Sensorless brushless DC (BLDC) motor control is one of today's industry's requirements. The quality of this control is strongly dependent on the exact identification of the rotor angle for switching. In this study, a new sensorless BLDC motor control is introduced that could determine the exact time of the commutation. This method is based on the line-to-line flux linkage. The unscented Kalman filter method is used to identify the parameters in the proposed method. In comparison with back electromotive force based methods, this approach has advantages such as reduction of torque ripple due to commutation operations and resistance to motor parameters’ changes. The correctness of the method and the performed comparison is proved by the computer simulation and practical results.

This paper deals with Life Cycle Assessment (LCA) of induction machines and try to determine whether a copper-cage rotor is better than an aluminium-cage one, for a given using time and considering the global environmental footprint. The paper focuses on induction motors directly connected to the power grid, without electronic converters. The LCA takes into account the materials extraction, the machine construction, the use and the end of life for several criteria. In the first part, a copper conductor is compared to an aluminium one and results are discussed considering the part of recycled material in the rotor manufacturing process. In a second part, two machines with the same efficiency are compared. The environmental impacts differences are discussed. In the third part, two machines of the same sizes, but with a different rotor, are compared considering various usage times. The lower losses of the copper-rotor machine yield a significant advantage for the efficiency but the gains are smaller when the global life cycle is considered.

Passive magnetic bearings offer significant advantages relative to common active magnetic bearings, such as simple, robust, and efficient structure. Permanent magnet (PM) passive magnetic bearings are composed of opposing magnet rings on rotor and stator. Although their stiffness has been improved using alternating or Halbach magnetisations in many previous studies, they still suffer from lack of damping force. In this study, the optimal design is focused on a combination of PM bearing and eddy current damper by adding a conductive layer along the magnets of the stator or rotor. This will moderate the magnetic material consumptions; thereby, the cost and overall size of the bearing are reduced. A complete analytical method is performed to calculate the stiffness and axial, radial, and rotating damping coefficients. The accuracy of the analytical model is estimated quantitatively using 3D finite element method simulations. Moreover, all of the parameters are normalised and optimised for maximum stiffness and damping.

Accurate rotor position is necessary for the control of switched reluctance motors (SRMs). Generally, three position sensors are ideally installed 120 electrical degrees apart for three-phase SRMs. However, the placement of position sensors may be inaccurate, particularly in small-size SRMs, and there is no method reported to deal with this problem up to now. Firstly, the position signals and the influence of the misaligned sensors on the detected rotor position are investigated. Then a novel method is developed to identify the misaligned position sensors with dynamic time warping (DTW) algorithm. The DTW distance versus the misaligned angle is calculated, and the relationship between them is described with linear regression analysis algorithm. Then the rotor position tolerant detection method is realised by compensating the misaligned angle in real time. Finally, comparative experiments are carried out on a three-phase 12/8 SRM drive system, and it can be found that the proposed strategy is capable of providing an accurate rotor position for the SRM drive system. The presented method is easy for online implementation and can be integrated into the control system conveniently.

This article presents a design improvement of the dual-pole, two-speed line start permanent magnet (LSPM) synchronous motor. For this purpose, the operational performance of the motor with dual-pole structure is first compared with the conventional single-pole motor to identify its performance limitations. Next, the structure of the dual-pole rotor is modified accordingly to address the related limitations. The proposed, modified design reduces the number of PMs in the rotor structure and offers a better steady state and transient performance. The motor is analysed using 2D finite element analysis (FEA), and results are verified by experimental tests on the motor prototype.

Hysteresis behaviour of the magnetic materials is an interesting physical concept and has important practical applications in physics and engineering. In this study, a new approach is developed to evaluate the quality of magnetic cores, based on the measured dynamic hysteresis loop. In this study, artificial inter-laminar faults of different configurations were applied on stacks of four standard Epstein size laminations of 3% grain oriented silicon steel. Dynamic hysteresis loop of the samples was measured and analysed over a range of magnetising frequency and flux density, to calculate the extra power losses caused by the artificial faults. The results show an accurate evaluation of the extra power loss compared to the bulk measurement, with a maximum difference of <4%.

Nowadays the flux switching machines offer pivotal role in high speed applications. The flux sources (field excitation coil and armature winding or permanent magnet) are confined to the stator leaving rotor completely passive, and thus making the flux switching machine (FSM) more suitable for industrial applications. This paper emphasizes salient rotor pole and non-overlapping windings embedded in electrical machine design possess some pertinent features such as reduced copper losses, low-cost, and usage in high speed applications. The proposed design is analyzed for coil test analysis and flux linkage and torque. On the basis of the analysis performed, it is clear that 12-slot/13-pole has low cogging torque, high flux linkage, and maximum torque, compared with other topologies of outer rotor field excitation FSM. A deterministic optimization technique is adopted to enhance the performance of 12-slot/13-pole design. Further, finite element analysis (FEA) results are verified through Global Reluctance Network (GRN) methodology, which show close resemblance with error less than 1.2%. Hence, it validates the proposed design for outer rotor field excitation FSM direct drive application. The proposed design for hybrid electric vehicle torque characteristic is compared with existing interior permanent magnet synchronous machine (IPMSM) and 6-slot/7-pole wound field flux switching machine (WFFSM).

