JPS59118673A - Controller 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 a control device for an AC elevator.

Recently, as a control method for an AC elevator, there is a method in which the speed is controlled by varying the primary frequency and primary voltage of an induction motor, that is, a method in which the speed of the elevator is controlled by a variable voltage variable frequency inverter device. In this method, the primary frequency applied to the motor is sequentially changed, and in order to obtain torque characteristics that are not related to the primary frequency, the ratio between the internal induced voltage and the primary frequency is kept constant, and the motor is rotated at a rotation speed close to the synchronous speed. The motor is designed to allow smooth speed control by operating the motor, but since the voltage and current applied to the motor contain harmonics, the motor may experience large vibrations and torque, especially at low speeds such as when landing on the floor. It has the disadvantage of causing Ritz stains. Therefore, when controlling the speed of an elevator using an inktor device, when the deceleration of the elevator is almost completed (for example, when the speed reaches about 1/10 of the rated speed), it is necessary to switch from inverter operation to DC braking operation. A method for preventing deterioration of riding comfort upon landing on the bed has been proposed, and this method is shown in FIG.

In Figure 1, 1 is an induction motor (motor) that drives the elevator, 2 is a DC power supply unit that converts the three-phase AC power of power supplies R, S, and T into DC, and 6 is a DC power supply unit that converts the output current of DC power supply unit 2. 4 is an inverter that receives the input from the DC power supply unit 2 and converts it into variable frequency three-phase AC power; 5 is a voltage detector that detects the output voltage of the inverter 4; 6 is a DC power supply unit : a current detector that detects the input current to 2; 7 is an induction; a speed generator that generates a voltage proportional to the rotational speed of the conductive motor 1; 8 is a speed regulator that generates disconnection; 10 is an inverter 4; 11 is a current regulator that controls the input current to the DC power supply section 2 and thus the output current; 12 is a phase shifter that controls the ignition of the DC power supply section 2; 16 is a voltage command 14 is a pulse distributor that controls the ignition of the impark 4 in accordance with the frequency signal, 15 is a pulse amplifier, and 16 is a direct current for flowing a constant DC braking current. The braking current command generator, 5W14, is normally turned on on the voltage regulator 10 side, and when the elevator decelerates and reaches a predetermined speed, the DC braking current command generator 16 side is turned on. SW2 is interlocked with switch SW1. This is a switch that turns on when the elevator decelerates and reaches a predetermined speed.

- In the above configuration, since the acceleration of the elevator is normal inverter operation, the explanation will be omitted, and only the deceleration will be explained.

When the elevator decelerates, the switches SW1 and S Vtl 2 are in the state shown in FIG. 1 until the predetermined speed is reached, and the V/F converter 13 is set to an appropriate level in order to follow the speed command and perform inverter operation. Generates a pulse of the following frequency,
Further, the voltage regulator 10 generates an appropriate primary current command to generate a motor terminal voltage commensurate with the primary frequency,
Regenerative braking of the induction motor 1 is performed. When the elevator decelerates to a predetermined speed, the switch SW1 switches, and in synchronization with this, the switch SW2 turns on, and the V/F
The converter 16 stops generating new pulses, maintains the conduction state of the thyristor in the inverter 4, and switches to DC braking operation to decelerate and stop the elevator. At this time, a constant DC braking current is supplied according to a command from the DC braking current command generator 16.

By the way, if the DC braking current is constant as described above, the DC braking torque when switching to DC braking will be constant regardless of the load condition of the elevator, and therefore the deceleration when switching to DC braking will vary depending on the load, that is, the switching shock will be Occur. For this reason, it is possible to change the DC braking current depending on the load condition of the elevator, but since the DC braking torque also changes depending on the speed of the electric motor, stable deceleration cannot be obtained and the ride comfort may deteriorate. connected (particularly when a big shock occurs just before stopping). Other methods to eliminate the shock of switching from inktor operation to DC braking operation are 111, P Vtl 1φ
It is also possible to adopt a method (pulse width modulation), but
In the case of a small-capacity inverter device such as an elevator motor, the cost of the control circuit section relative to the main circuit section is higher than that of a large-capacity one, and therefore the PWM method is adopted. This is undesirable as it leads to an increase in the overall cost.

