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High‐frequency audible noise and high‐frequency vibrations (HFVs) in electrical vehicles are primarily caused by vibrations and ripples generated in the traction motor. The appositeness of permanent magnet synchronous motors (PMSMs) has been boosting in traction applications due to their high energy density, compact size and high torque to weight ratio. A novel and step‐by‐step design of medium power, high speed, surface PMSM, suitable for e‐bus or e‐truck applications, with suppressed torque ripples, is presented. Initially, a conventional machine design approach has been used to design 100 kW PMSM. In the next step, the design has been ameliorated by making it a fractional slot winding machine to suppress the winding harmonics. Finally, the effect of the permanent magnet embrace size on the torque ripple has been investigated. A nonlinear relationship between the torque ripple and PMSM magnetic embrace has been developed. The developed relationship has been validated in the finite element model of the machine. Gradient‐based nonlinear sequential programming has been used to find out the optimum magnetic embrace for the minimised torque ripple. The effectiveness of the optimised design has been revalidated in the FE software. The step‐by‐step design process described here can reduce the torque ripple by 85% of optimised design compared to the conventionally designed PMSM. [ABSTRACT FROM AUTHOR]

In this paper, an optimum design for a three-phase line-start synchronous reluctance motor (LS-SynRM) with respect to efficiency, maximum torque, and starting torque is proposed. The design variables, objective functions, and constraints are selected for this optimum design, which is divided into two steps. Step I maximizes the rated efficiency, while maintaining balanced operation and minimizing the stator copper loss. Step II calculates the precise starting torque using finite element analysis (FEA). The validity of the optimum design is verified by comparing the efficiency, maximum torque, and starting torque characteristics of the time-step FEA with experimental results. [ABSTRACT FROM AUTHOR]

This paper offers methods to analyze the performance of three-phase synchronous machines operating with an unsymmetrical stator winding caused by cutting out and bypassing coils. The resulting unsymmetrical current distribution in the stator winding tends to produce overheating in parts of the stator and damper windings at full load as well as torque pulsations. Thus, the main objective of this study is to determine the maximal load, under which the unsymmetrical machine may operate without exceeding the permissible temperature limit. Based on the multiloop method, a mathematical model of a synchronous machine with missing coils in the stator winding is developed. In order to determine the current distribution, the machines’ system of differential equations is solved by using a numerical integration method (Runge–Kutta method). As an alternative method, the system of differential equations in the steady state is reduced to a system of algebraic equations, which can be solved with the Gaussian elimination method. Both methods are validated by the measurement results of a 25-kW salient pole synchronous machine. Furthermore, both the circulating current within the parallel branches and the line currents of the different phases as a result of coil or coil group cut-outs are analyzed for a large 41-MW cylindrical rotor synchronous motor. [ABSTRACT FROM AUTHOR]

Reliable and safe operation of electric motors in the industry is highly desirable. Accurate modelling is the first step in developing a diagnostic tool for different types of failures. This study presents a generalised dq-model for interior-mount line start permanent magnet synchronous motors under asymmetrical stator phase's windings. The presented dq-model has been derived using winding theorem. Implementation and simulation of the derived dq-model has been done using MATLAB/ SIMULINK software. For validation purposes, interior-mount line start permanent magnet synchronous motor (LSPMSM) under this fault condition is implemented using the JMAGTM-finite-element-based software. The performance of a 1-hp interior-mount LSPMSM motor under different loading levels and stator winding asymmetric conditions has been investigated using the simulated MATLAB and JMAG models. Simulation results of MATLAB and JMAG are in very good agreement and show that under asymmetrical stator winding condition, oscillations are obvious in the torque characteristics of the motor. In addition, the torque experience high oscillations at a steady state due to the asymmetry between stator phases. Finally, investigating torque frequency spectrum showed that they can be good signatures in diagnosing asymmetrical stator winding faults in interior-mount LSPMSM. [ABSTRACT FROM AUTHOR]

In this paper, an investigation into an alternative topology for reluctance synchronous machine rotor flux barriers is presented. The investigated topology employs a high number of flux barrier variables with an alternative asymmetric rotor structure. The focus in this paper is on maximizing average torque and minimizing torque ripple, using finite element-based design optimization, in order to study the possibility of achieving acceptably low torque ripple. A subsequent investigation into the effect of rotor skew on the proposed optimized design to reduce torque ripple even further is also conducted, as well as the manufacturing and testing of the proposed flux barrier prototype. [ABSTRACT FROM PUBLISHER]

A new synchronous-frame current-regulator configuration for a surface permanent-magnet machine is presented, which utilizes incomplete phase-current measurements from the integrated pilot current sensors to deliver an attractive regulator performance. Since the pilot current sensors are directly integrated into the power switching devices, they provide opportunities to reduce the cost, size, and weight of the three-phase inverters by eliminating the dedicated current sensors in the motor-drive applications. However, a three-phase inverter equipped with these sensors in the three low-side switches cannot measure the complete load-current waveforms, requiring the development of this new current-regulator algorithm. An autotuning method is described that significantly reduces the sensitivity of the regulator to errors in the estimated machine parameters. Experimental results are provided to verify the appealing performance characteristics of the proposed regulator. [ABSTRACT FROM AUTHOR]

This paper reports on optimized fabrication technologies for electromagnetic actuator systems and their characterization. These actuators consist of three-dimensional microstructures of increasing complexity like electroplated micro coils, flux guidances, insulation and planarization layers. The microstructures are fabricated by UV depth lithography using AZ9260, electrodepositable photo resist and Epon SU-8. Electroplated nickel iron and copper is used for the generation of flux guidance and coils. The magnetic flux is generated and guided in plane by a three dimensional double meander coil wound around laterally toothed stator poles. The traveller's comb shaped poles reach in between the stator poles and, therefore, are attracted from both sides. Thus, the attraction forces exceeding thrust, common to any VR-motor concept, are eliminated. The micro actuator was simulated, fabricated and successfully tested. [ABSTRACT FROM AUTHOR]

Dual Y shift 30° six-phase motors are expected to be extensively applied in high-power yet energy-effective fields, and a harmonic-suppressing control strategy plays a vital role in extending their prominent features of low losses and ultra-quiet operation. Aiming at the suppression of harmonic voltages, this paper proposes a six-phase space vector pulse width modulation method based on an optimization model, namely OM-SVPWM. First, four adjacent large vectors are employed in each of 12 sectors on a fundamental sub-plane. Second, the optimization model is constructed to intelligently determine activation durations of the four vectors, where its objective function aims to minimize the synthesis result on a harmonic sub-plane, and its constraint condition is that the synthesis result on the fundamental sub-plane satisfies a reference vector. Finally, to meet the real-time requirement, optimum solutions are obtained by using general central path following algorithm (GCPFA). Simulation and experiment results prove that, the OM-SVPWM performs around 37% better than a state-of-the-art competitive SVPWM in terms of harmonics suppression, which promise the proposed OM-SVPWM conforms to the energy-effective direction in actual engineering applications. [ABSTRACT FROM AUTHOR]