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The purpose of this paper is to provide an analysis of the performance of a new five-phase doubly fed induction generator (DFIG).

This paper presents the results of a research work related to five-phase DFIG framing, including the development of an analytical model, FEM analysis as well as the results of laboratory tests of the prototype. The proposed behavioral level analytical model is based on the winding function approach. The developed DFIG model was used at the design stage to simulate the generator’s no-load and load state. Then, the results of the FEM analysis were shown and compared with the results of laboratory tests of selected DFIG operating states.

The paper provides the results of analytical and FEM simulation and measurement tests of the new five-phase dual-feed induction generator. The use of the MATLAB Simscape modeling language allows for easy and quick implementation of the model. Design assumptions and analytical model-based analysis have been verified using FEM analysis and measurements performed on the prototype. The results of the presented research validate the design process as well as show the five-phase winding design advantage over the three-phase solution regarding the control winding power quality.

The main disadvantage of the winding function approach-based model development is the simplification regarding omitting the tangential airgap flux density component. However, this fault only applies to large airgap machines and is insignificant in induction machines. The results of the DFIG analyses were limited to the basic operating states of the generator, i.e. the no-load state, the inductive and resistive load.

The novel DFIG with five phase rotor control winding can operate as a regular three-phase machine in an electric power generation system and allows for improved control winding power quality of the proposed electrical energy generation system. This increase in power quality is due to the rotor control windings inverter-based PWM supply voltage, which operates with a wider per-phase supply voltage range than a three-phase system. This phenomenon was quantified using control winding current harmonic analysis.

The paper provides the results of analytical and FEM simulation and measurement tests of the new five-phase dual-feed induction generator.

Literature, spanning industrial organization and strategic management disciplines, uses variance decomposition to understand the relative importance of firm, industry and business group effects in shaping profitability variations. Some literature analyzes firm profitability under transition to liberalization. Previous research has taken a static before-and-after view on institutional change. This paper aims to focus on the dynamic process of liberalization in India, analyzing how different institutional regime changes alter firm behavior leading to changes in profitability patterns.

Based on a panel data set of several thousand Indian firms, spanning the 26-year period between 1980-1981 and 2005-2006, the authors determine the relative importance of firm, industry and business group effects in explaining manufacturing firms’ profitability variances across different institutional phases. The authors evaluate three propositions that help assess transition dynamics between phases. They determine the quantum of catch-up or falling behind by firms.

Different industries emerge as profitability leaders, as the economy progresses through different liberalization phases. Business groups that have been more effective in resource appropriation, rent-seeking, politician management and non-market activities in a controlled regime are replaced as profit leaders by those that, in a free-market economy, can be capable of intra-business resource allocation tasks and leveraging corporate capabilities.

The approach demonstrates how to analyze the underlying detailed structure of firm-level data, and performance outcomes, to derive nuanced interpretation of factors giving rise to the effects that explain profitability variances, and how to assess the way these effects behave over time. The dynamic evidence-based approach highlights what factors matter, where, when and why, in influencing profitability variances, which are a key dimension of industrial and economic performance.

The purpose of this article is to treat the nonlinear optimal control problem in EV traction systems which are based on 5-phase induction motors. Five-phase permanent magnet synchronous motors and five-phase asynchronous induction motors (IMs) are among the types of multiphase motors one can consider for the traction system of electric vehicles (EVs). By distributing the required power in a large number of phases, the power load of each individual phase is reduced. The cumulative rates of power in multiphase machines can be raised without stressing the connected converters. Multiphase motors are also fault tolerant because such machines remain functional even if failures affect certain phases.

A novel nonlinear optimal control approach has been developed for five-phase IMs. The dynamic model of the five-phase IM undergoes approximate linearization using Taylor series expansion and the computation of the associated Jacobian matrices. The linearization takes place at each sampling instance. For the linearized model of the motor, an H-infinity feedback controller is designed. This controller achieves the solution of the optimal control problem under model uncertainty and disturbances.

