Decoupled d-q Model of Double-Star Interior Permanent Magnet Synchronous Machines

This paper describes a d-q transformation to be applied to double-star permanent magnet synchronous machines with interior magnets. The d-q model consists of two d-q reference frames decoupled with respect to each other and applies to a generic angular displacement between the winding sets. The decoupled d-q model simplifies the analysis of the machine behavior and the drive control implementation. Machine parameters are determined by a sequence of finite element (FE) analyses. The effectiveness of the proposed modeling method is verified by a comparison with the results related to measurements on a test machine and FE simulations. It was assumed that the mutual inductances between the two winding sets can be represented with two coefficients. Although such an assumption inevitably leads to inaccuracy in the machine model, the simulation results with the proposed d-q model agree remarkably well with the experimental results and FE simulations.