An Enhanced Linear Extended State Observer-Based Sensorless IPMSM Drives With Robustness Against Current Measurement Offset Error

Back-electromotive force (EMF) estimation has attracted a lot of attention in sensorless interior permanent magnet synchronous motor (IPMSM) control. However, the conventional linear extended state observer (LESO) method will obtain back EMF estimations with phase lag and is vulnerable to dc errors caused by current measurement offset error due to its low-pass characteristic. To deal with the phase lagging and dc errors problem, an enhanced LESO (ELESO) with the super-twisting sliding mode observer (STASMO)-based current measurement offset error compensation is proposed in this article. The sinusoidal tracking unit is added to the disturbance loop in LESO to obtain the rapid-varying back EMF estimation accurately. Besides, the current measurement offset errors can be compensated by the STASMO-based method after analyzing the dynamic equation of offset error. Therefore, the proposed sensorless method is able to observe back EMF accurately and compensate an offset error for position estimation improvement. Finally, the comparative experiments based on 1.5-kW IPMSM are given to certify the advantages of the proposed sensorless method, which shows the effectiveness and superior control performance of the proposed sensorless method in back EMF estimation and current measurement offset error compensation under different conditions.