1 Introduction
With 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 lives. Current elevator control two commonly used methods, first microcomputer as a signal control unit, Wan Cheng elevator signal acquisition, ¨¨??¨¨?? status and functioning, Sheding, to achieve the elevator systems within Collective selective operation functions, drag the control from inverter to complete; the 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 two methods are not much different. Most domestic manufacturers to choose second way, the reason lies in the production of smaller, their own design and manufacture of high cost of computer control devices; the PLC reliable, convenient and flexible program design. The design of PLC control in the use of frequency control for current, speed, based on double closed loop, without additional hardware conditions, for current, velocity, displacement loop control.
2 hardware
system hardware structure shown in Figure 1, the function of each are described below.
Q1 - 8-string three-phase power circuit diagram
K1-- Power control contactor
K2 - the load off motor control contactor
VS - converter
BU - brake unit
RB - braking resistor
M - the 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. As a result of AC - DC - AC voltage inverter, the load potential role in the elevator, the braking energy can feed back to back grid, to limit the pumping voltage, using controlled braking means.
2.2 PLC control circuit
use OMRON Corporation C Series 60P type PLC. PLC receives from the operation panel and the ladder on each call box call signal, the functions car and door systems and wells, and the signal state of signal transducer, to judge by the procedures and operations to achieve control of the elevator assembly election. PLC in the output display and control signal while the direction to the Inverter issue run, start, add / deceleration operationLadder brake line and stop signals.
2.3 current, speed, dual-loop circuit
use YASAKWA s VS-616G5 CIMRG5A 4022 inverter. Inverter with current sensing device itself, which constitutes the current loop; through and motor coaxial rotary encoder connected to produce a, b two-phase pulse into the transducer, the direction in identifying the same time, constitute a closed loop speed pulse counting.
2.4 Displacement Control circuit
manned elevator as a tool for site 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 constitute a speed loop, while the PG card through inverter output and motor speed and lift the number of pulses proportional to displacement, to the introduction of PLC high-speed counting input 0000 through the accumulated number of pulses by the World-style (1) calculate the pulse equivalent and, thus, the lift position. Elevator displacement
h = SI
String 7
The formula I - total number of pulses
S - pulse equivalent
S = lpD / (pr) (1)
reducer used in this system, the reduction ratio l = 1 / 32, sheave diameter D = 580mm, motor rated speed ned = 1450r/min, rotary encoder pulses per revolution corresponds to p = 1024, PG card division ratio r = 1 / 18, substituting into equation (1) was
S = 1.0mm / pulse
3 Programming
PG card using inverter output (TA2.1) the pulse signal into a high-speed counting input of the PLC 0000, constitute the position feedback. High-speed counter (CNT47) cumulative number of pulses reflects the location of the lift. The value of continuous high-speed counter with the signal points compared with the numbers corresponding to the pulses, resulting from the operation of the elevator, for speed points, leveling points for electricity and parking brake signal. Theoretically, this control method the error of their leveling B11 pulse equivalent in scope. In considering the meshing gear reducer case of mechanical factors such as space, elevator leveling accuracy up to B15mm, the significantly lower than the national standard B115mm standards, to meet the smooth starting and braking the lift, run flatStable, accurate leveling requirements. Lift during operation, by position signal detection, Real-time calculation of the following position signal: lift position where the floor, fast-for-speed point, the speed-for-speed point, the door zone signal level position signals of peace. Thus eliminating the need for each level in the shaft in the original set of the signal detection device, greatly reducing the shaft and the signal detection device to connect and reduce costs. The following set of elections for the realization of control based on the new counts added to the floor, fast-for-speed, medium speed for speed, gate signal 5 sub-district level peace process are introduced.
3.1 Floor count
the design of the relative counting method. Before running through the self-learning, measure the floor height of the corresponding pulse number, corresponding to the 17th floor elevator into 16 memory units, respectively DM06 ~ DM21.
floor counter (CNT46) is a two-way counter, when reaching the floor count points on each floor, under the direction of running or minus 1 to plus 1 count. Floor count process flow diagram shown in Figure 2.
running, high-speed counter and floor count of the cumulative value of real-time point compared with the numbers corresponding to the pulses, when the issue of equal floor count signal, up by 1, down by 1. To prevent the counter in the count during the high pulse repetition count, along with floor count signal to trigger floor counter.