JPS6143276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the landing accuracy of an AC feedback control type elevator that controls the speed of an induction motor.

Some AC feedback control type elevators perform speed control by generating driving torque by controlling the primary voltage of an induction motor and generating braking torque by DC generation braking.

Figure 1 shows the change in speed of the elevator from startup to stop using the above method, where the horizontal axis represents time and the vertical axis represents speed, where X is acceleration, Y is constant speed, and Z is deceleration. shows.

Generally, when a motor is running at a constant speed Y, when a full AC voltage is applied to the induction motor, there is no speed feedback when the load changes, so the fluctuations in the constant speed are extremely large. or,
Even when speed control is adopted during uniform running Y, speed regulators that amplify speed deviations are configured with proportional elements, but due to control system constraints, large fluctuations in uniform speed still occur, resulting in large landing position deviations. Leads to.

The present invention has been made in view of the above points, and is intended to compensate for phase lag in the speed control system of an AC feedback control elevator to reduce fluctuations in constant velocity and improve landing accuracy. Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 shows a conventional example of a control device for driving and braking an induction motor having two windings.

E is a speed command, 1 is a feedback circuit that detects the actual speed of the elevator, 2 is a speed regulator with an amplification degree K that amplifies the difference between the speed command and the output of the feedback circuit 1, and 3 is according to the output of the speed regulator 2. a phase shifter 4 for controlling the power amplifier SCR1 composed of a thyristor and the like;
is a phase shifter that similarly controls the power amplifier SCR2, which is composed of a thyristor, etc., H is a drive winding of the induction motor, L is a brake winding, and TG is a tachometer generator that detects the motor rotation speed. It is. Speed command E
When the output of the feedback circuit 1 is smaller than , the speed regulator 2 outputs a positive voltage and the phase shifter 3 operates. Phase shifter 3 outputs power amplifier SCR1 according to its input.
The firing angle of is controlled, and the driving three-phase alternating current flows through the driving winding H to obtain driving force. Conversely, when the actual elevator speed is greater than the speed command, the speed regulator 2 outputs a negative voltage and the phase shifter 4 operates. Phase shifter 4 outputs power amplifier SCR2 according to its input.
The braking direct current flows to the braking winding L to obtain a generated braking force.

FIG. 3 shows an embodiment of the configuration of the control device of the present invention. Reference numeral 5 denotes a speed regulator having phase delay characteristics, and the other parts are the same as in FIG.

FIG. 4 shows a frequency response curve of the open loop transfer function of the control system, with the horizontal axis representing the logarithm of the angular frequency and the vertical axis representing the gain. The dotted line is the characteristic of the conventional control device shown in FIG. 2, and the solid line is the characteristic of the present invention.

The phase delay characteristic of the speed regulator 5 is generally
It is written in the form K'1 + ST ₂ /1 + ST ₁ (K' is the amplification degree, T ₁ and T ₂ are the time constants, S is the Laplace operator, T ₁ > T ₂ ), and in the low frequency region, that is, the angular frequency is 1/ The gain is increased between T ₁ and 1/T ₂ .

On the other hand, if the part larger than 1/T ₂ has a constant characteristic that is gentler than that between 1/T ₁ and 1/T ₂ , and the cutoff angular frequency ωc is a certain distance from 1/T ₂ , the control system will be stable. Gender is not affected much. That is, the steady-state deviation, that is, the deviation between the set value (speed command E) and the actual value (elevator speed) during constant speed travel can be reduced without impairing stability.

Therefore, the constant velocity in the case of light load raising and heavy load lowering operation (hereinafter referred to as lowering load), heavy load raising,
It is possible to reduce the difference in constant velocity in the case of light load descending operation (hereinafter referred to as "lifting load"), and it is possible to improve landing accuracy.

Generally, due to the non-linear characteristics of the torque gain of the induction motor, the response delay of the elevator speed to the speed command during deceleration traveling varies depending on the load and driving direction.

