KR900008057B1 - Control device of ac-elevator - Google Patents

Abstract

An AC elevator control system includes an AC power source, an induction motor driving an induction motor driving an elevator car, an inverter unit receiving DC power obtained by converting the AC power as its input and supplying an output of a variable voltage and a variable frequency to said induction motor, speed commanding means for commanding the speed of said elevator car, speed detecting means for detecting the speed of said elevator car, and normal-operation switching signal generating means for generating a switching signal for controlling the frequency and duty factor of the output of said inverter unit depending on the error between the speed command and the detected speed of said elevator car in a normal operation mode.

Description

Control device of AC elevator

1 to 12 are for explaining an embodiment of the present invention, Figure 1 is an overall configuration diagram of the AC elevator control device.

2 is a main circuit diagram of an inverter device.

3 is a relationship between frequency and voltage of the inverter device.

4 is an output voltage waveform diagram at low frequency output of an inverter device.

5 is an output voltage waveform diagram of a high frequency output of an inverter device.

6 is a torque characteristic diagram of an induction motor by inverter control.

7 is a configuration diagram of a switching signal generator for normal operation.

8 is a signal waveform diagram of each part for explaining the operation of FIG.

9 is an output voltage waveform diagram of an inverter during normal operation.

10 is a waveform diagram of an output voltage of an inverter during emergency operation.

11 is a configuration diagram of a switching signal generator for emergency operation.

FIG. 12 is a signal waveform diagram for explaining the operation of FIG.

13 is another embodiment of the AC elevator control apparatus according to the present invention, the overall configuration diagram.

The present invention relates to a control device of an alternating current elevator using an induction motor.

The operation of an elevator includes the normal operation which performs normal acceleration / deceleration control, and the emergency operation which performs operation in the case of emergency, such as a power failure.

Conventionally, in an AC elevator driven by a three-phase induction motor, a control device for normal operation and a control device for emergency operation are provided separately, and a method of switching them is adopted.

An example of this normal operation is US Patent No. 3,876,918 (April 8, 1975). This method uses a control device composed of a thyristor or the like during normal operation, and provides direct torque to the primary winding of the induction motor during deceleration by the primary voltage control of the induction motor during acceleration. Acceleration and deceleration control is carried out by speed feedback control of the DC braking torque, respectively, by controlling the current.

In such a driving method, in case of an emergency such as a power failure, the motor is switched and operated in the following manner.

(A) A method of driving an induction motor with the inverter device comprising an emergency DC power source such as a battery and an inverter device for converting the same into a three-phase AC power.

(B) As proposed in British Patent No. 2,020,926 (Patented on August 25, 1982), an emergency direct current power source, such as a battery, and a small DC motor powered by the power supply, How to drive the elevator.

However, since the methods (a) and (b) require a battery, an inverter device, or a small DC motor in addition to the normal operation device, the device is large and expensive.

On the other hand, in the normal operation, since the induction motor is controlled in a large slip range during both acceleration and deceleration, there is a problem that the rotor loss is large and the power consumption is large.

Therefore, as a method of solving such a problem, a method of controlling an induction motor for driving an elevator with an inverter device is known, for example, from British Patent Publication No. 2,081,534 (published February 17, 1982).

As is known, this inverter device controls voltage and frequency applied to an induction motor in a constant relationship. For example, PWM control (Pulse-Width Modulation control) is known. In this case, the induction motor can be controlled in a low slip range, thereby enabling efficient operation.

In addition, since the power supply of this inverter device is DC, it can obtain by converting AC power into DC in normal operation, and can use DC power, such as a battery, as it is in an emergency. That is, emergency operation can be performed only by connecting DC power supplies, such as a battery, to an inverter device.

However, since the inverter device controls the induction motor on the basis of the DC voltage obtained by rectifying the AC power source, when the low voltage battery or the like is connected, the generated torque of the induction motor is reduced. On the other hand, in the case of an elevator, the load of an induction motor is applied with torque (unbalanced torque) determined by the difference between the weight of the cage and the counterweight, and varies greatly depending on the number of passengers. That is, when the cage is full, there is a large unbalanced torque in the downward direction and when there are few passengers in the upward direction. For this reason, if the generated torque of the induction motor is small, it is dangerous to be attracted to the unbalanced torque and become impossible to control.

Therefore, the emergency DC power supply such as the battery requires a very large voltage close to the rectified voltage of the AC power supply. Therefore, high cost and large size are inevitable.

