JPS60170483A - Controller of ac elevator - Google Patents

Abstract

PURPOSE:To prevent a regenerative converter from damaging by composing the converter of a self-extinguishing element, and interrupting the element when a commercial AC power source is failed or abnormal regenerative power is detected. CONSTITUTION:AC power is supplied to a power drive converter 2, its output is supplied to an inverter, and an induction motor for driving an elevator is driven by the AC power from the inverter. A regenerative converter 11 is connected in parallel with the converter 2, and the converter 11 is composed of self-distinguishing elements 11G-11L. When the failure in the commercial AC power source or the abnormal regenerative power is detected by a controller 17, the controller 17 interrupts the conduction of elements 11G-11L.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a device for controlling an elevator driven by an induction motor.

[Prior art]

Some elevators use an induction motor as the motor that drives the car, and supply variable voltage/variable frequency alternating current power converted by an inverter to control the speed of the motor. In this device, when the car is descending under a heavy load,
During light load increase or deceleration, mechanical energy is converted into electrical energy and returned to the DC side via the inverter.

When the DC power supply is composed of a rectifier and a smoothing capacitor, the terminal voltage of the smoothing capacitor increases, and there is a possibility that dielectric breakdown of the elements forming the inverter will occur. Also,
If the ratio between the voltage applied to the motor and the frequency exceeds a predetermined value, the magnetic flux of the motor may become saturated and an excessive current may flow. Therefore, in order to process the regenerated power on the DC side,
For example, a regenerative converter as shown in Japanese Patent Laid-Open No. 58-16247'7 is used. This will be further explained with reference to FIG.

In the figure, R, S, and T are commercial three-phase AC power supplies, (1) is a molded case circuit breaker that cuts off AC power supplies]'(, S, and T, and (2) is a diode ( 2A) to (2F) form a three-phase full-wave rectifier circuit, (3) is a smoothing capacitor connected to the direct current side of (2), and (4) is a smoothing capacitor ( 3) with an inverter connected to both ends of the 6 transistors (4
A) ~ (4F) and 6 diodes (4a) ~ (4f)
The transistors (4A) to (4F) are connected to each other by 2
Three sets of transistors connected in series are connected in parallel, and diodes (4a) to (af) are connected in parallel to transistors (4A) to (4F), respectively. An inverter (5) is a three-phase induction motor connected to the AC side of the inverter (4), and (6) is a hoist driven by the motor (5). Machine driving sheave, (7
) is the main rope hooked to the sheave (6), (8) is the main rope (
7) is a cage connected to one end, (9) is a counterweight also connected to the other end, and (10) is a breaker (1) on the negative side.
) is connected to the three-phase transformer □, 01) is connected to the transformer (l■
Thyristors (IIA) to (IIF) connected to the secondary side of
This is a regenerative converter in which a three-phase full-wave rectifier circuit is formed.One end of the DC side is connected to one end of a smoothing capacitor (3) via a DC reactor (6), and the other end of the DC side is connected to one end of a smoothing capacitor (3). 3) connected to the other end.

That is, during power operation, the AC power from the AC power supplies R, S, and T is converted to DC by the power converter (2), smoothed by the smoothing capacitor (3), and then converted by the inverter (4). Pulse width controlled, electric motor (5
) supplies variable voltage/variable frequency AC power. The electric motor (5) is now started, the wheels (8) are running, and their speed is controlled. On the other hand, during regenerative operation, the electric motor (5)
The generated power is converted to DC through an inverter (4), and then connected to AC power sources R, S,
Returned to T. At this time, the transformer OQ is connected to the AC power supply R,
This is a transformer that makes the AC side voltage of the regenerative converter (l) slightly higher than the voltages of S and T, and is an autotransformer or an isolation transformer.

Now, if the circuit breaker (1) operates for some reason during regenerative operation or the AC power supplies R, S, and T are interrupted, the electric motor (5) is braked by a brake (not shown), but the smoothing capacitor The charge stored in 0 (to) flows into the transformer (1G) through DC reactor 0 and regenerative converter 01, and the 0 DC reactor 0, through which a large short-circuit current flows, suppresses this current and converts it into regenerative converter α.
Although this is to prevent the destruction of D, it is inevitable that it will be large and expensive. Another way to prevent this short-circuit current is to insert a high-speed circuit breaker into the circuit, but a circuit breaker that interrupts a large DC current in a short time is also large and expensive. Overview] This invention improves the above-mentioned problems, and by using a self-arc-extinguishing element in the regenerative converter, it prevents the regenerative converter from being destroyed by the large current that flows when the AC power supply is lost or when there is an abnormality in the regenerative power. It is an object of the present invention to provide a control device for an AC elevator that can be constructed at low cost.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

FIG. 2 shows an overall configuration diagram of the present invention.

In the figure, (IA) is a circuit breaker operation detection contact that operates in conjunction with the operation of circuit breaker (1) and closes when circuit breaker (1) interrupts the circuit; The power failure detection relays (15A) and (15B) are current transformers that detect the current on the AC side of the regenerative converter aυ, and the contacts (
When IA) is closed, power failure detection relay 0→ is deenergized, or the output of current transformer (15A) or current transformer (15B) becomes abnormal, an arc extinguishing signal is sent from control circuit 0Q for regeneration. given to the converter θυ. At this time, regeneration converter α
Since 1) is constituted by a self-extinguishing element as described later, the regenerative converter 0 is cut off and the regenerative current is not returned to the AC side. Figure 3 shows a circuit diagram of the embodiment.

