JPS61280785A - Controller for ac elevator - Google Patents

Abstract

PURPOSE:To make it possible to process reactive power without smoothing condenser by connecting a resistor and a transistor in series with the DC side of a converter. CONSTITUTION:A resistor 16 and a transistor 17 are connected in series with the DC side of a converter 3. When a reactive power is generated in a motor 6 and the voltage of the DC side of the converter 3 becomes the prescribed value by the reactive power, a reactive power controller 18 operates to conduct the transistor 17 and to control the conducting time. Thus, the reactive power is consumed by the resistor 15. Accordingly, the smoothing condenser 4 of the conventional device can be eliminated to obviate a danger of electric shock and to prevent the power factor of a power source side from decreasing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an elevator driven by an induction motor supplied with electric power from an inverter.

[Conventional technology]

The second factor is, for example, the configuration of a conventional AC elevator control device shown in FIG. 2 of Japanese Patent Application Laid-Open No. 59-10170.

In the figure, R, S, T are three-phase AC power supplies, (1) is a molded circuit breaker connected to the power supply R0S, T, (2) is a circuit breaker connected to the circuit breaker (1), ) is the operating electromagnetic contactor contact that closes when starting and opens when stopping, (3) is the contact (2
) is connected to a converter configured with a diode and converts alternating current to direct current, (4) is a smoothing capacitor connected to the direct current side of converter (3) and smoothes the direct current output, (5)
) is connected across the smoothing capacitor (4) fl! -Constructed of transistors and diodes to convert direct current into variable voltage and
An inverter that converts variable frequency three-phase alternating current.

(6) is a three-phase induction motor connected to the AC side of the inverter (5), (7) is the driving sheave of the hoist driven by the motor (6), and (8) is the sheave ( The main rope is wrapped around 7) and has a heel (9) and a kuku weight αq connected to each end.

αυ is a speed detector that is directly connected to the electric motor (6) and emits a speed signal;
The floor is an inverter control device that gives a firing command to control the voltage and frequency to the inverter (5) from the speed command signal and speed signal, α4 has the AC side connected to the input side of the contact (2), and the line on the DC side is the resistance α 'J through the smoothing capacitor (4
) and the other wire is connected to one end of the smoothing capacitor (4).
A rectifier connected to the other end of the

The conventional AC elevator control device is configured as described above, and when a start command is issued, the contact (2) closes.
Three-phase AC power with variable voltage and variable frequency is supplied to the motor (6) via the converter (3), smoothing capacitor (4), and inverter (5).

The electric motor (6) is now activated and the car (9) runs.

Then, the inverter (5) is controlled by the inverter control device α, and its output voltage and frequency are adjusted, thereby increasing the speed of the electric motor (6), that is, the car (9).
The traveling speed of the vehicle is automatically controlled with high precision.

By the way, the smoothing capacitor (4) smoothes the DC output of the converter (3). It is used to absorb the reactive power generated by the dynamic @(6). but.

When the car (9) is stopped, the contact (2) is open, so
The smoothing capacitor (4) is not charged and the smoothing capacitor (4) is not charged.
The charge in 4) is transferred to the inverter (5) or converter (3).
It gradually discharges due to reverse leakage current of the elements. Basket (9
) is stopped for a long time, the voltage across the smoothing capacitor (4) will drop significantly. Here, when a start command is input and the contact (2) closes, a large charging current flows through the smoothing capacitor (4), and the melt layer of the contact (2) and the smoothing capacitor (
Unfavorable events such as shortening of the life of the converter (4) and damage to the converter (3) occur. The rectifier α4 and resistor (L!9) prevent this problem, and if the circuit breaker (1) is turned on, the smoothing capacitor (4) will remain connected to the rectifier I and resistor α9 even when the car (9) is stopped. Therefore, when the contact (2) closes, the smoothing capacitor (4)
Inrush current for charging does not flow into the battery, and the above-mentioned problem is prevented.

