Propulsion Electric Motors Research Articles

Comparison of DTC between two-level and three-level inverters for LV propulsion electric motor in ship

Comparison of DTC between two-level and three-level inverters for LV propulsion electric motor in ship

Improving the operational characteristics of electrical power systems of marine vessels

THE PURPOSE. Consider the experience of use and conduct a study of the electrical power systems of sea vessels to determine the possibility of improving their operational characteristics. Obtain data on noise and vibration levels of electrical power systems elements.METHODS. The article analyzes the electrical power systems of the Azipod type steering columns of the Baltika icebreaker. The issue of regulating the rotation speed of propulsion electric motors using frequency control based on a DC link and parallel-connected inverter units on IGBT transistors is considered. Motor control on the frequency converter side can be based on direct torque control, scalar and vector control. There are control modes for reducing and increasing voltage.RESULTS. Typical dependences of structure-borne noise levels of main engines and generators are given. Measurements were taken at various frequencies of engine sound power levels, exhaust gases and vibration of generator sets. Experimental oscillograms of studies of the parallel operation of diesel generator sets were obtained, on which power exchange and common-mode oscillations were recorded.CONCLUSION. It is proposed to use multiphase AC electric motors to improve performance characteristics, including reducing noise and vibration. The existing experience in using frequency converters based on a rectifier section and inverter units in electric rowing installations with Azipod propellers makes it possible to implement such a change. To do this, it is necessary to parallelize the inverters that supply each of the three phases and provide the appropriate phase shifts.

직접토크제어를 이용한 저압용 친환경 선박 추진 전동기의 속도제어

직접토크제어를 이용한 저압용 친환경 선박 추진 전동기의 속도제어

Разработка системы управления компенсатором реактивной мощности преобразователя частоты для управления гребным электродвигателем

Object and purpose of research. The control of the operating modes of the propulsion electric motor (PEM) is carried out by semiconductor frequency converters, the use of which significantly worsens the quality of electricity on the common buses of the Marine Power Systems. The main reasons are a decrease in the power factor and the appearance of higher harmonics in the consumed current. As a result of this, the reliability of consumers' operation decreases, and power losses increase. Therefore, reducing these negative consequences is an urgent task. Materials and methods. Methods of theoretical electrical engineering, power theory were used. Main results. The method of operation of the reactive power control device for ensuring the quality of electricity, increasing the power factor and filtering higher harmonics in Marine Power Systems was considered and proposed. Conclusion. To ensure the quality of electrical energy of the reactive power compensator, it is necessary to use modern pulse-modulation control algorithms with direct microprocessor control.

MAIN DIRECTIONS FOR THE DEVELOPMENT OF SHIP ELECTROTECHNICS AND AUTOMATION

In recent decades, the level of electrification and automation of ships has grown significantly. This is due to the increased requirements for technical, operational and technical and economic characteristics on the part of shipowners. The implementation of the requirements has become possible due to the development of related branches of science, engineering and technology: materials science, power converter technology, microprocessor electronics, and information technology. The main directions of development of ship electrical engineering and automation, namely, improvement of power generation and distribution systems, improvement of electric propulsion systems and propulsion systems, improvement of automation systems are considered in the paper. The expediency of using valve generator sets and the transition to electric power distribution on direct current is shown. Static power sources of new generation are actively developing and spreading both in industry and in maritime transport. Good control characteristics, no restrictions on the number of reverses and minimum speed, high efficiency when operating at fractional loads, high torque overload capacity on the propeller significantly expand the scope of modern AC electric propulsion systems. The desire to combine the advantages of different types of propulsion systems has stimulated the creation of combined (hybrid) propulsion systems. Combined installations incorporate a traditional thermal main engine and a propulsion electric motor. The activation of one or another engine is carried out depending on the mode of operation and the speed of the vessel. The introduction of information technologies makes it possible to automate the management and control of maintenance and repair of ship equipment. The modern development of software and hardware and algorithmic support makes it possible to create unmanned ships that can be controlled remotely and move independently (autonomously) according to predetermined algorithms, including algorithms for divergence from other ships at sea. It is concluded that the main tasks within the framework of the directions for development of ship electrical engineering and automation are increasing the energy efficiency of the process for generating electricity by introducing valve generator sets, introduction of innovative sources of electricity with high rates of efficiency and environmental friendliness, including static sources of electricity, the use of rowing electric motors with permanent magnets and inductor type, the use of combined propulsion systems with reversible electric propulsion systems, and increasing the level of automation through the introduction of information technology and artificial intelligence.

