Method to Predict the Non-Uniform Potential Distribution in Random Electrical Machine Windings under Pulse Voltage Stress

This article describes a practical method for predicting the distribution of electric potential inside an electrical machine’s winding based on design data. It broadens the understanding of winding impedance in terms of inter-winding behavior and allows to properly design an electrical machine’s insulation system during the development phase. The predictions are made based on an frequency-dependent equivalent circuit of the electrical machine which is validated by measurements in the time domain and the frequency domain. Element parameters for the equivalent circuit are derived from two-dimensional field simulations. The results demonstrate a non-uniform potential distribution and demonstrate that the potential difference between individual turns and between turns and the stator core exceeds the expected values. The findings also show a link between winding impedance and potential oscillations inside the winding. Additionally, the article provides an overview of the chronological progression of turn-based models and shows how asynchronous multiprocessing is used to accelerate the solution process of the equivalent circuit.

A prototype of 3D-printed permanent magnet generator for low power applications

Recently, there has been a growing interest in the field of using 3D-printing technology for electrical machine manufacturing. However, almost research works have been done majorly on the 3D-printing technology of individual working parts for various electrical machines. This research presents a study of design, fabrication and testing of the protopype of permanent magnet generator using 3D-printing technology. The major parts of proposed generator are fabricated though 3D-printed materials. The stator winding of designed generator consists of 12 slots. The stator coil is designed to have 250 turns per slot and 12 pieces of neodymium magnets are used in to generate magnetic field in the rotor core. The prototype generator is tested under different condition; no-load and loaded-test. The experimental have been shown that in the no-load condition, this generator is able to generate output voltage of 3.3-64.5 V, when rotated at speed of 100-2,500 rpm. In the loaded-test, the output voltage and output current are also generated. Furthermore, it can be seen that a proposed generator can generate the output power of 4,245.28 mW, when rotated at speed of 2,500 rpm.

PEMANFAATAN MATLAB SIMULINK SEBAGAI MEDIA PEMBELAJARAN PRAKTIKUM SECARA DARING

Abstrak: Penelitian ini bertujuan untuk mendeskripsikan pemanfaatan software Matlab Simulink sebagai alternatif media pembelajaran praktikum secara daring pada matakuliah Praktek Mesin Listrik di Program Studi Pendidikan Teknik Elektro Fakultas Teknik Universitas Negeri Medan. Subjek penelitian terdiri dari seluruh mahasiswa angkatan 2019 yang mengambil matakuliah Praktek Mesin Listrik di kelas C dan D yang berjumlah 25 orang. Pengumpulan data ditempuh mulai dari observasi, wawancara, dan analisis dokumen yang berkaitan dengan permasalahan tersebut.. Teknik validasi pada penelitian ini menggunakan validasi triangulasi teknik. Hasil penelitian menunjukkan bahwa pemanfaatan software Matlab Simulink dalam proses pembelajaran pada matakuliah Praktek Mesin Listrik cukup efektif membantu dosen dan mahasiswa dalam mencapai tujuan pembelajaran. Lebih lanjut, sebagian besar para mahasiswa memberikan respon positif terhadap proses pembelajaran yang dilaksanakan. Kata Kunci : Matlab Simulink, media pembelajaran praktikum daring Abstract: This research aims to describe the use of Matlab Simulink software as an alternative to online practicum learning media in the subjects of Electrical Machine Practice in the Electrical Engineering Education Study Program of the Faculty of Engineering, Medan State University. The study subjects consisted of all students of the class of 2019 who took electrical machine practice courses in grades C and D which amounted to 25 people. Data collection is taken starting from observation, interview, and analysis of documents related to the problem. The validation technique in this study uses the validation of triangulation techniques. The results showed that the use of Matlab Simulink software in the learning process in the electrical machine practice course is quite effective in helping lecturers and students in achieving learning goals. Furthermore, most of the students gave a positive response to the learning process carried out. Keywords: Matlab Simulink, online practicum learning media

MATH MODEL OF A DIRECT CURRENT MOTOR FOR STEERING ACTUATOR OF A LIQUID-PROPELLANT ENGINE

The paper presents the results of development of a math model for a direct current motor of a liquid-propellant engine steering actuator In accordance with the electrical machine theory, the math model of the motor uses a single electromagnetic coefficient. It is shown that the motor math model accuracy can be improved through the use, instead of a single electromagnetic coefficient, of two different coefficients of the math model: Electromechanical velocity coupling coefficient and torque curve coefficient. Elaborated and proposed are methods for identifying parameters of a math model of a dc motor that has natural and artificial static characteristics, which include determining its experimental static characteristics, calculating the values of static characteristics parameters using the linear regression method and calculating the values of the electric motor math model parameters using the proposed formulas. Key words: direct current electric motor, math model, parameter identification method.

