R Hanitsch

Numerical optimization of the electromagnetic field by stochastic search and MEC-model

The increase of output power of an electromagnetic device by the raise of flux density is limited by the nonlinear behaviour of the iron parts of the electromagnetic circuit. An improved power output can be achieved by optimizing the nonlinear magnetic circuit. A combination of evolution strategy and simulated annealing leads to a robust numerical optimization method. Evaluation of the objective function is done by a nonlinear flux tube model called magnetic equivalent circuit (MEC). Results from field calculations and optimizations will be presented for an example of automated optimal design of an electromagnetic device. >

Simulation of a completely controlled switched reluctance drive with eccentric rotor using a time-stepping technique realised outside numerical field calculation programs

In this paper, indirectly coupling time-stepping techniques using quasi Newton-Raphson solvers and online field calculations are extended to simulate a completely controlled switched reluctance motor drive. While the coupling between the electromagnetic system is strong, the coupling between the electromagnetic and the mechanical subsystem is weak. Simulations performed for a completely controlled three-phase SRM drive with and without an eccentric rotor are performed and compared.

Design and performance of electromagnetic machines based on Nd-Fe-B magnets

Abstract The application of rare-earth permanent magnets - replacing wound coils - in electrical devices is advantageous concerning performance and cost. The benefits are: increased efficiency, reduced time constant, smaller volume and weight, and cost effective production. These magnets have mainly been installed in high-precision small-size motors such as brushless dc motors, stepping motors and coreless motors. Motors of these types are used in computer peripherals and portable electronic products. Because of improvements in the materials rare-earth magnets are now also used for automotive applications and industrial drives. In addition to sintered materials bonded materials are also used for motor and actuator designs.

CAT: computer assisted teaching in magnetics

Starting with the 3/sup rd/ academic year the students taking electrical energy as their major subject at the K.U. Leuven are following theoretical lectures and laboratory sessions supporting the basic knowledge on the finite element method (FEM). The numerical sessions take place in front of workstations. The students are working with commercial FEM program packages and the numerical sessions are always followed by a practical laboratory measurements. Here, the students have to measure the beforehand computed results such as currents, induced voltage and inductances of simple magnetic circuits. In the following 4/sup th/ academic year more complex tasks are demanded such as computations of DC machines or AC induction machines. For a better insight into the physical behaviour and to make the field solutions of induction machines understandable, a multimedia software program is available to the students distributed via the Internet. The methodology of the step by step approach of computer assisted teaching, performed at the K.U. Leuven, to transfer the knowledge of the complex numerical field computation techniques are discussed.

Some aspects of the design of rotating actuators

Abstract Mathematical modelling of the magnetic and mechanical properties can be carried out by different methods. For optimizing or investigation of material-dependent properties, simple models with reasonable accuracies are needed to reduce the computational time. Different methods were used for the solution of the electromagnetic field problem. The design rules for a rotating actuator will be given.

Novel disc type motors

Abstract The use of high energy permanent magnets can lead to significantly improved efficiency and performance, especially for subfractional horsepower motors. Obviously motors with air gap windings equipped with Nd-Fe-B magnets benefit from the high remanence of this new material. Integrated designs using Nd-Fe-B magnets are cost effective. The trend towards high flux density drives will continue.

Indirectly coupling time-stepping techniques for electro-magnetic systems using quasi Newton-Raphson solvers and on-line field calculations

The paper describes indirectly coupling time-stepping techniques using quasi Newton-Raphson solvers and on-line field calculations. Due to the quasi Newton-Raphson solvers the electric and magnetic subsystems are strongly coupled and the number of independent currents exciting the magnetic field is not limited. Compared to indirectly coupling time-stepping techniques using state-space models and on-line field calculations, the number of field calculations can be reduced significantly. As a first test, these indirectly coupling time-stepping techniques are used to simulate the dynamic response of a ring-core transformer. The simulation results are in good accordance with the measurements.

Elektronisch gesteuerte kleinmotoren mit dauermagnetischen rotor

Zusammenfassung In den letzten Jahren wurden verschiedene Kommutierungsschaltungen fur burstenlose Gleichstrommotoren entworfen, die mit Halbleiterschaltern eine elektronische Kommutierung sicherstellten. Durch einfachen Austausch der elektronischen Steuerkarten kann sich der burstenlose Gleichstrommotor auch wie ein Schrittmotor oder wie ein Synchronmotor verhalten. Es werden Parameter angegeben, mit denen der Synchronmotorbetrieb beschrieben werden kann. Durch Anwendung neuer Magnetwerkstoffe einerseits und Anwendung der Bruckenschaltung andererseits lasst sich die Leistung pro Volumeneinheit vergrossern.

Torque Calculation of a Small, Axial Flux Permanent Magnet Motor

The paper deals with the design of a disc-type motor excited by permanent magnets. For the finite element model reference is made to previous work. In this paper the calculation of the torque using the same model is described. Out of three torque calculation methods investigated, the best one is current - field interaction. The resulting torque curve when all phases are operated, is constructed. The theoretical results are compared to values obtained from measurements.

Optimization of a rotating actuator with permanent magnets

Abstract To reduce development expenditure, the trend is to simulate the behaviour of the technical product. For optimization or investigation of material dependent properties, simple mathematical models with reasonable accuracy are needed to reduce computation time.