I. Analysis of the original system: The 26-ton gantry crane is a lifting and handling equipment used to lift, lower and carry heavy objects and move the heavy objects horizontally within a certain distance. It has an important application in the production process. 26 tons gantry crane, the original equipment electrical drive system is divided into crane lift, car, cart three parts. The lifting of the crane is driven by a 55kW ac induction motor, which consists of four 11 kW ac induction motors and a trolley driven by two 4.0 kW ac induction motors. In the original transmission control, due to the poor working environment, dust and harmful gases are corrosive to the motor's collector rings, brushes, and contactors. In addition to heavy work tasks, the actual overload rate is high. Because of the large inrush current, it is easy to cause the motor. Burning of contacts, igniting of brushes, burning and breakdown of resistors in series of motors and rotors, etc., affecting on-site production and safety. Workers' maintenance costs and resulting maintenance costs are high, and the original speed control mode has poor mechanical properties. The speed is not smooth enough, and the string of resistors waste heat for a long period of time. In summary, the main drawbacks of the original equipment are as follows: (1) The capacity of the drag motor is large, the current at the start of the power system has a large impact on the power grid, and the electrical energy is wasted. (2) The lifting and lowering of cranes, trolleys, and carts are too quick to start and stop, and they are all inertial loads. The mechanical impact is also large, the service life of mechanical equipment is shortened, the safety factor of operators is poor, and the reliability of equipment operation is low. (3) Since the motor is always operated at the rated torque, the load of each lift is changed, and thus it is easy to cause a relatively large amount of wasted electric energy. (4) The crane needs a lot of loading and unloading operations every day. Because the speed regulation of the winding motor is through the main control element in the electric drive system---AC contactor to connect and disconnect the series resistance of the motor rotor, switch Very often, in the relatively large current state, it is easy to burn out the contacts. At the same time, due to the harsh working environment, the copper resistance of the rotor circuit is often burned out and broken due to dust, equipment vibration and other reasons. Therefore, the equipment failure rate is relatively high and the maintenance workload is relatively large. The same problem exists with the operation of trolleys and carts. (5) At the moment when the crane is lifted, the lifting motor sometimes suffers from non-uniform force and is easily overloaded, which directly results in damage to the motor or wire rope breakage. (6) In order to adapt to the working conditions of the crane, the crane operator often operates repeatedly, the electrical components of the crane and the electric motor are always in a large current working state, which reduces the service life of the electrical components and the motor. (7) The coordination of crane work depends mainly on the proficiency of the operators. Because there is no fixed connection between the three cam controllers of the lift, the cart, and the trolley, the labor intensity of the operator during the operation of the crane is relatively large, it is easy to fatigue, and misoperation is easy to occur. In view of the deficiencies of the above-mentioned existing technologies, the cranes used in this transformation adopt advanced programmable control technology (PLC) and frequency converter technology to replace relay----contactor control with program control. The speed adjustment method of AC motor adopts variable-frequency adjustment. Speed, and then realized the semi-automatic control of the crane. Second, the system's main functions and features: Rising, large and small car electric drive parts are used frequency control and programmable control, most of the components are imported equipment, with advanced technology, safe and reliable. (1) The lifting system adopts a device to reduce the weight of the trolley and the rated lifting load is 26 tons. (2) According to the different lifting objects, the lifting hooks, hooks, main hooks, and tonnages can be switched automatically. (3) The weight signal is transmitted to the control system by the QCXB weight measurement and control instrument to realize the automatic switching of the weight speed. (4) The hoisting system adopts flux vector closed-loop control to increase the starting torque, and can provide full-speed control at zero speed, effectively preventing the motor accident due to insufficient torque. (5) Improve the crane's steel structure performance: The use of frequency conversion can achieve smooth acceleration and deceleration, reducing the current surge when lifting and stopping, improving the crane's steel structure performance, increasing the value of the door lifting stiffness. Third, the crane transformation part: 1, the car walking part: (1) The motor uses the original motor (YZ132M-6 4.0KW two In=9.2A n=915rpm) (2) Speed ​​control system adopts Yaskawa G7-A4011 (11Kw power) inverter and braking resistor (3) The original gearbox is used. 2. The walking part of the cart: (1) The motor uses the original motor (YZ180L-8 11.0Kw four In=25.8A n=694rmp FC=40%) (2) Inverter adopts Yaskawa G7-A4055 (power 55Kw) Braking unit CDBR-4030 Two Braking resistor 2500W/60Ω six (3) Reducer box uses original gear box 3, lifting part: (1) The motor adopts the original hoisting frequency conversion special motor (without change) in Shanghai Crane Motor Co., Ltd. YZB280M—8,55Kw FC=40% (2) Inverter adopts Yaskawa G7-A4075 (power 75Kw) Braking Unit CDBR-4045 Two Braking resistor 2500W/54Ω eight Japan's Yaskawa Electric Corporation G7 inverter has the following characteristics: With full flux vector points, reliable torque control, magnetic flux detection control technology, direct control of motor torque. With a wide range of precise control, high-precision operation can be performed from 1/100 low speed to high speed no matter how the load changes. No output distortion has been achieved, reducing motor noise. The excellent zero-feed service function is highly adaptable to rapidly changing load fluctuations. The control function is complete and the control is convenient. (3) The reducer adopts the original reducer, model: JZQ750 (speed ratio I=31.5) 4, the operating part: The cam controller is used for large, small car and hoist speed control. Technical indicators: Rated lifting weight: 26t (tons) Lifting speed: 0~18m/min Main hook 10~26t 9.8m/min Vice hook 0~10t 18m/min Travel speed of cart: 0~43m/min Travel speed of trolley: 0~39.5m/min Load weight signal accuracy: within 3% Power supply voltage: 360~420V Frequency: 50Hz Accuracy: 10% Ambient temperature: -10~50 degrees Celsius Saving electricity rate: 20% or more Fourth, the gantry crane using frequency conversion speed effect analysis: Variable frequency speed control and programmable control and speed control lift cranes, large and small car systems. The safety and reliability of the gantry crane can be provided, and the loading and unloading efficiency can be significantly improved, the energy consumption can be reduced, the maintenance cost can be reduced, and the labor intensity can be reduced. To meet its industrial and mining and operational needs, to meet the requirements of the development of containerized transport operations. 1. The protection function of the inverter speed control system is strong: A. The frequency conversion speed regulation is superior to any previous speed regulation method with its excellent performance such as small size, high versatility, fast dynamic response, high operating frequency, perfect protection performance, good reliability, and easy use; B. Using the inverter to control the running of the motor, the motor can be soft-started, and the motor has a very fast dynamic response and stepless speed regulation; in addition to some parameters of the motor to do compensation; the lack of phase, the lack of power Pressure, over-pressure, over-current, etc. can all achieve timely and accurate detection and automatically take contingency measures to protect the motor; 2. The reliability of the work has been significantly improved, mainly in the following areas: A, the life of the electromagnet can be greatly extended The original drag system is a brake in the state of motion, after adopting the frequency conversion speed regulation, the brake can be carried out in the state of basically stopping, and the wear condition of the brake shoe is greatly improved. ; B. The operating handle is not easy to damage The operating handle of the original system is often subjected to excessive force and is a wearing part. With variable frequency speed regulation, the force of the operating handle will be greatly reduced, and it is not easy to damage; C. The failure rate of the control system is greatly reduced. The original system is controlled by a very complicated contactor and relay system, and the failure rate is high. With the variable frequency speed control system, the control system can be greatly simplified and the reliability greatly improved. 3, to enhance the safety of the system, according to the different weight, in line with the automatic control speed, can effectively avoid the phenomenon of overload, to prevent accidents. At the same time, maintenance work and maintenance costs are reduced. 4, improve the reliability of the system and improve the performance of crane steel structure. Because the frequency converter itself has perfect protection function, self-diagnosis function and strong anti-jamming function, the main and pay hooks can be combined with a set of lifting device, the weight of the car is reduced, the lifting and deceleration can be stabilized, and the impact of lifting and stopping can be reduced. Improve the performance of crane steel structure. Therefore, the reliability of the overall system is greatly improved, and the failure rate of the gantry crane is greatly reduced. 5, to improve the stability of loading and unloading operations and handling efficiency. The system can modify the process parameters such as lifting speed and acceleration/deceleration time at any time, so that the gantry crane can always be kept in the best running state, and the goods can be accurately positioned in the air to ensure the safety of the goods. In addition, the safety and reliability of the system can not only greatly increase the efficiency of loading and unloading, but also improve the working efficiency. The working efficiency is not more than 30% of the frequency converter installed. 6. The quality of the speed regulation is obviously improved. After adopting the variable frequency speed control system, the speed control range is 1:1000 for PG vector control, 1:100 for vector control without PG, and the speed control accuracy is 0.01% for speed sensor vector control. No speed The sensor vector controls 0.1% of the highest frequency, and the speed is stable. It can run at low speed for a long time and has high positioning accuracy and operating efficiency. 7. The energy saving effect is improved significantly. When the wound rotor asynchronous motor runs at a low speed, a large amount of electric energy is consumed in the external resistance of the rotor circuit. With the variable frequency speed control system, not only the large amount of electric energy consumed in the external resistor can be fully saved, but also the position energy of the heavy object can be fed back to the power supply when the crane puts down heavy objects.