It is a first object of the present invention to provide a control device of an alternating current elevator that can perform an emergency operation simply by a low-voltage emergency DC power supply.

A second object of the present invention is to provide a control device of an alternating current elevator that can improve the reliability of an emergency operation.

A third object of the present invention is to provide a control device of an alternating current elevator capable of improving the riding comfort and the accuracy of conception during driving in an emergency.

A first feature of the present invention is to control the frequency and voltage applied to an induction motor for driving an elevator by means of an inverter device, and to perform normal operation control, which supplies power to the inverter device from an emergency emergency DC power supply of the elevator. At the same time, the inverter device is controlled by a switching signal different from the flow-through rate characteristic with respect to the frequency in the normal operation.

A second feature of the present invention resides in that the switching signal for emergency operation is generated by an independent device configured separately from the switching signal for normal operation.

A third feature of the present invention is to generate a speed command for emergency operation and to generate the switching signal in the emergency according to the speed command.

Objects and features of the present invention other than those described above will be described in detail in the following Examples.

Next, it demonstrates based on the Example shown about this invention. In addition, the present invention, when the cage is stopped between floors due to any cause other than the occurrence of power failure or the like, or when the normal operation is not possible, such as when the elevator control device, etc. breaks down, that is, when operating with DC power All can be applied. In this case, it is obvious that the abnormality detecting device of the present invention may be configured to detect an abnormality corresponding thereto. In the following embodiment, an example of a power failure will be described.

1 is an example of the overall configuration of an alternating current elevator device according to the present invention.

In Fig. 1, reference numeral 19 denotes a power failure detection device for detecting a power failure of the three-phase AC power supply 1 which is a power source for normal operation, and inputs a detection signal of this device to the sequence controller 22 of the elevator. The main circuit contacts 20 and 21 and the control signals contacts 20a ₁ , 20a ₂ , 21a ₁ , and 21a ₂ are switched by the presence or absence of a power failure.

In normal operation, the contacts 20, 20a ₁ and 20a ₂ are closed, the contacts 21, 21a ₁ and 21a ₂ open, and the converter 2 The three-phase alternating current voltage is converted into a direct current voltage, which is applied as a direct current power source of the inverter 3. This inverter 3 is a well-known circuit as shown in FIG. 2, and is composed of transistors Tr _1- (Tr ₆ ) and diodes D _1- (D ₆ ), which are transistors Tr ₁ . Switching control of-(Tr ₆ ) converts the DC voltage V _DC into a three-phase alternating voltage and supplies it to the induction motor 4.

When the operation start signal of the elevator is generated by the sequence controller device 22, the electromagnetic brake 5 is released, and the speed command device 13 generates a speed command which rises with an increase in time.

The difference between the speed command signal and the speed signal from the speed detection generator 12 connected to the elevator driving three-phase induction motor 4 is detected by the comparator 14, and the PWM control switching signal during normal operation is detected. Input to the switching signal generator 15 for normal operation which generate | occur | produces.

The switching signal generator 15 is for controlling the transistors Tr _{1 to} Tr _{8 in} FIG. 2 so that the ratio of the voltage and frequency applied to the induction motor 4 is constant. Is controlled according to the difference between the speed command and the speed signal.

In this case, in order to perform efficient operation, it is necessary to perform V / f constant control so that the voltage V applied to the induction motor and the frequency f are in the relationship of FIG. For this purpose, since the period is long in a low frequency region, as shown in FIG. 4, the number of switching cycles (hereinafter referred to as pulse number N) between the half cycles is increased and the flow rate Tp / T of this pulse is increased. (T is the time between half cycles, and Tp is the pulse width). On the contrary, since the period is short in a high frequency region, as shown in FIG. 5, the number of pulses N is reduced and the flow rate Tp / T of the pulse is increased. This is called PWM control as described above. When the voltage applied to the induction motor is controlled by this method, the torque characteristic is as shown in FIG. By controlling the speed of the elevator by using this characteristic, the induction motor can be controlled in a range with a small slip, so that efficient operation can be performed.

FIG. 7 is a specific circuit example of the switching signal generator 15, in which the number of pulses between half cycles is changed into three steps of N ₁ pulses, N ₂ pulses, and 1 pulse according to the output frequency of the inverter.

8 is a waveform of each part in the case where N ₁ = 8 pulses in FIG. The frequency command signal d ₂ which is a control input of the switching signal generator 15 is generally obtained by adding a speed command or a feedback speed to a deviation between the speed command and the feedback speed.

