A Robust Current Controller Design Method for Highly Nonlinear Synchronous Reluctance Motors

Due to the rotor construction, Synchronous Reluctance (SynRel) machines exhibit high magnetic saturation and cross-saturation. This leads to strongly variable dq inductances, which affect the current loop response. In order to achieve constant current loop dynamics, controller gains need to be adapted according to the current bias. In this paper, three different methods for implementing a PI current controller are analyzed and tested. The magnetic characteristics of the tested SynRel are obtained using the FEA and also a state-of-the-art experimental procedure. The experimental verification of the current loop response is given for a 15 kW 3-phase SynRel motor, using a standard industrial 3-phase inverter.