[Problem that the invention seeks to solve]

In the conventional AC elevator control system as described above, a rectifier +141 and a resistor α$ are required to prevent rush current in the smoothing capacitor (4). Even if the circuit breaker (1) is shut off for inspection, etc., the smoothing capacitor (4) is still charged, so the DC side voltage of the converter (3) will not drop, and if a maintenance worker accidentally touches it, they may receive an electric shock. There is a danger of

Since the smoothing capacitor (4) has a limited lifespan, it must be replaced periodically. Power supply R for smoothing capacitor (4),
Problems such as poor power factor on the S and T sides will be identified.

This invention was made to solve the above problems, and eliminates the risk of electric shock by eliminating the smoothing capacitor, eliminates the need to replace the smoothing capacitor, and prevents a drop in power factor on the power supply side. The object of the present invention is to provide a control device for an AC elevator.

[Means for solving problems]

A control device for an AC elevator according to the present invention is as follows.

A resistor and a transistor are connected in series on the DC side of the converter, and when the voltage on the DC side of the converter exceeds a predetermined value,
A reactive power control device makes the transistor conductive and controls its conduction time.

[Effect]

In this invention, since a smoothing capacitor is not used, an initial charging circuit is not required, and the voltage on the DC side of the converter when stopped is zero. Also.

When the motor generates reactive power and the voltage on the DC side of the converter exceeds a predetermined value, the transistor becomes conductive and the reactive power is consumed by the resistor.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. (
11 to (3) and (5) to α3 are similar to those of the conventional device described above.

In the figure, the wire is a resistor whose one end is connected to one of the DC sides of the converter (3), and H is a transistor whose collector is connected to the other end of the resistor αe and the emitter is connected to the other DC side of the converter (3). (II is connected to the DC side of the converter (3), and when this voltage exceeds a predetermined value, the transistor (I
This is a reactive power control device that provides a signal to the base of the

In the AC elevator control system constructed as described above, the smoothing capacitor (4), rectifier I, and resistor (I!19) shown in FIG. 2 are not used.

When reactive power is generated in the motor (6), the smoothing capacitor (4) absorbs it in the conventional device, but in this embodiment, it is consumed by the resistor U. That is, when the voltage on the DC side of the converter (3) exceeds a predetermined value due to reactive power, the reactive power control device α operates.

The transistor αη is made conductive and its conduction time is controlled. As a result, reactive power is consumed by the resistor αe.

Since the smoothing capacitor (4) is not used, the rectifier (141) and the resistor (to) shown in FIG. 2 are unnecessary, and the DC side voltage of the converter (3) when stopped is also zero, so there is no risk of electric shock.

Although not shown in the drawings, current control is performed by detecting the current of the motor (6) and feeding it back, so even if there is a ripple in the DC voltage, the control performance will not deteriorate. Therefore, voltage smoothing by the smoothing capacitor (4) is not particularly required.

〔Effect of the invention〕

As explained above, in this invention, an induction motor is driven by the output of an inverter connected to the DC side of the converter, a resistor and a transistor are connected in series to the DC side of the converter, and the voltage on the DC side of the converter is maintained at a predetermined level. When the value exceeds this value, the transistor becomes conductive and the conduction time is controlled, so reactive power can be handled without using a smoothing capacitor, eliminating the risk of electric shock and eliminating the need to replace the smoothing capacitor. , and has the effect of preventing a drop in power factor on the power source side.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an AC elevator control apparatus according to the present invention, and FIG. 2 is a block diagram showing a conventional AC elevator control apparatus. In the figure, R and iT are three-phase AC power supplies, and (2) is the operating electromagnetic contactor contact. (3) is a converter, (5j is an inverter, (6) is a three-phase induction motor, (9) is a cage, αe is a resistance,
(Iη is a transistor or a reactive power control device. Note that the same reference numerals in Figure 9 indicate the same parts.

Claims (1)

[Claims] An inverter is connected to the DC side of a converter that is connected to an AC power source through contacts that are closed at startup, and the output of this inverter drives an induction motor to drive a car. A resistor and a transistor connected to the DC side of the converter, and a resistor that operates when the voltage on the DC side of the converter exceeds a predetermined value due to reactive power generated by the motor to conduct the transistor and control the conduction time. A control device for an AC elevator, comprising: a power control device.