This will be explained with reference to FIG. FIG. 5 is a diagram showing the torque generated by the induction motor with respect to the drive voltage or DC braking current. Now, considering the point in time when the elevator decelerates, in the case of lifting a load, the driving torque indicated by point a ₁ gradually decreases and enters the braking torque region, and a ₁
The motor is controlled to stop between point A and point _A , but during this period the induction motor generated torque gain is extremely small. Therefore, when the lifting load starts to decelerate, the gain of the control system decreases, resulting in a large response delay. On the other hand, in the case of unloading, the control is performed between points b ₁ and b ₂ , but since the braking torque shown at point b ₁ has already been generated when traveling at a constant speed, the induction motor generated torque at the deceleration start point is The gain never becomes small, so there is almost no response delay. That is, in the case of lifting a load, the speed at the start of deceleration is lower than in the case of lowering a load, but the response delay is larger, while in the case of lowering a load, the speed at the start of deceleration is higher than in the case of lifting a load, but the response delay is smaller.

As a result, the speeds of the elevator during deceleration when lifting and lowering loads are as shown in FIG. 6. Figure 6a shows the case where no phase delay element is inserted into the speed regulator, and Figure 6b shows the case where the phase delay element is inserted into the speed regulator, where Vd ₁ and Vd ₂ are the speeds when the load is being lowered, Vu ₁ and Vu ₂ indicate the speed when lifting the load, respectively. In condition a, the area S ₁ shown with diagonal lines is the landing error, but in condition b, the area
S ₂ and S ₃ cancel each other out, and the difference between S ₂ and S ₃ becomes the landing error. As is well known, the phase delay element is easily composed of a resistor and a capacitor, and if these are made variable, an arbitrary time constant can be obtained. Therefore, by adjusting this time constant, the area S ₂ and S ₃
It is possible to make the difference between the two positions almost zero, that is, the landing error can be made almost zero. The value of the time constant at this time varies depending on the rated speed and load of the elevator, but is approximately T ₁
= 1.9 seconds and T ₂ = about 0.6 seconds are appropriate. In addition, by adjusting the amplification degree K', the deviation during constant speed running can be changed and the relationship between the areas S ₂ and S ₃ can be adjusted, so the time constant can be fixed and adjusted by the amplification degree K'. You can do it like this. Note that these values do not need to be calculated in advance, but if the amplification factor K', resistor, and capacitor are made variable as described above, the magnitude of the load can be determined by trial and error by actually operating the elevator at the installation site. This can be set to a value such that the landing error caused by

In this way, a phase delay element is inserted into the speed regulator, and the time constant or amplification degree of the phase delay element is
By making K′ variable, not only can deviations in uniform speed due to load size and driving direction be reduced, but also by appropriately setting the above time constant or amplification K′, it is possible to reduce landing errors caused by the above deviations. minute,
This can be offset by the landing error caused by the difference in response disturbance delay depending on the load size and driving direction.
In other words, the landing error can be made almost zero regardless of the magnitude of the load.

[Brief explanation of the drawing]

Figure 1 shows the elevator speed curve, Figure 2 shows the speed curve of the elevator.
Figure 3 shows an example of the configuration of a conventional control device, Figure 3 shows an example of the configuration of the present invention, Figure 4 shows a frequency response curve, and Figure 5 shows the torque generated by an induction motor. The explanatory diagram shown in FIG. 6 is a diagram showing a speed curve during deceleration. 1... Feedback circuit, 2... Speed regulator, 3, 4...
...Phase shifter, 5...Speed regulator with phase delay characteristics, SCR1, SCR2...Power amplifier device such as thyristor, TG...Tachometer generator.

Claims (1)

[Claims] 1. A power amplifier device consisting of an induction motor for hoisting the elevator, a thyristor, etc. that controls the driving and braking torque generated by the induction motor, a feedback circuit that detects the actual speed of the elevator, and a feedback circuit output and speed command. and a speed regulator that controls the power amplifying device according to the deviation of the power amplifier, wherein a phase delay element whose time constant or amplification is adjustable is inserted into the speed regulator, and the phase delay element The time constant or degree of amplification is determined by the landing error caused by the deviation of the constant speed of the elevator due to the magnitude of the load and the direction of operation, and the difference between the response delay after deceleration due to the magnitude of the load and the direction of operation. An AC elevator control device characterized in that settings are made so that landing errors are substantially canceled out.