JPH0378357B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a control device for an AC elevator that converts direct current smoothed by a smoothing capacitor into variable frequency alternating current power and drives an alternating current motor with this alternating current power. be.

[Prior art]

Conventionally, in elevators that drive induction motors with variable frequency AC power, the AC is converted to DC, this DC is smoothed by a smoothing capacitor, and then converted to variable frequency AC by an inverter. In this type of elevator, if the capacity of the smoothing capacitor decreases, the riding comfort deteriorates, so a method for detecting the decrease in the capacity of the smoothing capacitor was proposed in Japanese Patent Laid-Open No. 154395/1983.

FIG. 1 shows a conventional AC elevator control device.

In the figure, R, S, and T are three-phase AC power supplies, and 1 is a power switch that turns on or shuts off the AC power supplies R, S, and T.
2 is a converter connected to the power switch 1, which is composed of a thyristor and rectifies the power supply voltage into a DC voltage;
3 is a smoothing capacitor connected to the DC side of the converter 2; 4 is a well-known inverter connected to the smoothing capacitor 3 and composed of transistors and diodes and converts DC power into AC power of any voltage and any frequency; A control circuit that controls the converter 2 and the inverter 4, 6 is the inverter 4
a three-phase induction motor for hoisting, connected to the alternating current side of the
7 is a driving sheave of the hoist driven by the electric motor 6; 8 is a main rope wound around the sheave 7; 9, 10
are a car and a counterweight connected to both ends of the main rope 8, respectively. 11 is a rectifier circuit connected to the power switch 1 and one end of the DC side is connected to one end of the smoothing capacitor 3; 12 is a resistor connected to the other end of the DC side of the rectifier circuit 11; 13 is a connection between the resistor 12 and the smoothing diode 3; Connected to the other end and power switch 1
14 is a smoothing capacitor 3, which is closed for a certain period of time after the switch is turned on (circuit omitted).
This is a charging time measuring circuit that is connected to both ends of the smoothing capacitor 3 and measures the charging time of the smoothing capacitor 3, and sends an abnormal signal to the control circuit 5 in the event of an abnormality. The rectifier circuit 11, the resistor 12, the electromagnetic contactor contact 13, and the charging time measuring circuit 14 constitute a detection means 100 for detecting a decrease in the capacitance of the smoothing capacitor 3.

Next, the operation of this conventional example will be described.

That is, the three-phase AC power is converted into DC power by the converter 2 and the smoothing capacitor 3, and is provided to the inverter 4. The inverter 4 converts the applied DC power into variable voltage/variable frequency AC power and supplies it to the electric motor 6. These are controlled by a control circuit 5. The electric motor 6 is now driven and the car 9 is moved up and down.

On the other hand, when power switch 1 is turned on, contact 1
3 is closed for a certain period of time (time until the smoothing capacitor 3 is charged). Now smoothing capacitor 3
starts charging through the resistor 12, and the charging current gradually increases according to a time constant determined by the capacitance of the smoothing capacitor 3 and the resistance value of the resistor 12. During this time, the control circuit 5 does not issue an ignition command to the thyristor of the converter 2 and an operation command to the inverter 4 .

On the other hand, the charging time measuring circuit 14 measures the charging time of the smoothing capacitor 3 and monitors this charging time. If it is detected that the time is shorter than a predetermined time, an abnormality signal is generated. In response to this abnormality signal, the control circuit 5 sets the output of the inverter 4 to zero to prevent the car 9 from operating, and attempts to replace the smoothing capacitor 3 before the car 9 can no longer be serviced normally. However, when a power outage occurs, the result is the same as if the power switch 1 were shut off. At this time, if the capacity of the smoothing capacitor 3 has decreased, even if the power is restored, the operation of the car 9 will remain blocked. For this reason, there may be a problem in which passengers are trapped in the car 9 for a long time.

[Summary of the invention]

This invention was made in view of the above-mentioned problems, and it is possible to continue operating the elevator even if the smoothing capacitor is abnormal, and it is only when the automatic operation is switched from manual operation for maintenance to automatic operation for transporting passengers. The purpose of this system is to notify passengers of abnormalities in the smoothing capacitor without trapping passengers in the car by preventing the car from driving.

[Embodiments of the invention]

FIGS. 2 and 3 show an embodiment of the present invention.

In the figure, (+) and (-) are control power supplies, 13a is a normally open contact that is closed for a certain period of time after the power switch 1 is turned on, and 14a is opened when the charging time measuring circuit 14 issues an abnormal signal. Normally closed contact, 21A is a normally open contact that is closed during automatic operation, 21B is a normally open contact that is closed during manual operation (operation performed during elevator maintenance), 21Ba is a normally closed contact that is also opened, 20 is an operation mode check relay that identifies automatic operation or manual operation. One end is connected to the control power supply (+) through a series circuit of normally closed contact 21Ba, normally open contact 21A, and normally open contact 13a, and the other end is connected to the control power supply. Connected to (-). 20a and 20b are normally open contacts of the operation mode check relay 20, and 22 is an operation prevention contactor that enables operation of the elevator in an energized state and prevents operation in a deenergized state. Control power supply (+) via a parallel circuit consisting of open contacts 20b and 21B
The other end is connected to the control power supply (-). 2
2a is a normally open contact consisting of three poles of the operation blocking contactor 22, which is connected between the power switch 1 and the converter 2, and enables the elevator to operate in the closed state;
This prevents operation in the open state.

