Conventional model-based sensorless surface-mounted permanent magnet synchronous motor (SPMSM) drivers suffer deteriorated estimation performance of speed and position in transient-state operation such as accelerating during wide-speed range or encountering large load torque disturbance. In this paper, 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-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 a SPMSM demonstrate the superior robustness of the proposed method to that of the conventional method in transient-state operation.

Conventional active disturbance rejection controller (ADRC) for interior permanent magnet synchronous motor (IPMSM) drives suffers deteriorated performance in dealing with low-order harmonic disturbances. To enhance the capability of ADRC in rejecting such disturbances, this article proposes a complex coefficient active disturbance rejection controller (CCF-ADRC). The complex coefficient filter (CCF), which is capable of extracting signals with selective frequency and selective phase sequence from the input orthogonal signals, is incorporated into the extended state observer to enhance its estimation accuracy on the d-q -axis harmonic disturbances. With the harmonic disturbances accurately estimated, the subsequently designed CCF-ADRC can achieve enhanced performance in rejecting such disturbances. Theoretical analysis on the stability, the harmonics rejection capability, the command tracking capability, and the influence of parameter mismatches are systematically conducted. Comprehensive experiments on a 1.0-kW IPMSM verify the effectiveness of the proposed method.

This paper proposes a novel axial-radial flux permanent magnet machine (ARFPMM). The design and optimization process for higher torque density and lower cogging torque are presented. T-type SMC core, axial rotor, and radial rotor are applied to sup-port axial-radial flux path and make full use of the space. The structure and operation principle of ARFPMM are introduced. To improve the power density, different types of radial rotor are analyzed by finite element method (FEM) and the optimal PM radial rotor is determined. To reduce the cogging torque, bidirec-tional PM skewing technique is applied. The optimal combination of skewing angle and position angle is derived. The comparison between the initial and revised model shows the effectiveness of the PM radial rotor and the bidirectional PM skewing technique in the ARFPMM. Compared with the conventional axial flux permanent magnet machine, the proposed ARFPMM shows ad-vantages in average torque and space utilization.

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. Firstly, an electromechanical energy conversion voltage (EECV), considering the effects of the non-sinusoidal back-EMF and the rotor salience property, is proposed in $\alpha \beta$ -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.