Claudiu Oprea

Novel Permanent Magnet Tubular Linear Generator for Wave Energy Converters

Clean and sustainable alternative energy is becoming attractive as oil costs rise and the negative side effects of traditional energy systems begin to become apparent. One often overlooked, but still rapidly growing alternative is wave power. There are fascinating new designs for harnessing the tremendous power of the waves. Hence any contribution in this field could be of real interest for numerous specialists. In the paper a novel modular permanent magnet tubular linear generator is proposed and analyzed by means of numeric field computations. It was designed for wave power take off systems to be placed in the Black Sea near the Romanian coasts.

Electrical Machines Virtual Laboratory: Grid Connection of a Synchronous Generator

Virtual laboratories can become important components of the teaching process, because using them several experiment-oriented problems can be solved easily and also from the distance. Graduates using virtual laboratories will be better trained when they enter the job market. In the paper a laboratory work will be presented having two components: a simulation and an experimental module. Both can be used for the preparation of a real lab and for accessing the real-world experiments. The virtual lab modules can also allow multiple students to remote access the experiments, the multicast data transfer mechanisms and arbitration mechanisms

Fault tolerant permanent magnet synchronous machine for electric power steering systems

Multiphase motor drives posses many advantages over the traditional three-phase motor drives such as reducing the amplitude and increasing the frequency of torque pulsation, reducing the stator current per phase without increasing the voltage per phase, lowering the dc link current harmonics and higher reliability. By increasing the number of phases it is also possible to increase the torque per ampere for the same volume and improving the fault tolerance of the drive. The present paper approaches in a comparative manner two winding connection for a 12 stator slots/10 rotor pole permanent magnet synchronous machine. The magnetic filed and developed electromagnetic torque will be analyzed.

Wave Energy Plants for the Black Sea Possible Energy Converter Structures

It is crucial for the mankind to develop clean renewable energy sources. Ocean energy is one of the candidates being a huge, yet unexploited renewable energy source on the Earth. Preliminary surveys show that marine power has a potential to supply a significant part of the future energy needs. Hence all the researches done in the field of the wave energy conversion should be of real interest. In this paper the wave energy potential of the Black Sea near the Romanian coasts, a possible power take off system to be set up here, respectively a comparative study on two possible linear generators to be used in such wave energy power converters will be presented.

Axial-flux vs. radial-flux permanent-magnet synchronous generators for micro-wind turbine application

This paper presents a comparative study between the axial-flux and radial-flux permanent-magnet synchronous generators for a 3 kW wind turbine application. This study emphasizes the most cost-effective solution to be implemented by the industrial partner. There are three constructive types of electric generators considered in this work. All are based on permanent-magnet synchronous generators (PMSGs), but one has an axial-flux topology, the other one is a radial-flux outer-rotor machine and the third one is a radial-flux inner-rotor machine. Finite-element field analysis was made for the three PMSGs in order to compare their efficiency and active materials estimated cost. The results show that the axial-flux PMSG is the best solution for micro-wind turbine application.

Design and testing of a four-sided permanent magnet linear generator prototype

In the perspective of the fossil fuels deposits depletion new energy resources must be developed; amongst them the renewable energy sector seems to be able to provide a long term solution. Besides the already popular wind, solar or thermal energies, the ocean energy sector offers a virtually infinite energy potential; many solutions for harvesting and converting this energy into usable form are under investigation, most of them using complex mechanical or hydraulic systems to convert the slow, linear movement specific to waves into rotational movement, compatible with the classical electric generators. Our focus is on systems using linear electric generators, offering higher efficiency and reliability, the present paper presenting the stages covered to choosing, designing, building and testing a linear generator.

Comparative analysis of different synchronous reluctance motor topologies

Synchronous reluctance machines become more popular nowadays. Development of power electronics allowed reluctance motors to be used in many drive applications. Due to increased interest in electric vehicles and high prices of PMs, the research on electric drives is mainly focused on reluctance machines. Lack of rotor winding lowers copper losses, simplifies power supply system and increases machines robustness. SynRM produces torque due to rotors magnetic anisotropy, which is achieved in machines with transversally laminated rotor by introducing flux barriers. The main goal when designing rotors flux barriers is to achieve the highest saliency ratio possible. However, since operation of the machine depends on interaction between stator magnetic field and the rotor, both stator and rotors topologies should be taken into account when designing the machine. This paper presents a comparison of SynRMs with stators of three different slot numbers and two different rotors topologies.

Permanent magnet linear generator for renewable energy applications: Tubular vs. four-sided structures

While the exhaustion of carbon based fuels has become a certitude, the use of alternative fuels became more popular in the last decades. The renewable energy sector emerged, providing an alternative to conventional energies; amongst them the wind and solar energies became extremely popular in the last decades, supplying important parts of the total energy required in countries like Germany or the United States of America. Besides these, the wave energy sector represents a huge, yet unexploited domain, which could prove to be a long time solution for the forthcoming energy shortages.

Comparative study on Switched Reluctance Machine based fault-tolerant electrical drive systems

The Switched Reluctance Machine (SRM) based electrical drive systems are ideal for critical applications (aerospace, automotive, defense, medical, etc.) where the fault tolerance is a basic requirement. The phase independence characteristics of the SRM enable it to operate also under partial phase failure conditions also in its classical construction. Its reliability can be improved by applying special fault-tolerant designs, respectively monitoring its condition and applying fault detection techniques. The SRMs used in such safe electrical drive systems has to be fed from power converters having also fault-tolerant capability. In the paper two SRMs are proposed together with their converters. The fault tolerance capacities of the two electrical drive systems are compared by means of simulations. Two advanced simulation platforms were coupled together to simulate the drive system. The results of the comparative study emphasize the usefulness of the proposed fault-tolerant electrical drive system. The conclusions of study help the users to select the best fitted variant for they specific application.

Analysis of innovative design variations for double-sided coreless-stator axial-flux permanent-magnet generators in micro-wind power applications

An analysis of variations of innovative design for double-sided inner-coreless-stator axial-flux permanent-magnet (AFPM) generators intended for micro-wind turbine applications is presented in this paper. The 3-D finite-element field analysis proves that design variations of ironless stator with non-overlapping concentrated winding, sandwiched between two opposing steel rotor disks with embedded circumferentially-magnetized ferrite permanent magnets (PMs) in flux-concentration arrangement, may represent good-performance and cost-effective double-sided topologies for AFPM machines in micro-wind power generation applications.