Integrated field and armature current control strategy for variable flux reluctance machine using open winding

This paper proposes an integrated field and armature current control strategy for variable flux reluctance machine (VFRM) with open winding topology. By using open winding inverter, the field and armature currents can be injected into a single coil as sinusoidal current biased by dc offset, rather than the separated field and armature windings. With this method, the integrated current control can reduce the copper loss to half and extend the operating speed range owing to the reduction of winding resistance. Besides, the voltage utilisation ratio can be also increased with the open winding inverter. The integrated current control scheme is performed in synchronous reference frame with space vector modulation (SVM). The experimental results validate that the proposed strategy can effectively reduce the copper loss and extend the operating speed range.