramp to reach the optimal speed C0 _R ^θpt calculated is the acceleration ramp RA of the initially planned control profile and that the deceleration ramp applied after reaching the optimal speed ω _R ^opt is also the deceleration ramp RD of the initially planned control profile.

From the control profile defined above in connection with FIG. 1B, with ω designated as the current speed of the load and θ the current position of the load, the following reasoning is carried out:

Between 0 and Ta (acceleration phase), we have:

What gives in Ta: θ _R = ω ₀ - T _A + - - γ _A - T _A ²

Let with T _A = ^^

Y.

We then obtain: Θ _R = ^R °

2 - γ _A

Between Ta and Ta + Tp, the speed being constant, we have ω = ω _R θ = θ _R + ω _R -t

What gives in Ta + Tp: θ _p = θ _R + ω _R -T _p

Between Ta + Tp and Ta + Tp + Td (deceleration phase), we have: ω = ω _R -γ _D -t θ = θ _p + ω _R -t --- γ _D -t ²

What gives in Ta + Tp + Td: ω _R = ω _L + γ _D -T _D θ _D = θ _p + ω _R -T _D --- γ _D -T _D ²

With

We obtain then: A _ ω _R ² -ω ₀ ² ω _R ² -ω _L ²

Then between Ta + Tp + Td and T _R = Ta + Tp + Td + T _L , we have: ω = ω _L θ = θ _D + ω _L -t

What gives in T _R : a _AT , ω _R -ω ₀ ω _R -ω _L θ _Dd = θ _D + ω _L -T _L = ^ - + ^ - ^ + ω _L -T _L + ω _R -T _p

2-γ _A 2-γ _D under the condition that T _L > 0, it then comes: n _r , _τ ω _R ² -ω ₀ ² ω _R ² -ω _L ²

'Dd - ¹ R ^A P

2-γ _A 2-γ _D

T _L = ω _L

We then get:

With:

₌

We thus obtain that the travel time is a function of the speed ω _R.

If T _L <0, this means that the end acceleration and deceleration movements have consumed too much distance. Therefore, the time T _L must be positive, which leads us to the following relationships:

and to study the constraint:

We then get the following relation:

ft 2 y 9

To fulfill the condition T _L > 0, it is therefore necessary that (ϋ _R - 2ω _R ^• (ϋ _R - ω _R ≥ 0

By solving this equation of the second degree, we obtain the optimal speed ω _R ^opt to reach taking into account the constraint: ω _R opt = -ω _R Y +. ^ / CO _R Y +. ω _R 6 In order to confirm that the speed ω _R ^opt is indeed the optimal speed making it possible to minimize the travel time, it suffices to study the following function and its evolution as a function of ω _R :

The variation of T _R is determined from its derivative:

By definition ω _R is greater than ω _L , it follows that the function T _R is monotonically decreasing on its definition space, that is to say ω _R in [ω _L , ω _R ^opt ].

We thus note that the time T _R is minimum when ω _R is maximum allowing opt to justify the choice of ω _R = - ω _RR ^γ ++ VΛ / cCO _R + ω _R. We then obtain

In the second example, the speed ramps are calculated from a polynomial of order 6, a function of time. By construction, speed follows a continuous and non-linear profile. We also consider that the acceleration ramp to reach the optimal speed ω _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 ^θpt is also the deceleration ramp RD of the initially planned control profile. Consider the following order P polynomial 6:

P = a ₆ -X ⁶ + a ₅ -X ⁵ + a ₄ -X ⁴ + a ₃ -X ³ + a ₂ -X ² + a ₁ -X + a ₀ Let us define the function of time f such that:

By definition, we can express the position θ, the velocity ω, the acceleration γ, and the pulse j from the function f and its derivatives.

0 = f (0) θ _Dd = f (t _D ) ω _o = f '(θ) ω _L = f' (t _D ) with the constraints and γ _o = r (o) o = r (t _D ) ^ YMAX 'J ^ JMAX

(ω _o , γ _o ) represents the trajectory point at the moment of reception of the deceleration order, (ω _L , θ) represents the point to reach of the trajectory, and θ _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

We therefore have to find the coefficients of the polynomial P satisfying the constraints:

He comes: a ₆ = -10 • θ _Dd + 6 - ω _L - t _D + 4 - ω ₀ - t _D + - - γ ₀ - t _D ² a ₅ = 36 - θ _Dd - 21 - ω _L - t _D - 15 - ω ₀ - t _D - 2 - γ ₀ - t _D ² a ₄ = -45-θ _Dd + 25-ω _L -t _D + 2O-ω _o -t _D + 3-γ _o -t _D ² a ₃ = 20-θ _Dd -10-ω _L -t _D -10-ω ₀ -t _D -2-γ ₀ -t _D ²

_ 1 to ₂ Yo -t _D

^~ 2 ^{~ '} ai = ω ₀ ^• t _D ₀ = 0

By definition, the optimal speed reached during the motion is then defined by ω _R ^opt - t _D = P '(x), where x is such that P "(x) = 0.

