Repetitive Control Technique for Motor Drive Applications

This paper proposes a phase-based repetitive controller for motor drive systems undergoing speed variations. The proposed phase-based repetitive controller differs from the conventional repetitive controller, especially in the output and memory update methods. The output method performs linear interpolation using two adjacent data values corresponding to the currently sampled phase and compensates for digital time delay based on speed. The memory update method utilizes average calculation or linear interpolation of the current error, and the calculated values are added to the output of a phase-based stabilization filter. The resulting values are stored in memory, whose index is determined by the phase. As a result, the proposed method has a wider operating range, keeps a fixed memory size, and enhances control performance in an adjustable speed system. The proposed method is verified by experiments with 17kW IPMSM.