Computer-supported laboratory for production-oriented electrotechnical systems

At the electrical engineering department of the K.U.Leuven an education research project was started in October 1997. The target is to develop a powerful environment to teach students to solve practice-oriented problems as they will encounter them in industry furtheron in their career. In order to give a wide use to the developed environment, a close collaboration has been established with three polytechnical engineering institutes. Self-dependence has to be stimulated by creating possibilities for real “hands-on experience”. Such an educational environment implicates time-problems, high investment costs and last but not least safety restrictions. The project contributes to the solution of these problems by using simulation- and softwareenvironments, without loosing the real hands-on feeling

Improved transistor-controlled and commutated brushless DC motors for electric vehicle propulsion

The development, design, construction, and testing processes of two electronically (transistor) controlled and commutated permanent magnet brushless dc machine systems, for propulsion of electric vehicles are detailed. One machine system was designed and constructed using samarium cobalt for permanent magnets, which supply the rotor (field) excitation. Meanwhile, the other machine system was designed and constructed with strontium ferrite permanent magnets as the source of rotor (field) excitation. These machine systems were designed for continuous rated power output of 15 hp (11.2 kw), and a peak one minute rated power output of 35 hp (26.1 kw). Both power ratings are for a rated voltage of 115 volts dc, assuming a voltage drop in the source (battery) of about 5 volts. That is, an internal source voltage of 120 volts dc. Machine-power conditioner system computer-aided simulations were used extensively in the design process. These simulations relied heavily on the magnetic field analysis in these machines using the method of finite elements, as well as methods of modeling of the machine power conditioner system dynamic interaction. These simulation processes are detailed. Testing revealed that typical machine system efficiencies at 15 hp (11.2 kw) were about 88% and 84% for the samarium cobalt and strontium ferrite based machine systems, respectively. Both systems met the peak one minute rating of 35 hp

Measurement of the Self-Sensing Capability of Synchronous Machines for High Frequency Signal Injection Sensorless Drives

Signal injection sensor-less control for synchronous machines is known to be afflicted by an estimation error dependent on the load current. The estimation error is related to the cross- saturarion and the saliency of the adopted synchronous machine. A motor can be more or less suitable for signal injection sensorless control compared to other motors with different designs or sizes. A sensorless drive can even be afflicted by the control divergence when the machine is highly saturated, resulting in a useless drive. Moreover, even when the control converges, the actual current control trajectory is different from the given reference. In this paper, a measurement procedure of the convergence region, i.e. the operating points where the motor can be successfully controlled without a position sensor is presented and validated. In particular, two different synchronous motors are considered, a permanent magnet assisted synchronous reluctance motor (PMA-SynRM) and a synchronous reluctance motor (SynRM

Cogging Torque Minimization of PMBLDC Motor for Application in Battery Electric Vehicle

Since the beginning, researchers have focused globally on the automotive industry, which recently yielded a notable increase in the development of electric vehicles. The cogging torque of the motor is the leading cause of acoustic noise and vibration. Therefore, this paper aims to reduce the cogging torque of Brushless DC motors in electric vehicles. The power rating of the two-wheeler battery electric vehicle is determined with kinematic dynamic equations. The choice of material and the combination of pole slots impact the vehicle’s overall performance, particularly in raising the average torque of the motor. Finite element based Ansys Maxwell electromagnetic field simulation software has been used to design and analyze the electric and magnetic field parameters of BLDC motor using several rotor poles embrace factor values. The findings of this study are expected to reduce vibration and noise in electric vehicles with increased average torque

Segregation of Iron Losses From Rotational Field Measurements and Application to Electrical Machine

This paper presents a methodology for identifying a novel iron loss model and segregating the different loss components from measurements on a single sheet tester with alternating and rotating fields. The eddy current losses are first extracted with a 1D numerical approach and the hysteresis and excess losses are then estimated with an analytical method that allows the separation of alternating and rotational hysteresis as well as excess losses. The elaborated iron loss model can be applied in case of distorted flux density and on a wide range of frequencies. The identified model is further applied in the time-stepping computation of an induction motor in view of better estimation and segregation of iron losses. The results of no-load simulations at different voltage levels are in good agreement with the measured ones. All presented computations and models are validated experimentally too.Peer reviewe

Program of Research in Aeronautics

A prospectus of the educational and research opportunities available at the Joint Institute for Advancement of Flight Sciences, operated at NASA Langley Research Center in conjunction with George Washington University's School of Engineering and Applied Sciences is presented. Requirements of admission to various degree programs are given as well as the course offerings in the areas of acoustics, aeronautics, environmental modelling, materials science, and structures and dynamics. Research facilities for each field of study are described. Presentations and publications (including dissertations and theses) generated by each program are listed as well as faculty members visting scientists and engineers

Sources of vibration and their treatment in hydro power stations-A review

AbstractVibration condition monitoring (VCM) enhances the performance of Hydro Generating Equipment (HGE) by minimizing the damage and break down chances, so that equipment stay available for a longer time. The execution of VCM and diagnosing the system of an HPS includes theoretical and experimental exploitation. Various studies have made their contribution to find out the vibration failure mechanism and incipient failures in HPS. This paper gives a review on VCM of electrical and mechanical equipment used in the HPS along with a brief explanation of vibration related faults considering past literature of around 30years. Causes of the vibrations on rotating and non-rotating equipment of HPS have been discussed along with the standards for vibration measurements. Future prospectus of VCM is also discussed

Analytical Model for magnetic Anisotropy Dedicated to Non-Oriented Steel Sheets

Recent investigations on magnetic properties of Non-Oriented steel sheets enhance the comprehension of the magnetic anisotropy behavior of widely employed electrical sheets. Our investigation consists of developing an analytical model to consider these magnetic properties while modelling electromagnetic systems. From rotational measurements, the anhysteretic curves are interpolated in order to extract the magnetic energy density for different directions and amplitudes of the magnetic flux density. Furthermore, the analytical representation of this energy is suggested based on statistical distribution which aims to minimize the intrinsic energy of the material. Our model is finally validated by comparing measured and computed values of the magnetic field strength.Non Peer reviewe

Brushless doubly fed machine magnetic field distribution characteristics and their impact on the analysis and design

This paper contributes to the characterisation of the brushless doubly fed induction generator (BDFIG), which is attractive as a variable speed generator in applications (offshore wind turbine) with minimum maintenance requirements. The BDFIG has two three-phase stator windings of different pole numbers housed within the same stator slots and a shortcircuited rotor winding capable of coupling fields of different pole numbers. The stator windings and rotor winding create a magnetic field distribution with a range of characteristics different to those of conventional induction generators. This paper presents an analysis to identify the field characteristics and discusses their impact on the analysis and design of the BDFIG. The characteristics are determined from an analysis of the sum of two rotating sinusoidal field waveforms and confirmed by comparison with time-stepping finite element results and measured magnetic flux density data