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This study investigates the influence of stator coil pitch on the electromagnetic performance of squirrel‐cage induction machine (IM) with emphasis on the flux‐weakening (FW) capability for electric vehicle applications. Three different winding topologies, obtained by changing the coil pitch, namely integer‐slot distributed winding (ISDW), integer‐slot concentrated winding, and fractional‐slot concentrated winding (FSCW), are studied. Their merits and demerits are revealed by comparing their performances characteristics, including winding harmonic index, total axial length, average torque, torque ripple, power losses, efficiency, and FW capability. It is revealed that due to the very high Magnetomotive force (MMF) harmonics induced in the bar current, the bar copper loss of the IM with FSCW is significant. It is also revealed that the parasitic effects of the double‐layer winding configurations are lower than those of the single‐layer (SL) winding configurations. It is also demonstrated that for the slot/pole/phase combinations lower than two q≤2, the higher the coil pitch, the lower the parasitic effects and the higher the efficiency. Moreover, it is found that the combinations q≥2, especially those having longer coil pitch and higher stator slot number, and the SL combinations offer better FW capability. Finally, the Finite‐element analysis (FEA) results of IM with long‐pitch ISDWs are validated by experimental measurements. [ABSTRACT FROM AUTHOR]

Some key features to be satisfied by electric motors catering a wide range of applications are high specific power, lower manufacturing cost, rugged construction, and fault‐tolerant operation. Switched reluctance motor is one such motor technology satisfying all the above requirements and is an emerging competitor to the induction and permanent magnet motors in domestic, industrial and electric vehicle applications. The present‐day research on this motor is moving towards improving efficiency at lower speeds, power density, and the torque density. Certain challenges in achieving the same are (a) minimising the losses, (b) mitigation of torque ripple, noise, and vibration, and (c) material advancements. A review based on the estimation and mitigation techniques of each of these over the past three to four decades has been dealt with in this study. The salient features and results in each section provide a clear understanding of how each of these challenges can be overcome in the aspect of design and control strategies. [ABSTRACT FROM AUTHOR]

In electric drive applications that are based on high‐speed induction motors (IMs) with an extended speed range, stator winding pole‐changing is a possible technique to avoid oversizing the driving motor. The electronic pole changing employed in multiphase IMs has gained recent interest because it avoids physical winding reconfiguration. The effective number of poles of the air gap flux distribution can be electronically altered by simply changing the applied current sequence to a multiphase stator. The main problem associated with this technique is the significant increase in machine magnetising current with the increase in effective pole number when conventional multiphase distributed windings are employed. This study proposes a new fractional‐slot concentrated winding layout with a special stator connection suitable for pole‐amplitude modulated IMs that offers a 2:1 pole ratio while maintaining equal magnetising current for both winding pole pairs. Moreover, constant power operation can be achieved for a speed range of over 4 pu. The main concept is discussed and verified through simulations and experimentally. The machine mathematical model and the required vector space decomposition‐based controller are also presented. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous motors are widely accepted in automotive applications. The high torque density, high rotational speed with maximum efficiency in electric vehicle applications is technically challenging for motor design. However, these machines are expensive and difficult to work at high-temperature harsh environment due to permanent magnets demagnetisation features. Alternatively, switched reluctance motors can provide similar output characteristics and a wider speed. Thus these are considered to be more fault tolerant and more reliable. This study proposes a 20 kW, three-phase switched reluctance motor and analyse its overall performance and harmonic contents. The study is conducted by optimising the slot filling factor, excitation voltage and switching sequence of an asymmetrical half bridge converter. A finite element model is used to predict the core and copper losses and other influencing parameters. Simulation results are presented and analysed the effectiveness of the proposed switched reluctance motor (SRM). [ABSTRACT FROM AUTHOR]