Next, the operation of the above embodiment will be described.

This is different from the conventional example shown in FIG. 1 in that the three-phase induction motor 6 is driven with variable voltage and variable frequency AC power to raise and lower the car 9, and that the charging time measuring circuit 14 measures the charging time of the smoothing capacitor 3. It's the same.

Assume that the vehicle is now in automatic operation and the normally open contact 21A is closed. When the power switch 1 is closed, the normally open contacts 13 and 13a are closed. Operation mode check relay 20 is (+)-13a-2
It is energized by the circuit 1A-21Ba-20-(-). Self-holding occurs via the normally open contact 20a before the normally open contact 13a is opened. Further, the operation blocking contactor 22 is energized via the normally open contact 20b and the normally closed contact 14a, thereby closing the normally open contact 22a. The three-phase induction motor 6 is driven in the same manner as the conventional example shown in FIG.

Even if the capacity of the smoothing capacitor 3 decreases during automatic operation, the normally closed contact 14a remains closed, so automatic operation is continued.

Furthermore, if there is a power outage during automatic operation, and the capacity of the smoothing capacitor 3 has decreased when the power is restored, the normally closed contact 14a will be opened, but the operation mode check relay 20 will be energized, so the operation will not start. The blocking contactor 22 is energized and automatic operation continues.

Next, the case of manual operation will be described. Since the operation blocking contactor 22 is energized via the normally open contact 21B, the operation can be continued regardless of the reduction in the capacity of the smoothing capacitor 3.

Next, a case will be described in which manual operation is switched to automatic operation while the power switch 1 is closed. Since the normally open contact 13a is open, the operation mode check relay 20 remains deenergized. Furthermore, the normally open contact 21B is opened due to automatic operation. At this time, assuming that a decrease in the capacity of the smoothing capacitor 3 is not detected, the normally closed contact 14a remains closed, so the operation blocking contactor 22 is energized and automatic operation becomes possible. Furthermore, if a decrease in capacity is detected, the normally closed contact 14a remains open, so when switching to automatic operation, the operation blocking contactor 22 is deenergized and automatic operation is inhibited.

In addition, a case will be described in which the power switch 1 is closed after the vehicle is in manual operation, and then the manual operation is switched to automatic operation. If the capacity of smoothing capacitor 3 has decreased, power switch 1
This capacitance drop is detected when the normally closed contact 14a is closed, and the normally closed contact 14a remains open. During manual operation, the run-blocking contactor 22 is energized via the normally open contact 21B, as already mentioned. When switching to automatic operation, the operation prevention contactor 22 is deenergized and operation is inhibited.

According to the above embodiment, a decrease in the capacity of the smoothing capacitor 3 is detected when the power switch 1 is closed, and furthermore, when the manual operation is switched to automatic operation, the operation is blocked. Manual operation is normally used by elevator maintenance personnel, so when automatic operation is blocked, there are no passengers in the car, so not only will the maintenance personnel not be trapped, but the maintenance personnel will still be in the elevator. Therefore, maintenance personnel can easily find a defective smoothing capacitor and replace it.

〔Effect of the invention〕

As described above, the present invention provides an elevator that converts direct current smoothed by a smoothing capacitor into variable frequency alternating current power to drive an alternating current motor.
This system is designed to prevent automatic operation only when the identification means switches from manual operation to automatic operation while the detection circuit detects a decrease in the capacitance of the smoothing capacitor. .

However, since manual operation is performed without passengers in the car, even in automatic operation, the inside of the car is unmanned immediately after switching from manual operation.

Therefore, by preventing this automatic operation, it is possible to easily detect a problem with the smoothing capacitor without trapping passengers in the car.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram showing a conventional elevator control device, Figs. 2 and 3 show an embodiment of the present invention, and Fig. 2 is an electric circuit diagram for preventing operation;
FIG. 3 is a diagram corresponding to FIG. 1. In the figure, R, S, and T are three-phase AC power supplies, 3 is a smoothing capacitor, 6 is a three-phase AC motor, 21A is a normally open contact that is closed during automatic operation, 21B is a normally open contact that is closed during manual operation, and 22 is a normally open contact that is closed during manual operation. 11 is a converter, and 100 is a detection circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 Smooth the DC converted from AC power by a converter with a smoothing capacitor, convert this smoothed DC to variable frequency AC power, drive an AC motor with this AC power, and operate the elevator car. a detection circuit for detecting a decrease in the capacity of the smoothing capacitor; an identification means for identifying whether the elevator is in an automatic operation state when transporting passengers or in a manual operation state during maintenance; An elevator characterized in that the detection circuit detects a reduction in capacity, and operation prevention means prevents the automatic operation when the identification of the identification means switches from the manual operation to the automatic operation. Control device.