To select the feedback gains of the nonlinear optimal (H-infinity) controller, an algebraic Riccati equation has to be solved repetitively at each time-step of the control method. The global stability properties of the control loop are demonstrated through Lyapunov analysis. Under moderate conditions, the global asymptotic stability properties of the control scheme are proven. The proposed nonlinear optimal control method achieves fast and accurate tracking of reference setpoints under moderate variations of the control inputs.

Comparing to other nonlinear control methods that one could have considered for five-phase IMs, the presented nonlinear optimal (H-infinity) control approach avoids complicated state-space model transformations, is of proven global stability and its use does not require the model of the motor to be brought into a specific state-space form. The nonlinear optimal control method has clear implementation stages and moderate computational effort.

In the transportation sector, there is progressive transition to EVs. The use of five-phase IMs in EVs exhibits specific advantages, by achieving a more balanced distribution of power in the multiple phases of the motor and by providing fault tolerance. The study’s nonlinear optimal control method for five-phase IMs enables high performance for such motors and their efficient use in the traction system of EVs.

Nonlinear optimal control for five-phase IMs supports the deployment of their use in EVs. Therefore, it contributes to the net-zero objective that aims at eliminating the emission of harmful exhaust gases coming from human activities. Most known manufacturers of vehicles have shifted to the production of all-electric cars. The study’s findings can optimize the traction system of EVs thus also contributing to the growth of the EV industry.

The proposed nonlinear optimal control method is novel comparing to past attempts for solving the optimal control problem for nonlinear dynamical systems. It uses a novel approach for selecting the linearization points and a new Riccati equation for computing the feedback gains of the controller. The nonlinear optimal control method is applicable to a wider class of dynamical systems than approaches based on the solution of state-dependent Riccati equations.

More electric aircraft (MEA) is defined as the extensive usage of electric power in aircraft. The demand for electric power in new generation aircraft rises due to environmental and economic considerations. Hence, efficient and reliable starter/generators (SGs) are trending nowadays. The conventional main engine starting system and power generation system can be replaced with an individual SG. The constraints of the SG should be investigated to handle the aviation requirements. Even though the SG is basically an electric machine, it requires a multidisciplinary study consisting of electromagnetic, thermal and mechanical works to cope with aviation demands. This study aims to review conventional and new-generation aircraft SGs from the perspective of electric drive applications.

First of all, the importance of the MEA concept has been briefly explained. Also, the historical development and the need for higher electrical power in aircraft have been indicated quantitatively. Considering aviation requirements, the candidate electrical machines for aircraft SG have been determined by the method of scoring. Those machines are compared over 14 criteria, and the most predominant of them are specified as efficiency, power density, rotor thermal tolerance, high-speed capability and machine complexity. The features of the most suitable electrical machine are pointed out with data gathered from empirical studies. Finally, the trending technologies related to efficient SG design have been explained with numeric datasets.

The induction motor, switched reluctance motor and permanent magnet synchronous motor (PMSM) are selected as the candidate machines for SGs. It has been seen that the PMSM is the most preferable machine type due to its efficient operation in a wide range of constant power and speed. It is computationally proven that the using amorphous magnetic alloys in SG cores increases the machine efficiency more. Also, the benefits of high voltage direct current (HVDC) use in aircraft have been explained by a comparison of different aircraft power generation standards. It is concluded that the HVDC use in aircraft decreases total cable weight and increases aircraft operation efficiency. The thermal and mechanical tolerance of the SG is also vital. It has been stated that the liquid cooling techniques are suitable for SGs.

The demand for electrical power in new generation aircraft is increasing. The SG can be used effectively and efficiently instead of conventional systems. To define requirements, constraints and suggestions, this study investigates the SGs from the perspective of electric drive applications.

The purpose of this paper is to obtain an accurate methodology for modelling and analysis of the permanent magnet synchronous generator connected to power electronic components.

This paper presents the methodology of the co-simulation of a permanent magnet synchronous generator. It combines Simulink, Maxwell and Simplorer software to demonstrate the electrical machine behaviour connected with the power electronics’ circuit. The finite element analysis performed on the designed machine exhibit a more accurate behaviour over simplified Simulink models. Results between both simulation and co-simulation are compared to measurements.

