Review of Current Distribution Strategies and Nonlinear Optimization Methods for Flux Adjustable Synchronous Machine Systems

In this paper, the current distribution strategies and nonlinear optimization for flux adjustable synchronous machine (FASM) systems are summarized. Among FASMs, wound field synchronous machines and hybrid excited machines are mainly analyzed for their magnetic fields are regulated through field windings. For these two kinds of machines, there are three currents controllable under the field-oriented control so that the current distribution plays an important role in improving system performances. This paper summarizes the existing current distribution strategies and divides them into two categories, fixed and optimal current distribution, which are applied in different situations under variable requirements. Besides, the nonlinear optimization methods for FASMs, including improving the mathematical models and establishing the look-up table, are listed in this paper. Finally, the potential future development directions and research focuses of the FASM control system are proposed.