JPS63283493A - Controller for elevator - Google Patents

Abstract

PURPOSE:To restrain the deterioration of control characteristics accompanying the voltage drop of a reactor, by a method wherein boosting DC-DC converter is provided between a converter, converting AC into DC, and a smoothing capacitor. CONSTITUTION:A converter 2 rectifies the power of 3-phase AC power source 1 and supplies the power to an inverter 4 through a DC-DC converter 17 and a capacitor 3. A controller 12 controls a switching element, constituting the inverter 4 so that the speed command of a speed commanding device 11 is equalized to the speed detecting value of a tachometer generator 12, through pulse modulation. Further, the controller 12 decides whether an elevator is being accelerated or not and when it is being accelerated, the controller 12 commands boosting operation to the DC-DC converter 17 to increase the voltage of the capacitor 3 to a desired value. According to this method, the deterioration of control performance, which is due to the voltage drop of a reactor, may be restrained.

Description

[Detailed Description of the Invention] [Field of Application in Industry A] This invention transforms alternating current into direct current using a converter, smoothes it with a capacitor, and converts the obtained direct current into alternating current with variable voltage and variable frequency using an inverter. The present invention relates to an elevator control device that controls an induction motor for hoisting a lever car.

[Prior Art] Fig. 6 is a schematic diagram of a conventional elevator control device disclosed in, for example, Japanese Unexamined Patent Publication No. 59-163276. In the figure, (1) is a three-phase AC power supply, and (2) is a A converter that converts three-phase alternating current to direct current, (3) a capacitor that smoothes the converted direct current, and (4) an inverter that converts the converted direct current to variable voltage/variable frequency alternating current by pulse width modulation. (5) is a reactor for reducing the ripple of the output current of this inverter, (6) is a three-phase electric conduction motor for car hoisting, (7) is a sheave driven by this motor, (8) is an elevator car, (9)
is a counterweight, (10) is a lobe, (11) is a speed command device that commands the running speed of the elevator, (12)
is a speedometer generator that detects the rotational speed of the electric motor (6), (
13) is a control device that controls the output voltage and frequency of the inverter (4) so that the speed command of the speed command device (11) and the speed detection value of the speedometer generator (12) are equal.

Next, the operation will be explained. When the converter (2) obtains electric power from the three-phase AC power supply (1), rectifies it, and outputs it, it is smoothed by a capacitor (3), converted into DC with less pulsation, and supplied to an inverter (4). On the other hand, the speed command device (11) operates when the car starting command is output and applies a speed command to the control device (13). The control device (12) controls switching elements such as transistors constituting the inverter (4) using pulse width modulation (PWM) so that this speed command and the speed detection value of the speedometer generator (12) become equal. As a result, variable voltage/variable frequency three-phase alternating current is output from the inverter (4) and supplied to the electric motor (6) via the reactor (5). Thus, the electric motor (6) is rotated according to the speed command from the speed command device (11), and the sheave (7) is driven to control the operation of the elevator.

Generally, the output of a pulse width modulation type inverter contains a large amount of harmonics, so if the electric motor (6) is directly connected to the inverter (4), noise will be increased. The reactor (5) is provided to reduce ripple included in the output current of the inverter (4) and to suppress noise from the electric motor (6).

[Problems to be Solved by the Invention] In the conventional elevator control device described above, a reactor (5) is provided in order to suppress motor noise. It may become impossible to ignore. This will be explained below.

When the car (8) is loaded with the rated load and is operated in an ascending manner, if the car (8) is run according to the speed curve A shown in Figure 7(a), the electric motor (6) has the same A current shown by current curve B in Figure (b) flows. At this time, the output voltage of the inverter (4) changes according to the output voltage curve C in the same figure (C), and correspondingly, the input voltage of the electric motor (6) changes according to the input voltage curve in the same figure (C). It turns out. Of these curves, the deviation between the output voltage curve C of the inverter (4) and the input voltage curve of the motor (6) is the voltage drop of the reactor (5), and especially the voltage drop near the end of acceleration. It is the largest.

This means that even though a large voltage is output near the end of acceleration in order to make the car run according to the speed curve A, the necessary voltage is not applied to the electric motor (6). In this case, if the output voltage of the inverter (4) is further increased, the input terminal of the motor (6) will also be increased accordingly, but the output voltage of this type of voltage type inverter is determined by the voltage of the capacitor (3). , the voltage of the capacitor (3) is determined by the voltage of the three-phase AC power supply (1).

However, in the conventional elevator speed control device, voltage drop of the reactor to reduce motor noise,
In particular, even if the inverter is requested to output a large voltage to compensate for the voltage drop near the end of acceleration, the inverter cannot respond to this request, resulting in a decrease in acceleration due to deterioration of control characteristics, which impairs ride comfort. was there.

This invention was made to solve the above problems, and provides an elevator control device that can suppress the deterioration of control characteristics due to voltage drop in the reactor, thereby ensuring a comfortable ride. The purpose is to

[Means for Solving the Problems] This invention provides a DC-DC elevator for step-up between a converter that converts AC to DC and a smoothing capacitor, so that when it is predicted that the output voltage of the inverter will be insufficient, , which causes this DC-DC converter to perform step-up operation.

[Function] In this invention, when the output voltage of the inverter is predicted to be insufficient, such as during acceleration of the elevator, when the three-phase AC power source/voltage decreases, or when the car has a particularly large load, the DC-DC converter is activated. This step-up operation is performed to supply DC at a sufficiently large voltage to the inverter, thereby suppressing deterioration of control characteristics due to voltage drop in the reactor.

