JPH0319151B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to an emergency control device for an elevator;
In particular, the present invention relates to an emergency control device for an elevator that shortens the stopping distance during an emergency stop.

[Prior art]

An elevator uses a hoisting motor to move a rope connected to the car up and down, thereby moving the car up and down and transporting passengers. In this case, in recent years, it has been proposed to use an induction motor as the hoisting motor and to control this induction motor with a variable voltage/variable frequency power source.

FIG. 1 is a circuit diagram showing an example of an elevator controlled by the above-mentioned variable voltage/variable frequency power supply, in which a three-phase commercial power supply is converted to direct current in a converter 1 and then supplied to an inverter 2. be done. The inverter 2 converts the input DC power into a three-phase variable voltage/variable frequency power and then supplies the power to an induction motor 4 as a hoisting motor via contacts 3a to 3c. Therefore, the induction motor 4 rotates according to the frequency and voltage of the power supplied from the inverter 2. When the induction motor 4 rotates, the sheave 5 connected to the rotating shaft winds up or unwinds the rope 6, thereby causing the cage 7 and the fishing rod provided at both ends of the rope 6 to Move the weight 8 up and down.

A brake drum 9 is attached to the rotating shaft of the sheave 5, and braking is achieved by pressing a shoe 11 provided on a part of an arm 10 onto the outer periphery of the brake drum 9 by the reaction force of a spring 12. is being carried out. Further, the regenerative output of the induction motor 4 is returned to the three-phase commercial power source as regenerative power via the inverter 2 and the regenerative converter 13.

On the other hand, a speed detector 1 is connected to the output shaft of the induction motor 4.
4 is provided, and this speed detector 14 generates a speed signal A corresponding to the rotational speed of the induction motor 4. This speed signal A is a speed command signal B generated from the speed pattern generator 15.
The difference between the two is calculated in an adder 16, and the deviation signal is supplied to a speed control device 17. When the speed control device 17 receives the deviation signal, it generates a voltage control signal C and a current control signal D to control the deviation signal to zero, and outputs the voltage control signal 18.
and is supplied to the current control device 19. The voltage control device 18 controls the voltage of the DC output power supply supplied to the inverter 2 by controlling the gate circuits of the thyristors forming the converter 1 and the regenerative converter 13 in accordance with the voltage control signal C. Further, the current control device 19 controls the output current of the three-phase AC power supply by controlling the base current of the transistors forming the inverter 2 according to the current control signal D. Therefore, converter 1, inverter 2, speed control device 17, voltage control device 18 and current control device 19 are connected to speed pattern generator 15.
This constitutes a variable voltage/variable current control power supply unit that performs power supply control for controlling rotation in accordance with the speed command signal B output from the motor. In addition,
2a is a capacitor that smoothes the output of the converter 1. FIG. 2 is a circuit diagram showing a specific example of the converter 1, the regenerative converter 13, and the inverter 2.
1f, and the regenerative converter 13 is composed of thyristors 13a to 13f. Further, the inverter 2 is composed of transistors T ₁ to _{T 6} .

FIG. 3 shows an abnormality control unit, in which 20 is a safety circuit that detects an abnormality in the elevator and executes safety control in an emergency, and 21 is a circuit that connects the power line (+) and (-) via the safety circuit 20. 22 is a brake coil connected to the emergency operation relay 21, and 23 is an emergency operation relay 2 connected to the emergency operation relay.
A power supply switch connected between the power line (+) and (-) via the normally open contact 21a of 1, and whose contacts 3a to 3c are connected between the inverter 2 and the induction motor 4 shown in FIG. connected between each line.

FIG. 4 is a block diagram showing an example of the voltage control device shown in FIG. 1, in which the voltage supplied from the speed control device 17 is A gate control signal for obtaining an output voltage according to the control signal C is generated and applied to gates 1ag to 1fg and 13ag to 13fg.

FIG. 5 is a block diagram showing an example of the current control device 19 shown in FIG.
During the period when the normally closed contact 21d is open,
Current control signal D supplied from speed control device 17
Each transistor T ₁ to _{T 6} that generates a base current to obtain a current corresponding to the inverter 2 constitutes the inverter 2.
Feeding the base of T ₁ g to T ₆ g.

In the circuit configured in this manner, when an abnormality occurs in the elevator, the safety circuit 20 is activated to deenergize the emergency operation relay 21 and the brake coil 22. When the emergency operation relay 21 is deenergized, its normally open contact 21a opens, so the power switch 2
3 operates to open its contacts 3a to 3c, thereby cutting off the power supply to the induction motor 4.

On the other hand, when the brake coil 22 is deenergized, the attraction to the brake arm 10 is released, so this arm 10 becomes free and the spring 12
The force causes the brake shoe 11 to be pressed against the brake drum 9, and the brake on the sheave 5 is applied. In addition, since the contacts 21c and 21d close when the emergency operation relay 21 is deenergized,
Voltage control measurement device 18 and current control device 19 become inoperable, and the outputs of converter 1 and inverter 2 are cut off.

