JPS61236377A - Controller of elevator - Google Patents

Abstract

PURPOSE:To eliminate a switching shock by controlling a torque on the basis of the first inverter control command generator for controlling the torque of an induction motor even if a slip frequency command signal becomes from positive to negative when a speed command signal or a speed signal has the prescribed value or lower. CONSTITUTION:A switching unit 18c receives as inputs the output of a compensating element 14, i.e., a slip frequency command signal 14a and a speed command signal 12. If the signal 12 has the prescribed value or lower, even if the signal 14a becomes from positive to negative, it is ignored so that the unit 18c does not switch from the contact (a) side of contactors 18a, 18b to a contact (b) side. Accordingly, in this case, an inverter controller 21 controls a switching element of an inverter 45 on the basis of a voltage command signal 16a and a frequency command signal 17a, and generates an induction motor 6 corresponding to the signal 14a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is developed in a control device for an elevator driven by an induction motor to forcibly perform regeneration control.

[Conventional technology]

Some systems use an induction motor as the motor that drives the elevator and the car, and control the slip frequency of the induction motor to control the torque of the motor to drive the car.

FIG. 2 is a block diagram of a conventional elevator control device disclosed in, for example, Japanese Unexamined Patent Publication No. 59-17879.

In the figure, 1 is a three-phase AC power supply terminal, 2 is an electromagnetic contactor contact that is connected to this three-phase AC power supply terminal, and is closed when the car 9 is started and opened when the car 9 is stopped, which will be described later. 3 is an electromagnetic contactor contact 2. This is a converter that converts the three-phase AC power obtained through the converter into DC.

A smoothing capacitor 4 is connected between the output terminals of the converter 3, and the smoothing capacitor 4 smoothes the output of the converter 3 and supplies it to the inverter 5.

The inverter 5 is a pulse width modulation type inverter that converts constant DC voltage to variable voltage/variable frequency AC.
With this inverter 5, three-phase induction electric motor 1f! (below,
(called an induction motor) 6 is driven, and this induction motor! fi
6 drives a drive sheave 7 of the hoisting pan. A main rope 8 is wound around the driving sheave 7, with a basket 9 at one end of the main rope 8 and a counterweight 10 at the other end.
are combined.

On the other hand, 11 is a tachometer that detects the rotational speed of the induction motor 6 and outputs a speed signal 11a, and this speed signal 11a and a speed command signal 12 are added to an adder 13.

The adder 13 subtracts the speed signal 11a from the speed command signal 12 and outputs a deviation signal, which is passed through the compensation element 14 to the adder 15.

The compensation element 14 is for improving the response of the speed control system and has a transfer function G(S), and its output becomes the slip frequency command signal 14a. This slip frequency command signal 14a and the speed signal 11a passed through the contactor 18b are added by an adder 15 616
inputs the output 15a of the adder 15 and generates the voltage command signal 16
17 is a frequency command generator that also generates a frequency command signal 17a, and 18 is a contact 18a when the sliding frequency command signal 14a is positive or zero.

18b is brought into contact with the contact a side, and when the sliding frequency command signal 14a is negative, these contacts are brought into contact with the contact side.

The gain converter 19 is connected to the contact point to which the contactor 18a is switched, and when the output 15a of the adder 15 is inputted, it generates an output having a value set according to the value of this input.

In addition, the power control device 20 operates at a frequency such that the regenerative power regenerated from the induction motor If 116 to the DC side becomes zero when the contact bl: connected and the speed signal 11a is input. It generates command signals.

The inverter control device 21 receives a voltage command signal 16a.

Based on the frequency command signal 17a, the output of the gain converter 19, and the frequency command signal of the power control device 20, the inverter 5
control the output voltage and output frequency of the

A conventional elevator control device is configured as described above.
When the induction motor is running, the slip frequency command signal 14a obtained from the deviation signal between the speed command signal 12 and the speed signal 11a is positive, and therefore the contacts 18a, 18b
are in contact with the contact a side, respectively, as shown.

Therefore, the slip frequency command signal 14a and the speed signal 11
a is added by an adder 15, and its output signal 15
a is input to the voltage command generator 16 and frequency command generator 17.