The present invention has been made in view of the above points, and P W M
It is an object of the present invention to provide a control device that can smoothly switch from inverter operation to DC braking operation with a simple configuration without adopting a system.

The present invention will be explained below based on the drawings.

FIG. 2 is a block diagram showing an embodiment of an AC elevator control device according to the present invention, in which 9A is a first speed regulator for inverter operation that amplifies and outputs the deviation between the speed command and the actual speed; Similarly, a second speed regulator for DC braking operation, and other components that are the same as those in FIG. 1 are designated by the same reference numerals. Here, a second speed regulator 9B dedicated to DC braking operation
The reason for this is that if the speed regulator 9A for impark operation is used as is after switching to DC braking, the value output by the speed regulator 9A during deceleration due to inverter operation and the value required immediately after switching to DC braking will be different. This is because the input value to the current regulator 11 differs, so there is a delay time until the values match, and during this time the state is close to an uncontrolled state, which has a negative effect on ride comfort. .

According to the configuration shown in FIG. 2, when the elevator decelerates to a predetermined speed, switch SW2 is turned on and switch SW1 is switched to the second speed regulator 9B side, as in the case of FIG. can be switched to DC braking operation.

At this time, as is clear from FIG. 2, since speed feedback control is performed even during DC braking operation, the second speed regulator 9B is configured to automatically compensate for changes in braking torque depending on the load condition and speed of the elevator. A DC braking current command is generated, and as a result, after switching to DC braking, stable braking and stopping can always be performed at a predetermined deceleration.

By the way, according to the configuration shown in Fig. 2, stable deceleration can be obtained during DC braking operation as described above regardless of the load or speed, but there is a slight transition shock (deceleration (instantaneous increase) is observed. This is the braking torque TE that is generated transiently by the switching product.
This is due to Expressing this in a formula, ITBI
-(3/2)(P/2)11111φ2R1 principle θ,
, (2). However, P is the number of poles of the motor, θ is the phase difference between φ2R and φ2R.

Here, the residual secondary magnetic flux component φ2R rotating with the rotor
decreases over a nearly constant time determined by the second-order time constant of the motor. On the other hand, θ increases faster as the rotor rotational speed at the time of switching increases, so the maximum value of the braking torque TB increases as the elevator speed at the time of switching increases.

Therefore, in order to reduce this transient braking torque,
It is desirable that the elevator speed at the time of switching be low, but on the other hand, if inverter regenerative braking is performed to a too low speed, the effect of torque ripple will appear as mentioned above, which is unfavorable for riding comfort, so the elevator speed at the time of switching should not be set too low. It is not possible. Therefore, the above phase difference θ will increase at a certain rate after switching, so (2)
In the equation, if 1 time 11 is decreased for i time, the transient braking torque TB can be suppressed.

As is clear from equation (2), it is sufficient that the time required to reduce this 1-stroke 11 is the time required for 1φ2R1 to decrease, that is, the time corresponding to the second-order time constant of the motor.

On the other hand, the braking torque due to the magnetic flux φ2g based on the primary current vector E1 gradually increases with the first-order lag of the motor's secondary time constant, and the sum of this and the transient braking torque TE is given as the braking torque after switching. is shown in FIG.

In the figure, a is the torque due to φ2H, b is the torque due to φ28, and C is the combined torque of a and b. As mentioned above, 11
If is reduced by a time corresponding to the motor's secondary time constant, the transient torque due to φ2R will be reduced, and therefore even in the composite torque, the generation of excessive braking torque immediately after switching can be suppressed, and the shock immediately after switching can be almost eliminated. You can do that.

Below, in the configuration shown in Figure 2, the primary current after switching (
Some specific means that can reduce the DC braking current will be explained below.

