JPS6359945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for an AC elevator, and more particularly to a speed control device that controls braking force and decelerates the elevator using negative feedback control.

Recently, in order to simplify and reduce the cost of equipment in AC elevators, during deceleration, the speed signal detected by the speed generator is compared with the command signal from the speed command generator, and braking is applied according to the difference. A method of feedback control of only torque is adopted.

However, with this method of controlling only the braking torque during deceleration, if you try to control the same deceleration distance over the entire load range of the elevator, the inertia of the mechanical system must be increased, which makes it difficult to save power. undesirable.

Therefore, conventionally, the inertia energy required for coasting after the deceleration start point is supplemented by power running operation, so that the inertia of the mechanical system can be reduced. By the way, after the elevator has finished accelerating, it is more efficient to operate at the slip frequency determined by the load at that time without controlling the induction motor. The elevator speed with a light load is higher than the elevator speed with a heavy load such as during full load up operation or no load down operation, and there is a relationship as shown in Figure 1 (curve a in Figure 1 is During ascending operation, curve b is the relational curve during descending operation). Using the speed signal obtained from the speed generator which is similar to that in Fig. 1, the speed command signal during constant speed operation is determined as shown in Fig. 2. V _s is set between the speed signals V _p1 and V _p2 during light loads and heavy loads, and the switch is made from power running to braking at the point where the speed signal ≧ the speed command signal after the deceleration start point a of the speed command signal. ing.

For example, when the load is light and requires a large braking force, V _p1 −V _s > 0 at point a, so the switch is immediately made from power running to braking, and when the load is heavy and does not require much braking force, the transition is made immediately before the landing point. The speed command signal V _s is decreased from a predetermined point a, and at a point b where V _p2 =V _s , the control is switched to the braking side and deceleration control is performed.

In this way, by comparing the speed signal and the speed command signal, braking is switched from point a when the load is light and from point b when the load is heavy, and the actual deceleration distance is controlled to change according to the elevator load. This suppressed the inertia of the mechanical system from increasing.

However, in order to obtain good ride comfort and landing characteristics, it is desirable that the relationship between the elevator load and the deceleration distance be proportional, but in the conventional method shown in Figure 2, cannot be realized. The first reason is that in order to satisfy the above relationship, the speed command signal must be a command that decreases linearly at a constant rate from a predetermined position before the elevator's landing point. but,
If such a command is given, ride comfort near the start of deceleration will deteriorate. The second reason is that, as is clear from the characteristics shown in Figure 1, there is no linear relationship between elevator load and speed, so even if you compare the speed signal and speed command signal, the deceleration distance will not be proportional to the load. , it is not possible to obtain good characteristics over the entire load range.

Furthermore, when the power supply voltage changes, the relationship shown in FIG. 1 also changes, so the switching point from power running to braking changes and the characteristics deteriorate.

In addition, the range of change in the speed signal with respect to the load during constant speed driving is extremely small, approximately ±5% based on the balanced load, and due to variations in circuit components or the effects of temperature changes, the speed signal and speed In the method of comparing the command signal with an analog signal, the gain of the circuit that compares the speed signal from the speed generator with the speed command signal and detects whether the difference is a predetermined value is determined on-site at the elevator. must be adjusted while moving. Moreover, in this case,
If adjusting the circuit that detects the above-mentioned predetermined value is not enough, the gain of the speed signal, that is, the loop gain of the control system, must also be adjusted, which has the disadvantage of requiring a considerable amount of time for adjustment. be. That is, in the conventional analog system as shown in FIG. 2, VP ₁ and VP ₂ in FIG. 2 must be adjusted. Moreover, since this adjustment is affected by variations in the parts of the control device, it must be performed by a skilled person while the elevator is operating, and the adjustment takes time.

An object of the present invention is to provide an AC elevator that eliminates the drawbacks of the prior art described above, provides stable ride comfort and landing performance over the entire load range, and reduces maintenance and adjustment man-hours. The object of the present invention is to provide a speed control device.

A feature of the present invention is that after the speed signal generator that generates a signal corresponding to the speed of the elevator and the position detector that detects a predetermined position before the elevator touches the floor, the main circuit of the AC motor that drives the elevator is activated. Stores a switching reference pattern that is based on a digital signal for determining the operating point of a switching device that switches from power running to braking. a switching reference pattern storage means capable of updating the switching reference pattern; a comparison means for comparing the output of the speed signal generator with the switching reference pattern; and a comparison means for comparing the output of the speed signal generator with the switching reference pattern, and The present invention is characterized in that the position detecting device includes a switching signal output means for outputting a switching signal for switching the switching device after the position detection device operates.

The present invention will be described in detail below with reference to the embodiments shown in FIGS. 3, 5, and 7, and FIGS. 4, 6, 8, and 9.

FIG. 3 is a block diagram showing one embodiment of the elevator speed control device of the present invention. An elevator car 1 and a counterweight 2 are suspended from a sheep 4 via a rope 3 in a hanging manner.

Sheep 4 is a three-phase induction motor 5 for driving an elevator.
A three-phase AC speed generator 6 is connected to the induction motor 5.

