To suppress the disturbance caused by the parameter mismatch, this article proposes an adjustable model predictive control (AMPC) strategy for an interior permanent-magnet synchronous motor (IPMSM) drives. The key of the proposed method is that an improved model reference adaptive system (IMRAS) is applied to identify online parameters. The traditional proportional-integral (PI) controller in the adaptive law of IMRAS is replaced by a fuzzy logic controller, it can improve the identification accuracy and enhance the robustness of sudden variations in speed reference and load torque. Then, the identified parameters can be used in the AMPC to replace constant parameters. Compared with the traditional model predictive control, the AMPC strategy can effectively decrease motor system current distortion and torque ripple when parameter mismatch occurs. Moreover, the maximum torque per ampere control (MTPA) control strategy based on the formula solution is adopted. And the optimal MTPA operation points can be found automatically by online parameter identification to achieve the minimum amplitudes of the phase current. Finally, the validity and correctness of the proposed method are verified by experiments.

This paper introduces a novel fault-tolerant control for the maximum torque per ampere (MTPA) operation in five-phase interior permanent magnet synchronous machine (IPMSM), termed MTPA fault-tolerant control. The key of this fault-tolerant control is that the reluctance torque is considered and used by MTPA under open-circuit fault. Based on the decoupled model of five-phase IPMSM on synchronous frame and the computing method of d-axis and q-axis voltages under various open-circuit faults, the virtual signal injection control (VSIC) can be applied to realize the MTPA under the fault-tolerant operation by the postfault field-oriented control (FOC) and carrier-based PWM (CPWM). This method is parameter independent in tracking of the MTPA points under the fault-tolerant operation. Besides, it can effectively reduce the amplitude of the fundamental current and improve efficiency compared with traditional i _d = 0 fault-tolerant control. Moreover, it is robust to current and voltage harmonics and machine torque disturbances under the postfault operation. The proposed method is verified by experiments under various postfault operating conditions on an IPMSM prototype drive system.

This paper proposes a torque ripple reduction method for a five-phase interior permanent magnet (PM) motor by shifting asymmetrical rotor poles. The key of this method is to consider the PM torque ripple, reluctance torque ripple, and cogging torque simultaneously from two aspects. First, the main interactional harmonic, contributing to PM torque ripple, between stator magnetic motive force (MMF) and rotor MMF is developed. Then, the appropriate combination of unequal pole arcs is adopted to eliminate the main interactional harmonic. Second, the asymmetrical rotor pole-pair is selected as a repeating unit which produces cogging torque and reluctance torque with consistency in waveforms and phases. Then, three methods for shifting asymmetrical rotor pole-pair are proposed showing that the torque ripple can be reduced greatly and the lower-order harmonics of radial force is acceptable when the shifting angle of the repeating unit is 4.5 mechanical degrees. Through theoretical analysis and experimental test, it is verified that the proposed motor can offer lower torque ripple even under deep flux-weakening region.

Linear permanent-magnet (PM) motors incorporate the merits of high efficiency, simple mechanism, and low cost, which have a bright future in urban rail transit. However, the position sensor costs are huge, which is the main barrier against a wider implementation. In this paper, a type of modified disturbance observer is newly proposed to improve the precision. Two disturbance observers are utilized to estimate the back electromotive force. Then, position information is detected by a phase-locked loop. Finally, the linear PM motor runs with the feedback of estimated position and speed instead of position encoder measuring. The algorithm avoids designing filters and injecting signals. Experimental results based on a linear primary PM vernier motor demonstrate the accuracy and dynamic performance. The comparisons in the aspect of the robustness to measurement errors certify that the modified disturbance observer is superior to the conventional disturbance observer.

This paper proposes a novel spoke-type permanent magnet (PM) motor with auxiliary salient poles (ASPs). With these ASPs, unequal ASPs and shifted ASPs in the circumferential direction can be realized and combined to reduce the torque pulsation, while their functions are different. Unequal ASPs are employed to eliminate the second-order torque pulsation. Nevertheless, the shifted ASPs are selected to reduce the first-order torque pulsation. Additionally, the relationship between the unequal angle or shifted angle of the ASPs and the order of the torque pulsation is revealed. Furthermore, the revealed principle of torque pulsation reduction can be extended to other slot-pole combinations. Finally, a prototype is manufactured for experiments to evaluate the low torque pulsation spoke-type PM motor. Through theoretical analysis and experimental testing, it is verified that the proposed motor offers low torque pulsation and that the revealed principle for torque pulsation reduction of different orders is feasible and effective.

The aim of this paper is to design and investigate two fault-tolerant interior-permanent-magnet motors for high reliability operation. The first one is the spoke type, while the second one has V-shape magnets embedded in the rotor. The structures and features of both motors are presented and the optimal designs are performed. The electromagnetic performances, such as $dq$ -axis inductances, torque, flux weakening, and partial demagnetization, are investigated and compared. In order to calculate the $dq$ -axis inductances accurately and segregate the torque components, the frozen-permeability method is adopted. Additionally, a method to obtain the maximum flux-weakening speed is introduced. Moreover, the partial demagnetization performances of both motors are evaluated under no-load, on-load, overload, and short-circuit conditions. Also, the fault-tolerant capacities of both motors are compared. Finally, both motors are built for exemplification. The analysis is confirmed by experimental results.