Sensorless interior-PMSM control with rotational inertia adjustment

Mechanical model is generally required in high dynamic sensorless motor control schemes for zero phase lag estimation of rotor position and speed. However, rotational inertia mismatch will cause dynamic performance deterioration of the sensorless control system. Therefore, this paper proposes a high dynamic performance sensorless control strategy with on-line adjustment of rotational inertia. Based on "active flux" concept, an extended nonlinear observer is designed for interior permanent magnet synchronous motor (IPMSM), which estimates rotor position, speed, and load torque simulteneously. The effect of inaccurate rotational inertia on the dynamic performance of rotor position and speed estimation is investigated and a novel approach for rotational inertia adjustment that employs the gradient descent algorithm is proposed to suppress the dynamic estimation errors. The effectiveness of the proposed control strategy is demonstrated by experimental tests.