JPH08208138A - Inverter for elevator - Google Patents

Abstract

PURPOSE: To restrain unnecessary vibration and noise in addition to improved speed controllability at the time of starting. CONSTITUTION: A proportional and integral amplifier 41 for proportioning and integrating a deviation between the speed command SP and detected speed SFB of a motor 3 is provided, the output of the amplifier 41 is added to the speed command, and the result is taken as an output frequency command Fs. An inverter main circuit 2 is controlled as an output voltage command VS which is made to have a fixed ratio to the frequency command by a setter 42 . At the time of starting to operate the motor, a normal/reverse rotation detector 11 detects the rotational direction of the motor, and a static friction torque compensation part 43 bias-adds a torque compensation corresponding to the static friction torque of a mechanical system to the proportional and integral amplifier 4, with a polarity suited to rotational direction at the time of starting to operate the motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elevator inverter for controlling the speed of an induction motor, and more particularly to starting compensation control of the inverter.

[0002]

2. Description of the Related Art FIG. 3 shows a T-type equivalent circuit of an induction motor, in which the air gap magnetic flux φ is proportional to the ratio of the induced voltage E to the frequency f.

[0003]

[Equation 1] φ = K ₁ · E / f K ₁ : Motor constant In the above equation, if the influence of the primary side impedances r ₁ and x ₁ can be ignored, the inverter output voltage V = E, and therefore can be expressed by the following equation.

[0004]

[Mathematical formula-see original document] φ = K ₁ · V / f Therefore, controlling V / f means controlling the magnetic flux φ, but actually the inverter output voltage V
In the small area of, due to the influence of the primary impedance,
The output will decrease.

On the other hand, if V / f is increased too much, over-excitation occurs and problems such as vibration and noise occur. Therefore, in controlling the electric motor, it is necessary to perform control to keep V / f at an appropriate value.

Therefore, various V / f curves have been prepared conventionally according to the application of the load.

FIG. 4 shows the V / f characteristic of the torque boost. The torque boost characteristic is such that the amount of increase in the output voltage is increased in the region where the output frequency f is lower, and the influence of the primary side impedance is compensated.

As another conventional example, there is one in which a PWM inverter having a current control system is subjected to torque boost and the amount of this torque boost is added to a current command. For example,
JP-A-3-36178.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The torque required by the mechanical system such as the electric motor and the gear with respect to the speed change has the speed-torque characteristic shown in FIG.

As shown in this characteristic, the elevator has a large friction torque at rest, and a large driving torque is required for starting the electric motor control.

In order to compensate for the torque shortage in the low speed region including the starting time, in the conventional control, the V / f becomes lower in the low speed region.
The torque boost control is performed to increase the ratio.

However, in order to compensate the influence of the static friction torque to the extent that it can be ignored, V / f becomes too large, and when the electric motor starts to rotate, the exciting current is increased to a level that can be said to be unnecessary. . This causes over-excited operation, which causes unnecessary vibration and noise.

An object of the present invention is to provide an elevator inverter for suppressing unnecessary vibration and noise while improving speed controllability at the time of starting.

[0014]

In order to solve the above-mentioned problems, the present invention provides a proportional / integral amplifier for proportionally / integrating the deviation between the speed command of the electric motor and the speed detection value, and the output of the amplifier is set to the speed. In an inverter for an elevator that drives an electric motor by adding it to an instruction and using the output frequency instruction and an output voltage instruction with a constant ratio as an output voltage instruction, the proportional / integral amplifier with a polarity according to the rotation direction of the electric motor at the start of operation of the electric motor. In addition, a means for bias-adding a torque compensation amount corresponding to the static friction torque of the mechanical system is provided.

[0015]

The torque boost amount suppresses unnecessary vibration and noise only by compensating for the influence of the primary side impedance of the electric motor, and the torque compensation corresponding to the static friction torque is added to the bias only at the time of starting. Improves speed control characteristics at startup.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention. The DC power obtained from the converter unit 1 is converted into AC power whose voltage and frequency are controlled by the inverter main circuit 2, and the induction motor 3 is driven.

The control device for the inverter main circuit 2 performs constant V / f control with the microcomputer 4 as a central part, and is provided with a compensation by torque boost and a speed control loop.

[0018] The loop type the deviation between the speed detection value SFB pulse encoder 5 comprising the speed command SP and the speed detector proportional-integral (PI) amplifier 4 _1, P amplifier the amplifier 4 ₁ In deviation The gain is amplified and integrated by the I amplifier. The I amplifier functions to eliminate the deviation in speed control due to the finite gain of the P amplifier.