In the figure, (Iσ is 6 transistors (:ue) to (II
The transistors (IIG) to (:uL) are connected in parallel, two of which are connected in series, and the transistors (IIG) to (:uL) are connected in parallel. (ILL) is a regenerative converter in which diodes (l1g) to (111) are connected in parallel, and its DC side is connected to both ends of the smoothing capacitor (3) (DC reactor θno in Figure 1). is not used).

The θ motor is a control device composed of a microcomputer.
Central processing unit (hereinafter referred to as CPU) (1'7A),
Read-only memory (hereinafter referred to as ROM) (17B) that stores programs and fixed value data, read/write memory (17C) that temporarily stores data such as calculation results.
), a conversion device (lr/D) that is connected to the circuit breaker operation detection contact (IA) and converts the input/output signal level, and a conversion device (1'/E) that also inputs the signal of the power failure detection relay a4).
), conversion devices (17F) and (17G) that also input the signals of current transformers (15A) and (15B), and base cutoff signals, that is, arc extinguishing signals, of transistors (11G) to (IIL) of the regenerative converter θ. A conversion device (1
7H).

Other than the above, the configuration is the same as in FIG. 1.

Next, the operation of this embodiment will be explained using the flow chart of the operation shown in FIG.
circuit breaker (1) is not operating (contact (IA) open)
If it is determined that this is the case, normal operation is performed using the hand J@ (c).

When it is determined in step (a) that the circuit breaker (1) has operated (contact (IA) closed), an extinguishing signal is issued in step (a). Now, the transistor (of the regenerative converter 01) (
IIG) to (ILL) become non-conductive, and no current flows through the regenerative converter α1). In addition, the voltages of AC power supplies R, S, and T are detected in step (c), and it is determined that AC power supplies R, S, and 'f' are not in a power outage (power outage detection relay 04 is energized) in hand IFj (c). Then, normal operation is performed in step (g), and if it is determined that there is a power outage (power outage detection relay 04 deenergized), an arc extinguishing signal is issued in step (c). Detects the current on the alternating current side of the regenerative converter 0]), and if the above current is below a predetermined value in step (c), normal operation is performed in step (goods), and if the above current exceeds the predetermined value. , an arc extinguishing signal is issued in step (c).

In this way, the contact (1) is closed, the power failure detection relay 04) is deenergized, or the current transformer (15A).

(15B) detects a large current, an arc extinguishing signal is issued, the regenerative converter 0]) is cut off, and the discharge circuit of the low tide capacitor (3) is no longer formed.

Therefore, since no large current flows through the regenerative converter 0η and the transformer H, they are prevented from being destroyed.
, 1L), but the same function can be achieved by using a gate turn-off transistor.

〔Effect of the invention〕

As described above, in this invention, AC power is supplied from an inverter to an induction motor for driving an elevator, a regenerative converter is connected in parallel to a power converter that supplies DC power to the inverter, and the regenerative converter is connected in parallel to the inverter. The self-arc-extinguishing element is configured to generate an arc-extinguishing signal to make the self-arc-extinguishing element non-conductive when a loss of commercial AC power or an abnormality in regenerated power is detected.

As a result, it is possible to inexpensively construct a device that blocks a large current flowing due to regenerative power and prevents damage to the regenerative converter when commercial AC power is lost or when regenerative power is abnormal.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional AC elevator control device, FIG. 2 is an overall configuration diagram showing an embodiment of an AC elevator control device according to the present invention, FIG. 3 is a circuit diagram of the main parts, and FIG. The figure is a flowchart of the operation by the control circuit of FIG. 3. In the figure, R, S, and T are commercial three-phase AC power supplies, (1) is a molded case circuit breaker, (IA) is a circuit breaker operation detection contact, (2) is a power supply converter, (4) is an inverter, ( 5) is a three-phase induction motor, (8) is a cage, (lυ is a regenerative converter, α
→ is a power failure detection relay, (15A) and (15B) are current transformers, and 07) is a control device. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 2 Figure 3

Claims (3)

[Claims] (1) A converter for power running connected to a commercial AC power source converts AC into DC, and an inverter converts this into AC with variable voltage and variable frequency, which is supplied to an induction motor, and this motor operates the car. , in which a regenerative converter is connected in parallel with the power running converter to return regenerated power to the commercial AC power supply side, the regenerative converter becomes non-conductive when an arc extinguishing signal is applied. an abnormality detection circuit configured with an arc-extinguishing element and detecting loss of the commercial AC power supply or abnormality of the regenerated power; and control for supplying the arc-extinguishing signal to the self-arc-extinguishing element when the abnormality detection circuit operates. Control device 0 for an AC elevator characterized by comprising: (2) The AC elevator control device according to claim 1, which uses a transistor as the self-extinguishing element. (3) The control device for an AC elevator according to claim 1, which uses a gate turn-off thyristor as the self-extinguishing element.