Features of operation of ship electrical power systems with electrical propulsion systems

THE PURPOSE. Consider the issue of the presence of distortions in the form of sinusoidal voltage and current in autonomous electrical power systems with electrical propulsion systems, built on the principle of the unified electric power system. Compare the results of the study of voltage distortion for electrical power systems with electrical propulsion systems of various structures and give recommendations for their application.METHODS. For research, unified electric power systems with DC electrical propulsion systems on the Yeysk ferry and alternating current on the asymmetric icebreaker Baltika are considered. The possibilities of programming with frequency control of modern drives of rudder propellers with AC motors are analyzed.RESULTS. Oscillograms of voltages and currents of generators were obtained using thyristor converters and inverters to control electrical propulsion systems in various modes. Significant ripples and distortions of the sinusoidal voltage and generator currents were noted when thyristor converters are used to power DC propulsion electric motors. Also, small deviations from the sinusoidal form of the ship's network voltage were recorded when inverters were used to control AC propulsion motors as part of rudder propellers.CONCLUSION. The issue of ensuring the quality of electricity produced in autonomous electrical power systems of sea vessels is of great relevance and importance. To ensure the best results, it is advisable to use azimuthing podded drive with AC electric motors, the rotation speed of which is implemented by inverter frequency converters with a DC link.

Optimization of the control system for an electric power system operating on a constant-power hyperbole

For an electric power system (EPS) of the combined propulsion complex (CPC), working on a constant-power hyperbola (CPH), the strategy of managing power distribution between propulsion electric motors and own needs consumers has been improved. The study reported here aimed to reduce fluctuations in current consumption and load by optimizing voltage controllers and the rotation frequency of generator assemblies (GA). The system of EPS GA voltage and frequency stabilization was synthesized by determining, in the system of equations, the dynamics of the values of EPS links' time constants and the coefficients that correspond to control parameters. To define the characteristics of the control signals from the regulators of EPS GA rotation frequency and excitation voltage, the laws that control the speed and excitation current were calculated. After sampling the coefficients of the GA speed control regulator, the tasks for the excitation voltage controller were determined. The methodology of data acquisition was applied on the basis of a correlation between the EPS characteristics and the experimental characteristics of GA. The system of EPS dynamics equations was optimized in accordance with the structure and settings of the optimal controller and the probability of a situational error by using Spearman's rank correlation coefficient. The optimization has made it possible to reduce the likelihood of a situational error during the synchronization of GA and enable the stable operation of GA close to the mode of operation on CPH. The power controller was tested under the mode of changing the load of own needs with the power levels of EPS on CPH in the range of 50‒100 % of the rated power. The range of deviations of the current consumed with an enabled GA rotation controller was 10 % of the average value. The range of EPS power deviations with the power controller turned on was 5 %.

