CN105384084A - Variable-frequency-speed-adjusting control system and method of tower-crane lifting mechanism - Google Patents
Variable-frequency-speed-adjusting control system and method of tower-crane lifting mechanism Download PDFInfo
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- CN105384084A CN105384084A CN201510999515.1A CN201510999515A CN105384084A CN 105384084 A CN105384084 A CN 105384084A CN 201510999515 A CN201510999515 A CN 201510999515A CN 105384084 A CN105384084 A CN 105384084A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
- B66C23/16—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes with jibs supported by columns, e.g. towers having their lower end mounted for slewing movements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C13/00—Other constructional features or details
- B66C13/18—Control systems or devices
- B66C13/48—Automatic control of crane drives for producing a single or repeated working cycle; Programme control
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- Control Of Ac Motors In General (AREA)
Abstract
The invention discloses a variable-frequency-speed-adjusting control system and method of a tower-crane lifting mechanism. The control system comprises a linkage table, a limiting signal collecting device, a PLC, a frequency converter and a speed measurement encoder, wherein the limiting signal collecting device and the frequency converter are connected with the PLC, the frequency converter is connected with the linkage table and a lifting motor of the lifting mechanism, and a control closed loop is formed by the linkage table, the frequency converter, the lifting motor and the speed measurement encoder. Compared with the prior art, the variable-frequency-speed-adjusting control system and method have the advantages that as a current control step-less-speed-adjusting mode is adopted, the zero speed of the tower-crane lifting mechanism can be smoothly and stably increased to the maximum speed under controlling of a driver, the maximum speed of the tower-crane lifting mechanism can be also smoothly and stably decreased to the zero speed under controlling of the driver, and the whole work efficiency and the working stability of a tower crane are improved accordingly.
Description
Technical field
The present invention relates to a kind of tower machine lifting mechanism frequency-converting speed-governing control system and control method.
Background technology
At present, the lifting mechanism of tower crane is for tower machine hangs the driving device that the behavior of carrying provides power, this device is primarily of motor, drop-gear box, reel, and the formation such as lift control system, because tower machine lifting power is large, running velocity is fast, the physical shock produced in speed-change process is larger, with regard to the speed control technology of tower machine lifting mechanism, lifting mechanism many employings motor pole changing speed control and the speed governing of winding rotor motor series resistance, these mode of speed control all can not realize stepless speed control, and impact larger to transmission device, because above-mentioned mode of speed control belongs to full power speed governing, equipment operation energy consumption can be caused large, reliability reduces, fault rate raises, maintenance cost increases, the problem such as difficult in maintenance.In order to overcome these problems, also the variable-frequency control technique having employing more advanced in prior art, but its lifting motor speed governing many employings gear mode, set position frequency, the given frequency of gear is adopted to realize the effect of step frequency conversion, between gear, speed is steps, cannot realize the smooth stepless speed-regulating of lifting motor.
Summary of the invention
In order to overcome the above-mentioned shortcoming of prior art, the invention provides a kind of tower machine lifting mechanism frequency-converting speed-governing control system and control method, adopt current control infinite speed variation mode, make tower machine lifting mechanism under driver's manipulation, stably maximum speed can be raised to smoothly from zero-speed, from maximum speed to zero-speed, adjustment is also identical, which improves complete machine work efficiency and the working stability of tower machine.
The technical solution adopted for the present invention to solve the technical problems is: a kind of tower machine lifting mechanism frequency-converting speed-governing control system, comprise joint action table, limit signal harvester, PLC, frequency converter and speed measuring coder, wherein: described limit signal harvester, frequency converter are connected with PLC respectively, described frequency converter is connected with the lifting motor of joint action table and lifting mechanism respectively, and described joint action table, frequency converter, lifting motor and speed measuring coder form one and control C/LOOP.
Further, described joint action table is also provided with electric current speed adjusting module, for the handle position information of joint action table being converted to the current signal of 4-20mA, enter frequency converter by frequency converter analog input end, frequency converter coding is the corresponding different frequency exported between 0-100Hz respectively.
Further, between PLC and frequency converter, low speed resistance branch is had by low speed resistance loop switch in parallel.
