Real-Time Induction Motor Speed Control with a Feedback Utilizing Power Line Communications and a Motor Feeder Cable in Data Transmission

In a motor speed control, a feedback loop is used to transfer the measured motor rotational speed information to the controller. The implementation of the feedback loop requires cabling between the motor and the frequency converter both for signalling and powering. However, the motor feeder cable could be used as a medium for data transmission. A feedback loop that utilizes a motor cable as a communication channel is researched in this article. The method is applied in this application for the first time. The data transmission utilizes a standardized PLC (power line communications) method that forms an Ethernet connection over the motor feeder cable. The applied method generates an additional latency to the feedback loop and hence, sets some limits to the performance of a speed controller. In this article, the performance of the method is researched and analyzed with simulations and laboratory experiments