Since the output voltage and frequency of this AC speed generator 6 are proportional to the rotation speed of the electric motor 6, this output voltage is pulsed by a waveform shaping circuit 7 and integrated, and the running position of the elevator is detected and the AC speed is Rectifying the output of the generator 6 and converting it to direct current,
This is compared with the speed command signal, and the driving force and braking force of the electric motor 5 are controlled according to this difference.

R, T, and S are three-phase AC power supplies, and the main contacts 11 ₁ , 11 ₂ of the contactor 11, the main contacts 12 ₁ of the contactor 12,
The combination of 12 _{and 2} switches between rising and falling operation, and the thyristors 13a, 13b and diode 14
a, 14b and main contacts 15 of contactors 15, 16
₁ , 15 ₂ , 15 ₃ , 16 ₁ , and 16 ₂ constitute a power running torque control element and a control torque control element, and the thyristors 13a and 13b are controlled by the phase shifter 8.

The phase shifter 8 inputs the speed command signal V _s output from the microcomputer 9 and the speed signal V _p obtained via the AC speed generator 6 and the waveform shaping circuit 7 to perform feedback control. By this feedback control, the elevator car 1 is operated at a speed equal to or higher than the speed command signal _Vs generated by the microcomputer 9.

The speed command signal V _s is a command signal that increases over time during acceleration and decreases in response to the deceleration position during deceleration, so the time to obtain the acceleration command depends on the internal clock of the microcomputer 9. The position signal required for the deceleration command is generated by counting the pulses of the pulse signal from the AC speed generator 6, and interrupting the microcomputer 9 every time a predetermined number of pulses from the internal clock and the AC speed generator 6 are counted. The speed command data stored in the read-only memory of the microcomputer 9, which will be described later, is read out, converted into an analog value by a D/A converter, and increased in a stepwise manner as shown in FIG. 4a. and decreasing command signal, and further,
A smoothing circuit smoothes the signal to create a speed command signal as shown in FIG. 4b.

The microcomputer 9 includes a microprocessor MPU, a programmable counter/timer PTM ₁ for counting output pulses from the AC speed generator 6 necessary for generating speed commands, as shown by the broken line in FIG. AC speed generator 6 to be described later
A programmable counter/timer PTM ₂ for measuring the pulse period and number of pulses, a read-only memory ROM containing instructions and data for the operation of the microprocessor MPU, and a programmable counter/timer for measuring the pulse period and number of pulses. Random access memory used for temporary storage as an area
Consists of RAM and input/output circuit PIA.

The speed command signal _Vs is sent to a D/A converter 17 that converts a digital signal to an analog signal, and a smoothing circuit 18.
It is output from the microcomputer 9 via.

With such a circuit configuration, when an operation start signal is generated from the elevator control device 10, the signal shown in FIG.
At the same time as the acceleration command signal is generated, the main contacts 15 ₁ to 15 ₃ of the contactor 15 are closed, and the contactor
For example, in the case of upward operation, the main contacts 11 ₁ and _{11 2 of} the contactor ₁₁ are closed, and the antiparallel connected thyristors 13a and 13b are connected to the power source and the motor. 5 to form a power running circuit, and the phase shifter 8 controls the gates of the thyristors 13a and 13b according to the difference between the speed command signal and the speed signal to control the acceleration of the elevator. Do the following.

During deceleration, main contacts 15 ₁ to 15 ₃ are open, 16 ₁ ,
16 ₂ is closed to supply the output of the mixed bridge circuit consisting of thyristors 13a, 13b and diodes 14a, 14b to the motor 5, and perform feedback control of the dynamic braking force using the method described above to perform deceleration control.
At this time, the switching point from power running to braking is detected using the following method.

That is, focusing on the fact that the output frequency of the AC speed generator 6 used for speed feedback control is proportional to the rotation speed of the electric motor 5, that is, the speed of the elevator, A provided pattern for switching from power running to braking (in the present invention, this is referred to as a switching reference pattern).
A comparison is made using the programmable counter/timer PTM ₂ shown in FIG.

FIG. 6 is an explanatory diagram of a comparison operation between the pulse period of the AC speed generator 6 and the switching reference pattern. Figure 6a
b is for heavy load operation with a long pulse period, and b is for light load operation with a short pulse period.
A switching reference pattern _D0 , which will be described later, stored in the read-only memory ROM is read from the falling point e of this pulse, and the number of internal clocks corresponding to this data is input to the counter timer PTM _{2 .} If the count of the above data is completed by the next falling point f of the pulse, a flag is set in the status register of counter/timer PTM ₂ , and if the count is not completed, the flag is not set. .

In this way, the pulse period of the AC speed generator 6 and the switching reference pattern are compared. Next, a method of switching from power running to braking using this principle will be specifically explained.

The first data D ₀ of the switching reference pattern is set according to the pulse period of the AC speed generator 6 at a balanced load during constant speed running, and this data is kept constant until the deceleration start point of the speed command. From the start point of deceleration to the point of switching to braking, the data D ₁ ,
D ₂ , D ₃ , . . . are set, and these are stored in advance in the ROM shown in FIG. 5, as shown in FIG.