Further, between PLC and frequency converter, reduction of speed resistance branch is had by reduction of speed resistance loop switch in parallel.
Present invention also offers a kind of tower machine lifting mechanism variable frequency regulating speed control method, comprise the steps:
Step one, limit signal harvester send the limit signal collected to PLC;
Step 2, PLC are carried out judging and are sent different control signals to frequency converter according to different judged results, make frequency converter drive lifting motor to perform and rise or down maneuver:
(1) when lift hook position is positioned at superelevation district or ultralow district, then PLC sends signal and makes low speed resistance loop switch connection shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, the rotating speed of lifting motor is reduced;
(2) when lift hook position is positioned at superelevation limiting district and lifting motor is in propradation, then PLC sends signal and makes rising output point cut-out output, thus the forward direction input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down; When lift hook position is positioned at ultralow spacing zone and lifting motor is in decline state, then PLC sends signal decline output point and cuts off output, thus the reverse directions input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down;
(3) when moment exceedes the characteristic maxim of tower crane load, then PLC sends signal and rising output point is cut off export, and the input of frequency converter ascent direction is cut off, and frequency converter is out of service, and frequency converter exports the lifting motor controlled and rises to run and stop;
(4) when frequency converter is operated in 100Hz, and lift heavy is when being greater than 50% of Maximum Loading Capacity, then PLC sends signal and makes the first reduction of speed resistance loop switch connection first shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency reduces, frequency converter automatically switches to 75Hz power frequency and following frequency operation, and the lifting motor rotating speed that frequency converter exports reduces, and lifting motor ascending velocity is maximum is no more than 75HZ;
(5) when frequency converter is operated in 75Hz, and lift heavy is when being greater than 80% of Maximum Loading Capacity, then PLC sends signal and makes the first and second reduction of speed resistance loop switches connect first, second shunt resistance branch road simultaneously, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency continues to reduce, frequency converter automatically switches to 50Hz power frequency and following frequency operation, the lifting motor rotating speed that frequency converter exports reduces, and lifting motor ascending velocity is maximum is no more than 50Hz;
(6) when frequency converter is operated in 50Hz, and lift heavy is when being greater than 110% of Maximum Loading Capacity, then PLC sends signal rising output point and cuts off and export, thus the forward direction input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down.
Further, when lift hook position distance superelevation district or ultralow district less than one meter and the speed of lifting motor is fast state time, then PLC sends signal and makes low speed resistance loop switch connection shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, the rotating speed of lifting motor is reduced.
Further, described frequency converter to the shifting control method of lifting motor is: the real-time rotate speed being detected lifting motor by speed measuring coder, feed back to frequency converter, realize velocity close-loop control, according to speed measuring coder, frequency converter is detected that the goal pace that the actual speed of motor and the analog input end of frequency converter produce compares, when the actual speed of lifting motor is lower than goal pace, frequency converter continues to increase rate-adaptive pacemaker, makes the actual speed of lifting motor continue to increase; Final when the actual speed of lifting motor is consistent with goal pace, frequency converter frequency stable output also keeps, and the position of frequency and the joint action table handle kept is matched.
Compared with prior art, good effect of the present invention is:
1, the size of joint action table control handle determining positions outgoing current, and directly control frequency converter frequency output.
2, can change as required through frequency converter frequency after power supply input.
3, infinite speed variation: the flatness increasing speed governing, increase speed adjustable range, adjusting speed accuracy is high, and efficiency is fast; Speed change is steady, nothing is impacted, and greatly can improve the service condition of lifting mechanism and steel structure, improve the safety in operation of tower machine.
4, during starting current low, speed change, curent change is little, and impact little to building site electrical network, alleviate the burden of consumer networks dilatation, power savings is obvious.
5, implementation procedure Automated condtrol is easy to.
6, can select to set speed adjustable range, improve the work efficiency of tower machine, energy-conservation mode of speed control, decrease system cloud gray model energy consumption.
7, zero-speed band-type brake, and the wearing and tearing to drg can be reduced.
8, lifting mechanism adopts the frequency control of current control can set lower seating velocity, for accurate lifting.
