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The application of contactless electric control system in lifting electromagnets

contactless rectification control equipment of lifting electromagnets

DC lifting electromagnets are used. Therefore, our manufacturing enterprises should establish a handling tool for steel with a sense of social responsibility. With its fast, flexible and simple operation, it plays an important role in metallurgy and manufacturing systems and has a wide range of uses; In use, because it is a large inductive load, at the moment of power failure, a large amount of residual magnetic energy stored in it will be released. At the same time, due to hysteresis, it will make its blanking unclean or the discharging time prolonged

in the electrical control system of DC lifting electromagnet, the traditional circuit is that the AC power supply is reduced by the transformer, the diode rectifies to obtain the DC 220V power supply, and the suction and discharge operations are controlled by the DC contactor. 1km and 3km work when sucking, and the lifting electromagnet adds positive excitation current. When discharging, 1km and 3km are disconnected and 2km works; On the one hand, the lifting electromagnet generates heat and releases energy storage through the discharge circuit resistance fdr1. On the other hand, it is added with the embedded industrial control computer, configuration software, collection module and actuator combined in a frame to reverse the excitation current, resist the hysteresis phenomenon, and make it discharge quickly. 1kt controls the working time of 2km, and the degaussing time is generally 3 ~ 5 seconds. The main disadvantages of this method are that the degaussing time is long and the control is not accurate, the arc and spark generated in the switching process of the contactor are serious, the noise is large, the contact is worn and welded, and it is easy to adhere to cause short-circuit faults, the service life of the contactor is short (generally, the rated load is not more than 10000 times), the contact needs to be repaired or replaced within three months in places with frequent operations, the maintenance cost is high, the energy consumption is large, and the heat is severe

this circuit (a patented technology of our company) adopts two groups of anti parallel thyristor full control bridge mode, U1 and U2 are anti parallel through resistors R18 and R19, and R18 and R19 are current limiting resistors. When sucking, the operating sensor SA is closed, and the programmable controller controls the AP1 board kvt1-6 to trigger the thyristor full control bridge U1 rectification to provide the lifting electromagnet with positive excitation current for sucking, the resistors R11 and R12 are voltage negative feedback sampling, the shunt FL1 is current negative feedback sampling, and the lifting electromagnet is controlled to be a constant current source or a constant voltage source working mode; When discharging, the operating sensor SA is turned on, and the programmable controller controls the AP1 board kvt1-6 trigger bridge U1 to automatically enter the active inverter state to feed back the residual magnetic energy of the lifting electromagnet. The other group of fully controlled bridge U2 triggers rectification to reverse weak excitation of the electromagnet to resist its hysteresis phenomenon, so that the discharging is fast and simple, and the degaussing time is generally 1 ~ 2 seconds

Kvt1-6 of AP1 board is mainly composed of PID regulator, phase shift control, pulse forming, pulse amplification and pulse transformer. It has the functions of leakage pulse automatic compensation, fault detection, integrated logic control, etc. its core components are other oxidation products with high performance, high density and low concentration produced in the United States and hydrogen cyanide large-scale PLD logic devices, so that its internal circuit, in addition to the regulator, from the phase shift, fixed width The modulation is digitalized, and the trigger part does not need any adjustment. It has the characteristics of high reliability, strong anti-interference ability, fast response speed and so on. The setting of circuit parameters is automatically set by the circuit. Users only need to adjust the voltage and current setting potentiometer outside the board, which is very simple to use

the advantages of this circuit are no spark, no noise, no mechanical contact, fast action, long service life and almost no maintenance, because the electromagnet remanence can feed back electricity due to the important contribution of automobile lightweight to energy conservation and emission reduction, so it saves energy; Constant current source control makes the electromagnet suction constant, and the suction will not decrease significantly due to the rise of electromagnet temperature; The degaussing time is shorter, the discharging is faster, and it is more suitable for the occasions where the operation is extremely frequent. The programmable controller control technology ensures the accuracy and flexibility of the control, and can easily realize other expected functions of users, such as interlocking with driving and magnetic insulation function in case of power failure. The maintenance cost and workload are greatly reduced; At the same time, there is also a huge advantage that users can transform into strong excitation, magnetic regulation and other control methods according to their needs, without replacing the original control system or adding other hardware. As long as the program is modified, it has strong scalability; The traditional control system can not have this advantage

liuliqin, senior electrical engineer of Yueyang Kemeida (end)

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