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 ω _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 ω _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 ω _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 ω _R ^opt when applying the initial acceleration ramp

RA, it is necessary to determine a new ramp that will be steeper.

This new control profile can include in particular a step of maintaining the speed of the load at the optimum speed ω _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).

It is understood that one can, without departing from the scope of the invention, imagine other variants and refinements of detail and even consider the use of equivalent means.

Claims

1. A control method implemented in a variable speed drive for controlling a lifting load, the control of the load being carried out according to a first control profile which comprises the following main steps: acceleration of the load in order to achieve a first speed (COR) following a first nonlinear acceleration ramp (RA), deceleration of the load following reception of a deceleration command (FLG1), stopping of the load, characterized in that when the load receives the deceleration order (FLG1) while it is at a current speed lower than the first speed (COR), the method comprises: a step of determining a second speed (G) _R ^0pt ) lower than the first speed ( COR) and greater than the current speed, said second speed (G) _R ^0pt ) having an optimum value for minimizing the travel time of the load to a standstill, a step of generation and application a second control profile replacing the first control profile and comprising a step of accelerating the load until reaching the second speed (G) _R ^0pt ) according to a second acceleration ramp (RA ^opt ) non-linear taking into account the distance remaining to be traveled, followed by a deceleration step and a stop step.

2. Method according to claim 1, characterized in that the second control profile comprises a step of maintaining the speed of the load at the second speed (ω _R ^opt ) for a predetermined period.

3. Method according to claim 1 or 2, characterized in that, between the deceleration step and the stopping step, the second control profile comprises a step of maintaining the speed of the load at a third speed ( COL) lower than the second speed (G) _R ^0pt ).

4. Method according to one of claims 1 to 3, characterized in that, at the end of the deceleration step, the second control profile comprises a step of receiving a stop command (FLG2).

5. Method according to claim 4, characterized in that after receiving the stop command (FLG2) the second control profile comprises a deceleration step to stop.

6. Method according to claim 4 or 5, characterized in that the deceleration order (FLG1) or the stop order (FLG2) is sent by a sensor in front of which the lifting load passes.

7. Method according to claim 4 or 5, characterized in that the deceleration order (FLG1) or the stop command (FLG2) is sent by a PLC connected to the variable speed drive.

8. Variable speed drive for controlling a lifting load, the control of the load being carried out according to a first control profile which comprises the following steps: acceleration of the load to reach a first speed (COR) following a first ramp nonlinear acceleration (RA), receiving a deceleration command (FLG1), decelerating the load, stopping the load, characterized in that when the load receives the deceleration order (FLG1) at a current speed less than the first speed (COR), the speed variator implements: means for determining a second speed (C0R ° ^P ) lower than the first speed (COR) and greater than the current speed, said second speed ( C0R ° ^P ) having an optimum value for minimizing the travel time of the load to a standstill, means for generating and implementing a second control profile replacing the first communication profile. and comprising a step of accelerating the load until reaching the second speed (C0R ° ^P ) according to a second nonlinear acceleration ramp (RA ^opt ) taking into account the distance remaining to be traveled, followed by a deceleration step and a stop step.

9. Drive according to claim 8, characterized in that it comprises means for maintaining the speed of the load at the second speed (ω _R ^0pt ) for a fixed period (Tp).

10. Drive according to claim 8 or 9, characterized in that the variable speed drive comprises means for maintaining the speed of the load at a third speed (COL) lower than the second speed (C0 _R ° ^pt ).

1 1. Drive according to one of claims 8 to 10, characterized in that the second control profile comprises a reception of a stop command (FLG2).

12. Drive according to claim 1 1, characterized in that the second control profile comprises a deceleration to the stop following receipt of the stop command.

13. Drive according to claim 1 1 or 12, characterized in that it is connected to an external sensor adapted to send the deceleration order (FLG1) or the stop command (FLG2) when it detects the passage of the lifting load.

14. Drive according to claim 1 1 or 12, characterized in that it is connected to a PLC capable of sending the deceleration order (FLG1) or the stop order (FLG2).