Providing basic human needs like water and household electricity is a challenging task at remote locations. To support both needs, this study presents the development of a multipurpose battery-assisted solar water pumping system (SWPS). The system consists of only two power electronics converter, viz., bidirectional DC–DC converter, and three-phase voltage source inverter (VSI). The detailed control system is presented, where the DC–DC converter controls the battery power and also ensures the maximum utilisation of stand-alone solar photovoltaic source. In pumping operation, the VSI is operated as a variable frequency motor drive and rotates an induction motor (IM) at the rated power to deliver rated water discharge. In power supply operation, the household electrical load is connected between the mid-point of DC-bus and the star point of an IM winding. The VSI, along with motor inductance, realises the single-phase inverter, which is controlled with synchronous sine pulse-width modulation to deliver single-phase output. The motor does not rotate during this operation and the motor winding acts as a current filter. This multipurpose SWPS assures rated water discharge during the irrigation period and availability of electrical power in the remaining period. A prototype is developed and extensive experiments are performed to investigate system performances.

This study presents a strategy for stator inter-turn faults diagnosis in induction motors (IMs) operating under time-variable load and time-variable speed conditions. The strategy consists in injecting a zero-sequence high-frequency signal in order to analyse variations in the stator inductances. Incipient stator inter-turn faults are detected by a simple signal processing of the derivatives of the currents. A feature of the strategy is that the zero-sequence high-frequency signal is generated by the inverter that feeds the machine, without modifying the standard space vector modulation of the IM-drive. Experimental results show that faults representing <1% of the stator winding can be detected, as well as the phase location of the fault, validating this proposal.

Load-independent constant current (CC) output with high-system efficiency is required in many cases of Wireless power transfer (WPT) applications. However, the existing topologies with CC output are hard to achieve both simple structure and enough design freedom. In this study, the series/parallel–series (S/PS) topology, which has three compensation capacitors, is presented to achieve CC output. The constant output current of the proposed S/PS topology is free from the constraint of the coils' self-inductance of the loosely coupled transformer (LCT). A thorough analysis of the proposed S/PS topology that implements CC and ZPA is provided. Besides, ZVS can also be obtained by reasonably setting the value of compensation capacitors. An experimental prototype with 50 V input voltage and 3 A output current is fabricated to validate the practicability and rationality of the proposed topology, and 92.18% power transfer efficiency is achieved. Furthermore, a design example with 2 A output current and the corresponding experimental results are provided to verify that the CC output of the proposed S/PS topology is free from the constraint of the LCT parameters. Finally, a comprehensive comparison with several existing topologies for CC output is conducted to reveal the advantages of the proposed S/PS topology.

A two-dimensional analytical model is presented for predicting the air-gap magnetic flux density due to the permanent magnet (PM) and armature currents in brushless surface inset PM (BSIPM) machines. The virtual current theory is used to model the effects of the stator slots and rotor grooves. In this approach, the BSIPM machine is initially modelled as a machine without any stator slot and rotor groove, and the rotor groove and stator slot effects are modelled by a set of surface currents. By extracting the governing Laplace and Poisson equations and applying the boundary conditions, the magnetic flux density due to the PM and armature current is obtained in different parts of the machine. The accuracy of the proposed analytical model is confirmed by comparing its results with those of the finite-element method and experimental results. The proposed model is also compared with the subdomain analytical model in terms of computational speed and accuracy.

In this study, a saturated model of an asymmetrical six-phase induction machine is presented. The model is based on the vector space decomposition approach, and it includes main and leakage flux saturation, as well as the mutual coupling between orthogonal planes while using the Gamma equivalent circuit approach. The accuracy of the proposed model in unbalanced operating modes that are characteristic for multiphase machines, such as post-fault and power-sharing operation, makes it advantageous compared to existing models. The model is developed assuming that the machine operates in asymmetrical conditions and that, therefore, there is fundamental frequency excitation in both planes. The inter-plane coupling effect is examined using finite element analysis and an experimental procedure for its quantification is developed. The model is verified by comparison with the experimental results obtained from a prototype asymmetrical six-phase induction machine, and its advantages compared to existing models are emphasised.

Planar motor is used as an actuator to directly produce multi-degree long stroke, high speed, and high precision movement. Its performance mainly depends on the topology and design of magnet array. In response to the rising trend of structural complexity, this study presents a novel easy-to-manufacture magnet array using permanent magnets with different magnetisation intensity and height. First, the flux density distribution of magnet array with different magnetisation intensity is derived by the Fourier analysis and the scalar magnetic potential equation. Then, the magnetic field model of magnet array using permanent magnets with different magnetisation intensity and height is obtained by the superposition method. Afterwards, the magnet array is raised and optimised based on the derived model. Calculations show that the high-order harmonics are significantly reduced. At last, the proposed analytical modelling method and magnet array are verified with experiments.

