Under the flux-weakening (FW) operation, the sensorless control of a five-phase flux-intensifying permanent magnet (FP-FIPM) motor faces the dilemma of reduced torque output and poor estimated accuracy caused by the serious space coupling between sensorless control and FW control. To overcome the abovementioned problems, a novel space decoupling sensorless control strategy for the FP-FIPM motor under FW operation is proposed in this article. Based on the decoupling model of the FP-FIPM motor, this article first proposes the dual space design to achieve the decoupling of sensorless control and FW control. For the FW control, an adaptive third-harmonic current injection strategy is proposed based on the fundamental space, which can effectively improve the torque output capability of the FP-FIPM motor. For the sensorless control, an adaptive frequency complex coefficient filter sliding mode observer (AFCCF-SMO) is developed based on the third-harmonic space, which can reduce complex disturbances and further improve the estimated rotor position accuracy. The feasibility of the proposed strategy is verified by experimental results.

A fault-tolerant MTPA control strategy of five-phase flux-intensifying fault-tolerant permanent magnet synchronous motor (FI-FTPMSM) under open-circuit and short-circuit faults is presented. In previous studies, existing fault-tolerant MTPA control strategies suffer from weak robustness to the parameter variation, which is not suitable for the utilization of reluctance torque of the FI-FTPMSM. In this article, a five-phase FTPMSM with flux-intensifying effect is designed and proposed. To fully utilize the reluctance torque with flux-intensifying effect under fault conditions, an extended VSI-MTPA control strategy with a compensation factor is proposed, which can improve the dynamic and steady-state performance of the motor drive system under fault conditions. In addition, an extended sliding-mode disturbance observer with adaptive gain is proposed to suppress the harmonic interference caused by faults, which possesses good resistance to complex disturbance. Finally, the feasibility and effectiveness of the proposed strategy are verified by experimental results.

Five-phase flux-intensifying fault-tolerant interior permanent magnet (FIFT-IPM) motor has high torque output, wide speed range, and strong fault tolerance, which is suitable for the drive control system of electric vehicles (EVs). To meet the high reliability under the complicated and variable operating conditions of EVs, the fault-tolerant sensorless control is applied when the five-phase FIFT-IPM motor faces unavoidable faults. Regarding fault-tolerant sensorless control strategies, previous studies almost ignored the strong mutual coupling between fault-tolerant control and sensorless control. In this paper, an adaptive harmonic decoupling (AHD) strategy for the fault-tolerant sensorless control of the five-phase FIFI-IPM motor is proposed. Firstly, a new sliding mode disturbance observer (SMDOB) with adaptive gain is designed for fault-tolerant control to reduce complex disturbances. Meanwhile, to suppress the extended back-EMF harmonics, a gradient descent adaptive filter (GDAF) with a dynamic learning rate is proposed from the perspective of sensorless control, which can greatly improve the estimated performance. Finally, the feasibility and effectiveness of the proposed strategy are verified by corresponding experimental results.

This paper proposes a hybrid adaptive robust observation (HARO)-based sensorless control strategy of a five-phase fault-tolerant permanent-magnet (FPFTPM) motor for electric agricultural equipment applications under various operating conditions, including fault conditions. Regarding fault-tolerant sensorless control, the existing studies usually treat fault-tolerant control and sensorless control as two independent units rather than a unified system, which makes the algorithm complex. In addition, under the traditional fault-tolerant algorithm, the system needs to switch after diagnosis when the fault occurs, which leads to a degraded sensorless control performance. Hence, this paper proposes a fault-tolerant sensorless control strategy that can achieve the whole speed range without fault-tolerant switching. At zero/low speed, a disturbance adaptive controller (DAC) architecture is developed by treating phase faults as system disturbances, where robust controllers and extended state observer (ESO) collaboratively suppress speed and position errors. At medium/high speeds, this paper provides a steady-healthy SMO, which combines the enhanced observer and universal phase-locked loop (PLL) without phase compensation. With above designs, the proposed strategy can significantly improve the estimated accuracy of rotor position under normal conditions and fault circumstances, while simplifying the complexity of the fault-tolerant sensorless algorithm. Furthermore, the proposed strategy is verified based on the experimental platform of the FPFTPM motor drive system. The experimental results show that compared with the traditional method, the torque ripple and position error are reduced by nearly 20% and 60%, respectively, at zero-low speed and medium-high speed, and the torque ripple is reduced by 55% during fault operation, which verifies the robustness and effectiveness of the proposed method.

This paper presents a sensorless control strategy of five-phase flux-intensifying interior permanent magnet (FPFT-IPM) motor based on sliding mode observer (SMO). Due to the back-EMF harmonics caused by inverter nonlinearity and motor secondary saliency, the position estimation errors will be increased. Thus, an adaptive filter (AF) based on gradient descent (GD) algorithm is proposed for improving estimated accuracy of rotor position. The feasibility of the algorithm is verified by simulation and experiment.