JPS5823824Y2 - escalator control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling an induction motor, which is a driving source for an escalator, by using a power switching element such as a thyristor.

FIG. 1 shows an example of a conventional escalator control circuit of this type.

Three-phase AC power supply terminals R and ST are connected to an input terminal of a three-phase full-wave rectifier circuit 1 composed of semiconductor rectifier elements and the like.

The positive output terminal of this three-phase full-wave rectifier circuit 1 is connected to the operating contactor 3 via the safety devices 2, and the other terminal of this operating contactor 3 is connected to the normally closed contact 4b of the upward operation contactor 4 and the downward operation contactor 3. It is connected to the normally closed contact 5b of the contactor 5.

The normally closed contact 4b is connected to a lowering lock pushbutton 6 via a lowering operation contactor 5, and the other terminal of this pushbutton 6 is connected to the negative output terminal of the three-phase full-wave rectifier circuit 1.

The normally closed contact 5b is connected to the lift lock pushbutton 7 via the lift operation contactor 4.

The other terminal of this push button 7 is connected to the negative output terminal of one three-phase full-wave rectifier circuit 1.

In addition, on the output side of the three-phase full-wave rectifier circuit 1, a normally open contact 4a of a contactor 4 for upward operation and a normally open contact 5a of a contactor 5 for downward operation are connected in parallel, and an escalator holding magnet is attached. A circuit in which the brake coil 8 and the normal 9 contacts 3a of the operating contactor 3 are connected in series is connected.

The three-phase AC power terminal R is connected to the induction motor 9 via the normally open contact 4a of the contactor 4 for upward operation and the normally open contact 3a of the contactor 3 for operation, and the three-phase AC power terminal S is connected to the contactor 4 for upward operation. Induction motor 9 through normally open contacts 4a &
The three-phase AC power supply terminal T is connected to the operating contactor 3.
It is connected to an induction motor 9 via a normally open contact 3a.

The three-phase AC power terminal R is connected to the power terminal S through the normally open contact 5a & of the contactor 5 for descending operation, and the three-phase AC power terminal S is connected to the power terminal Rfl! through the normally open contact Sa & of the contactor 5 for descending operation. connected to l.

Next, the operating state of this conventional control device will be explained by taking as an example the ascending operation of an escalator.

First, when the lift lock pushbutton 7 is turned on, if the safety devices 2 are normal, the operation contactor 3 and the lift operation contactor 4 are energized.

For this reason. The normally open contacts 3a and 4a are closed, and the induction motor 9 is energized with three-phase power.

At the same time, the coil 8 of the magnetic brake for escalator holding is excited, so the magnetic brake (not shown) is released, and the induction motor 9 is started at full voltage by the three-phase AC power supply voltage from the R, S, and T terminals. .

For descending operation, turn on the descending lock pushbutton 6,
The operating contactor 3 and the descending contactor 5 are energized to open the normally open contacts 5a and 3a, and the power terminals R and S to the induction motor 9 are switched, and the induction motor 9 is operated as described above. The engine is started at full voltage with reverse rotation, and the other operations are the same as during upward operation.

Next, the power consumption in this control system will be explained with reference to the simple equivalent circuit of the induction motor shown in FIG. 2 and the induction motor characteristic graph shown in FIG. 3.

FIG. 2 shows an equivalent circuit for the negative phase of a three-phase induction motor (simply referred to as a motor), and the symbols shown in the diagram are thorns.

vl: Three-phase AC power supply voltage tl: Primary current ■'2: Primary side converted secondary current rl: Motor primary winding resistance Xl: Motor primary winding leakage reactance X: Motor secondary winding also Primary side conversion value of the reactance r'2: Primary side conversion value of the motor secondary winding resistance go: Excitation conductance bo: Excitation susceptance Yo: Excitation admittance Y.

Nibi. -jb. S Nislip From this equivalent circuit, primary current ■1 and torque T.

It is known that the primary input (power consumption) Pl is given by the following equation.

From this equation, it is clear that the primary current (1) is proportional to the power supply voltage Vξ, and that the torque T and power consumption P1 are proportional to vl.

FIG. 3 is a characteristic graph showing the relationship between I"1 t T , Pl and the motor rotation speed.

Here, T and n are 0 0 Required torque and motor rotation speed at no load, respectively.

TN and nN are the required torque and motor rotation speed at full load, respectively, and No is the synchronous rotation speed.

At an arbitrary load torque between To and TNO, the motor rotation speed becomes a rotation speed between nn and n6.

Here, in a full load state, as the power supply voltage V1 gradually decreases, the motor rotation speed also gradually decreases, and when vl falls below a certain value, the electric motor stops.

