INOMAX ACS880 direct torque control VFD solution for mechanical tilting converter for metallurgy project

Converter requirements for the AC VFD control system:
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(1) The mechanical tilting converter can continuously rotate 360°, driven by 4 sets of 90KW variable frequency motors, and can stop at any position accurately. It should also have speed regulation performance according to process requirements. Its tilting position can have certain interlocking requirements with related equipment such as oxygen lance, ladle car and fume hood;

(2) In the process of operation, there must be maximum safety and reliability. When a certain part of the electrical or mechanical failure occurs, the tilting machine should be able to continue to operate for a short time and maintain it until the end of the first steelmaking furnace.

(3) The tilting machine should have good flexibility to buffer shock load and torsional vibration generated by starting and braking

Solutions:

Since these 4 motors are rigidly connected, the speeds of all motors are required to be absolutely synchronized, so the transmission of the 4 motors adopts master/slave control, and the data is transmitted between the 4 drives through internal communication.

The inverter is used as the host, which adjusts the speed and sets the output torque. Other inverters, as slaves, follow the torque response of the host, and completely solve the "nodding" and "shaking" problem caused by the asynchronous operation of the motor.

The converter capacity of Henan Yaxin Steelmaking Plant is 100t, the tilting motors of the converter are 4 sets of 90kW frequency conversion motors, and the oxygen lance motors are 2 sets of 75kW frequency conversion motors; the upper control system adopts GE's 90-70 series PLC.

Between the 4 drives, the master sends a control command to the slave, and the slave accepts the start and stop commands and the set value of the torque sent by the master to act. When a certain slave fails, it does not affect the communication and action of the master and other slaves, so it can continue to run until the appropriate time for maintenance; when the master fails, the slave receives a signal to switch to the master to make the system normal Operation, wait until the appropriate time to repair the faulty equipment.

Since the AC VFD is a load with high starting torque, direct torque control is adopted, the stop mode is ramp stop mode, and a braking chopper and braking resistor are used to absorb the feedback energy.