РОЗВ’ЯЗАННЯ ЗАДАЧІ ОПТИМАЛЬНОГО КЕРУВАННЯ ПОТУЖНІСТЮ ЕЛЕКТРОЕНЕРГЕТИЧНОГО КОМПЛЕКСУ СУДНА

Для забезпечення ефективного керування судновою електроенергетичною системою (СЕЕС) при стабілізації руху судна в умовах, які потребують використання динамічного компенсування збурень, зокрема хвиль та вітру, зазвичай реалізують метод динамічної компенсації. При цьому умови вітрових, хвильових навантажень і течій не обмежені. З огляду на тоннаж і конструктивні особливості суден, створення системи керування, інваріантної до збурень, є вкрай складним завданням. Взагалі, глобальна задача оптимізації включає задачі оптимального регулювання пропульсивного комплексу, оптимального керування дизель-генераторами, оптимальне керування СЕЕС за критерієм мінімальної узагальненої роботи та квазіоптимальне регулювання в СЕЕС. Особливості експлуатації пропульсивного комплексу судна значним чином змінюють навантаження на гребні електродвигуни (судновий пропульсивний комплекс), що призводить до необхідності створення спеціальних систем маневрування та керування СЕЕС. Перевагою електричних пропульсивних комплексів, на відміну від дизельних, є можливість гнучкого перерозподілу потужностей між приводними двигунами, висока точність та швидкодія, що є найважливішим фактором для суден з динамічним позиціюванням. При цьому основною задачею такої системи є оптимальне керування за критерієм мінімальної узагальненої роботи. У роботі розглянуто задачу оптимізації роботи дизель-генераторів при обмеженні з боку сталості упору гвинта. Показано, що для забезпечення сталості упору гвинта треба використовувати методи оптимального керування за критерієм максимуму швидкодії. Також проаналізовано гіпотезу опуклості функціонала цілі і керованості обмежень, яка дозволяє реалізувати принцип максимуму Понтрягіна та принцип Белмана і визначити залежність якості регулювання від ресурсу керування. Розв’язання задачі оптимального керування СЕЕС відповідає критерію мінімальної узагальненої роботи, а використання принципу Белмана дозволяє реалізувати в подальшому адаптивний регулятор, що забезпечує мінімальні витрати за керуванням.

МОДЕЛЮВАННЯ СХЕМИ СУДНОВОЇ ЕЛЕКТРОЕНЕРГЕТИЧНОЇ СИСТЕМИ НА СУДАХ З ЕЛЕКТРОРУХОМ

На морських судах з системами електроруху, для зниження втрат потужності в суднових електроенергетичних системах при передачі електроенергії від суднової електростанції до гребного електродвигуна можна виключити трансформатори. Застосування трансформаторів в ланцюзі живлення гребного електродвигуна можливо уникнути в разі застосування багаторівневих інверторів. Безтрансформаторні електроенергетичні системи мають один суттєвий недолік. Якщо навантаження на гальванічно не зв'язані трифазні обмотки одного і того ж генератора будуть різними, то напруги на виході обмоток будуть відрізнятися, і система стабілізації не зможе забезпечити стабільність напруги на всіх обмотках генератора. Метою даної роботи є моделювання схеми електроенергетичної системи, в якій використовують головні генератори з однією багатофазною обмоткою на статорі. Дані генератори не створюють взаємні спотворення напруги і забезпечують стабільну напругу на лініях головного розподільного щита. Застосування в судновій електроенергетичній установці кожного головного генератора з однією багатофазною обмоткою на статорі з числом фаз більше трьох, фази якої з'єднані зіркою або трикутником, а також, використання лінії головного розподільного щита з тим же числом фаз, що і обмоткок головних синхронних генераторів, дозволяє отримувати дві та більше системи гальванічно розв'язаних багатофазних напруг живлення, необхідних для роботи перетворювача частоти з багаторівневими інверторами. На основі схеми, в якій гребний електродвигун підключений безпосередньо від генераторних агрегатів, розроблена модель безтрансформаторної електроенергетичної системи та проведено комп'ютерне моделювання. В процесі моделювання оцінювалися якість напруги у невідповідальних споживачів і якість струму в обмотках гребних електродвигунів, живлення яких забезпечувалося від перетворювачів частоти на базі дво- та трирівневого автономного інвертора напруги. Показано, що схеми суднових електроенергетичних систем без трансформаторів відрізняються стабільними показниками.