The co-simulation approach offers a more accurate depiction of the machine behaviour and its interaction with the non-linear circuits.

This paper focuses on the interior permanent magnet type of PMSG and its interaction with a passive rectifier (nonlinear circuit).

The advanced capabilities of the co-simulation method allow to analyse more variations (geometry, materials, etc.), and its interaction with non-linear circuits, than previous simulation techniques.

The co-simulation as a tool for analysis and design of systems interconnected with unconventional and conventional electrical machines and prototypes, and the comparison of the obtained results with classical analysis and design methods, against measurements obtained from the prototype.

The concept of career stages or phases is extended to the career progression challenges faced by consultants in professional service firms. Professions such as consulting typically have rigorous entry requirements, demand newcomers to be individual contributors and revenue generators early in their careers, and often enforce up‐or‐out advancement policies. The nature of the work done changes significantly with advancement with the more senior professionals being responsible for the generation of demand for the firm’s services, the management of projects and people, and leadership of the institution. None of these activities is typically part of the formal education required to become a consultant, nor of the standards governments may enforce for one to remain in practice. These work changes and progression challenges are explored within five phases of professional development phases that parallel the personal growth and job challenges one confronts in moving from newcomer to senior professional.

The purpose of this paper is to give an overview of the design issues of permanent magnet machines for the hybrid electric and plug‐in electric vehicles, including railway traction and naval propulsion.

Focus is given on both synchronous permanent magnet and reluctance machines. An overview of the design rules are provided, covering the topics of: fractional‐slot windings, fault‐tolerant configurations, flux‐weakening capability, and torque quality.

The peculiarities of these machines and the advanced design considerations to fit the automotive requirements are analyzed.

The paper includes a wide description of innovative electrical machines for electric vehicles, including not only the traction capability, but also analysis of features as weight reduction, torque ripple reduction, increase of fault tolerance, and so on.

The purpose of this paper is to apply some surrogate-assisted optimization techniques in order to improve the performances of a five-phase permanent magnet machine in the context of a complex model requiring computation time.

An optimal control of four independent currents is proposed in order to minimize the total losses with the respect of functioning constraints. Moreover, some geometrical parameters are added to the optimization process allowing a co-design between control and dimensioning.

The optimization results prove the remarkable effect of using the freedom degree offered by a five-phase structure on iron and magnets losses. The performances of the five-phase machine with concentrated windings are notably improved at high speed (16,000 rpm).

The effectiveness of the method allows solving the challenge which consists in taking into account inside the control strategy the eddy-current losses in magnets and iron. In fact, magnet losses are a critical point to protect the machine from demagnetization in flux-weakening region.

In order to manufacture scaffolds for tissue engineering, a dynamic mask rapid prototyping system to cure UV‐curable biodegradable material was developed. The aim of this paper is to document this system.

A digital micro‐mirror device (DMD) was used as the dynamic mask generator, with each layer's mask pattern dictated by our self‐developed software. To build the scaffolds, UV light reflected by the DMD was then focused onto the biodegradable material to cure it. The biodegradable material used in this experiment was a mixture of 85/15 PLGA, PEG‐HEMA, and a photo‐initiator.

The dynamic mask rapid prototyping system was successfully built and scaffolds made of UV‐curable biodegradable material were fabricated to verify the system capacity. The working exposure time for each layer was 45 s except for the first layer, which was 60 s. Scaffolds with 0°/90° and 60°/120° strips in alternating layers were fabricated and the pore size error in X and Y axes of 0°/90° design was found to be 7.33 and 2.13 percent, respectively. Preliminary cell culture tests indicate the fabricated scaffold is not harmful to MG‐63 cell growth.

Different scaffold designs and more UV‐curable biodegradable materials may be further implemented and tested through this system.

This research developed a novel system for tissue engineering scaffold fabrication which can process UV‐curable biodegradable material.