Accompanying drawing explanation
Examples of the present invention will be described by way of reference to the accompanying drawings, wherein:
Fig. 1 is structural representation of the present invention.
Detailed description of the invention
A kind of tower machine lifting mechanism frequency-converting speed-governing control system, as shown in Figure 1, comprising: joint action table 1, limit signal harvester 2, PLC 3, frequency converter 4, speed measuring coder 5, lifting motor 6, reductor 7, cylinder 8 etc.; Wherein:
Limit signal harvester 2, frequency converter 4 are connected with PLC 3 respectively, and joint action table 1, frequency converter 4, lifting motor 6, speed measuring coder 5 form one and control C/LOOP; Lifting motor 6, reductor 7, cylinder 8 are lifting mechanism.
Described limit signal harvester 2 is the devices for the lead limit switch signal of the stroke and limit position limitation protection that gather tower machine mechanism running state in tower machine equipment operational process; Its formation comprises: the train of gears of band drive coupling, cam set, travel switch; By the no-load voltage ratio relation of train of gears being fed back to by the operation travel conditions of control object in cam running, with the turned position impact stroke switch of cam, travel switch contact action (open or close) transmission of signal is to controller; Its principle of work is: limit signal harvester is arranged on prearranged position, when being loaded on the module impact stroke switch on elevator machinery movable parts or because of stressed generation distorted movement, and the contact action of lead limit switch, the switching of realizing circuit.Therefore, limit signal harvester be a kind of according to the travel position of movable parts the electrical equipment of commutation circuit, its action principle and button similar.Limit switch is widely used in all kinds of lathe and elevator machinery, in order to control its stroke, to carry out terminal position limitation protection.In the control circuit of tower machine; with limit signal harvester input PLC; logic operation output control loop through PLC controls frequency converter and exports, and then changes the speed of lifting mechanism motor, reaches the upper and lower spacing protective effect to lifting mechanism and safe operation effect.
Described joint action table 1 is also provided with electric current speed adjusting module, for the handle position information of joint action table being converted to the current signal of 4-20mA, frequency converter is entered by frequency converter analog input end, frequency converter coding is the corresponding different frequency exported between 0-100Hz respectively, thus make frequency converter drive lifting motor running, lifting motor performs and rises or down maneuver, realizes the stepless change of lifting motor.
Described speed measuring coder 5 detects the real-time rotate speed of lifting motor 6, feeds back to frequency converter 4, realizes velocity close-loop control; Wherein frequency converter detects the actual speed of motor according to speed measuring coder 5, and the goal pace that the analog input end that the outgoing current of the electric current speed adjusting module determined with joint action table handle position enters into frequency converter produces compares; When the actual speed of lifting motor is lower than goal pace, frequency converter continues to increase rate-adaptive pacemaker, makes the actual speed of lifting motor continue to increase; Final when the actual speed of lifting motor is consistent with goal pace, frequency converter frequency stable output also keeps; And the position of the frequency of this maintenance and joint action table handle is identical.When PLC3 detects the direction instruction of rising or decline, the limit signal collected in conjunction with limit signal harvester 2 carries out comprehensive descision, PLC3 sends rising or dropping signal to frequency converter 4, frequency converter 4 drives lifting motor 6, rising or down maneuver is performed, the closed loop control process of lifting mechanism system that Here it is by lifting motor 6.
Present invention also offers a kind of tower machine lifting mechanism variable frequency regulating speed control method, comprise the steps:
Step one, limit signal harvester 2 send the limit signal collected to PLC 3:
Described limit signal comprises: the lift hook position (hereinafter referred to as lift hook position) of tower machine, suspension hook load-bearing center-point are to moment (hereinafter referred to as moment), tower machine suspension hook lift heavy (hereinafter referred to as the lift heavy) limit signal of tower machine tower body center-point.