In addition, in the no-load state, (1) decreases and the motor rotational speed also decreases, but the fluctuation range of the power supply voltage Vl until it stops is wider than in the full load state.

At no load voltage or and the motor stops.

That is, the load torque T between To and TM, and the power supply voltage Vl
Then, in the load torque state T, even if the voltage applied to the motor is reduced to It can be seen that there is an advantage that power consumption is also reduced because it is proportional.

In other words, the conventional escalator control method is a constant voltage operation method using an induction motor, which consumes relatively large amount of power at light loads, operates continuously like an escalator, and moreover, the degree of use by passengers changes from moment to moment. There is a drawback that there is wasteful power consumption when the ratio of light load operating time to the total operating time is large.

An object of the present invention is to provide an escalator control device that eliminates the above-mentioned drawbacks and achieves power saving without unnecessary power consumption.

The present invention supplies three-phase AC power to an induction motor that drives an escalator through a switching element such as a thyristor, and detects the load current of the induction motor, which fluctuates depending on the weight of the load on the escalator. The above object is achieved by controlling the voltage applied to the induction motor by controlling the phase shift of the switching element according to the load current.

An embodiment of the escalator control device of the present invention will be described below with reference to the drawings, using the same reference numerals for the same parts as in the conventional example.

FIG. 4 is a circuit diagram showing an embodiment of the escalator control device of the present invention.

The three-phase power supply terminal R is the normally open contact 4 of the contactor 4 for upward operation.
a. Thyristors 5CR1 and 5CR2 are connected in antiparallel to each other via the normally open contact 3a of the operating contactor 3, and this antiparallel circuit of SCR1 and 5CR2 is further connected to an induction motor 9.

The three-phase power supply terminal S is the normally open contact 4 of the contactor 4 for upward operation.
5CR3 and 5CR4 are connected to a circuit in which they are connected in anti-parallel through a.

The three-phase power supply terminal T is connected to a circuit in which 5CR5 and 5CR6 are connected in antiparallel through the normally open contact 3a of the operating contactor 3, and this circuit in which 5CR5 and 5CR6 are connected in antiparallel is connected to the induction motor 9. It is connected.

Note that symbols g1 to g6 indicate the control gates 5CRI to 5CR6.

An S-phase main current (load current) detection alternating current transformer 10 is attached to the S-phase power line connecting the three-phase power supply terminal S and the induction motor 9. Control input generation circuit 1 that rectifies AC voltage from the device and converts it to DC voltage.
Connected to 1.

In this control input generation circuit 11, a bias voltage 12 applied to the control input of the circuit is applied to the normally open contact 3 of the operating contactor 3.
It is given through a'&.

Further, the output side of this control input generation circuit 11 is the output voltage V of the generation circuit.

It is connected to the input side of a phase shifter 13 that provides gate pulses to the gates g1 to g6 of the thyristors in accordance with the control input.

Further, a branch line of the power line connected to the three-phase power terminals R9S and R9T is connected to the phase shifter 13.

Other structures or rods are the same as the conventional example shown in Figure 1, so
Explanation will be omitted.

FIG. 5 shows the human power V for controlling the phase shifter 130.

12 shows a phase shift characteristic diagram for V, and the horizontal axis is V.

In contrast, the vertical axis shows the firing angles of 5CR1 to 5CR6.

Figure 6 is a diagram showing the voltage and current waveforms of the R phase of the three-phase power supply.
is the R-phase power supply voltage, b is the load current, and C is the load voltage W-(
The firing angle of the gate hullless, which is attached to g1 to g6 of 5CR1 to 5CR6, is indicated by θ.

That is, based on the output voltage (which becomes the control input voltage VC to the phase shifter 13) detected by the load current 4 main current detection current transformer 10 and generated by the control input generation circuit 11 according to the load current. , the phase shifter 13 controls the firing angle θ of 5CR1 to 5CR6 from 1801i to 0 degrees.

As a result, the load voltage, that is, the voltage applied to the induction motor 9 changes from 0 to 100 degrees.

Next, the operation of this embodiment will be explained.

Now, when the escalator is in ascending operation, as in the conventional control method, when the ascending push button 7 is turned on, if the safety devices 2 are normal, the ascending operation contactor 4 and the operating conductor 3 are energized. be done.

Then the escalator's magnetic brake coil 8
is excited, a magnetic brake (not shown) is opened, and the normally open contacts 4a and 3a are closed.

At the same time, the normally open contact 3a' of the operating contactor 3
is also closed, and the initial setting bias voltage 12 is applied to the control input generation circuit 11, and this control input generation circuit 11 supplies the control input V to the phase shifter 13.

Then, VBo shown in FIG. 5 is given.

