Real-time control of a servosystem using the inverter-fed power lines to communicate sensor feedback

It is shown that the pulsewidth modulation inverter-fed power line is a feasible medium for the transmission of modulated digital information at data rates of over 40 kb/s and that this transmission path provides a suitable alternative to the sensor cabling between the actuator and the controller of an encoder-based servosystem. The encoder data is modulated and transmitted from the actuator to the controller, over the inverter-fed power cable. The data is modulated using frequency-shift keying, based on a center frequency of 5 MHz. Specialized magnetics design techniques are outlined for the coupling and decoupling circuits which transfer the modulated digital information to and from the power lines. A software observer is employed to improve the velocity derived from the received position information, and this velocity is used in the motion control algorithm to generate a reference torque signal for the controller.