Step 2, PLC 3 are carried out judging and are sent different control signals to frequency converter 4 according to different judged results, make frequency converter drive lifting motor 6 to perform and rise or down maneuver:
1, when lift hook position is positioned at superelevation district (apart from tower machine large arm 2 meters to 1 meter) or ultralow district (overhead 1.5 meters to 0.5 meter), then PLC sends signal and makes low speed resistance loop switch connection shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, the rotating speed of lifting motor is reduced;
When lift hook position distance superelevation district or ultralow district less than one meter and the speed of lifting motor 6 is fast state time (75 ms/min-100 ms/min), become low speed by mode above equally.Like this from the effect of practice, just make the position of the tower machine fast close rising limit or falling-threshold about 1 meter in rising or decline process, reliably slow down, play the effect of deceleration position limitation protection; Tower machine suspension hook lift heavy is in the danger of rising or effectively avoid the error of the driver inertia that deceleration-operation does not cause to rush to summit or contact to earth in decline process.
2, when lift hook position is positioned at superelevation limiting district (apart from tower machine large arm 1 meter to 0.5 meter) and lifting motor is in propradation, then PLC sends signal rising output point and cuts off output, thus the forward direction input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down; Only to carry out step-down operation.
When lift hook position is positioned at ultralow spacing zone (overhead less than 0.5 meter) and lifting motor is in decline state, then PLC sends signal decline output point and cuts off output, thus the reverse directions input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down; Only to carry out lifting operations.
3, when moment exceedes the characteristic maxim of tower crane load (such as: lifting brachium 60 meters, the biggest lifting capacity is the tower crane load characteristic curve maxim of 6 tons: work as (13.84*6=83.04) ton rice amplitude 3 meters to 13 meters, work as (60*1.05=63) ton rice in amplitude 60 meters of ends), then PLC sends signal rising output point and cuts off output, the input of frequency converter ascent direction is cut off, frequency converter is out of service, and frequency converter exports the lifting motor rising controlled and runs stopping; Only to carry out step-down operation.
4, when frequency converter is operated in 100Hz, and lift heavy is when being greater than 50% of Maximum Loading Capacity, then PLC sends signal and makes the first reduction of speed resistance loop switch connection (PLC3 being defined as the output point of 1 reduction of speed) first shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency reduces, frequency converter automatically switches to 75Hz power frequency and following frequency operation (middling speed operation), the lifting motor rotating speed that frequency converter exports reduces, and lifting motor ascending velocity is maximum is no more than 75HZ;
When frequency converter is operated in 75Hz, and lift heavy is when being greater than 80% of Maximum Loading Capacity, then PLC sends signal and makes the first and second reduction of speed resistance loop switches connect (output point PLC3 being defined as 1 reduction of speed and 2 reductions of speed) first simultaneously, second shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency continues to reduce, frequency converter automatically switches to 50Hz power frequency and following frequency operation (low cruise), the lifting motor rotating speed that frequency converter exports reduces, lifting motor ascending velocity is maximum is no more than 50Hz, make lift heavy rising or falling speed run according to standard like this, ensure safety.
When frequency converter is operated in 50Hz, and lift heavy is when being greater than 110% of Maximum Loading Capacity, then PLC sends signal rising output point and cuts off output, thus the forward direction input of frequency converter is cut off, frequency converter is out of service, frequency converter exports the lifting motor controlled and shuts down (forbid rising and run, only to carry out step-down operation).
Principle of work of the present invention is:
The first, present system is when carrying out infinite speed variation, and position limitation protection function process, operational process are as follows:
Above-mentioned whole system, in driver operation tower machine operational process, the lift hook position of tower machine, or suspension hook load-bearing center-point is to the moment of tower machine tower body center-point, or when tower machine suspension hook lift heavy exceedes the value specified according to tower machine design regulation in advance, trigger the travel switch on limit signal harvester 2, limit signal harvester 2 collects (position, moment, lift heavy) limit signal also does following multilevel iudge from the input of PLC3 signal input part PLC3, PLC3 by built-in logic control program by circuit:
1, slow down or ultralow deceleration when PLC3 receives position limit signal such as the superelevation that limit signal harvester 2 collects, then PLC3 plug-in judges to export low speed, then low speed resistance loop switch connection (PLC3 being defined as the output point of low speed) shunt resistance branch road, makes the electric current entering frequency converter Analog control loop reduce according to the flow-blocking relationship of parallel shunt; If the motor speed of lifting mechanism is in fast state before PLC3 receives superelevation deceleration or ultralow deceleration, become low speed equally; Like this from the effect of practice, just make the position of the tower machine fast close rising limit or falling-threshold about 1 meter in rising or decline process, reliably slow down, play the effect of deceleration position limitation protection; Tower machine suspension hook lift heavy is in the danger of rising or effectively avoid the error of the driver inertia that deceleration-operation does not cause to rush to summit or contact to earth in decline process.In like manner, when PLC3 receives position limit signal that limit signal harvester 2 collects as superelevation limiting or ultralow spacing, then PLC3 plug-in judges rising or down maneuver stopping at once, PLC3 rising output point or decline output point cut off and export, PLC3 rising output point or decline output point are linked into the rotating direction input end of frequency converter, the input of frequency converter direction is cut off, and frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down.
