JPS597629B2 - elevator control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for non-contact braking control of an AC motor using a semiconductor such as a thyristor.

When decelerating an elevator driven by an AC motor, DC rectified by a semiconductor such as a thyristor is used to decelerate the elevator.
DC braking is used.

On the other hand, at startup, various startup controls such as resistance control and thyristor control are performed. These systems require dedicated control devices for braking and starting, respectively, and are expensive. This invention solves the above-mentioned problems, and aims to provide an inexpensive and high-performance elevator control device by using a thyristor used during braking also during starting.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In the figure, R, S, and T are three-phase AC power supplies, 1 to 3 are primary windings of a three-phase induction motor, 4 and 5 are thyristors, 6 and T are diodes, and 8a to 8c are energized when the elevator starts. normally open contact of the starting magnetic contactor, which is deenergized at the start of deceleration.
9a and 9b are normally open contacts of deceleration electromagnetic contactors that are energized when the elevator starts decelerating and are deenergized when the elevator starts, and 10 is a thyristor 4 that is energized when the elevator starts and will be described later.
, 5 is a normally closed contact of an operating electromagnetic contactor that is deenergized when fully ignited and is further energized at the start of deceleration.

At the start of startup, when the startup electromagnetic contactor and the operation electromagnetic contactor are energized, contacts 8a to 8c close, and contact 1
Since 0 is open, a circuit as shown in FIG. 2 is formed, and the thyristors 4 and 5 are connected in antiparallel to each other and inserted between the power supply R and the winding 1. When the thyristors 4 and 5 are turned on in this state, the electric motor generates a power running torque as shown in FIG. 3. By controlling the firing angles of the thyristors 4 and 5, a well-known comb activation is performed. When the thyristors 4 and 5 are fully fired, the electromagnetic contactor for operation is deenergized, and the contact 10
is closed and thyristors 4 and 5 are short-circuited. Then,
Cut off thyristors 4 and 5. The motor is now operated with all three-phase voltages applied to its primary windings 1-3. In this way, the powering torque of the electric motor is
Single-phase powering J when thyristors 4 and 5 are cut off
Powering torque curve 1 when applying three-phase full voltage from torque curve 12
It can be widely controlled over the range of A up to 1.

In addition, since the thyristors 4 and 5 are short-circuited by the contact 10, the thyristors 4 and 5 are energized only for a short time, extending their lifespan. A single-phase lock current flows for a long time,
Prevent the electric motor from burning out. Furthermore, it is possible to prevent the single-phase torque from being overwhelmed by the load torque due to the load on the car, and thereby preventing the car from starting in the opposite direction to the intended direction. Next, when the starting contactor is deenergized and the operating contactor is energized at the start of deceleration, the contacts 8a to 8c, 10 are opened.

Further, when the deceleration electromagnetic contactor is energized, the contact 9a
, 9b are closed. This forms a circuit as shown in FIG. 4, in which the thyristors 4 and 5 and the diodes 6 and 7 constitute a single-phase full-wave rectifier circuit, and direct current flows in the direction of arrow B through the primary windings 1 and 2. As a result, the electric motor generates a braking torque as shown in FIG. If the thyristors 4 and 5 are controlled here, the braking torque can be changed.
When the car reaches a predetermined position, the deceleration contactor is deenergized and the contacts 9a and 9b are opened, so the current in the primary windings 1 and 2 is immediately cut off, and a brake (not shown) is applied to the motor. Once the basket stops. In this way, thyristors 4 and 5
is shared during startup and deceleration, so thyristors 4 and 5
There should be at least two.

As explained above, in this invention, the thyristor for direct current braking during deceleration of the AC motor is shared at the time of startup, and the thyristor is activated in a parallel manner, and the thyristor is short-circuited after startup. It is also possible to prevent burnout of the electric motor due to failure of the thyristor.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the elevator control device according to the present invention, FIG. 2 is a circuit diagram of the principle at startup of FIG. 1,
Figure 3 is a diagram of motor running torque vs. slip characteristics at startup, Figure 4
The figure is a principle circuit diagram during deceleration, and FIG. 5 is a graph of motor braking torque versus slip characteristics during deceleration. 1 to 3... Induction motor primary winding, 4, 5...
...Thyristor, 6,7...Diode, 8
a~8c...Starting electromagnetic contactor contact, 9a, 9
b...Magnetic contactor contact for deceleration, 10...
・Electromagnetic contactor contact for operation.

Claims (1)

[Claims] 1. In a device in which, when a car driven by an AC motor decelerates, a rectifier circuit including at least two thyristors supplies direct current to the motor for braking, and the thyristors are connected in antiparallel when the motor is started. a switching device which is inserted between a power supply and a terminal of the primary winding of the motor to start the motor; and a power supply which short-circuits the thyristor and applies full voltage to the motor after starting the motor. An elevator control device comprising: a contact connected between and the primary winding.