Theoretical and Experimental Investigation of the Brushless Doubly-Fed Machine with a Multi-Barrier Rotor

Abstract

Brushless doubly-fed reluctance machines (BDFRMs) have drawn much attention during the past two decades due to their brushless structure, robust rotor construction, unique variable-speed constant-frequency capability, excellent control property and inherent fail-safe nature. This paper presents an updated theoretical and experimental analysis of the BDFRM with a multiple-barrier rotor. The contributions of this paper are: 1) proposing a new analytical method to analyze the airgap field distribution, torque production and inductance characteristics of the BDFRM with a multiple-barrier rotor, 2) revealing the magnetic field modulation mechanism of multiple-barrier rotor in a more straightforward manner, 3) drawing insightful conclusions on the relationship between cross-coupling characteristics and pole pair combination and the relationship between torque capability and pole pair combination, 4) proposing a new experimental method to test the inductances, 5) reevaluating the potential of the BDFRM as a variable speed drive in wide-speed-range application. Steady-state tests were conducted on a scaled-down BDFRM prototype with a modular multiple-barrier rotor to validate the effectiveness of the developed theoretical and experimental analysis.