Therefore, the oscillator 31 outputs a pulse a of a frequency proportional to the frequency command signal d ₂ , and inputs it to the differentiator 35 through the pulse number converter 35 to prepare a pulse C, and again this. A pulse d ₁ is generated through the sawtooth generating circuit 37, and the frequency command signal d ₂ is compared with the comparator 38 to generate a pulse e.

의 논리화(論理和) 및 논리적(論理積)의 조합으로

의 펄스를 만들고, 상기 (g₁),(g₂),(g₃)와 이들의 반전신호

,

,

(도시생략)를 PWM 제어의 스위칭신호(펄스)로 한다.On the other hand, the output pulse a of the oscillator 31 is divided by the 1/2 frequency divider 32 (pulse a ₁ ) and inputted to the hex ring counter 33, so that the pulses b ₀ having different phases by 60 ° are used. Write (b ₅ ). In the PWM signal forming circuit 34, the signals (b ₀ ) − (b ₅ ), (e),

Is a combination of logical and logical logic

Make pulses of (g ₁ ), (g ₂ ), (g ₃ ) and their inverted signals.

,

,

(Not shown) is a switching signal (pulse) of PWM control.

를 제1도의 펄스증폭장치(17)로 증폭하고, (g₁) 및

을 증폭한 펄스(G₁)를 제2도의 트랜지스터(Tr₁)에, (

)을 (Tr₂)에, (g₂) 및

의 증폭펄스(G₂),

를 (Tr₃), (Tr₄)에, (g₃) 및

의 증폭펄스(G₃),

를 (Tr₅),(Tr₆)의 베이스에 부여하고, 속도 제어차에 따라서 주파수를 점차 증대시켜 유도전동기(4)의 역행토크를 제어하고, 이것을 감속기(6), 시브(7), 로프(8)를 통해서 엘리베이터케이지(9), 카운터웨이트(10)를 가속제어한다.The pulse (g ₁ )-(g ₃ ),

Amplifying a first-degree pulse amplifier 17, and, (g ₁₎ and

A pulse (G ₁₎ to amplify a second degree transistor (Tr _1), (

) In (Tr ₂ ), (g ₂ ) and

Amplified pulse of G ₂ ,

To (Tr ₃ ), (Tr ₄ ), (g ₃ ) and

Amplified pulse of G ₃ ,

To the bases of (Tr ₅ ) and (Tr ₆ ), and gradually increase the frequency according to the speed control difference to control the reverse torque of the induction motor (4). Acceleration control of the elevator cage 9 and the counterweight 10 is carried out through (8).

When the elevator is accelerated by such a method and travels a predetermined distance to reach a fixed position immediately before the landing point, the position from this location to the landing point is detected by the position detector 11 attached on the cage 9, and this speed is reached. Input to command device 13 is made.

The speed command device 13 generates a speed command which decreases in accordance with the deceleration position of the elevator, and outputs a frequency command signal d ₂ according to the control deviation between this and the return speed from the speed detection generator 12. Input to the switching signal generator 15 as described above.

Accordingly, the switching signal generator 15 gradually decreases the frequency in accordance with the frequency command signal d ₂ while maintaining the relationship of V / f (voltage / frequency) as described above, thereby reducing the frequency of the induction motor 4. Regenerative braking torque is controlled to decelerate the elevator.

The regenerative power in this case may be returned to the power supply by a known method or consumed by an external resistor.

When the elevator decelerates and arrives at the landing point, it is input to the sequence controller 22 to generate a stop signal from the sequence controller 22, and the electromagnetic brake 5 is applied to stop and hold the elevator.

In such an elevator control system, when the AC power supply 1 is out of power, the elevator is operated by the following method.

In this case, when the power failure occurs within the door open zone in which the elevator cage 9 can open the doors of each floor, the elevator is not operated until power is supplied again. Then, only when the power failure occurs during the operation of the elevator and stops outside the range where the door can be opened, rescue operation is performed to avoid an accident in which the passenger is confined in the cage 9. In this case, it is advantageous to operate at a speed lower than the rated speed in terms of economy and stability.

When the AC power supply 1 in FIG. 1 is out of power, a power failure is detected by the mental detector 19, and the contact 20, the contacts 21a ₁ and 20a ₂ are opened, and the contact 21 ) And the contacts 21a ₁ and 21a ₂ are closed.

