Dynamics of a series-connected two-motor five-phase drive system with a single-inverter supply

Utilization of multi-phase machines in variable speed drives is nowadays extensively considered for electric ship propulsion, 'more-electric aircraft' and traction applications, including EVs and HEVs. In addition to well-known advantages, use of multi-phase machines enables independent vector control of a certain number of machines that are connected in series in an appropriate manner, with the supply coming from a single voltage source inverter (VSI). The concept was initially proposed for a five-phase series-connected two-motor drive, but is applicable to any system phase number greater than or equal to five. The number of connectable machines is a function of the VSI phase number and detailed theoretical and simulation studies have already been reported for various multi-phase multi-motor drive configurations of this type. However, the available experimental proofs of decoupled dynamic control within series-connected drive systems are currently restricted to the six-phase two-motor drive. The purpose of this paper is to present, for the first time, results of an experimental study on a five-phase two-motor series-connected drive system. A brief overview of the operating principles is provided first This is followed by a description of the experimental rig. The emphasis in the paper is placed on the experimental results, which illustrate dynamics of the vector-controlled two-motor drive during acceleration, deceleration and speed reversal. An experimental proof of the existence of decoupled dynamic control is thus provided.