2, when PLC3 receives the moment limit signal that limit signal harvester 2 collects, then PLC3 plug-in judges to stop rising, PLC3 Logic judgment cuts off to rise and exports, PLC3 rising output point is linked into the direction input end of frequency converter, the input of frequency converter ascent direction is cut off, frequency converter is out of service, and frequency converter exports the lifting motor rising controlled and runs stopping, only to carry out step-down operation.
3, when PLC3 receives the lift heavy limit signal " superhigh frequency weight limit 50% " that limit signal harvester 2 collects, then the motor ascending velocity of PLC3 Logic judgment lifting mechanism is maximum is no more than 75HZ, reduction of speed resistance loop switch 1 is connected (output point PLC3 being defined as 1 reduction of speed), shunt resistance branch road, the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency also reduces, and the lifting motor rotating speed that frequency converter exports reduces.In like manner, when PLC3 receives the lift heavy limit signal " overclocking weight limit 80% " that limit signal harvester 2 collects, then the motor ascending velocity of PLC3 Logic judgment lifting mechanism is maximum is no more than 50Hz, reduction of speed resistance loop switch 1, switch 2 are all connected (output point PLC3 being defined as 1 reduction of speed and 2 reductions of speed), two resistance branch in parallel, the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency continues to reduce, and the lifting motor rotating speed that frequency converter exports reduces.When PLC3 receives the lift heavy limit signal " power frequency weight limit 110% " that limit signal harvester 2 collects; then the Motor disable of PLC3 Logic judgment lifting mechanism rises; rising stop-working protection; PLC3 Logic judgment cuts off to rise and exports; PLC3 rising output point is linked into the direction input end of frequency converter; the input of frequency converter ascent direction is cut off, and frequency converter is out of service, and frequency converter exports control lifting motor and forbids that rising runs.
By above-mentioned detailed annotation position limitation protection function process, operational process; Ensure the safe operation of tower machine in normal use procedure.
In the course of the work, speed measuring coder 5 detects the real-time rotate speed of lifting motor 6 to tower machine rising-falling tone speed control system of the present invention, feeds back to frequency converter 4, realizes velocity close-loop control; Wherein frequency converter detects the actual speed of motor according to speed measuring coder 5, and the goal pace that the analog input end that the outgoing current of the electric current speed adjusting module determined with joint action table handle position enters into frequency converter produces compares; When the actual speed of motor is lower than goal pace, frequency converter continues to increase rate-adaptive pacemaker, makes the actual speed of motor continue to increase; Final when the actual speed of motor is consistent with goal pace, frequency converter frequency stable output also keeps; And the position of the frequency of this maintenance and joint action table handle is identical.When PLC3 detects the direction instruction of rising or decline, the limit signal collected in conjunction with limit signal harvester 2 carries out comprehensive descision, PLC3 sends rising or dropping signal to frequency converter 4, frequency converter 4 drives lifting motor 6, rising or down maneuver is performed, the closed loop control process of lifting mechanism train of mechanism that Here it is by lifting motor 6.