Therefore, an emergency DC power supply 18 such as a battery is connected to the DC power supply terminal of the inverter 3, and at the same time, the power supply is connected to the emergency operation switching signal generator 16, the pulse amplifier 17, and the sequence controller. (22) It is also connected to the power supply terminal of the electrostatic detection device 19.

In this way, the power supply and the switching signal generator of each device are switched for emergency use to form a circuit for emergency operation.

Here, if the output frequency of the inverter 3 corresponding to the emergency operation speed is fa and the voltage is Va, the emergency operation switching signal generator 16 generates a pulse in which Va / fa satisfies the fV characteristic of FIG. It needs to happen.

Therefore, in order to set the power supply voltage Via of the inverter in emergency lower than the power supply voltage Vin in normal operation, the output voltage of the inverter 3 for the same frequency is set to 9 as shown in FIG. In emergency operation, the number of pulses is set to 2 as shown in FIG. 10, and the effective voltage is controlled to be the same. That is, the pulses output from the switching signal generators 15 and 16 for normal operation and emergency operation are the number of pulses; Normal operation> Pulse flow rate during emergency operation; When normal operation is performed during the emergency operation and the voltages for the same frequency are the same, the induction motor 4 generates the torque as shown in FIG. 6 and can drive the elevator.

11 is a specific circuit example of the emergency operation switching signal generator 16, and its operation principle is substantially the same as that of the normal operation switching signal generator of FIG.

FIG. 12 is a waveform of each part in the case where two PWM control pulses are generated between half cycles in FIG. The oscillator 40 outputs a pulse h of a frequency proportional to the low speed emergency operation speed command signal k ₂ (frequency signal) input from the sequence controller 22, and differentiates the pulse h into the differentiator 43. This is input to the saw tooth generating circuit 44, and this output k ₁ and the command signal k ₂ are compared with a comparator, and pulse 1 is created.

의 논리화 및 논리적의 조합으로

의 펄스를 만들고, 상기 (q₁),(q₂),(q₃)와 이들의 반전신호

(도시생략)를 비상운전시의 PWM 펄스로 한다.On the other hand, by entering the output h of the oscillator 40 to the counter 6 Jinling 41. Each phase is 60 ° different pulse (m ₀₎ - Create a _5. In the PWM signal forming circuit 42, the signals m _0- (m ₅ ), (1),

As a combination of logical and logical

Make pulses of (q ₁ ), (q ₂ ), (q ₃ ) and their inverted signals.

Let (not shown) be a PWM pulse at the time of emergency operation.

를 제1도의 펄스증폭장치(17)로 증폭하여, 이 출력을 인버터(3)내의 트랜지스터의 베이스에 부여한다. 이 점에 대해서는 상술한 바와 같다.The pulse q ₁ -q ₃ ,

Is amplified by the pulse amplifier 17 of FIG. 1, and this output is applied to the base of the transistor in the inverter 3. As shown in FIG. This point is as described above.

When the emergency start signal from the sequence controller 22 is generated, the emergency operation switching signal generator 16 generates a pulse corresponding to the emergency operation speed, and the inverter 3 outputs the pulse corresponding to the inverter 3 through the pulse amplifier 17. ) To drive the elevator.

When the elevator travels to the landing point, the inverter is stopped by the stop signal generated from the sequence controller 22, and the electromagnetic brake 5 is operated to stop and maintain the elevator.

According to a first embodiment of the present invention, there is provided a means for connecting an emergency power source such as a battery to a DC power terminal of an inverter used for normal operation control in an emergency such as a power failure, and generating a switching signal for PWM control of the inverter. The control signal is different from that for normal operation, and the switching signal generated from this control means controls the same frequency with a pulse having a smaller number of pulses and having a larger pulse flow rate than during normal operation. The DC power supply voltage of the inverter can be reduced.

Therefore, since the emergency power supply equipment can be significantly small and inexpensive, there is an effect that an economical elevator control apparatus can be provided.

13 shows another embodiment of the present invention in which speed feedback control is performed even during acceleration and deceleration during emergency operation.

In Fig. 13, reference numeral 23 denotes a speed command device for emergency operation, and reference numeral 24 denotes a comparator, and other signals and operations during normal operation are the same as those in Fig. 5 and are omitted.

In the emergency operation, the speed command device 23 generates a speed command which is a function of time when accelerating and a function of elevator position when decelerating, and the difference between this and the return signal from the speed detection generator 12. Is detected by the comparator 24, and the PWM control pulse corresponding to the speed control deviation is output from the switching signal generator 16 for emergency operation to perform speed control during emergency operation.