In the elevator emergency control system having the above configuration, the torque T _M of the induction motor 4 and the load torque T _L when the load is lowered (when descending a heavy load).
are balanced at point P shown in _FIG .
Accelerate with T _L torque. Then, when the brake torque T _B is gradually generated and T _L =T _B , the acceleration operation is completed and the vehicle stops while decelerating with the braking torque T _B - T _L. In this case, the motor torque, brake torque, load torque, composite torque, and rotational speed are shown in Figure 6 a to e.
It will look like this.

However, the elevator emergency control system having the above structure has a problem in that the stopping distance becomes long because the elevator accelerates once and then stops as shown in FIG.

[Summary of the invention]

Therefore, the elevator emergency control device according to the present invention is intended to prevent the stopping distance from increasing during an emergency stop, and applies DC power to the induction motor during an emergency stop.

[Embodiments of the invention]

FIG. 8 is a circuit diagram showing an embodiment of an elevator emergency control system according to the present invention, and the same parts as in FIG. 1 are indicated using the same symbols. In the figure, 3d and 3e are normally closed contacts of the power switch 23, which are connected between the output end of the converter 1 and two input lines of the induction motor 4. This configuration is shown in FIG. 9 using a specific circuit. However, in this case, the power switch 23
It is assumed that the voltage control device 18 performs control so that the converter 1 continues to generate DC output even if the converter 1 operates.

In the circuit configured in this manner, when the safety circuit 20 shown in FIG. 3 is activated and the power switch 23 is deenergized, the contacts 3a to 3e are switched to the state shown in the figure. That is, the output of the inverter 2 is cut off from being supplied to the induction motor 4, and the DC output of the converter 1 is supplied only to the two selected coils 4a and 4c of the induction motor 4. As a result, the current is converter 1 - contact 3d - coil 4
It flows through the path a-coil 4c contact 3e-converter 1. And induction motor 4
When a direct current is passed through, a braking torque as shown in FIG. 10 is generated, and this braking torque T _p is approximately proportional to the square of the direct current. Therefore, the control of the voltage control device 18 on the converter 1 is set so that this braking torque T _p becomes an appropriate value (1 to 3 times the rated torque of the electric motor).

Note that by generating a DC braking force that is approximately proportional to the square of the DC current, excessive DC braking force may cause rope slip between the hoist sheave and the rope, increasing the braking distance. This is a braking state that does not give sudden shock to people riding in the elevator.

In this case, the relationships among the motor torque, brake torque, braking torque due to DC current, load torque, composite torque, and rotational speed are as shown in Figures 11a to 11f, and compared to Figures 6a to 6e. If we look at it as follows, braking will be applied without time delay by the amount of braking torque generated by DC current, and as a result, the car will start decelerating without accelerating, so less braking will be required. The car can be stopped reliably at a certain distance. Furthermore, the voltage control device 18 can be more effective by controlling the converter according to the driving direction of the car and the magnitude of the load.

In addition, in the above embodiment, contact point 3 is newly added.
d and 3e are provided to apply direct current _{to the} induction motor in an emergency. Similar effects can also be obtained by continuing to operate contacts 3a to 3c, converter 1, and inverter 2 during emergency control. If either of these transistors T ₁ or T ₂ fails,
A similar braking force can be obtained by passing direct current through only the two coils forming the induction motor 4 in combination with other transistors.

〔Effect of the invention〕

As explained above, the elevator emergency control device according to the present invention supplies DC current to the induction motor in an emergency, and doubles the supplied DC current.
Because the system generates a DC braking force that is approximately proportional to the height of the elevator, excessive DC braking force may cause rope slip between the hoisting machine sheave and the rope, increasing the braking distance and causing damage to people riding in the elevator. The car can be reliably stopped in a short braking distance with an acceleration that does not cause a sudden shock to the car, without causing a time delay. Further, since the mechanical brake can be made smaller and lighter due to direct current braking, it has various excellent effects such as being able to construct an inexpensive system.

[Brief explanation of the drawing]

Figures 1 and 3 are circuit diagrams showing an example of a conventional elevator emergency control system, Figures 2, 4, and 5
The figure is a circuit diagram showing a specific example of each part of the circuit shown in Fig. 1, Figs. 6 and 7 are operation waveform diagrams of each part to explain the operation of the circuit shown in Figs.
9 are circuit diagrams showing one embodiment of the present invention, and FIGS. 10 to 12 are operation waveform diagrams of each part of the circuit shown in FIGS. 8 and 9. 1...Converter, 2...Inverter, 3a~
3e... Contact, 4... Induction motor, 5... Sheave,
6...rope, 7...basket, 8...counterweight, 9...
... Brake drum, 10 ... Arm, 11 ... Brake shoe, 12 ... Spring, 13 ... Regeneration converter, 14 ... Speed detector, 15 ... Speed pattern generator, 16 ... Adder, 17 ... speed control device, 18 ... voltage control device, 19 ... current control device. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. In an elevator that includes an induction motor as a hoisting motor, a variable voltage/frequency power inverter that controls the rotation of the induction motor, and a converter that supplies direct current to the inverter, the elevator includes: a safety circuit that detects an abnormality in the safety circuit; and a DC application circuit that supplies DC current to the induction motor to generate a DC braking force when the safety circuit is activated, and controls the converter when the safety circuit is activated. to control the DC current supplied to the induction motor,
An elevator emergency control device characterized by suppressing DC braking force within a predetermined range.