Sliding Mode Control of Converter-fed DC Motor with Mismatched Load Torque Compensation

摘要

The combination of DC-DC power converters with DC motors for generating so-called smooth start of drives has numerous practical applications. Achieving high performance in such systems is however limited by the influence of unknown load torque disturbance. Furthermore, the conventional mathematical model used to express the dynamics of converter-fed motor systems effectively complicates the ability to compensate the load torque disturbance directly with control signal. In this work, a three-step control methodology is used to address those issues. First, a special state transformation is applied, making the load torque disturbance a sole perturbing term in the new system coordinates. Then, a disturbance observer reconstructs the information about the load torque based on already available input/output plant signals. In the last step, a sliding mode controller is used to achieve high performance of the resultant plant dynamics and to robustify the governing scheme against modeling discrepancies. The considered disturbance observer-based sliding-mode control (DOB-SMC) approach is validated here with both numerical and theoretical results.