According to this embodiment, since the current flowing through the induction motor 4 during acceleration / deceleration during emergency operation becomes small, there is an effect that the capacity of the battery 18 can be further reduced.

In addition, the speed feedback control is also performed during acceleration and deceleration, so that the idea of conception can be significantly improved.

In addition, when driving at a very low speed, it is expected that the conception error will not be a problem. Therefore, at this time, the inverter may be controlled by a speed command that increases or decreases at a constant acceleration and deceleration without performing speed feedback control to suppress the current of the induction motor, thereby reducing battery capacity.

1 and 13, the pulses for PWM control have been described with respect to the example in which the pulses have the same width. However, known inequality pulses having different pulse widths may be used. In this case, since the output voltage of the inverter is closer to the sine wave, the noise, heat generation, etc. of the motor are reduced.

In addition, the switching signal generators 15 and 16 of FIG. 1 and FIG. 13 are replaced with a microcomputer, and this microcomputer is equipped with the pulse generator function for normal operation and the pulse generator function for emergency operation, and these are switched. Pulses may be generated.

In this way, the device can be miniaturized and a uniform pulse can be generated.

In addition, only the switching signal generator for normal operation may be comprised by the elevator control microcomputer, and the switching signal generator for emergency operation may be set as a dedicated circuit. In this case, even when the microcomputer breaks down, emergency operation can be performed, and further stability can be improved.

As described above, according to the present invention, since the DC power is supplied to the inverter used for normal operation control in an emergency such as a power failure, and the inverter is controlled with a pulse having a larger flow rate than during normal operation for the same frequency, the DC power supply of the inverter in emergency The voltage can be reduced, and the compact and economical DC power supply can safely perform the emergency operation of the AC elevator. For example, when this DC power supply is constituted by a battery, this effect is more remarkable considering that periodic inspection and replacement are necessary.

Claims (11)

A three-phase alternating current power source, an induction motor for driving the cage of the elevator, a DC power obtained by converting the three-phase alternating current, an inverter device for varying the voltage and frequency supplied to the motor, and a speed of the cage A commanding speed command device, a speed detecting device for detecting the speed of the cage, and a switching signal generator for normal operation for controlling the frequency and output voltage of the inverter device according to the difference between the speed command and the detecting speed. An AC elevator comprising: an emergency DC power supply and an apparatus for detecting an abnormality of the elevator, and an emergency operation switching signal generator for generating a switching signal different from a flow rate characteristic with respect to the frequency for normal operation. When detecting, power is supplied from the DC power supply to the DC input side of the inverter device, and the emergency operation is performed. By the switching signal generator control apparatus of the AC elevator configured to control the output of the inverter device. 2. The control device of an AC elevator according to claim 1, wherein said emergency operation switching signal generator is configured to generate a switching signal having a smaller frequency than switching for normal operation and having a large flow rate per unit switching for the same frequency. The control device of an alternating current elevator according to claim 1, wherein said abnormality detecting device includes an electrostatic detection device of said three-phase AC power supply. 2. The control device of an alternating current elevator according to claim 1, wherein said abnormality detecting device includes a device for detecting that said cage is stopped between layers. 2. The control apparatus of an alternating current elevator according to claim 1, wherein said abnormality detecting device includes a device for detecting a failure of said elevator. The control device of an AC elevator according to claim 1, further comprising an emergency operation speed command generation device, wherein the emergency operation switching signal generation device is configured to generate a switching signal according to the emergency operation speed command. 7. The control device of an AC elevator according to claim 6, further comprising a comparator for detecting a deviation between the emergency operation speed command and the detection speed, and wherein the emergency operation switching signal generator is configured to generate a switching signal according to the deviation. . The control device for an alternating current elevator according to claim 6, wherein the speed command for emergency operation is set so that the acceleration / deceleration becomes constant. The AC elevator control apparatus according to claim 1, wherein the power supply other than the inverter device is also supplied from the emergency DC power supply when the abnormality is detected. The control device of an AC elevator according to claim 1, further comprising: a switching device for disconnecting the switching signal generator for normal operation and connecting the emergency switching switch signal generator to the inverter device when detecting the abnormality. 2. The control apparatus of an alternating current elevator according to claim 1, wherein said emergency operation switching signal generator is provided independently of said normal operation switching signal generator.

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