This study describes an extended approach to the differential protection of power transformers to identify turn-to-turn faults based on the second central moment (SCM). The proposal uses the differential currents as the input signals to the algorithm. Differential currents are filtered and normalised to allow the proposed algorithm to be independent of the transformer parameters (power, reactance, connection etc.). Then, the SCM magnitude of the differential currents is computed and compared with an established threshold to detect the internal faults. If the SCM magnitude exceeds the limit, an internal fault is detected. Otherwise, the event is determined as a transient event or steady state. The proposed algorithm was implemented in MATLAB and was tested on a three-phase system using a Real-Time Digital Simulator. For laboratory experiments, a real 55-kVA transformer setup was used to validate the effectiveness of the algorithm. The algorithm successfully identified turn-to-turn faults from steady state, as well as during transformer energisations, in over 1000 cases.

This study investigates an advanced finite-element (FE) technique for the evaluation of rotational iron losses based on a time-domain computation, where the bulk conductivity of the core materials is considered. The iron-loss characteristics are discussed for a radial flux permanent magnet synchronous machine (PMSM) for a wind generation application, with closed slots and outer rotor topology. The following factors are taken into account: (i) a real-time rotational iron-loss computation; (ii) the bulk conductivity of the steel laminations; and (iii) the influence of the controller harmonics on the system during transient conditions. The magnetic induction vector locus of each iron component is also discussed, where the magnetic induction is numerically modelled [three-dimensional (3D) finite element analysis (FEA)], computed using multiple magnetic antennae and is also experimentally verified. This comparative study shows a torque–frequency-loss computation that is presented from low to high frequencies (50–800) Hz. The FE model of the total iron losses for the PMSM using both pure sinusoidal and proportional–integral pulse-width modulation currents is studied and experimentally verified on a surface-mounted PMSM. The proposed method of iron losses prediction significantly reduced the rate of error between 3D FEA and experimental data to 1.7%.

Nowadays, electric motors and frequency converters have a great variety of applications. In motor feedback systems, communication is performed over separate sensor cables, which are notable for their high cost. Power line communication (PLC) over the motor cable is a promising and cost effective alternative. In this paper, a communication concept based on PLC and direct sequence spread spectrum (DSSS) channel access method is presented for motor cable communication. The channel characteristics and noise in the channel of a laboratory test setup are studied. Effect of the frequencyconverter output and switching frequencies on the channel noise are investigated. Capacitive and inductive signal coupling methods are evaluated and compared first theoretically by measurements and analysis of channel characteristics, and then practically by data transmission tests carried out in the laboratory test setup. Software-defined radios (SDRs) are used as the data transmission devices for the communication concept evaluation. Concept's performance against variation of a signal-to-noise ratio (SNR) and switching frequency of the converter are evaluated. The concept applicability limits and optimal settings are presented. It can be stated that the concept provides a wider application range, than available solutions and can be effective for motor monitoring and speed data transmission.

Coaxial iron-core coil system shielded by a magnetic screen is a complex model for analytical calculation, because a complicated boundary value problem must be tackled for obtaining inductances of the coils in this situation. Truncated region eigenfunction expansion method is a suitable way to work out such a problem containing complex boundary conditions. Three different models are taken into consideration in this study. Starting with coil system shielded by two infinitely large plates, the basic steps of the proposed method are introduced carefully. Then the relevant techniques and conclusions are applied to the iron-core coils shielded by a fully enclosed cylindrical screen of high permeability and a lidless one. The effectiveness of the proposed method is verified by comparing with finite element method software and experiments. From relevant data, it is evident that the proposed method is much faster and can be easily used for forecast and evaluation of new schemes in device design process.

Gearless and compact motors rotating at speeds above 10,000 rpm are finding many applications nowadays. This study presents the multiphysics modelling and analysis of a multilayer printed circuit board (PCB) stator for high-speed, low-power axial flux permanent magnet motor. The possibility of circulating current in the multilayer PCB is studied. The two major effects of eddy currents at high frequencies: skin effect and proximity effect are investigated for the PCB winding. The losses in the PCB stator are estimated, and thermal analysis is performed to ensure reliable operation of the motor. MagNet 3-D and COMSOL Multiphysics are used, respectively for the finite element analysis and optimisation of the motor; and the simulation results are presented. A prototype of the motor is fabricated and tested to validate the simulation results.

This study presents a model predictive control (MPC) for a doubly fed induction generator (DFIG) power control using a state-space prediction model. Genetic algorithms (GAs) have demonstrated their potential in finding good solutions for complex problems. However, GA in its original form lacks a mechanism for handling constraints. In this way, a method for tuning the MPC based on a novel constrained GA is proposed. In this way, the method permits a good solution for the weighing matrices with predetermined maximum requirements, such as maximum overshoot, just using the DFIG control simulation. Finally, experimental results are presented to endorse the proposed theory.

In order to accurately estimate the temperature rise for high-power high-speed permanent magnet machines (HSPMMs), a novel temperature calculation method considering the non-linear variation of material properties with temperature is proposed based on multi-physics co-simulation analysis. According to the theory of computational fluid dynamics and heat transfer, the computation model of fluid–solid–heat coupling heat transfer is established, and the coupled field is calculated using finite volume method with fundamental assumptions and corresponding boundary conditions. With the influences from temperature gradient and water flow rate considered, the heat transfer coefficients of water pipe surfaces are obtained by the application of the inverse iteration method. Thus, HSPMM temperature and fluid field can be simulated numerically by the finite volume methods, while the spatial temperature distributions for the machine main components are analysed in this study. The 1.12 MW, 18,000 rpm HSPMM is prototyped with experiments conducted on it, while the test data are then compared with the calculated results, which validate the correctness of the solution method of the coupled field.