A Robust Method for Estimation of Inductances at Standstill Considering Magnetic Saturation

This paper examines the effect of magnetic saturation and cross saturation on the d-q axis inductance in an interior permanent magnet synchronous motor (IPMSM) using a modified machine model that incorporates the saturation and cross saturation effects. A high-frequency injection (HFI) based practical and robust method is proposed to create the 3D/2D mapping of inductances for all operating regions. In addition, for motor applications where rotor is not accessible to lock it, a unique current sequence injection is presented such that, with the resultant torques, maintains the rotor stationary throughout the estimation process. The proposed method effectively eliminates the impact of inverter non-linearity on inductance estimation, and this is further discussed. The proposed framework has experimented on the IPMSM motor. The experimental results show that the proposed strategy accurately estimates the d-q inductances of the motor without actually locking the rotor.