Techniques for power sharing between winding sets of multiple three-phase machines

The paper presents a review of techniques for arbitrary power and current sharing between winding sets of a multiphase machine. This feature of a multi-star machine can be utilised for different purposes, such as fault-tolerant operation, increase of the total dc-link voltage by cascading multiple inverters, creation of dc voltages of different levels, or implementation of an arbitrary power flow sharing between different sources. After a brief review of recent developments in multiphase machine applications, an introduction to power sharing between windings is given. Examples with multiple d-q and vector space decomposition modelling approaches are presented. However, the emphasis is on machine modelling and control by application of vector space decomposition, due to the benefits of decoupled control that this method provides. Three different approaches to arbitrary power sharing have been selected and described in detail. Each solution is backed up by simulation or experimental results. Finally, a comparison of reviewed methods is presented.