Бортовая система электроснабжения для электрических самолетов

The development of electric aircraft, the design of which will use, apart from doing away with pneumatic and hydraulic transmissions, electric propulsion, is one of promising lines in aviation technology. As an example, the project of the X-57 Maxwell electric aircraft developed by NASA, which is equipped with 14 propulsion electric motors, is given. In view of insufficient energy efficiency of existing storage batteries, a combined storage battery-and-generator power supply system for electric aircraft is considered. In the considered system, the aircraft propulsion is provided by electric motors, which are powered by storage batteries in combination with permanent magnet generators. The generator shaft is rotated by an auxiliary internal combustion engine, which operates in an economical mode. The power circuit of an active rectifier producing the +270 V DC bipolar output voltage is proposed, with which the permanent magnet generator operates with a sinusoidal phase current waveform and a close-to-unity power factor. The active rectifier control system uses an enhanced phase-locked loop, which eliminates the need to use generator rotor position sensors. For determining the stability domains and revealing undesirable hidden attractors in the considered storage battery-and-generator power supply system, it is proposed to use special analytical-numerical computation procedures based on modifications of Lyapunov's functions methods. The article will be of interest for developers of both aircraft and ground-based self-contained electric power supply systems with a bipolar 270 V DC voltage that must meet stringent requirements for improvement of their mass-and-dimensions and power performance characteristics.

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Reduction of the resources consumption for generating the electric power, improving the parameters of a vessel electric network is one of the purposes of sea transport development. A direction of researches is hybridization of generation sources and the electric energy accumulation devices. The given concept is based on division or simultaneous use of several various energy sources, the choice and combination of which are intended for improving the power systems parameters. The overwhelming majority of modern sea-crafts use the systems of distribution of an alternating current. However, with introduction of power electronic converters into the power supply systems, the direct current networks with integration of sources and devices for accumulating electric energy, connected to a distributed DC bus, are increasingly being used in the fleet. This direction is one of the decisions for fuel consumption minimization, especially, for the vessels demanding high degree of maneuverability and various running cycles. The possibilities of a ship hybrid electric power system are defined in the paper. Comparison of various architectures of the given system is performed. The block diagram of the hybrid electric power system is considered. Formulas for calculating static load are given. The equations describing electromagnetic processes of the asynchronous electric motor as the propulsion electric motor are written down. The device for accumulating electric energy is considered. The calculation of the energy released by the propulsion electric motor during braking or reverse, which can be directed both to the braking resistor and stored in special systems of electric energy storage. The computer model of considered hybrid electric power installation on the basis of computer program SimInTech is made.

Energy and Exergy Evaluation of a Two-Stage Axial Vapour Compressor on the LNG Carrier.

Data from a two-stage axial vapor cryogenic compressor on the dual-fuel diesel–electric (DFDE) liquefied natural gas (LNG) carrier were measured and analyzed to investigate compressor energy and exergy efficiency in real exploitation conditions. The running parameters of the two-stage compressor were collected while changing the main propeller shafts rpm. As the compressor supply of vaporized gas to the main engines increases, so does the load and rpm in propulsion electric motors, and vice versa. The results show that when the main engine load varied from 46 to 56 rpm at main propulsion shafts increased mass flow rate of vaporized LNG at a two-stage compressor has an influence on compressor performance. Compressor average energy efficiency is around 50%, while the exergy efficiency of the compressor is significantly lower in all measured ranges and on average is around 34%. The change in the ambient temperature from 0 to 50 °C also influences the compressor’s exergy efficiency. Higher exergy efficiency is achieved at lower ambient temperatures. As temperature increases, overall compressor exergy efficiency decreases by about 7% on average over the whole analyzed range. The proposed new concept of energy-saving and increasing the compressor efficiency based on pre-cooling of the compressor second stage is also analyzed. The temperature at the second stage was varied in the range from 0 to −50 °C, which results in power savings up to 26 kW for optimal running regimes.

Modern Electric, Hybrid Electric, and Fuel Cell Vehicles, Third Edition [Book News

This book explains the dynamic modeling, simulation, and optimization needed for hybrid electric vehicles. It presents a comprehensive overview of technologies and how they are designed, integrated, and controlled. The book begins with environmental issues and transportation history, before continuing to fundamentals of vehicle propulsion and braking, theoretical bases of internal combustion engines, and explanations about vehicle transmission. Next, the authors explain in a wellstructured, clear, and concise manner, information about electric vehicles (EVs), hybrid EVs (HEVs), fuel cell vehicles (FCVs), and propulsion electric motors together with their controllers. The authors analyze design principles of series, parallel, series–parallel, and soft hybrid electric drive trains, and they explain design and control principles for plug-in hybrid electric vehicles, with examples showing simulation results using the overall drive train system, not just the individual components. A good grasp of such principles is essential for understanding the modeling before conducting research on advanced control methods for switching power converters. Storage (batteries, supercapacitors, fuel cells) and regenerative braking, together with off-road vehicles and their requirements, are expansively analyzed and discussed in this third edition. The book’s concluding chapters cover optimization of full-size engine HEVs and power-trains and include a guide for a multiobjective optimization toolbox. The authors are known around the world as specialists in power electronics; motor drives; hybrid vehicles and their control systems; architecture, modeling, and design of electric and hybrid electric drive trains; energy management and power-train control; mechatronic systems; and sustainable energy engineering.