The voltage command generator 16 and the frequency command generator 17 generate a voltage command signal 16a and a frequency command signal 17a that satisfy the relationship that the output voltage/output frequency is approximately constant. Inverter control device 21 controls switching elements constituting inverter 5 based on these command signals to cause induction motor 6 to generate torque corresponding to slip frequency command signal 14 .

By the way, in an elevator, when the car 9 is decelerated to a stop, mechanical energy is converted to electrical energy via the induction motor 6, and regenerated power is returned to the DC side via the inverter 5. If control is performed so that the output frequency is approximately constant, regenerative energy will be accumulated in the smoothing capacitor 4 and increase its voltage, which may destroy the capacitor 4 itself and the inverter 5.

Therefore, during regenerative operation of the induction electric motor 1fi6, the switching device 18 detects that the slip frequency command signal 14a becomes negative and switches the contacts 18a and 18b to the contacting side. As a result, the slip frequency command signal 14a is directly input to the gain converter 19, and its output is applied to the inverter control device 21 as a voltage command signal.

In addition, the power control device 20 inputs the speed signal 11a and generates a frequency command signal such that the regenerated power becomes zero, and outputs the frequency command signal to the inverter control device 21. The principle of the power control device 20 that generates a frequency command signal for this purpose will be explained with reference to the equivalent circuit of the induction motor shown in FIG. 3.

Referring to FIG. 3, inside the induction motor 6, ! The electric power P, however, is Z = (:ct + zt)” + (r + +
r2/S)2” (2) Here, ■...AC input voltage Z...total impedance of induction motor 11!6...
・Excitation function r+-t"2...Primary resistance and secondary resistance (-order conversion value) of induction motor W9.6 X-+t x-2...Primary leakage reactance and secondary leakage of induction motor 6 Reactance (-order conversion value) S・
...This is the slippage of the induction motor 1f16.

On the other hand, the electric power P2 generated as regenerative electric power is P
If the slippage S is controlled so that t+Pi=O (4), all the mechanical energy will be consumed inside the induction electric motor fi6.

Therefore, by substituting equations (1) and (3) into equation (4), Z = Z (S), which is unrelated to the input voltage (to find S that satisfies equation (5) If the slip S that generates a braking force without power transfer is determined by , and the speed signal 11a is also given, the frequency command signal to the inverter 5 is determined.Therefore, if only the speed signal 11a is given to the power control device 20, In addition, bo in FIG. 3 is the excitation susceptance 6. Thus, the conventional elevator control device shown in FIG. The slip frequency command signal 14 corresponds to the deviation of
The torque is controlled by a, and the speed signal 11a is used during regenerative braking.
The smoothing capacitor 4 and the inverter 5 are protected by controlling the frequency command signal 17a given to the inverter 5 to make the regenerative power of the induction motor 6 zero.

[Problem to be Solved by the Invention] By the way, when the inverter control command generation section is switched depending on the positive or negative sign of the slip frequency command signal, a switching shock occurs in the car due to torque discontinuity of the induction motor, albeit to a small extent. do. A problem arises when this switching shock occurs when passengers are particularly sensitive to the ride comfort of the elevator, such as when the elevator is started or stopped.

However, in conventional control devices, the slip frequency is simply switched depending on the positive or negative sign of the slip frequency command signal. The slip frequency command signal once changes from positive to negative, and then becomes positive again during acceleration when the speed command signal rises rapidly. As a result, a switching shock occurs, causing discomfort to passengers.

This invention was made in order to solve the conventional problems as described above, and provides an elevator control device that can prevent switching shock even if the slip frequency command signal switches between positive and negative when starting and stopping the elevator. The purpose is to obtain.

[Means for solving problems]

The elevator control device according to the present invention has a first inverter control command generator that controls the torque of the induction motor even if the slip frequency command signal becomes negative in the low speed region of the elevator, and a second inverter control command generator that controls the regenerative power of the induction motor. A switching means is provided to prevent switching to the inverter control command generation section.