Second, present system is when carrying out infinite speed variation, tower machine driver operation joint action table handle, send the different electric currents between (4-20mA) through excess current speed adjusting module, enter frequency converter by frequency converter analog input end, frequency converter coding is the corresponding different frequency exported between 0-100Hz respectively, frequency converter drives lifting motor running, lifting motor performs and rises or down maneuver, realizes the stepless change of lifting motor, raises the efficiency; And when high-grade speed governing, motor is with output-constant operation, be embodied in: the value obtained when this value of rated speed of rotation is motor idle running, this value for our meaning is, when reaching rated voltage and rating horsepower, this value is larger, and Driving Torque is less, and this is exactly a feature of speed control by constant power.Formula T=9550*P/N (rated speed of rotation).So when F>50HZ, (this time has exported as maximum power), we make N become large in, notice that T is diminishing, T be avoided too little and be less than load torque causing accident.When speed control by constant power, we reach reduction Driving Torque by reducing magnetic flux, thus the such process improving speed carrys out speed governing, so this is also weak-magnetic speed-regulating.When F≤50HZ, namely under speed control by constant torque, we also only need the voltage of the certain frequency being conveyed through modulation by frequency converter to motor, and (this is than being magnetic flux, a definite value), the torque of load is also a definite value, so N is certain, and T is certain, and the power P of input is also just fixed.If F increases, rotating speed N increases, and so power P also just becomes large, because torque T can not become large because speed increases.The feature of constant torque load is that load torque and rotating speed have nothing to do, and under any rotating speed, torque always keeps constant or substantially constant.Invariable power district and the permanent torque district selection on transmission scheme of load has impact, and electrical motor, when permanent magnetic flux speed governing, maximumly allows that Driving Torque is constant, belongs to speed control by constant torque; And when weak-magnetic speed-regulating, maximumly allow that Driving Torque and speed are inversely proportional to, belong to speed control by constant power.If when the scope of the permanent torque of electrical motor and speed control by constant power is consistent with the permanent torque of load and invariable power scope, namely when so-called " coupling ", the capacity of electrical motor and the capacity of frequency converter all minimum.When speed control by constant power refers to motor low speed, Driving Torque is large, and during high speed, Driving Torque is little, and namely horsepower output is constant; Speed control by constant torque refer to motor at a high speed, low speed time Driving Torque equally large, namely during high speed, horsepower output is large, and during low speed, horsepower output is little.
The present invention has following features:
1, the joint action table of current control mode is used.Increase the joint action table of electric current speed adjusting module, the handle position information of joint action table can be converted to the current signal of 4-20mA, these current signals can enter the analog input end signal of frequency converter, become frequency converter speed command signal.The joint action table of current control mode is that tower machine rising-falling tone speed control method implements one of necessary requirement controlled,
2, according to lifting mechanism job requirement PLC program.Lifting mechanism tower machine operation operating needs: along with the handle signal of tower machine driver operation joint action table, provide rising or decline instruction; PLC receives this instruction, and PLC controls according to following logical relation; Rise or down maneuver signal, produce intermediate state signals in running, judge be elevated whether in a safe condition and provide instruction; If safety, then time delay obtain the lifting frequency conversion band-type brake feedback signal of frequency converter, logic exports panel system moving winding and self-sustaining; Logically prevent reverse-starting braking operation maloperation from causing adverse consequences, carry out weight limit judgement, carry out judgement of transfiniting again in addition, carry out the judgement of band-type brake logic fault, carry out external fault judgement.
3, converter parameter is set, comprises size of current corresponding output frequency, electric motor protecting setting value and working parameter etc.A setting parameter mode has closed loop and open loop, vector controlled, and V/F controls; Purposes is chosen as and hoists; The given DC injection braking of B parameter starts frequency, DC injection braking time during startup; C setting parameter Acceleration and deceleration time, carrier frequency; D setting parameter frequency instruction; E setting parameter frequency converter input voltage, the highest output frequency, the parameter of electric machine; F parameter PG is conventional to be arranged; H setting parameter function terminal; Joint action table handle signal is after excess current speed adjusting module enters frequency converter, and the limit signal access PLC of limit signal collector, frequency converter just runs according to the mode of relevant parameters, carries out judging and processing, and exports and controls lifting motor.