FEM analysis of an single stator dual PM rotors axial synchronous machine

The actual e - continuously variable transmission (e-CVT) solution for the parallel Hybrid Electric Vehicle (HEV) requires two electric machines, two inverters, and a planetary gear. A distinct electric generator and a propulsion electric motor, both with full power converters, are typical for a series HEV.In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors. The proposed topologies, the magneto-motive force analysis and quasi 3D-FEM analysis are the core of the paper.

DETERMINATION OF TRANSMISSION GEAR RATIO IN MECHANICAL PART OF TRACTOR ELECTRO-MECHANICAL TRANSMISSION

A methodology has been developed for selection of gear number and transmission gear ratios in mechanical part of a wheel-type tractor with electro-mechanical transmission containing a propulsion asynchronous electric motor with variablefrequency control. The paper proposes to determine a transmission gear ratio on the basis of the following: provision of wheel torque dependence on tractor speed which is the best one for a traction process and during transfer from one gear to the other; provision of nominal operational mode of the electric motor for all tractor operations where it is working for a long period of time; provision of minimum possible number of gears; complete realization of internal combustion engine power on the tractor wheels at limit operational mode of the electric motor. As a characteristic of the asynchronous electric motor with variable-frequency control contains various portions which can be used either completely or partially due to operating conditions, the gear number is determined in the process of transmission gear ration finding but not prior to this. A wheel torque of the tractor with electro-mechanical transmission can be limited according to the following factors: grip of wheel with supporting surface; maximum power of an internal combustion engine which can be transferred to the wheels and a torque which is developed by a propulsion electric motor. It is not proposed to exceed nominal operational mode of the propulsion electric motor for all the operations of the tractor if it is working for a long period of time because in the case of significant excess of the nominal operational mode of the asynchronous electric motor its rather long operation leads to low efficiency and high losses in power, large heat liberation and consequently requires to develop more complicated system for electric motor cooling. An excess of nominal electric motor torque can be justified for short-term operational modes because in this case there is no need to select more powerful electric motor and create an additional gear in the gear-box.

Dual rotor single- stator axial air gap PMSM motor/generator drive for high torque vehicles applications

The actual e – continuously variable transmission (e-CVT) solution for the parallel Hybrid Electric Vehicle (HEV) requires two electric machines, two inverters, and a planetary gear. A distinct electric generator and a propulsion electric motor, both with full power converters, are typical for a series HEV. In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors, destined for hybrid electric vehicles (HEV) and military vehicles applications. The proposed topologies and the magneto-motive force analysis are the core of the paper.

A Systems Approach to the Propeller Redesign for the U.S. Navy SEAL Swimmer Delivery Vehicle (SDV)

ABSTRACTThis paper details work undertaken at the Massachusetts Institute of Technology (MIT) to improve the overall performance of the Navy SEAL swimmer delivery vehicle (SDV Mk VIII Mod 1) through the design of a wake adapted propeller to replace the existing stock propeller. First, an analysis was conducted of the currently installed propeller using a lifting surface vortex lattice propeller code developed at MIT by Kerwin. This gave the performance required for a new propeller. To start the design process, a lifting line propeller design code developed at MIT by Kerwin was used to find the potential efficiency gains possible with a wake‐adapted propeller with minimal hub drag. Then, a circuit model of the propulsion electric motor was derived and coupled with the lifting line program to match the operating point between the redesigned propeller and the motor. The result of this coupled analysis was a numerical prediction for the reduction in battery amperage draw. A prototype propeller was manufactured and tested, resulting in an 8.9 % reduction in battery current discharge.