Main technical indicators of driving mechanism
The main and vice hoisting mechanism of the gantry crane adopts AC frequency conversion speed control.
The gantry crane's large car walking and trolley walking mechanism adopts AC frequency conversion speed regulation.
In order to improve the reliability of gantry crane operation, the electrical drive system does not share motor drive devices by switching with each other, and each drive device is only used to drive the fixed motor.
Electric motor
The gantry crane main drive motor is selected from the best brands and strictly conforms to IEC standards.
Motor casing protection level:
- AC inverter motor (main drive) IP55.
- Maintenance crane and other auxiliary mechanism motors indoor IP23, outdoor IP56.
The motors of gantry crane's hoisting mechanism, large car travel mechanism and trolley travel mechanism are special motors with variable frequency speed regulation. It can meet the requirements of speed, acceleration, starting, braking, speed regulation and overload capacity of the mechanism. The output torque of the motor meets the technical requirements when the weak magnetic speed is increased.
The variable frequency motor has the following characteristics.
1.Raising motor:
- Insulation class F
- Voltage class ~500V/~400V
- Protection class IP55
- Forced air cooling
- Motor built-in moisture-proof heater
- Internal winding temperature sensor for warning and tripping
- Speed feedback encoder
- Over-speed protection for hoisting mechanism
Large car travel and small car travel motors:
- Insulation class F
- Voltage class ~500V/~400V
- Protection grade IP55
- Forced air cooling
- Motor built-in moisture-proof heater
- Internal winding temperature sensor for warning and tripping
- Speed feedback encoder (if available)
Drive unit
Gantry crane inverter speed control drive consists of a common DC bus rectifier/feedback unit (IGBT, four-quadrant operation) and inverter units for each mechanism. Closed-loop control with pulse encoder for speed feedback element.
The variable frequency speed control uses vector control or direct torque control.
When the hook is running synchronously, the synchronization accuracy is not more than 60mm when starting and braking (including emergency stop), and the synchronization accuracy is not more than 20mlm in the whole range of hook travel when running at steady speed.
When the upper and lower trolleys are running synchronously, the synchronization accuracy when starting and braking (including emergency stop) shall not exceed Shi 30mm, and the synchronization accuracy in the whole range of travel shall not exceed Shi 10mm when running at steady speed.
The synchronization accuracy of the crane running when starting and braking (including emergency stop) is not more than 120mm, and the synchronization deviation of the crane running when running at steady speed is not more than 60mlm.
The speed feedback component of the gantry crane drive system adopts imported products and is connected with the frequency converter.
The common DC bus rectifier/run-feed control cabinet provides power supply for the hoisting mechanism, large car and trolley running mechanism inverter. When the mechanism descends or decelerates to run, the feedback energy of the motor is fed back to the grid through the feed-back unit. In order to limit the electric leakage caused by the long set-up of the hand state grid and improve the current waveform, the rectifier/feedback unit must have the function of stifling voltage distortion and improving power factor.
Rectifier/feedback unit adopts parallel multi-loop system, when one of the loops fails, the other loop can still ensure the normal operation of the equipment when the mechanism speed is reduced. Multiple DC bus units automatically cut in and out of operation according to the rectifier/feedback device.
The inverter control cabinet for each mechanism includes:
- Up trolley lifting mechanism out of ground change product
- 2# inverter control board for the upper trolley lifting mechanism
- Up trolley running mechanism inverter control
- Up trolley lifting traverse mechanism 1# inverter control cabinet
- Top trolley lifting and traversing mechanism 2# inverter control panel
- Inverter control panel for the main lifting mechanism of the lower trolley
- Inverter control cabinet for lower trolley sub-lifting mechanism
- Seasonal machine li change control lake out
- Tai car running mechanism rigid leg inverter control cabinet
- Car running mechanism flexible leg inverter control cabinet
- Each inverter is powered by the common DC bus, and the control method of the inverter adopts the field bus control with the communication of PLC.