Study and design of an asynchronous electrical machine with inverted construction

This paper describes an adopted method which could be used in transient process modelling of three-phase asynchronous machines on the computer. Converter asynchronous electric machine feeding requires a detailed research of the transient process influence and the dynamic states of energy exchange between the electrical circuit feeding and the machine itself. A mathematical model has been formulated in order to solve the transient process of the three-phase asynchronous electric machine referring to the two asynchronous machines and containing two matrix models defined by Park?s d - q components. In the system of symmetrical components the state and the operation of the first machine was defined based on relations and operation conditions of a direct sequence system and of other machines based on relations and operation conditions of an inverse sequence system. The new method has been derived from the existing psbpwm MATLAB package. The new model simulates the state and operation of a single machine with identical parameters through the state and operation of the two machines with identical parameters: the first in a direct sequence system and the others in an inverse sequence system. Operation analysis of the three-phase induction machine is limited to a transient process occurring in the right angled shape of voltage feeding. The new presented model can, with certain limitations, be applied not only to a three-phase asynchronous machine model but to other alternating current machines which have a stator and a rotor. The experiment has been performed following an example of asymmetrical feeding followed by inverse component phenomena of electrical and mechanical values in the machine.

This article provides the equations of mathematical model of three-phase asynchronous electric machine recorded in the three-phase stator reference frame. Described in detail is the possibility of the proposed mathematical model. In particular, the possibility of modeling the rotor currents at their actual frequency. It is also an example of modeling a complex mode of asynchronous machine — its use as rotary electromechanical phase splitter onboard of a railway electric rolling stock. In this case, the machine receives the supply voltage from the secondary winding of a single-phase transformer. Then it converts it into three-phase voltage to three-phase consumers such as induction motors loaded by fans and air compressors. Simulation results show the adequacy of the proposed mathematical model of asynchronous electric machine.

The reliability of heat and power engineering systems (HPES) operation is largely determined by the reliability of asynchronous electric machines (AEM), being the part of them. The timely assessment of current operating conditions for AEM rotor and the risk of its operational integrity loss is an actual operational problem, the solution of which will increase the reliability of both AEM and HPES. The scientific component of the problem is implemented in the direction of developing methods for the operational diagnostics of AEM rotors and in the direction of developing appropriate characteristics of the current operating conditions for AEM rotors. The objectives of the investigation is to develop the approximate evaluations for the current operating conditions of AEM rotors and the risk of their current operational integrity loss. These evaluations will enable the operating personal to make quick decisions to continue or stop AEM operation. The set problems were solved by mathematical modeling methods. A mathematical model of a rotor is a system of linear equations including the equations for undamaged and damaged rotor cage loops. The currents and powers for a rotor of an electric motor with a production version 4A355M2C3 with damaged 0,1,2,…,6 rods of a 38-phase cage are calculated and analyzed according to the mathematical model. It is found out that the most significant consequence of AEM rotor damage is the decrease of its power. In this case, 10% rotor power reduction can be associated with AEM limiting state and be the reason to stop operation. The detection of a limiting state allows introducing a deterministic evaluation for a rotor operational integrity loss suitable to scale such risks during AEM operation in HPES and make controlling decisions.

This paper presents the design, performance and control details of traction electric machines for GM's second generation Extended Range Electric Vehicle (EREV). Chevy Volt was the first personal vehicle in the industry with EREV power flow configuration which is carried over to the second generation. Since its introduction in 2011 Chevy Volts have been driven over half a billion miles, 67% of which in EV mode. The second generation of Volt brings a significant mass reduction and increased performance, EV driving range and fuel economy while simultaneously reducing rare earth content in its traction electric motors. The electric propulsion system is built on two electric machines; both PMAC topology. While hybrid-electric vehicles are gaining in popularity in hopes of addressing cleaner, energy sustainable technology in transportation, materials sustainability and rare earth dependence mitigation has not been the first priority in the hybrids available on the market today. However, design robustness to material cost volatility is crucial in automotive industry success and therefore designing electric propulsion to minimize or eliminate rare earth usage plays a major role in HEVs success. The objective of this paper is to present the newly redesigned electric traction machines for added performance while simultaneously reducing the rare earth and heavy rare earth content by over 80% and 50% respectively and in turn the cost of the system and yielding all around “cleaner” and more sustainable vehicle. A tall order by any measure; so various technologies were utilized to achieve this goal. The paper discusses grain boundary dysprosium diffusion process in permanent magnets as means to rare earth reduction in PMAC machines and design challenges surrounding such material use. We also discuss innovative PMAC topologies employing ferrite magnets to completely eliminate rare earth usage while maintaining the electric drive unit performance. The design of electric machines is presented in detail along with performance measurement results as well as thermal and NVH aspects. It is absolutely crucial that high performance electric machines are coupled with high performance control algorithms to enable maximum system efficiency and performance. Specifically, key challenges toward that goal are inverter voltage utilization, for maximum power capability and switching loss minimization. In order to address those, six-step mode of inverter control is a must. We focus on a specific challenge associated with this operation mode to keep the closed-loop current control regulation in the full six-step mode while losing a degree of freedom in the controls scheme. We present a novel PMSM control algorithm with a closed-loop current control regulation that can be used in both the SVPWM and full six-step mode.

