JPS5834389B2 - AC elevator speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling an AC feedback elevator using an induction motor, and particularly relates to an improvement in the speed control device for an AC elevator that can run at a constant speed below the rated speed. .

Conventionally, in elevators that use an induction motor as the hoisting motor and control it by a feedback circuit, when running at a constant speed below the rated speed, such as during maintenance and inspection or each floor operation in a relatively high-speed elevator, the following Such control is being carried out.

That is, the first method is to continuously and selectively control power running and braking of the hoisting motor without contact, in response to a speed command signal corresponding to a constant speed below the rated speed and a deviation signal between the car speed signal. The second method is to use a two-speed motor as the hoisting motor and utilize its low speed side.

There are several methods, and the third method is to excite the low speed side of the two-speed motor with DC excitation and the high speed side with AC excitation to superimpose braking torque and powering torque.

However, a device that selectively controls power running and braking torque without contact as in the first method tends to be expensive because it requires a large number of semiconductor elements such as cynostars. Using the low speed side of a two-speed transformer motor, as shown in the figure above, would result in the speed being too low for operating each floor of a high-speed elevator, or too high for maintenance and inspection, making it impossible to obtain the optimum speed. Moreover, as in the third method, overlapping the running torque and the braking torque has the problem of large energy loss and becoming the basis for generating vibrations and noise.

The purpose of this invention is to improve the above-mentioned problems, and an object of the present invention is to provide a speed control device for an AC elevator that uses an induction motor to inexpensively and efficiently run a constant speed at an optimal speed lower than the rated speed. do.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In Figure 1, R, S, and T are three-phase AC power supplies, 1 is an induction motor, 2 is a steel wheel of the Sojo machine, 3 is a main rope, 4 is a cage, 5 is a counterweight, and 6 is the rotational speed of electric motor 1. 7 is a speed command signal generator that generates a speed command signal for driving at a constant speed lower than the rated speed; 8 is a speed command signal of this speed command signal generator; A bidirectional silisk whose firing angle is controlled by a deviation signal from the speed signal of the speed signal generator 6, 9 a diode bridge that converts alternating current to direct current only during braking torque control;
10 is a switching device that opens and closes the electromagnetic contactor group 11 according to the deviation signal; 12 is an electromagnetic contactor contact that is opened when transitioning from three-phase unbalanced torque control to single-phase power running torque control;
13a, 13b are electromagnetic contactor contacts 14a, 1 that are closed during power running torque control and opened during braking torque control;
4b is an electromagnetic contactor contact which is opened during power running torque control and closed during braking torque control; 15a and 15b are upward operation electromagnetic contact contacts; and 16a and 16b are downward operation electromagnetic contactor contacts.

In Figure 2, Po is the reference signal curve of the rated speed, P0 to P3
are lower than the reference signal curve po of the rated speed, respectively.
The third speed command signal curves (1) to (3) are speed signals when controlled in a three-phase unbalanced torque control region, a single-phase torque control region, and a braking torque control region, respectively, depending on the load and direction.

In Figure 3, A is the torque characteristic curve in the case of three-phase balanced excitation,
B is the torque characteristic curve in the case of single-phase excitation, C is the DC braking torque characteristic curve in the case of DC excitation, (no) is the synchronous rotation speed corresponding to the reference signal shown by the curve Po in Fig. 2,
(nl) to (n3) are the rotational speeds corresponding to the reference signals similarly shown by curves P1 to P3', the shaded areas are the same, M and N are the three-phase unbalanced torque control region, single-phase torque control region, and braking, respectively. Each of the torque control regions T1 to T3 is a load torque converted to the motor shaft, which is determined by the direction and the car heavy load.

Next, the operation of this embodiment will be explained.

Now, in FIG. 1, to describe the case of running at a constant speed below the rated speed, that is, at a speed corresponding to the first to third speed command signals P1 to P3, first, the electromagnetic contactor contacts 15a, 15b, 13a .

