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Elevator System Based on PLC
Composed by the order of relay control system is a realization of the first elevator control method. However, to enter the nineties, with the development of science and technology and the widespread application of computer technology, the safety of elevators, reliability of the increasingly high demand on the relay control weaknesses are becoming evident.
Elevator control system relays the failure rate high, greatly reduces the reliability and safety of elevators, and escalators stopped often to take with the staff about the inconvenience and fear. And the event rather than taking the lift or squat at the end of the lift will not only cause damage to mechanical components, but also personal accident may occur.
Programmable Logic Controller (PLC) is the first order logic control in accordance with the needs of developed specifically for industrial environment applications to operate the electronic digital computing
device. Given its advantages, at present, the relay control the lift has been gradually replaced by PLC control. At the same time, AC variable frequency motor speed control technology, the way the lift drag speed has been a gradual transition from DC to AC frequency converter. Thus, PLC control technology increases VVVF Elevator modern technology has become a hot industry.
1. PLC elevator control advantages
(1) used in elevator control PLC, with software for automatic control of lift operation, reliability greatly increased.
(2) layer was removed and a majority of the relay, the control system structure is simple, to simplify the external circuit.
(3) PLC can be a variety of complex control system, easy to add or change control functions.
(4) PLC can be automated fault detection and alarm display to improve the operation of security and ease of maintenance.
(5) for the group control the allocation and management, and improve the efficiency of elevator operation.
(6) do not need to change the control scheme changes when the hardware connection.
2. VVVF elevator control characteristics
With the power electronics, microelectronics and computer technology to control the rapid development of technology, communication technology VVVF also a very rapid rate. AC variable frequency motor speed control technology is the power to improve the process in order to improve product quality and improving the environment and promoting technological progress as a primary means. Frequency of its excellent performance and the speed brake from a smooth performance, high efficiency, high power factor and power-saving effect of a broad scope of application and many other advantages of being at home and abroad recognized as the most promising approach speed.
Exchange characteristics of VVVF Elevator.
(1)low energy consumption.
(2)low load circuit, the required emergency power supply device of small In the acceleration stage, the required start-up current of less than 2.5 times the rated current. Peak starting current and time is short. Since the starting current is drastically reduced, so power consumption and power supply cable
diameter can be reduced a lot. Required for emergency power supply devices are also relatively small size.
(3) high reliability and long service life.
(4)good comfort Elevator operation is best to follow the speed curve of a given operation. Their characteristics can be adapted to human feelings, and to ensure that noise operation, smooth brake Ping layer and high precision
(5) Stable noise-free
(6) In the car, the engine room and adjacent areas to ensure that noise. Because their systems use a high clock frequency. Always produce a true sine wave power supply current yet. Motor torque ripple does not appear. Therefore, to eliminate vibration and noise.
3. Elevator control technology
The so-called elevator control technology refers to the elevator drive system and electrical control system of automatic control. 70 as the 20th century in China's elevator was marked by the exchange of two-speed elevator. Its speed is used to change the elevator traction motor of the very few, two or m
ulti-level approach to the number of windings, very few of them as high-speed winding of the winding, a very few number of windings as the low-speed winding. Windings for high-speed elevator-speed start-up and running, low-speed windings for braking and the maintenance of elevators.
The early 80s, VVVF inverter controlled variable lift system available. It uses AC motor drives, are able to reach the level of DC motor, control the speed of the current has reached 6 m / sec. Its small size, light weight, high efficiency, energy saving, including the past almost all the advantages of the lift. Is the latest elevator drive system.controller翻译中文
Operation in vertical lift, there is also the starting point of the terminus station. For more than three-story elevator buildings, the starting point of the terminal stations and stops between the had not, the starting point for these stations at the first floor of the terminal located at the highest floor. Starting point in the first floor of the station known as base stations, known as the starting point at both ends of the terminal stations and stations at both ends of intermediate stops between stations.
Outside the station has a call box, box set are used by staff for elevator call button or touch the call button, the general ends of the lift stations in the call box on the Settings button or touch of a button. Middle layer of the station set up the call box button or touch button 2. No drivers for the control of elev
ators, at various stations are set up calls me on a button or touch button. Elevator car and the internal settings (except for debris elevator) to manipulate me. Control box switch on the handle or set up stations and the corresponding layer of buttons or touch-button control box on the touch-control button or command button or touch the city button. Outside the command button or touch-button issue as the signal outside the command signal, within the command button or touch-button issue within the signal as a command signal. 80 In the mid-20th century, the touch button has been replaced by micro-button.
As the elevator call box outside the base station, in addition to set up a call button or touch button, but also set a key switch in order to work the elevator clearance. Drivers or management staff to open the elevator to the base station can wriggle through a dedicated key to the key switch. Close the elevator in place to automatically cut off the elevator control power supply or power supply.
4. PLC Control Elevator Design
With the continuous development of urban construction, the increasing high-rise buildings, elevators and life in the national economy has a broad application. Elevator high-rise buildings as a means of transport in the vertical run of daily life has been inextricably linked with people. In fact the lift is based on external call control signals, as well as the laws of their own, such as running, and the call is rando
m, the lift is actually a man-machine interactive control system, simple to use control or logic control order can not meet the control requirements, and therefore , elevator control system uses a random control logic. Elevator control is currently generally used in two ways, first, the use of computer as a signal control unit, the completion of the lift signal acquisition,
operation and function of the set, to achieve the lift and set the automatic scheduling function to run the election, drag the control from inverter to complete; the second control mode with programmable logic controller (PLC) to replace the computer control signal sets the election. From the control and performance, these two types of methods and there is no significant difference. Most of the domestic manufacturers to choose the second approach, because the smaller scale of production, their design and manufacture of high cost of computer control devices; and PLC high reliability, convenient and flexible program design, anti-interference ability, stable and reliable operation of the characteristics of Therefore, the elevator control system is now widely used to realize programmable controller.
5. Elevator control system characteristics
Operation of the lift curve is above the start to run comfort indicators lift the key features, and comfort are directly related with the acceleration, according to control theory, for a certain amount of change ac
cording to the law must be directly controlled, for elevator control system, according to the ideal acceleration curve acceleration feedback to be used, in accordance with the motor torque equation: M-MZ = ΔM = J (dn / dt), can be seen reflected in the rate of change of acceleration of the system of dynamic torque changes on the control system to control the acceleration of the dynamic torque ΔM = M-MZ. Therefore, during this time to control the use of the principle of acceleration, when the start rate of increase in steady-state value above 90%, the acceleration control system by the switch to speed control, as in paragraph steady speed, speed control for the constant fluctuations in the smaller, little change in acceleration, speed and the use of closed-loop control can maintain a steady-state speed accuracy and precision for the braking section to create the conditions ping layer. Is rising at a rate in the system, and although the above-speed PI regulator used to control, but two of the PI parameters are different in order to improve the system dynamic response indicators. The brake

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