Adaptive torque ripple minimization of permanent magnet synchronous motors for direct drive applications

The lack of the filtering effect due to gear reduction in a direct-drive system necessitates the consideration of the full dynamics of the system for high performance control. This makes torque ripple a significant problem and its elimination is required for improved performance. In the study, adaptive linearizing control is applied for the solution of the problem in a single-link manipulator driven by a permanent magnet synchronous motor. Two parameterization methods, which were analyzed in terms of stability and robustness in a previous study, are implemented for the linearization of the direct-drive system. Speed and position control experiments are performed for both parameterizing approaches, also taking load torque variations into account and an improved performance is obtained in terms of torque ripple reduction and tracking error. Especially with the guaranteed persistency of excitation of the new parameterization approach, a significant reduction of torque ripple amplitude is achieved in addition to parameter and error convergence under load variations for both speed and position control. The experiments are performed through a DSP32 driven motion controller.