FIG. 8 is an explanatory diagram of the operation of detecting a switching point from power running to braking. Up to the deceleration start point a of the speed command, the first data _D0 of the switching reference pattern and the pulse period of the AC speed generator 6 are compared in the above-described manner,
In the case of a light load in which the time corresponding to the reference pattern D ₀ is longer than the pulse period, this information is output from the microcomputer 9 to the elevator control device 10, and from the deceleration start point a of the speed command, the main Contacts 15 ₁ to 15 ₃ are started, contacts 16 ₁ and 16 ₂ are closed to form a DC braking circuit, and feedback control is performed according to the difference between the speed signal and the speed command signal.

In the case of a heavy load where the time corresponding to the switching reference pattern D ₀ is shorter than the pulse period, the switching reference pattern D ₁ ,
D ₂ , . At time point b, power running is switched to braking, and deceleration control is thereafter performed in the same manner as described above.

As described above, according to the embodiment of the present invention, switching from power running to braking is performed without using a speed command signal, using a dedicated switching reference pattern and comparing this with a speed signal, In addition, since the switching reference pattern is set so that the actual deceleration distance is proportional to the load, stable ride comfort and stable landing performance can be obtained over the entire load range. In addition, since the pulse period of the pulse signal from the AC speed generator 6 for speed feedback control is used as the speed signal to be compared with the switching reference pattern,
Changes in the switching point due to power supply voltage fluctuations can be reduced. Furthermore, since it is a digital comparison, there are fewer variations in circuit components and changes in characteristics due to temperature.
This also has the effect of eliminating the need for adjustment.

FIG. 9 is an operation explanatory diagram for explaining another embodiment of the present invention. In FIG. 9, the setting of the switching reference pattern and the comparison with the pulse period of the AC speed generator 6 are the same as above, but the method of updating the switching reference pattern is different. That is, since the speed command signal is a signal that decreases according to the deceleration position, the switching reference pattern is updated in synchronization with the position signal for this speed command signal.

In this case, in order to improve accuracy, it is desirable that the position detection interval for changing the magnitude of the speed command signal from the speed command deceleration start point to the switching point be short. The same effects as described above can also be obtained by such a method.

In the above embodiment, the switching reference pattern and the pulse period of the output pulse of the AC speed generator 6 are compared, but the number of pulses at a fixed time interval is measured, and the switching reference pattern having the same dimension is compared. It is also possible to prepare patterns and compare them.

As explained above, according to the present invention, switching from power running to braking is performed by comparing a switching reference pattern using a digital signal exclusively for switching with a signal proportional to speed using a microcomputer. As a result, the main circuit can be switched with high precision without being affected by speed command characteristics or power supply voltage fluctuations, providing stable ride comfort and landing performance over the entire load range, and reducing operating point variations. This has the effect of reducing maintenance and adjustment man-hours.

[Brief explanation of the drawing]

Fig. 1 is a relationship diagram between elevator load and constant running speed, Fig. 2 is a diagram for explaining the operating principle in the conventional case, and Fig. 3 is an example of the elevator speed control device of the present invention. Block diagram showing the embodiment, No. 4
The figure is a speed command signal characteristic diagram, Figure 5 is a schematic diagram showing an embodiment of the microcomputer in Figure 3, and Figure 6 is a
The figure is an explanatory diagram of the comparison operation between the pulse period of the output pulse of the AC speed generator and the switching reference pattern, FIG. 7 is an explanatory diagram of the memory map of the switching reference pattern, and FIG. FIG. 9, which is an explanatory diagram of the switching point detection operation from power running to braking, is an explanatory diagram corresponding to FIG. 8 for explaining another embodiment of the present invention. 1... Car, 5... Three-phase induction motor, 6...
...AC speed generator, 7... Waveform shaping circuit, 8...
Phase shifter, 9...Microcomputer, 10...
Elevator control circuit, 11 ₁ , 11 ₂ , 12 ₁ , 1
2 ₂ , 15 ₁ to 15 ₃ , 16 ₁ , 16 ₂ ... Main contact of contactor, 13a, 13b ... Thyristor, 14a,
14b...Diode, MPU...Microprocessor, PTM ₁ , PTM ₂ ...Counter timer, ROM...Read only memory.

Claims (1)

[Claims] 1 Equipped with a position detection device that detects a predetermined position before landing of an elevator driven by an AC motor, and a switching device that switches the main circuit of the motor from power running to braking after the position detection device operates, and sends a deceleration command. deceleration is performed according to pattern data of the motor, and the braking force of the electric motor is controlled by negative feedback, comprising: a speed signal generator that generates a signal corresponding to the speed of the elevator; and an operating point of the switching device. a switching reference pattern which stores a switching reference pattern based on a digital signal for determining the switching reference pattern, the switching reference pattern being able to be updated in response to the time since the operation of the position detection device or the deceleration position of the elevator; reference pattern storage means; comparison means for comparing the output of the speed signal generator with the switching reference pattern; 1. A speed control device for an AC elevator, comprising a switching signal output means for outputting a switching signal for switching.