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Conventional model-based sensorless surface-mounted permanent magnet synchronous motor (SPMSM) drivers suffer deteriorated performance in transient-state operation such as accelerating during wide-speed range or encountering large load torque disturbance. In this article, an effective sensorless control solution is proposed to improve the robustness of sensorless SPMSM drivers in transient-state operation. Two extended state observers (ESOs) are utilized to estimate the αβ-axis back electromotive forces (EMFs). An adaptive bandwidth tuning scheme is proposed to online tune the parameters of the ESOs, with which the desired estimation performance of back EMFs can be achieved in wide-speed operation range. Additionally, the dynamic mechanical behavior of the sensorless control system during large load torque transient is investigated by using small-signal analysis, and then a corresponding speed estimation compensation scheme for the conventional quadrature phase-locked loop (QPLL) is developed, with which the capability of QPLL in tracking the rapidly changing speed can be significantly enhanced. Experiments on an SPMSM demonstrate the superior robustness of the proposed method to that of the conventional method in transient-state operation. [ABSTRACT FROM AUTHOR]

Optimal currents with appropriate harmonic components injected into the motor windings can effectively mitigate torque ripple for interior permanent magnet (IPM) type brushless dc motors (BLDCMs). However, existing approaches may fail to accurately inject the optimal currents into motors due to the limited current loop bandwidth. This paper proposes a simple enhanced generalized vector control strategy to mitigate the torque ripple for IPM-type BLDCMs. With the proposed vector control strategy, the control block diagram for IPM-type BLDCMs is as simple as that with traditional vector control for sinusoidal permanent magnet synchronous motors. First, an electromechanical energy conversion voltage (EECV), considering the effects of the non-sinusoidal back-EMF and the rotor salience property, is proposed in αβ-axis. Then, a novel coordinate frame is constructed with the proposed EECV, which is based on the arbitrary reference frame theory. As a result, the currents of IPM-type BLDCMs can be decomposed into two constant components, one being linked to the torque and the other one to the flux linkage. Thus, the bandwidth of current loop with simple proportional integral regulator can be equivalently expanded in the proposed coordinate frame. Finally, comprehensive experiments are conducted in different operation conditions to validate the effectiveness of the proposed vector control strategy. [ABSTRACT FROM AUTHOR]