Characterization Methods along the Process Chain of Electrical Steel Sheet—From Best Practices to Advanced Characterization

Non-oriented (NO) electrical steel sheets find their application in rotating electrical machines, ranging from generators for wind turbines to motors for the transportation sector and small motors for kitchen appliances. With the current trend of moving away from fossil fuel-based energy conversion towards an electricity-based one, these machines become more and more important and, as a consequence, the leverage effect in saving energy by improving efficiency is huge. It is already well established that different applications of an electrical machine have individual requirements for the properties of the NO electrical steel sheets, which in turn result from the microstructures and textures thereof. However, designing and producing tailor-made NO electrical steel sheet is still challenging, because the complex interdependence between processing steps, the different phenomena taking place and the resulting material properties are still not sufficiently understood. This work shows how established, as well as advanced and newly developed characterization methods, can be used to unfold these intricate connections. In this context, the respective characterization methods are explained and applied to NO electrical steel as well as to the typical processing steps. In addition, several experimental results are reviewed to show the strengths of the different methods, as well as their (dis)advantages, typical applications and obtainable data.

A Multi-Objective Design Optimization for a Permanent Magnet Synchronous Machine with Hairpin Winding Intended for Transport Applications

Nowadays, interest in electric propulsion is increasing due to the need to decarbonize society. Electric drives and their components play a key role in this electrification trend. The electrical machine, in particular, is seeing an ever-increasing development and extensive research is currently being dedicated to the improvement of its efficiency and torque/power density. Among the winding methods, hairpin technologies are gaining extensive attention due to their inherently high slot fill factor, good heat dissipation, strong rigidity, and short end-winding length. These features make hairpin windings a potential candidate for some traction applications which require high power and/or torque densities. However, they also have some drawbacks, such as high losses at high frequency operations due to skin and proximity effects. In this paper, a multi-objective design optimization is proposed aiming to provide a fast and useful tool to enhance the exploitation of the hairpin technology in electrical machines. Efficiency and volume power density are considered as main design objectives. Analytical and finite element evaluations are performed to support the proposed methodology.

Efficiency Enhancement of Switched Reluctance Generator Employing Optimized Control Associated with Tracking Technique

This article presents studies related to the driving and control of the switched reluctance generator in order to enhance its efficiency. This type of electrical machine is an option for wind energy conversion systems, favoring the generation of electricity in distributed generation systems and contributing positively to loads without access to the main grid. The studies developed in this paper verify the possibility of controlling the output voltage of the switched reluctance generator in parallel with an efficiency tracking technique acting on the switching angles of the power converter. Simulation and experimental results are presented in order to verify the feasibility of implementing this technique to enhance the efficiency of the generator.

Analysing Efficiency and Reliability of High Speed Drive Inverters using Wide Band Gap Power Devices

Within the project ‘ARIEL’ an electrical turbo compressor unit for fuel cell applications is deeply investigated. The necessary drive inverter is especially designed for high fundamental frequency and high switching frequency to cope with the requirements of the implemented electrical machine. This paper presents investigations on the inverter’s efficiency and its prospective lifetime at different stages of the development. In the design process different wide band gap power semiconductor devices in discrete packages are evaluated in terms of the achievable power density and efficiency, both by simulations and measurements. Finally, an optimised design using surface mount silicon carbide MOSFETs is developed. Compared to a former inverter design using silicon devices in a three-level topology, the power density of the inverter is significantly increased. The lifetime of power electronic systems is often limited by the lifetime of the power semiconductor devices. Based on loss calculations and the resulting temperature swing of the virtual junction the lifetime of the inverter is estimated for the most frequent operating points and for different mission profiles.

Estimation of the Equivalent Circuit Parameters of Induction Motors by Laboratory Test

The determination of equivalent circuit parameters for AC induction motors represents an important task in an electrical machine laboratory. Frequently used open-circuit and short current tests answer these requirements. However, the results have a low accuracy. This becomes especially obvious when the equivalent circuit is applied for the motor current and power prediction. The main obstacles in this circumstance lie in the difficulty of providing a pristine open-circuit test, the lack of which causes errors in parameter estimation. A much more accurate approach can be carried out with a test including several output points with measurements of the motor torque, velocity, current, and power magnitudes. Nevertheless, a relatively simple and accurate method to ensure determining parameters for such tests does not exist. This article tries to provide such a method by an approach based on Kloss’s simplified equation and the Thevenin theorem. The significant novelty of the method is the specially selected synergetic interaction between the analytical and numerical approaches, which give a relatively simple algorithm with a good accuracy and a convergence of the parameters’ estimation.