Reduction of On-Load DC Winding-Induced Voltage in Partitioned Stator Wound Field Switched Flux Machines by Dual Three-Phase Armature Winding

Abstract

Voltage induced in the dc winding by the armature field in wound field switched flux (WFSF) machines will induce voltage perturbation in the voltage supply and cause dc winding current ripple and field excitation fluctuation. This will challenge the dc voltage controller and deteriorate the control performance, especially when the load and/or the rotor speed are high. In this article, the dual three-phase armature winding design with a phase-shift of 30 electrical degrees is employed in the partitioned stator WFSF machines to reduce the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -load dc winding-induced voltage. Analytical deductions and finite element (FE) results demonstrate that the dominant sixth-order-induced voltage harmonic can be suppressed to zero. Hence, the peak-to-peak induced voltage in the 12/11- and 12/13-pole partitioned stator WFSF machines can be reduced by 83.35% and 82.53%, respectively. Due to the improvement of winding factors, the torque densities are 4.85% and 5.60% higher, respectively. Prototypes are built and tested to verify the analytical and FE results.