Guest Editorial for Special Issue: Design, Modeling and Control of Electric Vehicles: Selected papers from IEEE Vehicle Power and Propulsion Conference (VPPC 2015)

The research considers the development of topological theory of asynchronous electric machines (AEM). The results of the development of energy aspects of the topological theory are presented in the article. The facts proving the actuality of the research are also given. The central notion giving the topological theory the characteristic of being systematic is the vector space notion. The definition of AEM vector space, its dimension, canonical basis, power and energy field of AEM are presented. Mathematical and visual models of AEM energy fields are analyzed. Energy fields of electric losses and magnetic field dissipation having the spherical symmetry are analyzed in particular. Energy and visual models of the main magnetic field are analyzed using AEM with a short circuited rotor and linear AEM as examples. It is established that this field obtains cylindrical or elliptical symmetry. In general the main magnetic field and the main matrix of winding make AEM vector space fully or partially heterogeneous. Energy efficiency is analyzed and its differences for vector space currents are revealed. The areas of vector spaces with high and low energy currents efficiency are defined. According to this indicator longitudinal and transvers subsets of current having, correspondingly, high and zero energy efficiency are distinguished in the vector space. The description of practical application spheres of AEM topological theory is given.

The article considers the problem of improving power efficiency of the diesel generator power plants as one of the priority objectives for development of low power generation in Russia. Improving energy efficiency for autonomous facilities is directly related to the optimization of hydrocarbon fuel consumption by marine diesel engines. It is possible to optimize the fuel consumption of internal combustion engines by creating variable-speed diesel generators (VSDG), which are diesel-generator units with semiconductor converters, i.e. systems with valved generators. Optimization of specific fuel consumption by VSDG is provided by the forced regulation of the rotational speed of the shaft of the internal combustion engine in accordance with its multi-parameter characteristic in the shared load conditions of the power plant. The synchronous electric machine is used as a generator as part of a ship power station. Its use in the classic constant-speed diesel generators is more preferable than an asynchronous electric machine. In the development of VSDG - valved power plant - the use of an electric machine with a phase rotor as a generator is technically justified, because the installed capacity of the frequency converter in the rotor circuit of an asynchronous generator with a phase rotor is determined by the sliding power and, with a limited range of speed control, SDGV significantly reduces the installed capacity of the electrical equipment. Such power topology of a ship’s power plant is called VSDG based on a dual-power machine. There has been proposed to consider a variant of a ship power plant based on VSDG with a dual-power machine. Its functional diagram and mathematical model are developed. A structural diagram is presented and dynamic modes of the amplitude and frequency of the generated voltage are modeled during electrical load switching.

The article is devoted to the consideration of issues related to the design and circuits of broaching windings of three-phase asynchronous submersible electric machines in the marine environment on drilling rigs and platforms. The article describes the calculation of the winding pitch, the number of slots per pole and phase, as well as the angle of shift between the beginnings and ends of the phases. The mathematical apparatus for calculating and schematics of single-layer, double-layer and concentric windings of asynchronous electric motors is given. Some characteristic distinguishing features between single-layer, double-layer loop windings and windings with concentric coils of open-ended electric machines are also considered.

The mathematical models of the Asynchronous electrical machines developed on the basis of the experimental frequency-response characteristics are proposed in this paper. The latter ones are recommended for investigating the transient processes occurring at short-circuits and connections of the electrical machines to the bus bars of electrical system taking into account of their rotor speed changes. Key words: Asynchronous machines, frequency-response, networks connections short-circuit.

The process of pulse-width modulation in the converter-motor system is considered. It is noted that the main task of pulse width modulation of voltage formed by the electronic key converter in the converter-motor system is to reduce current pulsations during the modulation period. It is established, that the dynamic process of current change in the electric machine during the period of pulse-width modulation can be approximated by R, L filter. It is shown, that the most important task of pulse-width modulation is minimization of modulation error by current in electric motor. The analysis of possible criteria of estimation of modulation process quality in control systems of electric drive is carried out. It is noted that as a criterion of optimality to assess the quality of modulation in the converter-electromotor system, it is advisable to use the integral quadratic criterion of relative error, called the local variance of the current, as well as the average value of the local variance of the current at the period of the modulating function, called the integral variance of current. The process of estimating the filtering ability of electric machines as part of the electric drive is considered. A system of basic values based on nominal values of electric motor stator voltage, its nominal angular speed and nominal stator current has been selected. The index of filtering properties of the load considering introduction of basic values has been proposed. The equations of an asynchronous electric machine with constant coefficients in the complex form of writing are given. The dependency of the real part of roots of the characteristic equation for an asynchronous machine as a function of angular speed of the rotor rotation is constructed. An analytical expression for the estimation of the filtering properties of asynchronous machines is obtained. The comparison of different types of electric machines according to this parameter is made.

