Consequent-pole permanent-magnet machines are of particular interest owing to their special features. They have alternate hard and soft magnet poles. In this paper, a two-dimensional (2-D) analytical model is proposed for outer-rotor slotted-stator consequent-pole brushless PM (CPBLPM) machines. The model is developed from the quasi-magneto-static Maxwell's equations, which are analytically solved. The magnetic flux density expressions are initially derived and then other quantities such as the no-load induced voltage, electromagnetic torque, reluctance torque, cogging torque, self and mutual inductances as well as unbalanced magnetic forces (UMF) are computed. The suggested model is generic and applicable to CPBLPM machines with any number of poles and phases, type of magnetization patterns and current waveforms. A case study is presented to evaluate the performance of the proposed model. The accuracy of the 2-D analytical solutions is verified against those obtained from the finite element method (FEM). The proposed method can replace the FEM in designing and optimization of outer-rotor consequent-pole permanent-magnet motors.

Amorphous magnetic materials (AMMs) have been used in low-frequency power transformer applications for more than two decades but not commercially utilized in high-frequency rotating electrical machines despite their low iron losses, which is an order of magnitude lower than conventional silicon iron. This was primarily due to the lack of a suitable handling method and an economical cutting technique. This paper reports a novel brushless synchronous permanent magnet rotating electrical machine that combines the benefits of the previous machine topologies while offering higher torque (due to the larger air-gap surface area compared with the flat axial-field machine) and ease of manufacturing from AMM material, which is suitable for a range of high-efficiency, high-power density, and high-speed machine applications. This paper provides the details and the performance characteristics of this novel tapered-field AMM machine as a generator at high speeds using a bonded rotor magnet topology.

This paper covers the design methodologies and optimisation techniques studied in the performance improvement of line-start permanent magnet synchronous motors (LSPMSM). LSPMSM performance improvement using design techniques are chiefly limited to either the transient or the steady-state performance improvement, and a focus on only the transient performance improvement may degrade the steady-state performance of the LSPMSM and vice versa. Optimisation studies of LSPMSMs can be categorized in terms of optimisation aim in three classifications: transient performance improvement, steady-state performance improvement, and simultaneous improvement of both transient and the steady-state performance. This study indicates the impact of various variables on the LSPMSM performance improvement. The optimisation review shows that starting cage optimisation without considering the steady-state characteristics as constraints results in synchronous performance degradation. The steady-state performance optimization with transient characteristics as constraints results in a minor synchronous performance improvement though there is the lowest transient performance sacrifice. Multi-objective optimization including a transient and a steady-state characteristic as individual objectives resulted in a more optimum LSPMSM with overall performance improvement. Finally, suggestions for optimisation implementation of LSPMSMs are presented for future research work.

This paper presents research work on a 12-slot ten-pole tapered axial-flux permanent-magnet machine utilizing amorphous magnetic material in the stator core. Novel loss separation techniques are described, including mechanical loss and locked-rotor tests. Mechanical loss estimation is based on a combination of experimental tests and 3-D finite-element model analysis using an uncut stator. The locked-rotor test is introduced to separate the stator and rotor losses by eliminating the uncertainty associated with mechanical loss. High rotor yoke losses were identified in the baseline design. The rotor design was modified and a significant improvement in efficiency was demonstrated.

Efficiency maps (EffMs) illustrate the maximum efficiencies of electric machines over a range of torque-speed operating points. This paper reviews the available techniques for efficiency map calculation and gives a general understanding of EffM modelling and interpretation for traction motors. It shows the accuracy versus calculation effort trade-off for different methods. The process of efficiency map calculation for sample induction motor and permanent magnet synchronous machines is explained. Calculation of EffMs using commercial software is also covered. Finally, possible future research opportunities in this field are suggested.

Consideration of the overload (OL) performance of electric machines designed for EVs enables increasing the power density of the propulsion system. This paper aims to show the characteristics and advantages of the optimal IMs which have the capability of handling OL. A subdomain model (SDM) with the capability of the saturation prediction is developed and validated using experimental data. A lumped thermal model is developed to predict the transient temperature variation of the IMs. The thermal model is validated using the Motor-CAD transient thermal analysis. The fast speed and accuracy of the applied SDM allows to select twelve variables in a large search space for the optimization purpose. Initially, an optimization procedure is proposed to design three IMs over three different driving cycles. The optimal designs are validated from the electromagnetic and thermal aspects by the finite element analysis. IMs are then designed optimally with consideration of the OL capability. A transient thermal analysis is carried out to validate the designs. The optimal designs with and without consideration of OL are compared in terms of the machine parameters and geometry to understand how dimensions and equivalent circuit parameters of the IMs vary according to the driving cycles. The comparison allows more intuition about the consideration of OL capability in design.