JPS58152773A - Driving device for alternating current elevator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for driving an AC elevator. - An induction motor is used as the motor that drives the elevator car, and the motor is driven by supplying variable voltage/variable frequency AC power converted by an inverter. This is shown in FIG.

In the figure, R, S, and T are three-phase AC power supplies, (1) is a power switch that turns on or shuts off AC power supplies R1S and T, and (2) is connected to the power switch (1) to keep the power supply voltage at a constant DC voltage. A rectifier (3) is a smoothing capacitor connected to the DC side of the rectifier (2), and (4) is connected to the DC side of the rectifier (2) and is composed of a transistor and a diode. and a well-known inverter that converts the frequency to an arbitrary frequency, (5) is a three-phase induction motor with a hoisting capacity connected to the AC side of the inverter (4), and (6) is a hoisting machine driven by the electric motor (5). The sheave (7) is the main rope wrapped around the sheave (6), and (8) and (9) are the heel and counterweight connected to both ends of the main rope (7), respectively.

In other words, three-phase AC power is converted to DC power by a rectifier (2) and a smoothing capacitor (3), and then converted to DC power by an inverter (4).
given to. The inverter (4) converts the applied DC power into variable voltage/variable frequency AC power and supplies it to the electric motor (5). The electric motor (5) is now driven and the car (8) is moved up and down.

However, since a large capacity smoothing capacitor (3) is used, the self-discharge time constant of the applied voltage is long.

Therefore, when the power switch (1) is shut off, high voltage is generated across the smoothing capacitor (3), which may pose a risk of electric shock to personnel performing adjustments, maintenance, etc.

This invention improves the above-mentioned problem by short-circuiting the smoothing capacitor with the contact that closes when the power is cut off.
Adjust by discharging the smoothing capacitor.

An object of the present invention is to provide a drive device for an AC elevator that ensures the safety of personnel performing maintenance.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, αO is a short-circuit contactor contact that is connected to one end of the smoothing capacitor (3) and is open when the power switch (1) is turned on and closed when the power switch is turned off, and (b) is the contact αO. This is a resistor connected in series to the other end of the XfL sliding capacitor (3). The rest is the same as in FIG.

While the power switch (1) is turned on, the short-circuit contactor contact αQ is open, so the situation is exactly the same as that shown in FIG.

When the power switch (1) is cut off, the contact αQ is closed, so that the charge in the smoothing capacitor (3) is quickly discharged via the resistor Qη. Therefore, there is no danger of electric shock even if a person touches it.

The contact QO is a relay that is energized while the power switch (1) is turned on in the electric circuit of the elevator;
For example, contacts such as safety circuit relays may be used, and the structure is inexpensive.

As explained above, in this invention, the smoothing capacitor connected to the rectifier that rectifies the commercial AC power supply is short-circuited by the contact that closes when the power supply is cut off, so that personnel performing adjustment, maintenance, etc. cannot touch it. You can prevent yourself from getting an electric shock.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional AC elevator drive device, and FIG. 2 is a block diagram showing an embodiment of the AC elevator drive device according to the present invention. (1)...power switch, (2)...rectifier, (3
)... Smoothing capacitor, (4)... Inverter,
(5)...Three-phase induction motor, (8)...Elevator car, 00...Short-circuit contactor contact Note that the same parts in the figures are indicated by the same reference numerals. Agent Makoto Kuzuno - (1 other person) Figure 1 shows δ 21st! I

Claims (1)

[Claims] In a system in which commercial AC power is rectified into DC using a rectifier and smoothing capacitor, this DC is converted to variable frequency AC power using an inverter, and this converted AC power is used to drive an AC motor to operate the car. An AC elevator driving device, comprising a contact that is open while the commercial AC power is turned on and closes when the commercial AC power is turned off to short-circuit the smoothing capacitor.