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The flux-switching permanent magnet (FSPM) machine exhibits competitive torque capability and power density due to the high flux density. As a penalty, the cogging torque is relative large, resulting in unfavorable torque pulsation. Due to the simple and robust rotor construction, additional dummy slots are adopted to reduce the cogging torque without skewing magnets or teeth. The optimal dimensions...
In this paper, a method for predicting the electromagnetic vibration of PM brushless motors is presented. It has accounted for both PM blushless AC and DC motors. It calculates the electromagnetic force on individual stator teeth by the Maxwell stress method, based on 2-D finite element analysis of the electromagnetic field. The resulting radial force contour is then used in an analytical mechanical...
At present, structure design and performance optimization are the key points in the study of brushless doubly-fed machine (BDFM). By using ANSYS software, the finite element method (FEM) models of BDFM were established. These models have different rotor structures that are reluctance rotor with magnetic barriers, cage rotor with nested shorted-circuit windings, reluctance rotor with salient poles,...
The doubly-salient permanent magnet (DSPM) motor employing straight rotor and concentrated windings is conventionally operated by means of current chopping control in constant-torque region and angle-position control in constant-power region due to the trapezoidal back-EMF waveform. However, the rotor-skewing method can be used to improve back-EMF and inductances waveforms to be sinusoidal significantly...
In this paper, the static and dynamic electromagnetic performance, including the airgap field distribution, the back-emf waveform, the cogging torque, and the torque-speed characteristic and the efficiency, of three alternative Halbach permanent magnet brushless motors, employing anisotropic bonded NdFeB Halbach cylinder with and without rotor back-iron, as well as segmented Halbach cylinder with...
Several novel linear, either planar or tubular, flux-switching permanent magnet (FSPM) brushless machines with different winding configurations and mover slot/stator pole combinations are proposed and compared, with particular reference to the tubular format. Coil connections are determined from the coil back-EMF vectors. The influence of major design parameters, such as the split ratio, the stator...
A method is proposed for predicting the d- and q-axis inductances and flux-weakening performance of PM brushless AC machines accounting for skew and d-q axis cross-coupling. The method is based on a d-q-axis flux-linkage model, a hybrid 2-D FE-analytical method being used to predict the d- and q-axis inductances. However, it only requires 2-D FE analysis of the magnetic field distribution over a cross-section...
In order to extend the speed operation range for the constant generating voltage or the constant motoring power of the electrical machine, a new hybrid excitation machine with isolated magnetic paths is presented in this paper. The structure of the machine is described and its operation mechanism is analyzed in details. As an example, a conceptual prototype machine integrated with a rotating-armature...
New flux-switching permanent magnet (FSPM) brushless machine topologies with different stator and rotor pole combinations (Ns/Nr) are developed, with potentially reduced stator and rotor pole numbers without introducing the unbalanced magnetic force. The relative merits of FSPM and flux reversal permanent magnet (FRPM) brushless machines are evaluated. The electromagnetic performance, including back-emf,...
As a new type of induction machine, brushless doubly-fed machine (BDFM) has excellent speed regulation performance and can run in the condition of variable-speed-constant-frequency power generation. It has good applicable potentials on energy-saving-speed-adjusting motors and wind power generation system, but its structure and operating principle are more complex. To study the effect of different...
The paper considers the optimal design of an open slot, external rotor torque motor. Combinations of pole and slot numbers are presented for which the winding factor is maximal and torque ripple is minimal. A detailed optimisation of the magnetic circuit design of the six most promising pole-slot configurations has been undertaken using the combination of a genetic algorithm (GA) and a parametric...
The paper investigates the optimal multi-polar magnetization of an interior magnet brushless machine rotor comprising a permanent magnet (PM) array made up from discrete anisotropic arc segments. The particular case where the magnet array is constructed from two arc segments per pole is considered where the magnets are alternatively magnetised normal and tangential to the rotor surface. The influence...
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