Therefore, the phase shifter 13 has a firing angle θ for each of 5CR1 to 5CR6.

The induction motor (simply referred to as a motor) 9 is started at a reduced voltage, and a two-phase balanced current flows through each phase.

The main current detection current transformer 10 attached to the S phase outputs a voltage corresponding to the current flowing to the S phase to the control input generation circuit 11.

This voltage is the same as the initial setting bias voltage.

is superimposed on the signal by the control input generation circuit 11 and output to the phase shifter 13.

Since the starting current of the induction motor 9 is generally 3 to 5 times the rated current, even when the escalator is started (no load), the firing angle of the get pulse changes as shown by the broken line a in Figure 5.
It is stabilized in a steady state with no load, and the control input voltage at this time is VN.

Next, the control state when the escalator transitions from a no-load state to a heavy-load state will be described.

FIG. 7 shows the torque characteristics of the induction motor using the applied voltage as a parameter.

The operating point P in the no-load state is the motor rotation speed N8, the no-load required torque t1, the motor applied voltage V1, and the torque curve at this voltage is shown as T1.

When a load is applied to the motor in such a state, the motor rotational speed decreases slightly (because it is an escalator, there is no significant instantaneous change in load torque), and therefore the load current increases slightly.

The main current detecting current transformer 10 detects this increase in the load current, and the control input voltage vo that the control input generating circuit 11 provides to the phase shifter 13 increases.

Then, the phase shifter 13 shifts the thyristors 5CRI to 5CR.
6 firing angle decreases, electric motor operation 7JO voltage (load voltage)
increases in accordance with the increase in load current, and moves to an operating point P2 where the rotation speed is approximately equal to the no-load rotation speed.

The operating point P3 is the operating point when the firing angle is 0, that is, when full voltage is applied to the motor.

Furthermore, the transition from the single load state to the light load state is caused by the control input voltage (2) that the control input generation circuit 11 applies to the phase shifter 13 in accordance with the decrease in the load current of the motor.

As a result, the firing angles of the thyristors 5CR1 to 5CR6 increase and the voltage applied to the induction motor 9 decreases, but the motor voltage is decreased while the motor rotational speed remains approximately N8.

According to this embodiment, an increase or decrease in the load current to the induction motor 9 is detected by the main current detection current transformer 10, and when the load current increases, the control input voltage to be applied to the phase shifter 13 is transferred to the control input generation circuit. Increased by 11, thyristors 5CRI to 5CR6
Reduce the firing angle.

The motor applied voltage applied to the induction motor 9 is increased.

In addition, when the load current decreases, the control input generation circuit 11 decreases the control input voltage vc applied to the phase shifter 13 to increase the firing angles of 5CR1 to 5CR6 and increase the firing angle to the induction motor 9. By reducing the motor applied voltage,
It is possible to increase or decrease the voltage applied to the motor according to the load condition while keeping the rotation speed of the induction motor 90 substantially constant, which has the effect of suppressing wasteful power consumption and saving power.

Although the above embodiment has been explained by taking as an example the ascending operation of an escalator, it is of course applicable to descending operation of the escalator.

Further, the semiconductor switching element inserted into the motor main circuit is as in this embodiment.

In addition to antiparallel thyristors, for example, reverse conducting thyristors, bidirectional thyristors, etc. may be used.

As described above, according to the escalator control device of the present invention, by changing the voltage applied to the motor according to the motor load, it is possible to provide an escalator control device that achieves power saving without wasteful power consumption. .

[Brief explanation of drawings]

Fig. 1 is a -fII circuit diagram of a conventional escalator control circuit, Fig. 2 is a simplified equivalent circuit diagram of a three-phase induction motor, Fig. 3 is an induction motor characteristic diagram, and Fig. 4 is a diagram of the present invention. FIG. 5 is a circuit diagram showing one embodiment of an escalator control device, and FIG. 5 is a phase shift characteristic diagram of a phase shifter. FIG. 6 is a voltage and current waveform diagram of the R phase. FIG. 7 is a torque characteristic diagram of the induction motor. 9...Induction motor, 10...Main current detection current transformer, 11...Control input generation circuit, 13
・・・・・・Phase shifter, 5CR1 to 5CR6・・・・・・
Thyristor.

Claims (1)

[Scope of utility model registration request] A device for controlling an induction motor that drives an escalator includes a power switching device that supplies power to the induction motor, a device that detects the load current of the induction motor, and a device that generates an input control voltage according to the load current. and a phase shifter that operates as the power switching device according to the input control voltage, and increases the voltage applied to the induction motor in response to the increase in the load current, thereby reducing the load current. An escalator control device characterized in that the voltage applied to an induction motor is reduced accordingly.