www.bysj580.com / 2023-05-22
Design of five tier elevator control system based on SIEMENS PLC
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 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 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 is 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 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)ticurrent 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 frequently. 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 multi-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 elevators.
Elevator-speed start-up and running, low-speed windings for braking and the maintenance of elevators.
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. No drivers for the control of elevators, 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 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.
4.PLC Control Elevator Design.
With the continuous development of urban construction, the increasing high-rise building, elevators and life in the national economy has a broad application. Elevator high-rise building 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 random, 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 according 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=M=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 M=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. It 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 in the system, that is, to reduce the speed of control necessary to ensure the comfort, but also strictly in accordance with the operation of the lift of the relationship between speed and distance control to ensure the accuracy of flat layers. To the speed in the system before 120r/min, in order to take into account both be taken to control the acceleration of time-based and at the same time in each braking distance based on actual speed and speed deviations from the theory to fix the acceleration curve of a given method. For example, froma flat layer at the distance L, the speed should be  reduced to V m/s, while the actual high speed V m/s, it is illustrated by the increase in the braking torque is not enough here, therefore to calculate value determined by the speed-ag after it combined with a negative deviation of&, even here the value given by  the speed of amended-(ag+&)so that a given rate of deceleration and the actual increases of negative bias, which increases braking torque big, so fast down to the standard value, when the motor speed 120r/min down after the car at this time only a dozen or so cm layer anomaly, low speed lift, in order to prevent yet floor parking area on the phenomenon in order to enable faster access to the lift to floor area ratio adjustment used in this paragraph and the use of optimal control of time in order to ensure accurate and timely access to elevator floor area, in order to achieve accurate and reliable level layer.
在电梯运行曲线中的启动段是关系到电梯运行舒适感指标的主要环节,而舒适感又与加速度直接相关,根据控制理论,要使某个量按预定规律变化必须对其进行直接控制,对于电梯控制系统来说,要使加速度按理想曲线变化就必须采用加速度反馈,根据电动机的力矩方程式:M-MZ=   M=J*(dn/dt),
 可见加速度的变化率反映了系统动态转矩的变化,控制加速度就控制系统的动态转矩    M=M-MZ。故在此段采用加速度的时间控制原则,当启动上升段速度达到稳态值的90%时,将系统由加速度控制切换到速度控制,因为在稳速段,速度为恒值控制,波动较小,加速度变化不大,且采用速度闭环控制可以使稳态速度保持一定的精度,为制动段的精确平层创造条件。在系统的速度上升段和稳速段虽都采用PI调节器控制,但两段的PI参数是不同的,以提高系统的动态响应指标。在系统的制动段即要对减速度进行必要的控制,以保证舒适感,又要严格的按电梯运行的速度和距离的关系来控制,以保证平层的精度。在系统的转速降至120r/min之前,为了使两者得到兼顾,采取以加速度对时间控制为主,同时根据在每一制动距离上实际转速与理论转速的偏差来修正加速度给定曲线的方法。例如在距离平层点的某一距离L处,速度应将为V m/s,而实际转速高为V’ m/s,则说明所加的制动转矩不够,因此计算出此处的给定减速度值-ag后,使其再加上一个负偏差&,即使此处的减速度给定值修正为-(ag+&)使给定减速度与实际速度负偏差加大,从而加大了制动转矩,使速度很快降到标准值,当电动机的转速降到120r/min以后,此时轿厢距平层只有十几厘米,电梯的运行速度很低,为防止未到平层区就停车的现象出现,以使电梯能较快地进入平层区,在此段采用比例调节,并采用时间优化控制,以保证电梯准确及时地进入平层区,以达到准确、可靠地平层。