[Embodiment] FIG. 1 is a schematic diagram of an embodiment of the present invention, and the same reference numerals as in FIG. 6 indicate the same elements. Then, the converter (2) and the capacitor (
3), a reactor (14), a transistor (1
5) and a DC-DC converter (17) consisting of a diode (16) is added. Here, a reactor (14) and a transistor (15) are connected in series, and the reactor side of the series circuit is connected to the positive side terminal of the converter (2), and the transistor side (emitter) is connected to the negative side terminal of the converter (2). Further, a diode (16) is connected between the mutual junction of the reactor (14) and the transistor (15) and the positive electrode side of the capacitor (3). In addition, a transistor (1
5) is configured to be turned on and off by a control device (12).

The operation of this embodiment configured as described above will be described below with reference to FIGS. 2 and 3, with particular emphasis on the portions in which new elements have been added.

First, if the transistor (15) is kept in the off state, the positive terminal of the converter (2) and the capacitor (3)
Since the reactor (14) and the diode (16) are inserted between the positive electrode side and the positive electrode side of the circuit, the same operation as the conventional device is performed.

Next, as shown in Fig. 2, when the transistor (15) is turned on at time To, the circuit consisting of the positive terminal of the converter (2) - the reactor (14) - the negative terminal of the converter (2) is connected. Current flows and energy is stored in the reactor (14).

Subsequently, when the transistor (15) is turned off at time TI, the reactor (14) → diode (16)
- Capacitor (3) → Converter (2) - Reactor (
A current flows through the circuit 14), and the energy stored in the reactor (14) during the ON period of the transistor (15) is released to the capacitor (3) and the inverter (4). Further, at time T2, the transistor (15) is turned on again and the above-described operation is repeated.

Now, the output voltage of the converter (2) is Ed, and the capacitor (
3) voltage is Ec, )-on time of transistor (15) is T os (t+-to), off time is T OFF
('h-t+), there is a relationship between these: on time TON and off time T o,
By changing , the voltage of the capacitor (3) can be increased to an arbitrary level. However, since the DC-DC converter (17) can supply power even in a non-operating state, it is actually activated when the output voltage of the inverter (4) is predicted to be insufficient. ) is shown in Fig. 3.

That is, in step (101) it is determined whether or not the elevator is accelerating, and if it is accelerating, step (102) is performed.
), the DC-DC converter (17) is operated to boost the voltage, and the voltage of the capacitor (3) is increased to a desired value based on equation (1). If the elevator is not accelerating, the DC-DC converter (17) is activated in step (103).
is inactive and stops boosting operation.

Thus, according to this embodiment, the voltage of the capacitor (3) can be increased when the elevator accelerates.
This solves the problem of conventional devices in which control characteristics deteriorate due to insufficient voltage near the end of acceleration, impairing ride comfort.

Note that in the above embodiment, the boost operation is performed during acceleration when control characteristics tend to deteriorate, but deterioration of control characteristics can also occur when the power supply voltage drops or when the load inside the car becomes heavy. Therefore, it is also necessary to take measures against this.

Figure 4 is a countermeasure against power supply voltage, and is equipped with an undervoltage detector (18) that detects the voltage of the three-phase AC power supply (1) and operates when this voltage falls below a predetermined value. The control device (12) detects the operation of the converter (18) and causes the DC-DC converter (17) to perform a step-up operation.

Fig. 5 is a countermeasure against heavy loads. A load detector (19) is installed that operates when the load inside the car reaches a predetermined heavy load, and when the control device (12) detects that the load detector operates, - The DC converter (17) is in step-up operation.

[Effect of the invention] As is clear from the above explanation, according to the present invention,
A boost DC-DC converter is installed between the converter that converts AC to DC and the smoothing capacitor, and it is possible to predict when the inverter voltage will be insufficient when the elevator accelerates, when the power supply voltage drops, or when the load is heavy. DC when
Since the DC converter performs step-up operation, the problem of conventional devices in which control performance deteriorates due to insufficient voltage is solved, and good riding comfort can thereby be ensured.

Further, by providing a DC-DC converter for boosting the voltage, a reactor with a larger inductance may be installed to reduce motor noise, thereby enabling even quieter operation.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention, Fig. 2 is a time chart for explaining the operation of the embodiment, Fig. 3 is a flow chart for explaining the operation of the embodiment, and Fig. 4 is a flowchart for explaining the operation of the embodiment. 5 and 5 are block diagrams showing the configuration of main parts of other embodiments, FIG. 6 is a schematic configuration diagram of a conventional elevator control device, and FIGS. 7(a) to (C) are operations of the same device. 2 is a diagram showing the relationships between time and speed, time and current, and time and voltage, respectively, in order to explain the following. (2): Converter (3): Capacitor (4)
: Inverter (5)/Reactor (6) : Three-phase induction motor (12) Control device (17) : DC-DC converter Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] A converter converts alternating current to direct current, and a capacitor smoothes it, and an inverter converts the resulting direct current to variable voltage/variable frequency alternating current, which is then supplied to the induction motor for car hoisting via a ripple reduction reactor. A step-up DC-DC converter is provided between the converter and the capacitor, and
An elevator control device, characterized in that the DC-DC converter performs a step-up operation when the output voltage of the inverter is predicted to be insufficient.