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For permanent-magnet linear motors (PMLMs), high-temperature rise can deteriorate their electromagnetic performance and limit their thrust output. A water-cooling system can be employed to reduce the temperature rise and to improve the thrust density. In order to study the thermal performance of a water-cooled, 14-pole, and 12-slot PMLM, a finite-element model and thermal network model are developed. Under continuous duty, the temperature distribution of this PMLM is investigated based on the two developed models, which are validated by experimental results. The effect of the water-cooling system and the impact of its parameters on the temperature rise are investigated. Then, the influence of the temperature rise on the motor thrust force and efficiency is studied. Finally, based on the finite-element model, thermal characteristics of this PMLM under short-time duty and intermittent duty are studied, and the relationship is obtained between the operation duration and the maximum allowed short-time current, as well as the impact of load sustained rate. [ABSTRACT FROM AUTHOR]

A novel switched-flux (SF) surface-mounted permanent magnet (PM) memory machine is proposed by incorporating the flux-memorizable concept into the SF structure. It employs a temporary current pulse to magnetize/demagnetize the aluminum–nickel–cobalt (Al–Ni–Co) PMs so that the air-gap flux can be regulated online for extending its high-speed constant-power region. An analytical hysteresis modeling method is formulated and implemented by numerical nonlinear approximation of hysteresis loops, and then coupled with time-stepping finite element method to perform the analyses of both static and transient flux-regulatable characteristics. The preciseness of the coupling solution and the validity of machine design are verified by experimental results. [ABSTRACT FROM AUTHOR]

In order to facilitate the selection of machine whether it is suitable for high-frequency (HF)-signal injection-based sensorless control or not, this paper proposes a complete experimental investigation method for the analysis and validation of machine saliency level, including primary saliency, which is essential for HF injection-based sensorless control, and the secondary saliency, which will deteriorate the rotor-position estimation. The experimental results obtained on a new type of switched-flux permanent-magnet (SFPM) machine prove that with identified primary saliency, the accurate rotor-position estimation can be achieved, and with small secondary saliency, the estimation will not be deteriorated much in the SFPM machine. The conclusion is verified by the experiments based on the HF pulsating signal injection-based sensorless control at zero and low speeds. [ABSTRACT FROM PUBLISHER]

This paper develops a 2-D field analytical model for predicting the magnetic field distribution and the corresponding electromagnetic performance in air- and iron-cored permanent magnet (PM) brushless machines having radially or parallel magnetized two-segment Halbach array. A simple equation is derived to directly predict the optimal magnet ratio for maximum electromagnetic torque, while the influence of pole-pair number and magnet thickness on the optimal magnet ratio is investigated for both air- and iron-cored machines. The analytical model is validated by finite-element analyses and also measurements on a prototype 12-slot/10-pole PM brushless machine. [ABSTRACT FROM AUTHOR]

In this paper, cogging torque characteristics in both single-phase and three-phase flux switching transverse flux permanent magnet machines (FS-TFPMM) are analyzed by 3-D finite element method (FEM). It is found that the cogging torque of the FS-TFPMM is significantly influenced by the ratios of stator and rotor core circumferential widths to pole pitch, ks and kr. When kr>1-ks, the cogging torque waveform has additional two zero-crossing points, whilst its amplitude is significantly reduced. The optimal ratios of ks and kr are selected to reduce the cogging torque and to maximize the permanent magnet flux linkage. A 380 W three-phase prototype is designed, manufactured, and tested to verify the optimization. [ABSTRACT FROM AUTHOR]

A novel axial field flux-switching permanent magnet (AFFSPM) machine with a doubly-salient structure is presented as a wind power generator. One rotor is sandwiched between two stators in which both windings and permanent magnets are placed. This novel generator is suitable for the wind power generation system because of its shorter axial length and higher power density. A three-phase 12/10-pole 0.6 kW AFFSPM generator is designed. The power-size equation of the machine is deduced, and the size of generator is determined. Based on the 3-D finite element method, the electromagnetic performances of the generator are investigated. According to the theoretical calculation, a prototype is manufactured and the experiments are done. The analysis results are consistent with the experimental ones well. [ABSTRACT FROM AUTHOR]

This paper presents a method for analytically analyzing the magnetic field and predicting the cogging force and torque of a linear and rotary permanent magnet actuator (LRPMA). The tubular mover of the LRPMA is transferred into a planar one by using a proposed magnetic field curvature factor and a relative permeance function for the stator slotting so as to simplify the magnetic field calculation. Magnetic field distributions of the LRPMA when the stator slotting is neglected are analytically analyzed using the magnetic scalar potential, and validated by 3-D finite-element method. The linear cogging force and rotary cogging torque of slotted LRPMA are subsequently predicted by the Maxwell stress tensor method and verified by the experimental results on the prototype. [ABSTRACT FROM AUTHOR]

A new simplex wave winding permanent-magnet (PM) brushless DC machine is proposed in this paper. Besides PM excitation and electric commutation, the machine has close-connected winding identical to the brushed DC machine. By properly controlling the power electronic switch status, the current direction of coils under N or S pole is unchanged. Thus, the new machine's operation principle is exactly as same as the brushed DC machine. Furthermore, as the adoption of PM and electric commutation, the new machine can be designed with larger pole number and lower slot number per pole, which respectively leads to less iron yoke and shorter end winding. Therefore, the proposed new machine not only keeps the characteristics of a brushed DC machine, but also improves the efficiency and power density. A 200 W, 10-pole, and 11-slot new machine is designed, prototyped, and tested to verify the analysis. [ABSTRACT FROM AUTHOR]

The variation characteristics of flux density and field intensity of trapezoidal permanent magnets (PM) in the variable-flux memory motor (VFMM) under different demagnetizing magnetomotive forces are analyzed using the finite element method. A prototype machine is fabricated and tested. Good agreement between the calculated and experimental results is achieved. It confirms the easy controllability of air gap flux of the developed VFMM with trapezoidal PMs. [ABSTRACT FROM AUTHOR]