FIG. 4 shows an example of the configuration of the speed regulator 9B, and FIGS.
FIG. 7 is a diagram showing an example of the configuration of one current regulator. In each figure, A1-A4 are operational amplifiers forming an adder, R1-R46 are resistors, and RY1 to RY3 are DC brakes. RY4 is a contact that opens and closes for approximately the motor secondary time constant after switching to DC braking operation, and PG is a contact that opens and closes for approximately the motor secondary time constant after switching to DC braking operation. ), TO is the feedback speed (positive) from the speed generator 7, and TE is the current command (positive) from the speed regulator 9B.
(negative) 1, ■ is the feedback current from the current detector 6, (3) is the current command signal, and is the bias input (positive) with the opposite polarity to '.

In Fig. 4, when the contact RYI- is closed, the resistor R4
When the contact RY2 is closed in FIG. 5, the bias input 1B, which has the opposite polarity to the current command l', is added, and the 6th
In the figure, when the contact RY3 is closed, the resistor R12 is short-circuited and the current feedback gain is increased, and in FIG. 7, when the contact RY4 is opened, the resistor R16 is inserted and the current command input gain is decreased. After switching to DC braking operation, the primary current, that is, the DC braking current, is reduced for a time approximately equivalent to the motor's secondary time constant. I can do it. It goes without saying that the present invention is not limited to the above embodiments as long as the DC braking current can be temporarily suppressed after switching.

As explained above, according to the present invention, a dedicated speed regulator is provided to perform speed feedback control even after switching to DC braking operation, so it is possible to reduce the shock at the time of switching, and also to adjust the load condition of the elevator. Stable deceleration and ride comfort can be obtained regardless of speed.

Furthermore, immediately after switching, a time approximately equal to the motor secondary time constant,
Since the DC braking current is reduced, it is possible to eliminate the shock caused by the residual magnetic flux of the rotor immediately after switching, and it is possible to obtain a very good riding comfort.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional AC elevator control device, and FIG. 2 is an IJ diagram of an AC elevator according to the present invention.
a Block diagram showing one embodiment of equipment H; Figure 6 is a diagram showing changes in braking torque after switching to DC braking operation;
The figure shows an example of the configuration of a speed regulator, and each of FIGS. 5 to 7 shows an example of the configuration of a current regulator. 199. Induction motor 21. DC power supply section 411. Inhaak 511. Voltage detector 610. Current detector 781. Speed generator 801. Speed command generator 9.9A, 9B1. , speed regulator io, , voltage regulator 11, , current regulator 12, , phase shifter 1, , V/F converter i4. ,,pulse distributor 15, ,pulse amplifier 16, ,DC braking current command generator SW1. SW2, , Switch patent applicant Fujichik Co., Ltd. No. 1 Z1

Claims (1)

[Claims] (]) The primary frequency of the induction motor by an inverter device,
The primary voltage is made variable to control the gap magnetic flux at a constant level, and the speed of the elevator is controlled.When the elevator decelerates to a predetermined speed, the inverter operation is switched to DC braking and the elevator is braked. A second speed regulator used for direct current braking, which is different from the first speed regulator used for the impark operation, and a second speed regulator used for direct current braking, and a second speed regulator used for direct current braking, which is configured to stop the elevator when the elevator decelerates to a predetermined speed. A control device for an AC elevator, comprising means for switching the output of the speed regulator to the output of the second speed regulator. (2) The primary frequency of the induction motor is controlled by the inverter device.
The speed of the elevator is controlled by controlling the gap magnetic flux to be constant by making the primary voltage variable, and when the elevator decelerates to a predetermined speed, the inverter operation is switched to DC braking and the elevator is braked to a stop. A second speed regulator used for direct current braking, which is different from the first speed regulator used for inverter operation, and a second speed regulator used for direct current braking, and a second speed regulator for controlling the first speed when the elevator decelerates to a predetermined speed. means for switching the output of the motor to the output of the second speed regulator; and means for suppressing the DC braking current for a time substantially equal to a secondary time constant of the induction motor immediately after switching to the second speed regulator. A control device for an AC elevator, comprising: