Hoisting Machinery

Application case of synchronous correction control of large-span door crane lifting equipment based on Canopen fieldbus.
one. The particularity of door crane lifting equipment:
The safety requirements of door crane lifting equipment are becoming more and more prominent, and the concept of safety first is becoming more and more important in control. According to regulations, large-span door cranes above 40 meters must be equipped with dual-track synchronous correction control to prevent left and right double-tracks. The accident of the door machine wheel is too off and gnaws the track or even derails. Due to safety requirements, the left and right double track wheels of the door machine need to be controlled at multiple points. The reliable feedback of speed, position and other information directly relates to the safety and reliability of the control. The particularity of the environment of the crane's lifting equipment determines the particularity of the selection of these signal sensors and transmissions:
1. In the complex working environment on site, frequency converters, large motors and high and low voltage power supply systems, signal cables are often arranged together with power lines, and the electrical interference on site is very serious.
2. Equipment mobility, long moving distance, difficult to ground.
3. The signal transmission distance is long, and the safety and reliability of the signal data is high.
4. Synchronous control requires high real-time and reliable signal transmission.
5. Many of them are used outdoors, with high requirements for protection level and temperature level, but low level of worker training, and high requirements for product tolerance.
two. The significance of the absolute value multi-turn encoder in the application of door crane lifting equipment:
There are potentiometers, proximity switches, incremental encoders, single-turn absolute encoders, multi-turn absolute encoders, etc. in the use of position sensors for door cranes. In comparison, the reliability of potentiometers is low , Poor accuracy, dead zone in use angle; Proximity switches, ultrasonic switches, etc. are only single-point position signals but not continuous; Incremental encoder signal anti-interference is poor, the signal cannot be transmitted remotely, and the power failure position is lost; Single-turn absolute encoder It can only work within 360 degrees. If the measurement angle is expanded by changing the speed, the accuracy will be poor. If it is used directly in a single circle to achieve multi-lap control through memory, after a power failure, it will lose its position due to wind, sliding or artificial movement. Only the absolute value multi-turn encoder can be used safely in the hoisting equipment of the door machine. It is not affected by the power outage jitter. It can work with long distances and multi-turns. The internal full digitalization, anti-interference, and signal can also be realized. Long-distance safe transmission. Therefore, from the perspective of the safety of door hoisting equipment, the absolute value multi-turn encoder is an inevitable choice.