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The share of renewable energy sources (RESs) in the power system is increasing day by day. The RESs are intermittent, therefore maintaining the grid stability and power balance is very difficult. The purpose of this paper is to control the inverters in microgrid using different control strategies to maintain the system stability and power balance.

In this paper, different control strategies are implemented to the voltage source converter (VSC) to get the desired performance. The DQ control is a basic control strategy that is inherently present in the droop and virtual synchronous machine (VSM) control strategies. The droop and VSM control strategies are inspired by the conventional synchronous machine (SM). The main objective of this work is to design and implement the three aforementioned control strategies in microgrid.

The significant contributions of this work are: the detailed implementation of DQ control, droop control and VSM control strategies for VSC in both grid-connected mode and standalone mode is presented; the MATLAB/Simulink simulation results and comparative studies of the three aforementioned controllers are introduced first time in the proposed work; and the opal-RT digital real-time simulation results of the proposed VSM control show the superiority in transient response compared to the droop control strategy.

In the power system, the power electronic-based power allowed by VSM is dominated by the conventional power which is generated from the traditional SM, and then the issues related to stability still need advance study. There are some differences between the SM and VSM characteristics, so the integration of VSM with the existing system still needs further study. Economical operation of VSM with hybrid storage is also one of the future scopes of this work.

The significant contributions of this work are: the detailed implementation of DQ control, droop control and VSM control strategies for VSC in both grid-connected mode and standalone mode is presented; the MATLAB/Simulink simulation results and comparative studies of the three aforementioned controllers are introduced first time in the proposed work; and the opal-RT digital real-time simulation results of the proposed VSM control show the superiority in transient response compared to the droop control strategy.

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.

The purpose of this paper is to discuss the performance of a proposed machine design for an in‐wheel motor with the required torque‐speed characteristic.

Calculation of the winding factor of the machine with the star of slots theory is performed first. The field weakening capability of the machine is investigated and the operating speed range is determined. The tooth contour modeling method for calculating the performance of the machine with a limited number of elements is introduced. The method is used to construct two models of different complexity and the results obtained with the models are compared with the results obtained by finite element models.

The 14 pole 12 slot in‐wheel PMSM discussed in this paper is able to meet the stringent performance requirements. The results obtained with the tooth contour models show good agreement with the results obtained with finite element models despite the limited number of elements. Increasing the number of elements in the model allows for modeling of armature reaction and increases the accuracy of the model.

This work can be continued with investigating the possibilities to model the armature reaction more accurately.

This paper proposes a modeling method which accurately describes the performance of a PMSM with limited number of elements. With this method, the calculation procedure can be easily used for optimization of the machine design.

The purpose of this paper is to investigate the steady‐state stability and features of the brushless cascaded doubly fed machine (BCDFM), which is made up of two wound‐rotor induction machines: the power machine (PM) and the control one, with their rotors mechanically and electrically coupled.

The machine modelling is first treated considering a Park reference frame linked to the rotating field of the PM. Then, a state representation related to small perturbations is established following the linearisation of the BCDFM model around a steady‐state operating point. This allows the investigation of BCDFM steady‐state stability, power flow and the torque‐speed characteristics.

It has been found that the electrical variables of the control machine greatly affect the BCDFM steady‐state stability and characteristics.

The work should be extended considering a validation of the established results through experimental tests.

The steady‐state small perturbation of the BCDFM model has been introduced for the first time, which is the key of the machine steady‐stability analysis and features investigation.

The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor.

To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used.

The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness.

The main problem, despite the use of parallel calculations, is the long calculation time.

The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines.

The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.

Permanent magnet linear synchronous machines (PMLSMs) have large thrust ripple due to the longitudinal end effect caused by the finite length of the armature compared with rotary machines. The purpose of this paper is to analyze the influence of electric loading on thrust ripple performances based on a 12 slots/14 poles (12S/14P) PMLSM. Furthermore, the method of skewed PMs to reduce thrust ripple is investigated based on multi slices 2D finite element (FE) models.

