Vibration and noise in novel variable flux reluctance machine with DC-field coil in stator

The vibration and acoustic noise are investigated in a novel variable flux reluctance machine, which utilizes a DC-field coil in the stator to achieve on-line adjustment of air-gap flux density. The capability of adjusting air-gap flux density is expected to improve the efficiency and extend the speed range. The doubly salient structure in switched reluctance machines (SRM) is employed in the variable flux reluctance machine, together with the non-overlapping concentrated windings to reduce the copper loss. The 2D and 3D-finite element analyses are employed to predict the radial force and vibration modes in the variable flux reluctance machine, respectively. With the aid of vector control, which employs space vector pulse-width modulation, the vibration and acoustic noise in this novel machine are experimentally investigated, together with the comparison with SRM, which has the same stator/rotor pole combination. Compared with SRM, under the same load condition, the variable flux reluctance machine significantly reduces the vibration of mode 2, which is dominant in the SRM.