4, to collect through limit signal collector according to lift heavy and driver operation joint action table handle position and send to PLC, through the multilevel iudge of PLC, internal logic computing, output, in conjunction with the setting of frequency converter, Integrated comparative judges to adjust to export to the current control speed way of output of lifting motor.
For frequency converter lifting mechanism: when frequency converter is operated in 100Hz, if PLC receives the signal that super power frequency lifting is greater than 50% Maximum Loading Capacity, then PLC controls to output to frequency converter through logic operation, and frequency converter automatically switches to 75Hz power frequency and following frequency operation (middling speed operation).
For frequency converter lifting mechanism: when frequency converter is operated in 75Hz, if PLC receives the signal that super power frequency lifting is greater than 80% Maximum Loading Capacity, then PLC controls to output to frequency converter through logic operation, frequency converter automatically switches to the work of 50Hz power frequency and following frequency operation (low cruise), make lift heavy rising or falling speed run according to standard like this, ensure safety.
For frequency converter lifting mechanism: when frequency converter is operated in 50Hz, if PLC receives the signal that super power frequency lifting is greater than 110% Maximum Loading Capacity, then PLC controls to output to frequency converter through logic operation, and frequency converter is forbidden rising and exported; But decline instruction can be accepted; the output that declines is had (to forbid rising; have decline only); decline output is under weight in excess load; the embodiment of the defencive function of mechanism and using state, can not make tower machine work when transition overloads operation, when simultaneously to normal working limit load carrying ability like this; the sudden moment overload situations occurred, plays safety guard-safeguard effect.
Advantage of the present invention instead of backward electric machine speed regulation pattern as the speed governing of winding rotor motor series resistance in the frequency control that use is advanced, lifting motor all can accomplish seamlessly transitting of speed from zero velocity to operation maximum speed, to mechanism and framing member without impact, improve the safety in operation of tower machine; Lower starting current, owing to employing variable frequency starting mode, the starting current of variable-frequency motor can be made to drop to 3 Amps, starting current lower like this, good protective effect is had to motor, play the effect of flexible control, in like manner lower starting current can not produce large impact to supply line, alleviates the burden of consumer networks dilatation; Can select and can set tower machine lifting mechanism frequency control scope, the electric current of general corresponding 4-20mA exports 0-100Hz frequency, and the higher rising or falling speed of frequency is faster, the conventional speed adjustable range of lifting mechanism tower machine frequency control that Here it is; Which enhance the work efficiency of tower machine, can change according to different actual needs and speed adjustable range is set, as the tower machine according to different tonnage can set different high speeds, middling speed, low speed limit value; Energy-conservation mode of speed control, just because of have employed frequency control, such electric power acting is not wasted, can not unnecessary waste of energy in heating, size needed for actual conditions moment, under the situation instruction that various limit signal gathers, the motor running frequency of lifting mechanism is adjustable, decreases system cloud gray model energy consumption; In operational process, when lifting mechanism needs certain position in the process be elevated to stop according to the requirement of work, need to stop lifting action, rising or falling speed reduces to zero; When speed reduces to the moment of zero, lifting action steadily stops, and band-type brake function is enabled, and is exactly zero-speed band-type brake, like this promote weight can not slip hook glide; Safety when failure-free zero-speed band-type brake function makes tower machine lifting mechanism in use ensure that load, extremely important and merit attention, and the wearing and tearing to drg can be reduced; Lifting mechanism adopts the frequency control of current control can set lower seating velocity, can be low to moderate the seating velocity of 0.01m/s, and for accurate lifting.
Claims (7)
1. a tower machine lifting mechanism frequency-converting speed-governing control system, it is characterized in that: comprise joint action table, limit signal harvester, PLC, frequency converter and speed measuring coder, wherein: described limit signal harvester, frequency converter are connected with PLC respectively, described frequency converter is connected with the lifting motor of joint action table and lifting mechanism respectively, and described joint action table, frequency converter, lifting motor and speed measuring coder form one and control C/LOOP.
2. tower machine lifting mechanism frequency-converting speed-governing control system according to claim 1, it is characterized in that: described joint action table is also provided with electric current speed adjusting module, for the handle position information of joint action table being converted to the current signal of 4-20mA, enter frequency converter by frequency converter analog input end, frequency converter coding is the corresponding different frequency exported between 0-100Hz respectively.