[Effect]

In this invention, when the speed of the elevator is in a low speed region and the speed command signal or speed signal of the induction motor is below a certain value, the switching means always controls the first inverter even if the slip frequency command signal changes from positive to negative. The command generator controls the torque of the induction motor based on the slip frequency command.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an elevator control device of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, in which the same reference numerals as in FIG. 2 indicate the same or corresponding parts, and parts different from those in FIG. 2 will be explained with emphasis.

In FIG. 1, a switching device 18c is newly provided in place of the switching device 18 in FIG. 2. The switching device 18c receives the output of the compensation element 14, that is, the slip frequency command signal 14a and the speed command signal 12, as input signals.

The rest of the configuration is the same as in Figure tA2.

With this configuration, when the speed command signal 12 is below a certain value, even if the slip frequency command signal 14a changes from positive to negative, this is ignored, and the switching device 18c
, 18b is prevented from switching from the contact a side to the contact side. Therefore, in this case, as in the conventional case, the inverter control device 21 controls the switching elements of the inverter 5 based on the voltage command signal 16a and the frequency command signal 17a, and applies torque corresponding to the slip frequency command signal 14a to the induction motor 6. to occur.

In addition, in this invention, the case where the speed command signal 12 is used as an input of the switching device 18c is shown, but the tachometer 11
Even if the speed signal 11a from the above is used, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, even if the speed command signal or the speed signal is below a certain value and the slip frequency command signal changes from positive to negative, this is ignored, and the switching means causes the first inverter control command generation section to Since the torque of the induction motor is controlled based on this, there is no switching shock even if the slip frequency command signal switches between positive and negative when starting and stopping the elevator, resulting in a comfortable elevator ride. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an elevator control device according to the present invention, FIG. 2 is a block diagram showing the configuration of a conventional elevator control device, and FIG. 3 is a block diagram showing the configuration of a conventional elevator control device.
FIG. 2 is an equivalent circuit diagram for explaining power consumed inside an induction motor in the elevator control device shown in the figure.
3...Converter, 4...Smoothing capacitor, 5...
... Inverter, 6... Three-phase induction motor, 9... Car, 10... Counterweight, 11... Rotation speed meter,
14.15... Adder, 14... Compensation element, 16.
...Voltage command generator, 17...Frequency command generator, 1
8a, 18b... Contact, 18c... Switching device, 1
9... Gain converter, 20... Power control device, 21.
...Inverter control device. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa (and 2 others) Iraku a Draft procedure amendment (voluntary) 1. Indication of the case: Japanese Patent Application No. 60-74778 2, Title of the invention: Elevator control device 3, Person making the amendment Relationship with the case: Patent applicant Representative Moriya Shiki 4, Agent address: 2-chome Marunouchi, Chiyoda-ku, Tokyo 2 No. 3 No. 5
゜Subject of amendment (1) Detailed explanation of the invention in the specification (2) Brief explanation of the drawings in the specification -6. Contents of amendment (1) Page 2, line 9 of the specification: Correct the phrase "in relation to" to "in connection with". (2) On page 3, line 17, the phrase "output" is corrected to "output." (3) On the 4th page, line 2, replace "Adder 15" with "
The corrected value is "output to the adder 15". (4) In the 5th line of page 6, the phrase "to the command signal 14" is corrected to "to the command signal 14a." (5) On page 9, line 10, the phrase "frequency command signal 17a" is corrected to "frequency command signal." (6) Page 13, line 14 r14, 15...adder;
" is corrected to "13, 15...adder."

Claims (1)

[Claims] In an elevator control device that connects an inverter to a DC power source to convert DC power into AC power, and drives an induction motor using this AC power to operate a car, the control device uses a speed command signal and a speed signal of the induction motor to operate the car. a first inverter control command generating section that controls the torque of the induction motor by a corresponding slip frequency command signal; and a first inverter control command generator that controls the regenerative power of the induction motor by controlling a frequency command signal given to the inverter according to the speed signal. the first inverter control command generation section is used when the slip frequency command signal is positive when the elevator car speed is above a certain value, and the second inverter control command generation section is used when the slip frequency command signal is negative. When the car speed is below a certain value and the slipping frequency command signal changes from negative to positive, the second inverter control command generating section is used. 1. An elevator control device comprising switching means for always switching to use the first inverter control command generation section regardless of whether the frequency command signal is negative.