PLC Motor Speed Control Model

In this work it has been designed a small module for controlling the speed of motor by depending on the frequency for controlling its rotation speed, where in real stations a large and expensive motors would be utilized for controlling and performing different tasks as seen in picture. Such motors would require an efficient management in the turn on duration and number of rotational cycles. For that reason, there is a need for efficient controlling for such motors. In addition, the data storage and splitting timing of different working units would be controlled by using the PLC system. The proposed model of PLC in our work was PLC S7-300. Furthermore, in this work it has been utilized the VFD as a regulator for the speed of the three phase induction motor with a rotational speed of 300 rpm, the structure of connecting VFD with PLC can be seen in picture.

The control of the motor speed would be based on the utilized frequency, where it has been found that the speed would be in direct correlation with the source power. This scenario has been carried out based on the use of the program tiaportal. In the beginning, the frequency would be zero Hz, which is the same as in the VFD device, then an order would be taken for the three phase. So, the SCADA system would respond to this order by replying signal back to VFD from AC motor. Then this signal would be back to the PLC and finally to the SCADA system to read the current frequency. Increasing the frequency by the system we proposed and from the HMI screen we will see that the speed of the motor would be increased.

It is worth to mention, that the system screen of the SCADA has been designed using the program of WINCC of tiaportal. Clarify the design of the regular motor work within the SCADA system. Additionally, if the motor has stopped from working, the representation in the system would be as seen in figure. When an error would be occur for the proposed system then the SCADA system would give an indication for that error.

The final view for the entire system can be seen in picture, where the connection of MHI, PLC, VFD and the induction motor can be representing our proposed scenario in this work.