JPH0725500B2 - Elevator speed control method - Google Patents

Description

The present invention relates to an elevator speed control method using an open loop inverter.

B. Summary of the Invention The present invention is an elevator that drives an induction motor of an elevator prime mover by an open loop control inverter, and calculates the acceleration torque component from the inverter output current value during acceleration and constant speed, and in actual operation. The load torque is calculated by subtracting the above acceleration torque from the output torque during acceleration, and the inverter operating frequency is corrected based on this load torque during constant speed and deceleration, so that speed fluctuations and arrival This is a reduction in floor accuracy.

C. Conventional technology Most of the recent elevators employ an induction motor as a prime mover, and this induction motor is driven by an inverter with a variable voltage / variable frequency (VVVF). In such an elevator drive device that combines an induction motor and an inverter, speed control of the induction motor is generally performed by open loop control using a voltage source inverter for low-speed elevators and speed detectors for medium- and high-speed elevators. The speed feedback control provided with is adopted.

Among them, the open-loop speed control method controls the output frequency and further the output voltage of the inverter according to the speed pattern, thereby accelerating in accordance with the speed pattern.
Try to get constant speed and deceleration.

D. Problems to be Solved by the Invention The conventional open-loop speed control method has advantages that the speed detector is not required and the cost is low, and the backup means for failure of the speed detector is not required. However, since there is no speed detector that gives the motor speed, that is, the speed of the riding car, and also the ascending / descending distance data, load slips (load fluctuations) in the riding car cause the slippage of the motor in each region of acceleration, constant speed and deceleration. There is a possibility that the landing accuracy may be deteriorated due to the fluctuation of the traveling speed of the car from the start of deceleration to the end of deceleration, in addition to the fluctuation of the ascending / descending speed.

An object of the present invention is to provide a speed control method in which open loop speed control is performed and speed fluctuations due to load fluctuations and a decrease in landing accuracy are reduced.

E. Means and Actions for Solving the Problems In order to achieve the above object, the present invention uses an inverter-driven induction motor as a prime mover, and in an elevator that performs open-loop control of the inverter, during acceleration under constant load conditions and at constant speed. The output torque T _A during acceleration and the output torque T _L during constant speed are obtained from the measured inverter output current during high speed, and the output torque T _L is subtracted from the above output torque T _A to calculate the acceleration torque T
to previously obtain the _acc, obtains an output torque T _a during acceleration from the inverter output current measured value in the acceleration during actual operation, the load torque Tl from the output torque T _a by subtracting the acceleration torque component T _acc Calculate the slip frequency of the induction motor from this load torque Tl to correct the inverter frequency and voltage during constant speed and deceleration during actual operation, and calculate the inertia component of the elevator mechanical system before actual operation. During acceleration, the mechanical inertia component is subtracted from the output torque to obtain the load torque component by the occupant, and the inverter frequency and voltage are corrected by this load torque component to obtain predetermined constant speed operation and deceleration operation.

F. Embodiment FIG. 1 is a device configuration diagram showing an embodiment of the present invention. The AC power of the AC power supply 1 is converted into DC power by the rectifier 2 and smoothed by the capacitor 3. This DC power is converted into AC power whose output frequency and voltage are controlled by the voltage source inverter main circuit 4, and is supplied to the induction motor 5 that becomes the prime mover of the elevator. The control of the operating frequency and voltage of the inverter main circuit 4 is performed by the gate pulse frequency and pulse width control and further the pulse width modulation control from the control device 6, whereby the operating speed of the electric motor 5 is controlled.

The speed command given to the control device 6 is given as a speed pattern having a predetermined acceleration / deceleration and a constant speed time corresponding to the ascending / descending distance. From the speed command and the DC current detection signal of the inverter main circuit 4, the control device 6 is controlled. Then, perform the necessary inverter operating frequency and voltage correction.

The speed control method by the control device 6 described above will be described in detail below.

In the configuration of FIG. 1, the DC current of the inverter main circuit 4
I _DC is in proportion to the torque current I _T , I _DC ≈ (I _B + I _T ) K (1) I _B ; Excitation loss equivalent K; Constant proportional to the ratio of AC voltage to DC voltage . Strictly speaking, a perfect proportional relationship is not obtained due to the rotation speed of the electric motor, a change in the primary current, and the like, but in practical use, it is within an error range that can be treated as a proportional relationship.

From the relationship of the above equation (1), the control device 6 determines the torque current I _T from the measured value of the direct current I _DC as the inverter output current.
Further, the slip S is obtained from the proportional relationship between the slip S of the electric motor 5 and the torque current I _T , and the electric motor output torque is obtained from this slip S. In order to obtain this output torque, the control device 6 obtains the torque during acceleration obtained from the DC current during acceleration of the electric motor 5 at a constant acceleration (period T ₁ ) as shown in FIG.
Calculated as constant speed torque _TL calculated from T _A and DC current during constant speed driving. The control device 6 calculates these torques.
It is realized by the current sampling means and the software operation of the microcomputer.

