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Accurately measuring the cogging torque, hysteresis torque, and iron losses of permanent magnet (PM) motors is a challenging task. This is especially true for sub-fractional horsepower (SFHP) variants used, e.g., in auxiliary drives for automotive fan and pump applications. Their cogging torque and hysteresis torque peak values are often in the sub-milli-Newton meter range, causing conventional measuring methods and devices to fail as especially friction impedes the measurement significantly. Moreover, their iron losses are hard to determine and usually merely estimated in the literature. This article presents an unconventional rheometer-based method to determine both 1) the cogging torque and hysteresis torque of SFHP PM motors and 2) their iron losses by evaluating the observed offset torque. Two SFHP outer-rotor PM motor topologies for fan applications are analyzed, i.e., a claw-pole motor and a salient-pole motor. The results show that, with the proposed setup, settings, and evaluation, a rheometer can successfully be used to determine the cogging torque and hysteresis torque waveforms in the sub-milli-Newton meter range and the iron losses of SFHP motors, both with excellent accuracy. [ABSTRACT FROM AUTHOR]

Condition monitoring of the stator and rotor problems such as interturn short fault (ITSF) and partial irreversible demagnetization fault (PIDF) in an interior permanent magnet synchronous motor (IPMSM) is essential for achieving high efficiency and reliability. This article presents a torque angle-based inverter-embedded technique for the online detection and identification of ITSF and PIDF. This technique monitors the deviation in the torque angle caused due to ITSF and PIDF at a certain operating point. In steady-state operation, the torque angle decreases from its original value (healthy state) due to ITSF while increases in the case of PIDF. This particular trend of torque angle is used for the detection and identification of ITSF and PIDF. In this article, the torque angle for a healthy IPMSM is first obtained using multivariate regression analysis over the entire operating region and then compared with the torque angle during operation for any potential variation. The proposed method is verified using a finite-element method-based simulation and experiment on a 400-W IPMSM. The results suggest that the proposed method can be a viable candidate for efficient ITSF and PIDF detection and identification in real time. [ABSTRACT FROM AUTHOR]

This paper deals with the development and implementation of an on-line technique for the identification of the stator resistance and permanent magnet flux linkage on three-phase, open-end winding, permanent magnet synchronous motor (PMSM) drives. The stator resistance and permanent magnet flux linkage are independently determined by exploiting a special current vector control strategy, which holds one of the phase currents at zero while suitably modifying the other two in order to keep the magnetomotive force unchanged. As will be demonstrated, no additional sensors or special tests are required by the proposed technique; moreover, motor electrical parameters can be on-line estimated in a wide operating range, avoiding any detrimental impact on the torque capability of the PMSM drive. Finally, the electrical machine thermal status can be also estimated from obtained values of the stator resistance and permanent magnet flux linkage. [ABSTRACT FROM AUTHOR]

In this paper, we investigate rotor and stator designs of interior permanent synchronous motors for variable speed/load applications to reduce the carrier harmonic losses caused by pulsewidth modulated inverters. The rotor core and magnet shapes are determined by automatic optimization methods with electromagnetic field analysis, which considers the inverter carrier. Appropriate stator-winding configurations are also investigated by this analysis. It is clarified that the total carrier harmonic loss can be reduced by more than 20% by optimizing both the stator and rotor shapes, whereas the other important characteristics are not deteriorated. The mechanism of carrier loss reduction is also clarified. [ABSTRACT FROM AUTHOR]

This paper proposes a design method of stator cores to modify the component ratio of space harmonics in the magnetic field due to stator windings for 12-slot 10-pole concentrated winding motors. The method inserts slit-like magnetic flux barriers in stator wound teeth. In fractional-slot concentrated winding motors, the magnetic field due to stator windings includes dominant space harmonics with a specific space harmonic that produces drive torque. These space harmonics give rise to undesirable effects that increase iron loss in cores and eddy-current loss in magnets. For 12-slot 10-pole motors with single-layer windings, the proposed method increases the driving space harmonic and decreases dominant detrimental space harmonics. This modification of the space harmonics leads to torque enhancement and efficiency improvement. The efficacy of the proposed method is determined by deriving the winding factor, estimating magnetic flux distribution and motor performance through a finite element method analysis, and demonstrating the actual motor performance of a prototype. [ABSTRACT FROM AUTHOR]

This paper describes the design process of a 10 kW 19 000 r/min high power density surface mounted permanent magnet synchronous machine for a directly coupled pump application. In order to meet the required specifications, a compact machine with cooling channels inside the slots and flooded airgap has been designed through finite element (FE) optimization. For high power density, high-speed machines, an accurate evaluation of the power losses, and the electromechanical performance is always extremely challenging. In this case, the completely flooded application adds to the general complexity. Therefore, this paper deals with a detailed losses analysis (copper, core, eddy current, and mechanical losses) considering several operating conditions. The experimental measurements of ac copper losses, as well as the material properties (BH curve and specific core losses) including the manufacturing process effect on the stator core, are presented. Accurate 3-D FE models and computational fluid dynamics analysis have been used to determine the eddy current losses in the rotor and windage losses, respectively. Based on these detailed analysis, the no-load and full-load performance are evaluated. The experimental results on the manufactured prototype are finally presented to validate the machine design. [ABSTRACT FROM AUTHOR]

This paper proposes a novel proposal to improve reliability of a spoke-type brushless direct current (BLDC) motor using ferrite permanent magnets (Fe-PMs) through a new design. First, the design process for a neodymium permanent magnet (Nd-PM) free spoke-type BLDC motor without assistant permanent magnets (PMs) is presented. The proposed motor is designed by taking into account the demagnetization phenomenon. Second, the effect of the armature reaction on the PMs is analyzed by using the finite element method (FEM) in order to evaluate the robustness of the proposed motor with Fe-PM. In addition, another proposal to avoid the demagnetization phenomenon is suggested. Finally, a prototype motor is manufactured based on the proposed motor. The output characteristics of prototype motor and the demagnetization phenomenon are verified through an experiment. [ABSTRACT FROM PUBLISHER]

This paper proposes an online method for the estimation of the stator resistance and the permanent-magnet (PM) flux in sensorless PM synchronous motor drives. An adaptive observer augmented with a high-frequency signal injection technique is used for sensorless control. The observer contains excess information that is not used for the speed and position estimation. This information is used for the adaptation of the motor parameters: At low speeds, the stator resistance is estimated, whereas at medium and high speeds, the PM flux is estimated. Small-signal analysis is carried out to investigate the proposed method. The convergence of the parameter estimates is shown by simulations and laboratory experiments. The stator resistance adaptation works down to zero speed in sensorless control. [ABSTRACT FROM AUTHOR]