The output of the amplifier 4 ₁ is added to the speed command SP to form an output frequency command F _S. This command F _S is P
The basic frequency command of the PWM waveform generated by the WM waveform calculator (not shown) is used. Further, the command F _S is given to the setter 4 ₂ which is set to the frequency / voltage ratio, so that the output voltage command V _S is taken out from the output. This voltage command V _S
Is a modulation rate command of the PWM waveform calculation unit, and the PWM waveform calculation unit obtains PWM waveform data with a constant V / f ratio and torque boost.

This waveform data is D / D in the driver circuit 6.
It is amplified as A conversion and the gate output of each phase, and is used for ON / OFF control of each switching element of the inverter main circuit 2.

The voltage detector 7 and the A / D converter 8 perform output voltage compensation by detecting fluctuations in the DC voltage and correcting the output voltage command. Further, according to the comparison result of the comparator 9 having the reference voltage, the switch S1 and the resistor R are passed through the driver circuit 10.
By turning on the circuit of No. 1, the regenerated amount from the electric motor 3 is absorbed.

In the above structure, in this embodiment, the static friction torque at the time of starting is compensated. In this compensation, the forward / reverse rotation detector 11 detects the forward / reverse rotation of the electric motor 3 from the pulse phase from the pulse encoder 5, and the static friction torque compensator 4 ₃ corresponds to the static friction torque in the I amplifier based on the detection result and the speed detection value. Bias the initial value of minutes.

The compensating unit 4 _3, and when the speed detection value is static friction torque region in condition, the forward direction of the positive initial value, the negative initial value bias added to the I amplifier is reversed direction.

The control flow for this is as shown in FIG. 2, in which the operation start (S1) of the elevator is determined from the speed detection value, the rotation direction (S2) is determined from the forward / reverse rotation detection value, and the initial value ± The bias (S3, S4) of X is made by reading from the setting register. The initial value is the static friction torque compensation amount, which can be adjusted for each elevator.

By adding the bias of the initial value ± X, the output frequency command F _S and the output voltage command V _S are not zero even if the speed command SP is zero when the elevator is started.
A torque equivalent to static friction torque is generated in the electric motor 3,
It is possible to obtain a reliable starting torque and improve its speed control characteristic.

The torque boost amount is small enough to compensate for the influence of the primary side impedance, and unnecessary vibration and noise can be prevented.

Although the embodiment shows the case where it is applied to the V / f constant control, it can be applied to an inverter of another control system, for example, a vector control system or a slip frequency control system, to obtain an equivalent effect. . The control of the inverter is not limited to the PWM control.

[0028]

As described above, according to the present invention, when the operation of the electric motor is started, the proportional / integral amplifier is bias-added with the torque compensation amount corresponding to the static friction torque of the mechanical system with the polarity according to the rotating direction of the electric motor. As a result, the following effects are obtained.

(1) The static friction torque of the elevator can be compensated, the speed control characteristic at the time of starting the elevator is improved, and the riding comfort can be improved.

(2) The torque boost amount only has to compensate for the effect of the primary side impedance of the electric motor, which is the original purpose, and unnecessary vibration and noise can be suppressed by eliminating the control of overexcitation. It is possible to improve the riding comfort of the elevator and reduce noise.

(3) Since the torque boost amount can be reduced, the electric power required for operating the elevator can be reduced.

(4) By making the initial value of the proportional / integral amplifier changeable, it can be applied to elevators of all types and capacities.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an embodiment of the present invention.

FIG. 2 is a control flow of static friction torque compensation in the embodiment.

FIG. 3 is a T-type equivalent circuit of an induction motor.

FIG. 4 is a V / f characteristic of torque boost.

FIG. 5 is a speed-torque characteristic required for an elevator.

[Explanation of symbols]

2 ... inverter main circuit 3 ... induction motor 4 ... microcomputer 4 ₁ ... proportional and integral amplifier 4 ₂ ... setter 4 ₃ ... static friction torque compensation unit 5 ... pulse encoder 11 ... reverse rotation detector

Claims (1)

[Claims] 1. A proportional / integral amplifier for proportionally / integrating a deviation between a speed command of a motor and a speed detection value is provided, and the output of the amplifier is added to the speed command, and the output is made an output frequency command and a constant ratio. In an elevator inverter for driving an electric motor as a voltage command, at the start of operation of the electric motor, a bias corresponding to a static friction torque of a mechanical system is added to the proportional / integral amplifier with a polarity corresponding to a rotation direction of the electric motor. An elevator inverter comprising means.