JPH0132150B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an elevator speed control device,
In particular, it relates to improvements in restart operation after an emergency stop.

FIG. 1 is a circuit diagram showing an example in which the inverter disclosed in Japanese Patent Publication No. 56-12379 is applied to an elevator speed control device. In the figure, 1 is an AC power supply, 2 is a contact of the main circuit switch, 3 is a thyristor converter that converts the AC power supplied through the main circuit switch contact 2 into DC, and 4 is a contact of the thyristor converter 3. A smoothing capacitor smoothes the output voltage, 5 is an inverter that inverts the DC power smoothed by the smoothing capacitor 4 to AC, 6 and 7 are current detectors that detect the output current of the inverter 5, and 8 is an inverter. A hoisting induction motor is driven by the AC power output from the converter 5, and 9 is a speed detector provided on the output shaft of the induction motor 8, which generates an output signal according to the rotation speed. do.

10 is a driving sheave of a hoist driven by an induction motor 8, 11 is a main rope wound around the sheave 8, and 12 and 13 are a cage and a car connected to the ends of the main rope 11, respectively. It is a counterweight. 14 is a speed pattern generator; 15 is a speed calculation circuit that compares the output signal of the speed pattern generator 14 with the output of the speed detector 9 and supplies the output as a current command to the current limiting circuits 16 to 18; Limiting circuits 16-18
compares the output signal of the speed calculation circuit with the outputs of the current detectors 6 and 7, and controls the output current of the inverse converter 5 based on the outputs thereof. Note that 19 is a phase circuit that controls the thyristor converter 3 based on the output signal from the speed calculation circuit 15.

In the elevator speed control device configured as described above, the AC power is rectified and smoothed, and the smoothed DC power is converted into AC in the inverter 5 and then supplied to the hoisting induction motor. Speed control is performed by varying the output current and frequency of this inverter 5.

However, in the circuit configured as described above, when the safety switch of the elevator operates while the elevator is running, the main circuit breaker contact 2 is opened and the brake (not shown) provided on the hoisting machine is activated. and an emergency stop will occur. In this case, the smoothing capacitor 4 remains charged.

When the cause of the emergency stop is removed and the safety switch eventually returns, the main circuit breaker contact 2 closes.
The elevator will restart. by the way,
The voltage of the smoothing capacitor 4 is controlled to be approximately proportional to the output frequency of the inverter 5. Then,
At startup, the voltage command value output from the speed calculation circuit 15 is small. For this reason, when the main circuit switch 2 is turned on, the charge in the smoothing capacitor 4 is rapidly discharged by the action of the converter 3, and the voltage of the smoothing capacitor 4 decreases to the command value. At this time, a large current flows through the thyristor converter 3 due to the discharge of the smoothing capacitor 4. Since such a large current flows, there is a problem that the thyristor converter 3 and the smoothing capacitor 4 are destroyed.

Therefore, an object of the present invention is to prevent the thyristor converter 3 and the smoothing capacitor 4 from being destroyed when the elevator is restarted after an emergency stop.

In order to achieve this object, an elevator speed control device according to the present invention prevents rapid discharge of a smoothing capacitor when restarting after an emergency stop.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The elevator speed control device according to the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a circuit diagram showing an embodiment of an elevator speed control device according to the present invention, and the same parts as in FIG. 1 are indicated using the same symbols. In the figure, 22 is a voltage detector for detecting the voltage across the smoothing capacitor 4, and 23 is a first-order delay circuit which receives the output of the voltage detector 22 as an input, the details of which are shown in FIG.

In FIG. 3, 23b is a contact that closes when the main circuit switch 2 is opened, 23c is a capacitor, 23d and 23f are resistors, and 23e is an operation amplifier.

4A shows the operating state of the contact 2 of the main circuit switch, FIG. 4C shows the operation of the contact 23b, and FIG. 4E shows the output of the speed control calculation circuit 15.

In the circuit configured in this way, when the safety switch is activated while the elevator is running, the contact 2 of the main circuit switch opens, so the output of the smoothing capacitor 4 is charged as shown in Figure 4b. The status quo can continue.

On the other hand, when the contact 23b closes with the opening of the main circuit switch, the primary delay circuit 23 connects the voltage detector 22
The voltage across the smoothing capacitor 4 shown in FIG. 4d is stored through the capacitor. Next, when the safety switch returns with the recovery from the emergency stop and the main circuit switch is closed at time _t2 , the contact 23b is opened, so the output of the operation amplifier 23e is transferred to the capacitor 2.
3c and a time constant determined by the values of resistor 23d, as shown in FIG. 4d.
Here, the output of the speed control calculation circuit 15 gradually increases as shown in FIG. 4e in accordance with the rotational speed of the induction motor 8. Then, the sum of the output of the speed control calculation circuit 15 and the output from the first-order lag circuit 23 is added to the phase circuit 19 as a command value, and the thyristor converter 3 is controlled by this, so the output of the smoothing capacitor 4 is It changes as shown in FIG. 5b, and there is no rapid discharge. Therefore, in the circuit configured in this manner, rapid discharge of the smoothing capacitor is prevented at the time of restart, so electronic components such as the capacitor and the thyristor can be prevented from being destroyed.

In the above embodiment, a case where a voltage detection circuit is newly provided has been described, but a detection circuit for performing voltage control may also be used.
This can also be applied to elevators that have a control circuit using a microcomputer.

As explained above, the elevator speed control device according to the present invention is configured to gradually change the charge of the smoothing capacitor to a predetermined value when restarting the elevator after an emergency stop. This can prevent destruction of electronic circuit components due to rapid discharge of the smoothing capacitor.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a conventional elevator speed control device, FIG. 2 is a circuit diagram showing an embodiment of an elevator speed control device according to the present invention, and FIG. 3 is a circuit diagram showing an example of an elevator speed control device according to the present invention. The delay circuit circuit diagram, FIG. 4, is a waveform chart showing the operation of each part of the circuit shown in FIGS. 2 and 3. 1... AC power supply, 2... Main circuit breaker contact, 3
...Thyristor converter, 4...Smoothing capacitor,
5... Inverter, 6, 7... Current detector, 8...
Induction motor, 9...Speed detector, 14...Speed pattern generator, 15...Speed calculation circuit, 16-1
8... Current limiting circuit, 19... Phase circuit, 22...
...Voltage detector, 23...First-order lag circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A thyristor converter that converts AC power supplied through the contacts of a main circuit switch that opens and closes the main circuit into DC, a smoothing capacitor connected between the output terminals of the thyristor converter, and a smoothing capacitor connected between the output terminals of the thyristor converter. In an elevator speed control device equipped with an inverter that converts an output voltage into AC and supplies it to a hoisting induction motor, the charging voltage of the smoothing capacitor when the main circuit switch is opened due to an emergency stop of the elevator. a voltage detector that detects the voltage, a first-order lag circuit that stores the detected voltage from this voltage detector and sends out an output that gradually decreases this stored voltage with a desired time constant upon restart; control means for controlling the thyristor converter based on a signal of the sum of the output and the output of a speed control arithmetic circuit controlling the inverse converter and gradually changing the voltage of the smoothing capacitor upon restart; Speed control device.