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This article proposes a novel asymmetric interior permanent magnet (AIPM) rotor topology that has a mixed V-shape and spoke-type PM configuration, designated as a 1.5-layer PM structure, and asymmetric arrangement of V-shape PMs and asymmetric flux barriers. The AIPM rotor topology is employed for IPM synchronous machines to utilize the magnetic-field-shifting (MFS) effect for increasing average torque by reducing the current angle difference between peak PM and reluctance torque components. Three machines, i.e., the proposed 1.5-layer AIPM, a symmetrical 1.5-layer IPM-I, and a conventional V-shape benchmark IPM-II are designed and optimized using the same stator, rotor diameter, and total PM usage by global parametric optimization considering the mechanical stress. The effect of asymmetric features of the 1.5-layer AIPM rotor design, i.e., asymmetry of V-shape cavity as well as position and dimensions of flux barrier, on maximum torque and open-circuit air-gap field are investigated. The electromagnetic performances of three machines are compared. It confirms that the proposed AIPM machine has the highest maximum torque and the smallest cogging torque simultaneously. It is also revealed that the torque enhancement is achieved by both the 1.5-layer structure and MFS effect. Finally, a prototype of an AIPM machine is manufactured and tested to validate the analyses. [ABSTRACT FROM AUTHOR]

This article proposes a novel asymmetric interior permanent magnet (AIPM) rotor topology for torque enhancement and torque ripple reduction in IPM synchronous machines. The AIPM rotor structure is featured by a hybrid-layer permanent magnet configuration, i.e., for each pole, a part of PM configuration has one-layer while the other part has two layers. It allows the magnetic-field-shifting (MFS) effect to be utilized by reducing the current angle difference between maximum PM and reluctance torque components, thereby effectively increasing the maximum resultant torque. The proposed AIPM machine and a conventional V-shape IPM machine are designed and globally parametric optimized with the same 24-slot/4-pole stator, rotor diameter, and PM usage. The influence of key rotor geometric parameters of the AIPM machine on torque and open-circuit air-gap magnetic field characteristics are investigated. The comparison of electromagnetic performance confirms that significant torque enhancement and torque ripple reduction in the AIPM machine compared with the conventional V-shape IPM machine and reveals the MFS effect is essential for torque increase. Finally, an AIPM machine is manufactured and tested for validation. [ABSTRACT FROM AUTHOR]

This article investigates the influence of stator slot number on electromagnetic performance of two-pole high speed permanent magnet (HSPM) slotted motors with toroidal (TO) windings. Four two-pole slotted motors with different slot numbers, i.e., 3, 6, 9, and 12, are globally optimised for maximum torque, and their electromagnetic performance are compared, including winding factor, air-gap flux density, back electromotive force, cogging torque, electromagnetic torque, winding inductances, unbalanced magnetic force (UMF), and various loss components. It shows that the six-slot/two-pole HSPM motor with TO windings is eminently suitable for high speed application due to no UMF and easy to realise a modular structure. In addition, TO and tooth-coil windings are compared in the three-slot/two-pole motors, and the results confirm that TO windings are not suitable for use in the three-slot/two-pole HSPM slotted motor due to large airgap field harmonics. Finally, a six-slot/two-pole prototype motor is manufactured and tested to validate the finite element predictions. [ABSTRACT FROM AUTHOR]

An all-silica Fabry-Pérot interferometer (FPI) is demonstrated for high-temperature pressure monitoring. The pressure sensor is fabricated with single mode fiber and silica capillary by CO2 laser. Owing to slight mismatch of thermal expansion coefficient in all-silica structure, it can work stably under 600°C atmosphere. The influence of the temperature on the pressure sensor was investigated within a temperature range from 25°C to 700°C and a pressure range from standard atmosphere pressure to 4 MPa. The experimental results show that the wavelength shift versus the pressure at each temperature is linear, which indicates the proposed FPI pressure sensor has potential applications in industrial reactors, oil and gas wells, and so on. [ABSTRACT FROM AUTHOR]

This paper proposes a spoke-type interior permanent magnet (IPM) machine with novel alternate airspace barriers, through which higher torque capability and better manufacturability can be obtained, without remarkable deterioration in mechanical strength. Further, the influence of end leakage flux in the novel IPM design is investigated by three-dimensional finite element method, including the leakage flux characteristics and torque capability. Furthermore, a step-staggered rotor is proposed to reduce the unipolar leakage flux and magnetization of the end shaft. As an extension, unipolar leakage flux is further investigated in consequent-pole PM machines, as well as the validity of step-staggered method. Finally, prototypes are fabricated and tested to verify the foregoing analyses, including the magnetic field at the end shaft and the output capability. [ABSTRACT FROM AUTHOR]

The ill-convergence of multiparameter estimation due to the rank-deficient state equations of permanent-magnet synchronous machines (PMSMs) is investigated. It is verified that the PMSM model for multiparameter estimation under id = 0 control is rank deficient for simultaneously estimating winding resistance, rotor flux linkage, and winding inductance and cannot ensure them to converge to the correct parameter values. A new method is proposed based on injecting a short pulse of negative id current and simultaneously solving two sets of simplified PMSM state equations corresponding to id = 0 and id \neq 0 by using an Adaline neural network. The convergence of solutions is ensured, while the minimum \vert id\vert is determined from the error analysis for nonsalient-pole PMSMs. The proposed method does not need the nominal value of any parameter and only needs to sample the winding terminal currents and voltages, and the rotor speed for simultaneously estimating the dq-axis inductances, the winding resistance, and the rotor flux linkage in nonsalient-pole PMSMs. Compared with existing methods, the proposed method can eliminate the estimation error caused by the variation of rotor flux linkage and inductance as a result of state change due to the injected d-axis current in the surface-mounted PMSM. The method is verified by experiments, and the results show that the proposed method has negligible influence on output torque and rotor speed and has good performance in tracking the variation of PMSM parameters due to temperature variation. [ABSTRACT FROM AUTHOR]