Suppose that 13b and 12 are closed.

When the cylinder 8 is ignited, three-phase AC electrostriction is applied to the motor 1, causing the heel 4 of the motor 1 to move 1 in the upward direction.
drive

Thereafter, the firing angle of the thyristor 8 is controlled according to the speed command signal from the speed command signal generator 7 and the deviation signal of the speed signal from the speed signal generator 6, and the three-phase unbalanced torque control shown in FIG. 3 is performed. The torque in the area is controlled.

As a result, the car 4 is smoothly accelerated and runs at a constant speed along the lowest first speed command signal Pl.

By the way, when the load in the car 4 is heavy, a large torque is required when operating in the upward direction, so the load torque converted to the motor shaft generally has a magnitude as represented by T1 in Fig. 3. By controlling the torque in the control region, the vehicle can be driven in accordance with the first speed command signal Pl, so it is possible to run at a constant speed as indicated by the speed signal Vt.

In addition, if the load inside the car 4 becomes lighter than when it is a heavy load, and the load torque at that time becomes T2 shown in FIG. Even if the power is turned off and the actual three-phase becomes a single phase between S and T, the single phase torque shown by curve B is higher than the load torque T2.
Since it is larger than , control according to the first speed command signal P1 becomes impossible, and the speed increases.

Then, when the speed signal reaches the second speed command signal P2,
The contact 12 is opened by a signal from the switching device 10, and a single phase load between R-8 is applied to the motor 1.

Then, the current speed control signal 8 is controlled by the deviation signal between the second speed command signal P2 and the speed signal, and is indicated by the torque control region M shown in FIG.

Since the vehicle is controlled by single-phase torque control and can be operated in accordance with the second speed command signal P2, it is possible to run at a constant speed as indicated by the speed signal (2).

Furthermore, when the load in car 4 becomes unloaded, the load torque has a magnitude represented by T3, so the speed signal changes to the second
Even if the speed command signal P2 is reached and the contact 12 is opened, and the thyristor 8 is cut off and the power is not supplied, the car 4 is pulled by the counterweight 5 and speeds up, and within the torque control region M. Howling control in accordance with the second speed command signal P2 becomes impossible.

When the speed signal becomes higher than the second speed command signal P2 by a predetermined value or more or reaches the third speed command signal P3, a signal from the switching device 10 causes the contacts 13a and 1 to
3b is open, and contacts 14a, 14b are closed.

Now R-153-8-9-14a-1-14b-9
-15bS and S-15b 9-14a-114b
A circuit 98-15a-R is formed, and the motor 1 is DC-braked.

Then, the second or third speed command signal P2 or P3
The thyristor 8 is controlled by the deviation signal of the speed signal, and the braking torque is controlled to make the vehicle travel at a constant speed.

The torque control region in this case is indicated by N.

In an elevator, regardless of the load inside the car 4 and the driving direction, once it starts moving, the unbalanced weight of the main rope 3 (the main rope 3 from the steel car 2 to the car 4 and the weight from the steel car 2 to the counterweight 5) The change in the weight difference between the main ropes 3) has the effect of increasing the speed of the car 4 in the direction in which it started moving.

Therefore, there is no need to reversibly and selectively control torque from the forward torque control region M to the braking torque control region N1, and from the forward torque region M to the braking torque control region N unidirectionally and irreversibly. Even if the vehicle is moved, the vehicle can be stably driven at a constant speed below the rated speed without being affected by disturbances such as fluctuations in senior officials and fluctuations in the control system.

In other words, even if you run the car in a non-power state while running at a constant speed, determine whether the car 4 accelerates or decelerates, and irreversibly shift to a mode where you can control the braking torque when the car speeds up, the constant speed remains constant. Since the required braking torque to make the vehicle run faster continues to increase, it will never again require more power.

4 to 6 show another embodiment of the invention, in which the magnetic contactor contact 12 of FIG.
7 was used.

