Combining Induction and Permanent Magnet Synchronous Machines in a Series-Connected Six-Phase Vector-Controlled Two-Motor Drive

It has been shown recently that a number of multi-phase machines can be controlled independently, with the supply coming from a single multi-phase inverter, provided that the stator windings are connected in series in an appropriate manner. One such drive system is a two-motor drive, consisting of a symmetrical six-phase machine connected in series with a three-phase machine. The supply is provided from a six-phase current-controlled voltage source inverter (VSI). This paper examines operation of such a drive system when a six-phase symmetrical induction machine is connected in series with a three-phase permanent magnet synchronous machine (PMSM). Basic operating principles of the drive system are at first reviewed. This is followed by a brief description of the experimental system. An extensive presentation of experimental results, collected from a laboratory setup, is then provided. It is shown that a truly independent and decoupled vector control of the two machines results, although a single supply source is used. The two-motor drive system of the proposed structure is seen as a potentially viable industrial solution for applications requiring one high-power and one low-power machine