3. tower machine lifting mechanism frequency-converting speed-governing control system according to claim 1, is characterized in that: between PLC and frequency converter, have low speed resistance branch by low speed resistance loop switch in parallel.
4. tower machine lifting mechanism frequency-converting speed-governing control system according to claim 1, is characterized in that: between PLC and frequency converter, have reduction of speed resistance branch by reduction of speed resistance loop switch in parallel.
5. a tower machine lifting mechanism variable frequency regulating speed control method, is characterized in that: comprise the steps:
Step one, limit signal harvester send the limit signal collected to PLC;
Step 2, PLC are carried out judging and are sent different control signals to frequency converter according to different judged results, make frequency converter drive lifting motor to perform and rise or down maneuver:
(1) when lift hook position is positioned at superelevation district or ultralow district, then PLC sends signal and makes low speed resistance loop switch connection shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, the rotating speed of lifting motor is reduced;
(2) when lift hook position is positioned at superelevation limiting district and lifting motor is in propradation, then PLC sends signal and makes rising output point cut-out output, thus the forward direction input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down; When lift hook position is positioned at ultralow spacing zone and lifting motor is in decline state, then PLC sends signal decline output point and cuts off output, thus the reverse directions input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down;
(3) when moment exceedes the characteristic maxim of tower crane load, then PLC sends signal and rising output point is cut off export, and the input of frequency converter ascent direction is cut off, and frequency converter is out of service, and frequency converter exports the lifting motor controlled and rises to run and stop;
(4) when frequency converter is operated in 100Hz, and lift heavy is when being greater than 50% of Maximum Loading Capacity, then PLC sends signal and makes the first reduction of speed resistance loop switch connection first shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency reduces, frequency converter automatically switches to 75Hz power frequency and following frequency operation, and the lifting motor rotating speed that frequency converter exports reduces, and lifting motor ascending velocity is maximum is no more than 75HZ;
(5) when frequency converter is operated in 75Hz, and lift heavy is when being greater than 80% of Maximum Loading Capacity, then PLC sends signal and makes the first and second reduction of speed resistance loop switches connect first, second shunt resistance branch road simultaneously, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, frequency converter output frequency continues to reduce, frequency converter automatically switches to 50Hz power frequency and following frequency operation, the lifting motor rotating speed that frequency converter exports reduces, and lifting motor ascending velocity is maximum is no more than 50Hz;
(6) when frequency converter is operated in 50Hz, and lift heavy is when being greater than 110% of Maximum Loading Capacity, then PLC sends signal rising output point and cuts off and export, thus the forward direction input of frequency converter is cut off, frequency converter is out of service, and frequency converter exports the lifting motor controlled and shuts down.
6. tower machine lifting mechanism variable frequency regulating speed control method according to claim 5, it is characterized in that: when lift hook position distance superelevation district or ultralow district less than one meter and the speed of lifting motor is fast state time, then PLC sends signal and makes low speed resistance loop switch connection shunt resistance branch road, thus the electric current entering frequency converter Analog control loop is reduced according to the flow-blocking relationship of parallel shunt, the rotating speed of lifting motor is reduced.
7. tower machine lifting mechanism variable frequency regulating speed control method according to claim 5, it is characterized in that: described frequency converter to the shifting control method of lifting motor is: the real-time rotate speed being detected lifting motor by speed measuring coder, feed back to frequency converter, realize velocity close-loop control, according to speed measuring coder, frequency converter is detected that the goal pace that the actual speed of motor and the analog input end of frequency converter produce compares, when the actual speed of lifting motor is lower than goal pace, frequency converter continues to increase rate-adaptive pacemaker, makes the actual speed of lifting motor continue to increase; Final when the actual speed of lifting motor is consistent with goal pace, frequency converter frequency stable output also keeps, and the position of frequency and the joint action table handle kept is matched.
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| CN115490153A (en) * | 2022-10-27 | 2022-12-20 | 徐州建机工程机械有限公司 | Tower crane lifting frequency conversion all-in-one machine and control method thereof |
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