light industry

一、preface
With increasing of crane speed regulating performance requirements in industrial production, the traditional method of crane control such as: wound rotor asynchronous motor rotor series resistance speed, a thyristor tube stator variable voltage speed control and on stepless speed regulation and other common drawback is wound rotor asynchronous motor collector ring and brush, they require regular maintenance, by the collector ring and brush caused by the fault is common, coupled with the use of a large number of relays, contactors, resulting in the field of maintenance in large quantities, the speed control system of the fault rate is higher and poor speed control system of integrated technical indicators, has been unable to meet the special requirements of industrial production.
AC variable frequency speed control technology is widely used in the industrial field, which provides a new scheme for the wide range and high quality speed regulation of the AC asynchronous motor. It has a high performance speed control indicators can be used has the advantages of simple structure, reliable work, maintenance convenient mouse cage asynchronous motor, and efficient, energy saving, the peripheral control circuit is simple, small maintenance workload, improve the function of the monitoring and protection and reliability than the traditional AC adjustable speed system has greatly improved. Therefore, using AC variable frequency speed regulation is the main stream of the development of AC speed regulation technology.
AC variable frequency speed control technology is applied to the crane, and the large number of the use of the traditional winding asynchronous motor rotor series resistance speed control system, can bring the following significant economic benefits and safety and reliability:
(1) the AC variable frequency speed control technology of the crane due to the hard drive inverter motor mechanical properties, with the advantages of accurate positioning, won't appear traditional crane load change motor speed change phenomenon, can improve the productivity of loading and unloading operations.
(2) the frequency conversion crane is running smoothly, start and brake gently, the vibration and shock of the whole machine is significantly reduced, and the safety is improved, and the life of the mechanical part of the crane is prolonged.
(3) mechanical brake at low speed when the motor action, the main hook as well as large, car brake by the electric brake is completed, so the mechanical brake of the brake pad life greatly extended, maintenance costs decreased.
(4) the mouse has the advantages of simple structure, high reliability and cage asynchronous motor instead of winding rotor asynchronous motor, avoid the collector ring and brush wear or corrosion caused by poor contact caused by the fault of motor damage or could not be started.
(5) to reduce the amount of AC contactor, a main circuit of a motor realized control without contact, avoid the contactor frequent contact action and burn out, caused by the contactor contact burning motor damage and failure.
(6) AC variable frequency speed control system can be based on the field situation, flexible adjustment of the speed of the file and add, deceleration time, making the frequency conversion crane operation flexible, good site adaptability.
(7) AC variable frequency speed control system is a high efficiency, high efficiency, high efficiency, low heat loss, so a lot of power saving than the old speed control system.
(8) inverter with perfect protection, monitoring and self diagnosis function, such as the combination of PLC control, can greatly improve the reliability of frequency control system.

 

二、Characteristics of crane operation
(1) crane should have a large starting torque, usually more than 150% of the rated torque, if the consideration of overload and other factors, at least in the starting acceleration process to provide 200% of the rated torque.
(2) because of the existence of a mechanical brake, in order to make the inverter output torque and mechanical brake braking torque smooth handoff, does not produce slip of the hook must be full discussion of inverter starting signal and mechanical brake actuating signal timing control.
(3) when the lifting mechanism is running down or the translation mechanism is urgent to slow down, the motor will be in a state of regenerative power generation, and its energy should be back to the power supply side.
(4) the lifting mechanism is in the grip of lifting heavy load or contact with the sudden change of load on the ground, the inverter should be able to control the impact load.

