Integrated Field and Armature Current Control for Dual Three-Phase Variable Flux Reluctance Machine Drives

An integrated field and armature current control strategy is proposed for dual three-phase variable flux reluctance machines (VFRMs). The proposed method utilizes a sinusoidal current biased by dc offset rather than separated field and armature currents in an external field current control. In order to generate the dc and ac components together, a dual three-phase inverter is adopted, in which one side of each stator winding is connected to a neutral point. The dq-axis currents are controlled by the dual three-phase inverter, whereas zero sequence current is generated as a field current by the zero vector redistribution between two inverters. Since the integrated current control allows an integrated winding, which reduces the winding resistance to half, the copper loss can be also reduced to half. To apply the vector control scheme, the voltage and torque equations are derived for dual three-phase VFRMs in a synchronous dq-axis frame. These equations are also utilized for the dynamic simulation with the aid of MATLAB/Simulink. The experimental results validate that the proposed strategy can effectively increase the efficiency and extend the operating speed range.