In this case, the forward torque control controls the thyristor 8 and the thyristor 17, and the braking torque control cuts off one of the thyristors 17, and the contact point 13a.

13b is opened, contacts 14a and 14b are closed, and the torque control area is the shaded area and area N shown in FIG. 5, and the speed command signal is There is no need to provide many.

The relationship between the speed command signal P1 and the speed signals V 1 v V 3 is shown in FIG.

Therefore, as is clear from FIGS. 5 and 6,
Even with this vehicle, constant speed running below the rated speed is possible in the same way as the vehicle shown in FIG.

As explained above, the present invention connects a car and a counterweight by a main rope, raises and lowers this by an induction motor controlled by negative feedback, switches from a running torque control region to a braking torque control region by a switching contact, and It is designed to operate at a constant speed less than the synchronous speed of the motor.

This ensures that regardless of the car load and driving direction,
As the unbalanced weight of the main rope increases due to running, the required braking torque only increases, making it possible to keep the car running at a stable constant speed at low speeds, and to intercept this with a simple device. can.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the speed control device for an AC elevator according to the present invention, Fig. 2 is a curve diagram showing the relationship between the speed command signal and the speed signal in Fig. 1, and Fig. 3 is the same torque characteristic. 4 is a circuit diagram showing another embodiment of the present invention, FIG. 5 is a torque characteristic curve diagram of FIG. 4, and FIG. 6 is a curve diagram showing the relationship between speed command signals. 1...Induction motor, 2...Steel car, 3.
...Main rope, 4...Car, 5...
Counterweight, 6...Speed signal generator, 7...
...Speed command signal generator, 8...Bidirectional Sairisk, 9...Diode bridge, 10
......Switching device, 11...Magnetic contactor group, 12゜13a, 13b, 14a, 14b
=---...Magnetic contactor contacts, 15a, 15b...Upward operation magnetic contactor contacts, 16a, 16b...Downward operation magnetic contactor contacts.

Claims (1)

[Claims] 1. It has an induction motor that raises and lowers a car and a counterweight connected by a main rope, and has a constant speed range consisting of a speed signal corresponding to the actual speed of the car and a speed lower than a predetermined rated speed. The induction motor is subjected to power running torque control or braking torque control according to a bias signal with a speed command signal including a signal, so that the speed signal follows the speed command signal, wherein the speed signal is When the constant speed range signal of the command signal is not reached, the powering torque control is performed, and once the speed reaches the constant speed range signal of the speed command signal or higher, the powering torque control is irreversibly switched to apply the braking. A speed control device for an AC elevator, characterized by comprising a control circuit that performs torque control. 2. The constant speed range signal of the speed command signal is composed of at least a first constant speed range signal and a second constant speed range signal higher than the first constant speed range signal, and the control circuit is configured to: When the speed signal does not reach the second constant speed range signal, power running torque is controlled according to the deviation signal from the first constant speed range signal, and once the speed signal reaches or exceeds the second constant speed range signal. In this case, the power running torque control is irreversibly switched to perform braking torque control in accordance with the deviation signal from the second constant speed range signal.
A speed control device for an AC elevator as described in 2. 3. The induction motor is a three-phase induction motor, and the constant speed range signal of the speed command signal is at least a first constant speed range signal and a second constant speed range signal higher than the first constant speed range signal; and a third constant speed range signal higher than the second constant speed range signal, and the control circuit is controlled so that the speed signal is higher than the second constant speed range signal.
When the constant speed range signal is not reached, three-phase power running torque control is performed according to the deviation signal from the first constant speed range signal, and once it reaches the above second constant speed range signal, the above If the three-phase power running torque control is irreversibly switched and the single-phase power running torque control is performed in accordance with the deviation signal from the second constant speed range signal, and furthermore, the value exceeds the third constant speed range signal. For example, the single-phase power running torque control is irreversibly switched to perform DC braking torque control in accordance with a deviation signal from the third constant speed range signal. A speed control device for an AC elevator as described in 2.