Quick torque ripple suppression controlled fast position servo based on hybrid system of disturbance observer and torque ripple table

In the field of high-precision position control, the position response requires that there is no vibration. However, a permanent magnet synchronous motor (PMSM) has a wide variety of torque-ripple components, including cogging torque and flux harmonics, which degrade the control performance. Typically, these components are defined as a disturbance torque, and compensation is accomplished by using a disturbance observer. However, a disturbance observer uses a low-pass filter for noise reduction, and it causes phase and amplitude shifts in an estimated value. As a result, it is not possible to perform the appropriate compensation. This paper considers a new structure of disturbance observer based on a zero-order disturbance observer and torque ripple table. It is possible to accurately estimate the instantaneous disturbance torque by using the proposed disturbance observer. The effectiveness of the proposed disturbance observer is confirmed by numerical and experimental results.