High frequency (HF) sinusoidal pulsating voltage injection is a reliable method for position sensorless control in low speed range. For HF voltage injection based methods, position signal demodulation plays a key role. However, the conventional sinusoidal demodulation suffers from long settling time and limited bandwidth because of requirement of a low-pass filter (LPF) to suppress HF harmonics in the estimated position. Additionally, the overall performance is deteriorated due to the characteristic of linear demodulation. To address these issues, the cube of q-axis HF current instead of itself is used as the carrier of position estimation error. In this way, the input variable for phase-locked loop (PLL) is the cube function with respect to the position deviation. During steady state, the equivalent gain in PLL is very small and thus the estimated position is non-sensitive against high-frequency harmonics, thereby the LPF is no longer required in the proposed method. While during dynamic process, the equivalent gain is increased leading to a fast converging rate when compared with the conventional method. The stability and dynamic performance are theoretically analysed by the magnitude–frequency diagram. The superiority of the proposed method was experimentally justified and the obtained results show that both steady-state and dynamic performance are improved when compared with the prior art.

A novel dual three-phase permanent-magnet linear synchronous machine (DTP-PMLSM) is proposed for the large capacity ropeless elevator, where two sets of windings have 30 electrical degrees phase shift in space. First, the topology of DTP-PMLSM with 12-slot/11-pole (12 s/11p) combination is introduced. Second, the influence of each main parameter on thrust force performance is investigated by single variable sweeping method, and then DTP-PMLSM is optimised by global optimisation method. Moreover, the electromagnetic performance is predicted and analysed by two-dimensional (2D) finite element method (FEM) in detail. Compared with conventional single three-phase PMLSM, the proposed DTP-PMLSM shows better force performance. Furthermore, the analysis results are compared with 3D FEM which includes the transverse end effect. Finally, a 12 s/11p prototyped machine is built and tested to validate the theoretical analyses.

This study proposes a state formulation of the space-vector dynamic model of the Synchronous Reluctance Motor (SynRM) considering both saturation and cross-saturation effects. The proposed model adopts the stator currents as state variables and has been theoretically developed in both the rotor and stator reference frames. The proposed magnetic model is based on a flux versus current approach and relies on the knowledge of 11 parameters. Starting from the definition of a suitable co-energy variation function, new flux versus current functions have been initially developed, based on the hyperbolic functions and, consequently, the static and dynamic inductance versus current functions have been deduced. The dynamic inductance functions have been derived so to fulfill the reciprocity conditions. This study presents also a technique for the estimation of the parameters of the proposed magnetic model, which is based on stand-still tests without the need to lock the rotor. The identification process has been performed based on the minimization of a suitably defined error function including the difference between the measured and estimated stator fluxes. The proposed parameter estimation technique has been tested in both numerical simulation and experimentally on a suitably developed test set-up, permitting the experimental validation of the proposed model.

In this study, to maximise the performance and efficiency of 48 V integrated electric brake (IEB) system, a system-level optimal design process is proposed for inverter-driven brushless AC (BLAC) motor, taking into account the available input voltage that varies depending on the motor operating conditions. To get available input voltages, the voltage drops of battery wiring and inverter are reversely calculated from the motor output power. In the optimal design process, the resistance components in the inverter are separated into DC and AC parts, and these are analysed by including the dq equivalent circuit for motor analysis. The battery currents are obtained using the calculated maximum output performance and the loss between the battery and inverter. The proposed design process is applied to the optimal design of the 48 V motor for IEB systems. Also, to reduce the development cost of the 48 V motor, the manufacturing tools of the previously developed 12 V motor are shared. As an optimal design results, it is confirmed that there is an efficiency improvement effect of ∼5% compared to the conventional design of 12–48 V BLAC motor.

This study clarifies experimentally the effect of the secondary conductor bar on line-start characteristics in a line-start type self-excited wound-field synchronous motor. This motor is based on a brushless wound-field synchronous motor having a rotor winding connected to a diode rectifier circuit. And it has a secondary conductor bar that is independently connected at a pitch of one pole, without end-ring. First, the operation principle of the proposed motor and its magnetic circuit design are described, and then the details of the prototype for principle verification are clarified. Next, when the combination of the connecting of the secondary conductor bar is changed, an experiment of line-starting characteristics and measured rotor field current is demonstrated. Consequently, it was clarified that the influence on the synchronous pull-in, speed ripple, and rotor field current.