The thrust ripple of PMLSM under open-circuit condition results from the slotting and the longitudinal end effects. Therefore, periodical model has been designed to clarify the effect of the longitudinal end effect. Under on-load condition, the thrust ripple increases and exhibits an effective component of thrust force. To analyze the thrust ripple under on-load condition, frozen permeability (FP) technique is employed. In addition, the method of skewed PMs is analyzed in this paper to obtain more smooth thrust force performance. The effectiveness of skewing accounting for skew angles, step skew numbers and slot/pole number combinations was highlighted.

The longitudinal end effect dominates the thrust ripple of PMLSM in both cases, i.e., open-circuit and on-load conditions. Under on-load condition, the second harmonic component of thrust ripple related to flux linkage harmonics increases significantly. Moreover, the effectiveness of skewed PMs is largely reduced with the increase of magnetic saturation. At last, a proper skew angle and step skew number are obtained for the conventional PMLSM with fractional-slot winding.

By 60 electrical degrees and two or three step skewed PMs, the thrust ripple can be decreased to a tolerable limite for conventional PMLSM. The thrust ripple harmonics contributed by longitudinal end effect and flux linkage harmonics are analyzed, respectively, which is beneficial to exploring other techniques such as adding end auxiliary teeth to obtain lower thrust force pulsation.

Permanent magnet synchronous spherical motors can have wide use in robotics and industrial automation. They enable three-DOF omnidirectional motion of their rotor. They are suitable for several applications, such as actuation in robotics, traction in electric vehicles and use in several automation systems. Unlike conventional synchronous motors, permanent magnet synchronous spherical motors consist of a fixed inner shell, which is the stator, and a rotating outer shell, which is the rotor. Their dynamic model is multivariable and strongly nonlinear. The treatment of the associated control problem is important.

In this paper, the multivariable dynamic model of permanent magnet synchronous spherical motors is analysed, and a nonlinear optimal (H-infinity) control method is developed for it. Differential flatness properties are proven for the spherical motors’ state-space model. Next, the motors’ state-space description undergoes approximate linearization with the use of first-order Taylor series expansion and through the computation of the associated Jacobian matrices. The linearization process takes place at each sampling instance around a time-varying operating point, which is defined by the present value of the motors’ state vector and by the last sampled value of the control input vector. For the approximately linearized model of the permanent magnet synchronous spherical motors, a stabilizing H-infinity feedback controller is designed. To compute the controller’s gains, an algebraic Riccati equation has to be repetitively solved at each time-step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis. Finally, the performance of the nonlinear optimal control method is compared against a flatness-based control approach implemented in successive loops.

Due to the nonlinear and multivariable structure of the state-space model of spherical motors, the solution of the associated nonlinear control problem is a nontrivial task. In this paper, a novel nonlinear optimal (H-infinity) control approach is proposed for the dynamic model of permanent magnet synchronous spherical motors. The method is based on approximate linearization of the motor’s state-space model with the use of first-order Taylor series expansion and the computation of the associated Jacobian matrices. Furthermore, the paper has introduced a different solution to the nonlinear control problem of the permanent magnet synchronous spherical motor, which is based on flatness-based control implemented in successive loops.

The presented control approaches do not exhibit any limitations, but on the contrary, they have specific advantages. In comparison to global linearization-based control schemes (such as Lie-algebra-based control), they do not make use of complicated changes of state variables (diffeomorphisms) and transformations of the system's state-space description. The computed control inputs are applied directly to the initial nonlinear state-space model of the permanent magnet spherical motor without the intervention of inverse transformations and thus without coming against the risk of singularities.

The motion control problem of spherical motors is nontrivial because of the complicated nonlinear and multivariable dynamics of these electric machines. So far, there have been several attempts to apply nonlinear feedback control to permanent magnet-synchronous spherical motors. However, due to the model’s complexity, few results exist about the associated nonlinear optimal control problem. The proposed nonlinear control methods for permanent magnet synchronous spherical motors make more efficient, precise and reliable the use of such motors in robotics, electric traction and several automation systems.

