Stability Analysis and Parameter Design of Virtual-Winding-Based Harmonic Current Controller for Permanent Magnet Synchronous Machines

The multiple synchronous reference frame controller is a common method for harmonic control in permanent magnet synchronous machines (PMSMs), but its low-pass filter deteriorates the harmonic regulation dynamics and system stability. The virtual winding structure, as a novel alternative, can quickly separate each harmonic by vector space decoupling transformation. However, past studies have often assumed that the virtual winding structure does not affect closed-loop system performance or stability. This article constructs the equivalent transfer function of the virtual winding structure of a PMSM under resistance asymmetry. It is revealed that this structure is essentially a special filter. The stability of the closed-loop system is then studied in both continuous and discrete domains. The influence of speed and controller bandwidth on the stability boundary is analyzed. A parameter design method for the harmonic controller is proposed to optimize dynamic response while ensuring system stability. Finally, experimental results show that the theoretical and experimental stability boundaries have an error of less than 4%, validating the accuracy of the stability analysis and the effectiveness of the parameter design.