The performance requirement of a squirrel cage induction motor (IM) for application in electric vehicle (EV), with high efficiency, power factor and breakdown torque, is a challenging task for a machine designer. A new 5 hp wide speed operating range IM suitable for EV application has been designed here. The parametric study to analyse the effect of stator and rotor slot dimensions on different performance parameters has been carried out. This parametric study forms the basis of the multi‐objective optimisation problem taken in this study. An evolutionary algorithm has been used for the IM design optimisation and its performance is compared to that of a conventional one. The optimised IM is then fabricated and tested in the laboratory to validate the simulation results. [ABSTRACT FROM AUTHOR]

A charge equalisation controller (CEC) was developed for continuously monitoring individual battery cells and equalising the charge or voltage levels of all cells in a series pack. A charge equalisation control algorithm was developed to equalise undercharged, overcharged, and unprotected cells through the use of a bidirectional fly‐back converter. The equalisation involves charging and discharging by employing constant current–constant voltage and discontinuous current mode proportional–integral (PI) control techniques. Particle swarm optimisation is applied to optimising the PI controller parameters that generate the regulated pulse width modulation switching signal for the converter. A CEC model was applied to 90 lithium‐ion battery cells (nominally 15.5 Ah and 3.7 V each) connected in series. The results showed that the developed CEC model performed well at equalising both undercharged and overcharged cells with ∼92% efficiency and equalised every cell within the safe operation range of 3.73–3.87 V. The developed system realises excellent equalisation speed, a simple design and efficiency with low power loss. Thus, the CEC model has great potential for implementation in real‐world electric vehicle energy storage systems. [ABSTRACT FROM AUTHOR]

Supercapacitor is being widely used in electric transportation applications, particularly in electric vehicles (EVs). In the EV, the supercapacitor mainly serves as energy storage system for accelerating the vehicle and/or capturing the braking energy due to its prominent features such as high power density and long life cycle. However, during the vehicle braking and/or accelerating, deep and fast supercapacitor charging‐discharging cycles increase the electric and thermal stresses on the supercapacitor bank. Under such circumstances, condition monitoring of the supercapacitor bank is essential in EVs for safe operation of the storage system. In this paper, an effective method for condition monitoring and fault diagnosis of the supercapacitor banks is proposed. First, it is shown that the equivalent series resistance (ESR) and double‐layer capacitance (CDL) can be used as the key signatures for indicating the state‐of‐health. Subsequently, the recursive extended least‐square algorithm (RELS) is used for online estimation of the ESR and capacitance of the supercapacitor bank. Based on a residual signal which is defined as the difference between the voltages of the supercapacitor bank and RELS algorithm, the abnormal conditions of the supercapacitor bank are distinguished. Experimental results are presented to confirm the feasibility and precision of the proposed method. [ABSTRACT FROM AUTHOR]

In recent years, electric mobility is becoming a growing reality because of the increase of the oil demand and cost as well as the environmental effect of the conventional internal combustion engines. Since about a decade, in the USA, a public–private cooperative research initiative, called FreedomCAR (US Drive by mid 2012) has been working for developing high efficiency and cost competitive technologies for the electrification of private transport. This research presents the design and the comparison of two high performance, radial magnetisation, interior permanent magnets and synchronous motors, according to the FreedomCAR targets, equipped with different rotor shape geometries. The first is characterised by a non‐uniform airgap, whereas the second presents a conventional rotor shape. Both the machines are equipped with the same stator and a fractional slot concentrated winding. This paper highlights the benefits for using a non‐uniform airgap rotor design, especially concerning the efficiency, that represents the most difficult target to be satisfied. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a new soft‐switching non‐isolated bidirectional converter (BDC) for the energy storage systems in DC traction. For this proposed converter, the soft commutation is achieved by turning on the main power switches with the help of auxiliary active switches, the inductor, the capacitor, and diodes. The basic operation of the converter is characterized as two operating types: boost and buck. The switching devices obtained zero voltage transition (ZVT) in both operating types, but the major advantage of this topology is achieved by reducing turn‐on losses with improved efficiency and minimizing reverse recovery time of IGBTs' anti‐parallel diodes. This paper mainly describes the principles of operation, design analysis, simulation, and implementation of DC‐DC converter of laboratory prototype with 150 V/250 V system under 1‐kW output power. [ABSTRACT FROM AUTHOR]