  This paper proposes and implements a meter-range wireless motor drive (WMD)
system for promising applications of underground pipeline transportations or
in-pipe robots. To power a pipeline network beneath the earth, both the power
grid and the control system are usually required to be deployed deep
underground, thus increasing the construction cost, maintenance difficulty and
system complexity. The proposed system newly develops a hybrid repeater to
enable the desired meter-range wireless power and drive transfer, which can
offer a fault-tolerant network with a robust structure for the underground
sensor-free WMD while maintaining a high transmission efficiency. Hence, this
wireless pipeline network can reduce the maintenance requirement and regulate
the flow rate effectively. A full-scale prototype has been built for practical
verification, and the system efficiency can reach 88.8% at a long transfer
distance of 150 cm. Theoretical analysis, software simulation and hardware
experimentation are given to verify the feasibility of proposed meter-range WMD
for underground pipeline transportations.