 

三、Brief introduction of Yi chuangfei ECF500 crane dedicated inverter
1, the main functions and features
Yi Chong fei ECF500 crane special inverter is Shenzhen Yi Chong Fei Electric Co., Ltd. for the lifting industry professional design of a high performance vector frequency converter for all kinds of cranes liters, pitch, amplitude, a cart, a trolley, slewing, grab mechanism of AC stepless speed regulation. The main functions and features are as follows:
(1) a wide range of speed regulation, can achieve precise control of the positioning requirements of the job;
(2) soft start, soft stop function reduces the impact of mechanical transmission, can significantly improve the bearing capacity of the steel structure, and the service life of the crane is prolonged;
(3) brake logic control and monitoring, accurate brake open and close timing control, through brake real-time state feedback and starting pre torque compensation, to ensure the safety and reliability of control.
(4) the light load or speed, realize running speed 2 electronicauxiliary hook or light load, improve the efficiency of loading and unloading. The lifting speed function of light load is mainly applied to the lifting height of the crane, in order to shorten the time to improve the loading and unloading efficiency;
(5) the control circuit power supply and the main circuit power supply can be controlled to improve the safety of the user debugging, easy to fault diagnosis and maintenance.
(6) support MODBUS communication protocol, can realize the communication connection between multiple frequency converters and PLC.
(7) dangerous speed monitoring, fast parking and overspeed protection inverter real-time monitoring of the motor running speed when the motor speed is greater than the set maximum allowable speed or speed deviation value, inverter a fault alarm and immediately stop the output, mechanical brake action, make up heavy machine in a safe state.
Quick stop function to provide users with the following three ways to choose:
Mode 1: electric brake parking;
Way 2: electric braking and mechanical braking of parking;
Mode 3: mechanical brake parking.
(8) pre excitation function is before start automatically on the motor to implement DC excitation, to ensure that the motor quickly provide the starting torque, and through adjusting the time of excitation of the motor starting and mechanical brake release time matched, and avoid the "slip of the hook" phenomenon.
(9) crane operation mode: convenient and flexible
According to crane is different from the mode of operation, for the user provide operation mode in joystick mode, control mode, electric potentiometer mode, grading control rod for a given model, remote control for the given pattern classification, communication given mode.
2, braking function description
Yi Chong Fei ECF500 crane special frequency converter inside the mechanical brake logic sequence control function, as long as the set of parameters can solve the problem of mechanical brake logic. In the application of hoisting equipment, generally existing mechanical braking mechanism, which is mainly taking into account the safety aspects. Lifting mechanism in mechanical braking mechanism hold before and loosen the moment, prone to heavy to decline from the stop state phenomenon (known for the slip hook) to prevent slip hook is bridge crane control system design of safety control link. When the hook lifting stop in mid air, if to rise or fall as action, inverter and control of mechanical braking mechanism, the cooperation between the two is very important; with the bad, there may appear inverter alarm overload or over current), may appear the phenomenon of the slip hook weight. In view of this phenomenon, Yi chuangfei ECF500 crane dedicated inverter specially developed to facilitate the adjustment of parameters. The use of ECF500 inverter multi-function output terminal can be a good solution to this problem.
First set inverter output terminals of Y1 or Y2 for inverter output frequency level detection signal, the output frequency to detect the level of 2Hz. When the crane began work in raising or lowering the mechanical brake must be in the operation of the transducer above 2Hz to open. Mechanical braking must be shut down when the crane is working in the lifting or lowering of the machine when the machine is running at 2Hz.
According to the crane load characteristics, the decentralization of objects is the state of power, in order to decentralization of objects when the converter without creating an overpressure must will release the energy, so the inverter braking unit with, by a braking resistor will energy consumed.
3, the scope of application
Yi a fly ECF500 crane dedicated vector frequency converter, with excellent torque control performance, widely used in quayside container crane (STS), rail mounted gantry container crane (RMG), tyre type container gantry crane (RTG), portal crane, shipbuilding gantry crane, ship loader, unloader, dumper, heap reclaimer, etc. various kinds of port machinery, and all kinds of ordinary bridge, portal, tower crane and gantry crane, erecting machine, such as lifting lifting and luffing, truck, car, rotary, grab etc. mechanism of AC stepless speed regulation.

 

四、Concluding remarks
Through the use of Yi Chong Fei converter to solve the old control system fault rate is high, circuit complexity, cannot smooth speed regulation, maintenance and other ills, and simplify the design, making the electrical control performance to a new level. Its reliability and advanced nature is not comparable to the old speed control system, and its superior performance and price than by the user's welcome.