High specific power density and longer cycle life features made the supercapacitors as the most prominent option in managing the transient demands of the pulsed power loads. However, the discharging characteristics of supercapacitors confine them from the utilisation of their entire energy. Reflecting on these concerns, this study aims to provide an extensive review of various bank switching circuits of supercapacitors to enhance their energy utilisation. Also, a comprehensive analysis of these switching circuits in terms of power delivery duration, SC cell energy utilisation, terminal voltage variations, system efficiency, and total cost is carried out for the constant resistor, constant power, and constant current loads.

The direct torque control (DTC) of permanent magnet synchronous motor (PMSM) drives is a noticeable practice in industrial applications due to its quick dynamic performance. However, due to the presence of hysteresis controllers and inaccurate switching tables especially for the multilevel fed DTC drives are facing higher ripples in torque and flux response. An improved DTC for three-level open-end winding PMSM drive is proposed in this article and features reduction of flux and torque ripples. The torque and flux performances of the PMSM are directly controlled by the calculated reference voltage vector in the stationary reference frame. The voltage vector tables are proposed based on the length of the voltage space vectors and the actual voltage vector nearer to the calculated reference voltage vector is selected so that the minimum ripples exist in flux and torque responses. The steady-state and dynamic conditions of the proposed DTC method are verified in the real-time experiment and also compared with the conventional DTC as well as the recently developed control methods.

Compared with the conventional three-phase motors, the dual three-phase permanent magnet synchronous motors (PMSMs) have many advantages and have been widely used in various drive fields. However, one major disadvantage of these machines is that they are easy to generate large stator current harmonics, which makes it difficult to have an excellent performance in the drive field. To solve this problem, this study introduces a current harmonic elimination method based on a spatial analytical model of flux linkage. The study reconstructed the analytical model of flux linkage from finite element analysis. The analytical model can describe the spatial harmonics of flux linkage by considering the rotor position information. Based on the model, an active feedforward controller was proposed to eliminate current harmonics by actively injecting the corresponding voltage harmonics, the voltage harmonics are calculated by the model of flux linkage. The performance of the proposed method in eliminating current harmonics is verified by simulations and experiments.

The magnetic effects and consequently the radial force are the main causes of noise in switched reluctance motors (SRMs). In this study a new design for SRM is developed in order to reduce acoustic noise. In this research a new design for SRM is developed in order to reduce the acoustic noise. In this investigation, at first, different SRM structures are simulated using JMAG software. An 8/6-pole SRM is designed and built with special modification in the rotor and stator structures. For increasing mechanical strength, trapezoidal stator and rotor pole shape with poles arc β _r  = β _s = 21° are proposed. In this design the taper angles of stator and rotor poles are equal. For noise reduction, the mechanical restructuring is done according to stress analysis. The new designed SRM are simulated and tested experimentally under no-load and full-load conditions. The results are shown and compared. Comparison between these results and the results of other structures shows that the acoustic noise of the newly designed motor is reduced considerably. The results show an acoustic noise reduction of ∼72% in new structure SRM.

This study demonstrates the application of layer model theory to the analysis of synchronous machines. The derivation of the model from Maxwell's equations is briefly described. With the use of steady-state equations and terminal operation information, a methodology is established, and the synchronous machine operation is modelled. Two case examples are then analysed. It is shown that the layer model methodology can be applied to synchronous machines with promising results.

This study proposes an improved power density permanent magnet synchronous motor (PMSM) for more electric aircraft (MEA) and conducts a design study on aerospace motors. To improve the power density of PMSM, a dual permanent magnet structure using high-temperature resistant high-performance permanent magnets and high-performance soft magnetic alloy material is creatively designed. Methods of lightweight structure designed in both stator and rotor meanwhile are combined as another mean to increase power density. The optimisation models for 6-slot/8-pole and 12-slot/10-pole configurations are first established based on finite element analysis. Methods of improving the power density of PMSM are then given, including minimum core back yoke thickness and lightweight structure design. The electromagnetic characteristics of the optimised machine are analysed by finite element analysis software, including back electromotive force (back-EMF), inductance, and power loss. The configuration of 12-slot/10-pole is selected as the best design scheme for MEA, based on which a prototype is manufactured and tested. The experiment results of cogging torque and line back-EMF are in good agreement with the simulation results, which shows the rationality of the designed new machine. The design proves to be effective for improving the power density of aerospace motors.