Articles by conventional PLC and inverter to control the lift based on the issue of using rotary encoder position feedback pulse form to achieve precise displacement control elevator. PLC Program Design Floor count, change speed signal, the door area of peace layer digital control signal to replace the shaft position detection device to increase the level of system reliability, accuracy of the peace.
[Key words]
PLC elevator control displacement control assembly election
1 Introduction
the continuous development of urban construction, the increasing high-rise buildings, high-rise building in the vertical elevator is running as a means of transport has been closely linked with people s daily life. Elevator control now commonly used in two ways, first by computer as the signal control unit, complete Dianti signal acquisition, operation status, and feature set, to achieve lift systems within Jixuan run function, drag the control to complete by the transducer ; second control mode with a programmable logic controller (PLC) to replace the signal set to achieve selective control computer. From the controls and performance, this is not much difference between both methods. Most domestic manufacturers to choose second way, the reason the production of smaller, their own design and manufacture of high cost of computer control devices; and PLC reliable, convenient and flexible program design. The design of PLC control with frequency control for current, speed, based on double closed-loop, no additional hardware equipment conditions, for current, velocity, displacement loop control.
2. Hardware circuit hardware structure shown in Figure 1, the function of each are described below.
Q1— — three-phase power circuit diagram K1— — power control contactor K2— — load off control motor contactor VS— — inverter BU— — brake unit RB— — canConsumption of brake resistance M— — main drag traction motor
2.1 Main circuit
main circuit consists of three-phase AC input, variable frequency drives, tractors, and brake unit composed of several parts. By AC - DC - AC voltage type inverter, elevator potential under load, braking energy can feed back to grid feedback, to limit the pumping voltage, using controlled braking means.
2.2 PLC control circuit
use OMRON Corporation C Series 60P type PLC. PLC receives calls from the operation panel and the ladder on each call signal box, car and door signal system functions as well as wells and inverter status signal, to judge by the procedures and operations to achieve control of the lift assembly election. PLC output display and control signals at the same time, sent to the transducer direction of running, start, add / deceleration and braking stop running ladder signal.
2.3 current, speed, dual-loop circuit
use YASAKWA company VS-616G5 CIMRG5A 4022 inverter. Inverter with current sensing device itself, which constitutes the current loop; and motor coaxial rotary encoder connected to produce a, b two-phase pulse into the transducer to confirm the direction at the same time, constitute a closed loop speed pulse counting.
2.4 Displacement control circuit
manned elevator as a tool for potential load condition, in addition to required safety and reliability, but also need to run a smooth, comfortable ride, precise docking. Frequency control loop control can basically meet the requirements, but compared to the lift and foreign high-performance needs improvement. The design is based on this idea, the use of existing rotary encoder device and forms the speed loop the same time, inverter output and motor speed PG card and lift the number of pulses proportional to the displacement, will be introduced into PLC high-speed counting input port 0000, the cumulative number of pulses, The World-style (1) calculate the pulse equivalent and, thus, the lift position. Elevator displacement
h = SI
Type in I— — accumulated pulses
S— &mdasE3
running, high-speed counter counts the cumulative value of real-time point corresponding with the floor to compare the number of pulses, is equal to the signal issued by floor count, up by 1, down by 1. In order to prevent counter counting pulses during the count is high, with floor floor counting signals along the trigger counter.
3.2 fast-for-speed
when the high-speed counter value and the rapid exchange rate point corresponds to the number of pulses are equal, if the elevator is fast running and the layer and layer selection signal, made fast for speed signal. If the elevator is running or while fast running speed, but without the layer of layer selection signal, not made-for-speed signal. Process flow diagram shown in Figure 3.
Medium speed for speed and rapid method for judging a similar speed, not repeated.
3.3 District signal when the high-speed counter CNT47 door area corresponding to the numerical range of pulses, the fat gate area signal. Process flow diagram shown in Figure 4.
Layer signal and the signal level judging method similar to the area, not repeat them.
3.4 pulse signal fault detection
pulse signal and accurate collection and transmission of the system was particularly important for the detection of rotary encoders and pulse transmission circuit failure, design errors and omissions or without pulse signal and pulse detection circuit, real-time detection to ensure system uptime. Pulse count for the elimination of accumulated error, set the reset switch the base station, access to PLC high-speed counter CNT47 reset port 0001.
3.5 works fast for speed limitations, this article only fastWorking principle of introducing speed, ladder shown in Figure 5.
map data storage unit DM01 for the rapid exchange rate from the pulse number, DM30 for the floor space pulses, DM31 for the rapid exchange rate point corresponds to the number of pulses, DM34 for the high-speed change speed Comparison of range limit, DM35 for the relatively high exchange rate upper limit, HR01 starting point for the rapid exchange rate signal, 1507 is fast running signal, 1700 for the selected layer signal, zero speed signal 0010, 0503 exchange rate for fast output.
more acts cases, DM31 rapid exchange rate point corresponds to the number of pulses is the story space DM30 and DM01 for example fast for speed difference; DM31 and DM30 values were assigned to DM34 and DM35. High-speed counter running continuously accumulate pulses, each scan cycle counter value and the DM34 ~ DM35 section for comparison. When its value into the DM34 and DM35 section when, HR01 set, that access to rapid exchange rate interval; if the signal level at this time there are elections and the elevator was fast running, then made quick change speed signal (0503 set ON).
4 Conclusion
in this article control system based on the principles of electrical assembly elections, using pulse counting method, replace the shaft encoder pulse in the original position detection device, to achieve displacement control, using software instead of part of hardware features, while reducing system cost and improve system reliability and security, digital control to achieve lift.
Based on the debug lab, using the above method is indeed on the two 17-story elevator transformation over the past year by the relevant testing and practical operation shows that the system is reliable, comfortable ride, the failure rate greatly reduced, leveling accuracy ± 5mm or less, take a good operating results.