The treated research topic is central for robotic and industrial automation. Permanent magnet synchronous spherical motors are suitable for several applications, such as actuation in robotics, traction in electric vehicles and use in several automation systems. The solution of the control problem for the nonlinear dynamic model of permanent magnet synchronous spherical motors has many industrial applications and therefore contributes to economic growth and development.

The proposed nonlinear optimal control method is novel compared to past attempts to solve the optimal control problem for nonlinear dynamical systems. Unlike past approaches, in the new nonlinear optimal control method, linearization is performed around a temporary operating point, which is defined by the present value of the system's state vector and by the last sampled value of the control inputs vector and not at points that belong to the desirable trajectory (setpoints). Besides, the Riccati equation which is used for computing the feedback gains of the controller is new, and so is the global stability proof for this control method. Compared to nonlinear model predictive control, which is a popular approach for treating the optimal control problem in industry, the new nonlinear optimal (H-infinity) control scheme is of proven global stability, and the convergence of its iterative search for the optimum does not depend on initial conditions and trials with multiple sets of controller parameters. It is also noteworthy that 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 (SDRE). The SDRE approaches can be applied only to dynamical systems which can be transformed into the linear parameter varying form. Besides, the nonlinear optimal control method performs better than nonlinear optimal control schemes, which use approximation of the solution of the Hamilton–Jacobi–Bellman equation by Galerkin series expansions. Furthermore, the second control method proposed in this paper, which is flatness-based control in successive loops, is also novel and demonstrates substantial contribution to nonlinear control for robotics and industrial automation.

Synchronous Reluctance (SynRel) motors are known to suffer from excessive torque ripples. The classical way to avoid this drawback of the motor is skewing the slots. This paper aims to provide an analytic estimation of the best skew angle to minimize the ripples in such SynRel motors with tooth windings. The approach used in this paper consists of the minimization of the spectral components of the magnetic energy that cause these oscillation torques. The method was validated by means of a multi-slice finite element model (FEM).

An analytic model, based on permeance theory, is derived to analyse the electromagnetic phenomena taking place inside of the motor. This model allows the identification of the causes underlying the torque ripple production. Based on this understanding, the most suitable skew angle can be determined. The analytic method, together with the best skew angle, is validated by means of an FEM of a SynRel machine.

A method to determine the optimum skew angle for a SynRel machine is presented. It depends on the wave-number of the magnetic waves producing the torque ripple. It is twice the one typically chosen for induction machines.

The proposed approach allows improving on the design methodology for the production of smoothly running SynRel machines.

The methodology utilized in this paper is based on the relationship between the mechanical torque and the magnetic energy stored in the motor (virtual work law). From this, the best skew angle to eliminate the magnetic energy causing torque ripple can be determined. It, therefore, proposes an effective alternative to the common use of inductance models to determine such angles.

Immersive and collaborative virtual worlds can offer educationalists a future-focused solution to enhancing the learning experience they provide. Problem-based learning (PBL) is one option by which virtual worlds can provide a creative solution to providing physical-world experience within a safe and controlled environment free from the consequences associated with typical physical-world experiences. This collaborative approach to teaching and learning can be run synchronously or asynchronously and is based on sound pedagogical principles. PBL within virtual worlds can be used to provide an active and engaging learning experience that enables individuals to learn safely and effectively within a complex and realistic environment, allowing the student to be at the centre of, and in relative control of, their own learning experience.

Introduces a way to design geographically distributed virtual prototyping, a new Internet technology, in order to facilitate designer‐customer communication in the product development of small electronic devices, such as mobile telephones. First, we will present our research in the concept design domain with a set of requirements focusing on communication between the designer and the customer. Second, a technique called “smart virtual prototyping” will be presented to elaborate on the virtual prototyping techniques to be used over the World Wide Web. Third, we will present the main ideas, architecture and selected software techniques of WebShaman, which is an application built to demonstrate how a distributed virtual prototyping system could support geographically distant designer‐customer communication. Finally, we discuss the possible impact of the distributed virtual prototyping approach on the WWW community.