The output torque T _A during acceleration and the torque T _L during constant speed described above are measured in advance in a fixed load state (for example, a state without an occupant). Then, from the subtraction of both measured values T _A and T _L , the acceleration torque component T
ask for _acc .

T _acc = T _A −T _L (2) This acceleration torque component T _acc is measured under a fixed load condition.
It corresponds to the mechanical inertia determined by the mechanical system of the elevator. That is, the output torque T _A during acceleration has a relationship of T _A = inertial acceleration torque component + load torque component, and each torque component is inertia acceleration torque = mechanical inertia component + occupant inertia component load torque = mechanical load component + It is related to the occupant load.

From these relationships, in measurement under a fixed load condition, the output torque T _A during acceleration has a value obtained by adding the mechanical inertia component and the mechanical load component. Then, only the mechanical inertia component can be obtained by subtracting the load torque component (mechanical load component) from the output torque T _A by the equation (1).

The above-mentioned acceleration torque component T _acc can improve the measurement accuracy by obtaining it as an average value in a plurality of repeated operations.

Next, the control device 6 in actual operation of an occupant is present, to obtain a torque T _a during acceleration in the same manner as described above. By subtracting the previously _calculated acceleration torque component T _acc from this torque T _{a, the} load torque Tl Tl = T _a −T _acc of the occupant (3) is obtained. Then, the slip frequency f _s of the electric motor 5 is calculated from the load torque Tl, it corrects the inverter output frequency f _c and a voltage when moving to constant speed running from the end of acceleration.

f _c = f _c ± f _{s By} this correction, it is possible to match the actual riding car speed pattern during constant-speed running, and to obtain a constant constant-speed operating state even if the number of passengers increases or decreases. Also, during deceleration, deceleration starts from the corrected constant speed, and the deceleration is corrected to the frequency f _s and voltage described above. The constant deceleration and thus the landing accuracy are improved.

FIG. 3 shows a control flowchart by the control device 6,
Steps S1 to S5 are the acceleration torque component T _acc due to the fixed load.
The measurement accuracy is improved by measuring N times and obtaining the average value. In addition, steps S6 to S8 are
The output torque T _a during acceleration is measured to obtain the load torque component Tl by subtracting the acceleration torque amount T _acc, performs correction by frequency f _s slip when entering the constant-speed operation, by the occupant of change Also obtains a reliable landing gear by constant speed operation and deceleration operation that match the speed pattern.

These correction modes are as shown in FIG. 2, and the speed command A based on the speed pattern may fluctuate like the actual speeds B ₁ and B ₂ due to the increase or decrease of the occupant without correction,
The acceleration torque component T _acc is obtained by current sampling in the acceleration period T ₁ and the constant speed period T ₂ , and the output torque T _a is obtained by current sampling in the acceleration period T ₁ during actual operation.
When entering or after entering the constant speed operation, the frequency f _c is corrected to obtain a constant speed that matches the speed pattern, and the deceleration is also corrected during deceleration to achieve a predetermined deceleration and thus a highly accurate landing. obtain. In addition, during acceleration, a correction value corresponding to the load torque can be immediately obtained from the detected output torque, and even when the constant-speed running time is short (stops on each floor), sufficient correction can be made before deceleration starts, and a high floor Wearing accuracy can be secured.

It should be noted that the acceleration torque component T _acc can be measured periodically so that the acceleration setting can be changed and the readjustment can be automatically performed in response to changes in ambient conditions.

In addition, in the above equation (2) for obtaining the load torque Tl,
Since the acceleration torque component T _acc does not include the occupant inertia component, an error occurs due to the occupant inertia component.This is because the fixed load state is changed when accelerating torque component T _acc is measured and calculated. It can be corrected by individually _{obtaining the} torque T _acc .

G. Effects of the Invention As described above, according to the present invention, the acceleration torque of the mechanical system is obtained by measuring the inverter output current during acceleration and constant speed, and the acceleration torque is calculated from the output torque during acceleration during actual operation. Since the load torque is calculated by subtracting the calculated value and the inverter output frequency and voltage are corrected by this, there is an effect that speed fluctuations at constant speed due to changes in occupants can be reduced and landing accuracy can be improved.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram showing an embodiment of the present invention, FIG. 2 is a main part waveform diagram of the embodiment, and FIG. 3 is a flow chart of the embodiment. 4 ... Voltage-type inverter main circuit, 5 ... Induction motor, 6
……Control device.

Claims (1)

[Claims] In an elevator in which an inverter-driven induction motor is used as a prime mover and the inverter is open-loop controlled, an output torque T _A during acceleration is obtained from an inverter output current measurement value during acceleration under a fixed load condition and at constant speed. And the output torque T _L during constant speed are calculated, the output torque T _L is subtracted from the above output torque T _A to obtain the acceleration torque component T _acc , and the inverter output current measurement value during acceleration during actual operation is _calculated. obtains an output torque T _a during acceleration from seeking load torque Tl from the output torque T _a by subtracting the acceleration torque component T _acc, the actual operation and from the load torque Tl seeking the slip frequency of the induction motor A method for controlling a speed of an elevator, which comprises correcting an inverter frequency and a voltage during constant speed and deceleration.