In this paper, we consider new possibilities realized in alternating current electric machines that are designed for controlled electric drives and powered by semiconductor frequency converters. We concentrate on the possibility of improving the technical and economic performance of the system by taking into account the combined work of the semiconductor converter and the engine under development. The design of asynchronous electric machines for a semiconductor converter is shown to allow significantly improve its energy performance and expand the control range in terms of electromagnetic moment. The possibility of improving the mass–dimension parameters of synchronous machines operating in frequency-controlled systems is substantiated. We show that it is possible for these machines to exclude completely loss from synchronism. We established that synchronous reluctance machines can have specific indices close to those of asynchronous motors, and they realize a significantly larger overload torque in this case. Calculated methods for the synthesis of asynchronous electric drives that were successfully tested in the development of a series of main drives of the D423 drilling rig are proposed. These electric machines were designed for mechanisms with a fanlike load (mud pump) and with an active reluctance torque (winch drive). A synthesis method for the SRMTD synchronous reluctance engines that were tested on an engine for a cold pipe rolling mill is developed.

Purpose. The models of electrical machines in the phase coordinates, the universal algorithm for the simulation of separate elements in a d-q coordinates system and in a phase-coordinates system are proposed. Methodology. Computer methods of investigation of transients in electrical systems are based on a compilation of systems of differential equations and their numerical integration solution methods. To solve differential equations an implicit method of numerical integration was chosen. Because it provides to complete structural simulation possibility: firstly developing models of separate elements and then forming a model of the complex system. For the mathematical simulation of electromagnetic transients in the elements of the electrical systems has been accepted the implicit Euler-Cauchy method, because it provides a higher precision and stability of the computing processes. Results. In developing the model elements identified two groups of elements: - Static elements and electrical machines in the d-q coordinates; - Rotating electrical machines in phase coordinates. As an example, the paper provides a model of synchronous and asynchronous electric machines in the d-q coordinates system and the phase coordinate system. The generalization algorithm and the unified notation form of equations of elements of an electrical system are obtained. It provides the possibility of using structural methods to develop a mathematical model of power systems under transient conditions. Practical value. In addition, the using of a computer model allows to implement multivariant calculations for research and study of factors affecting the quantitative characteristics of the transients.

Nowadays, the electric machines used in urban electric vehicles are, in most cases, three-phase electric machines with or without a magnet in the rotor. Permanent Magnet Synchronous Machine (PMSM) and Induction Machine (IM) are the main components of drive trains of electric and hybrid vehicles. These machines have very good performance in healthy operation mode, but they are not redundant to ensure safety in faulty operation mode. Faced with the continued growth in the demand for electric vehicles in the automotive market, improving the reliability of electric vehicles is necessary over the lifecycle of the electric vehicle. Multiphase electric machines respond well to this constraint because, on the one hand, they have better robustness in the event of a breakdown (opening of a phase, opening of an arm of the power stage, intern-turn short circuit) and, on the other hand, better power density. In this work, a diagnosis approach using a neural network for an open circuit fault or more of a five-phase induction machine is developed. Validation on the simulator of the vehicle drivetrain, at reduced power, is carried out, creating one and more open circuit stator phases showing the efficiency and the reliability of the new approach to detect and to locate on-line one or more open phases of a five-induction machine.

The purpose of this paper is to propose a novel concept of a high-speed electric machine system with integrated airfoil-shaped rotor designed to perform axial-flow compression for vehicle applications. The proposed high-speed machine is both a motor for electromagnetic (EM) energy conversion and an axial flow compressor for thermodynamic energy conversion. Conventional designs usually have a separate motor and compressor that are connected through a common shaft with or without a gearbox. The proposed design simplifies the high-speed machine and compressor system by eliminating the components that connect the motor and the compressor. The integrated motor-compressor design can achieve a more compact system. The flux-switching permanent magnet (FSPM) machine is chosen out of several possible electric machine topologies with salient rotor pole features for the integrated motor design. The feasibility of this integrated motor-compressor design is discussed from both the EM and thermodynamic perspectives in this paper. The selection of slot/pole combination and EM sizing equations for the integrated FSPM motor-compressor are discussed. Mean-line design equations for the axial flow compressor are studied for the proposed integrated motor-compressor. The EM torque production capability of the proposed integrated motor-compressor is verified for one possible design in this paper by finite element analysis (FEA). The effects of two different attack angles of the rotor blades are studied compared to the conventional FSPM machine. The FEA results show that the proposed integrated motor-compressor achieves the expected output performances.

The article considers the problem of determining the parameters of the equivalent circuit of an asynchronous electric machine with a massive rotor. To solve the problem, a technique was used to determine the structure and parameters of the mathematical model of an asynchronous electric machine with a massive rotor from known geometric relationships and parameters of the materials used. The equivalent circuit parameters of an asynchronous electric machine are determined by the least squares method. To do this, a series of calculations of the distribution of the magnetic field in an asynchronous electric machine is performed when the stator winding is powered by a sinusoidal current and a locked rotor (short circuit mode). The approximation is calculated using the theory of the field using the dependence of the parameter, taking into account losses in the rotor, and the stator phase inductance on the frequency of the stator current with a stationary rotor. The questions of the numerical solution of equations for determining the approximation parameters are considered. It is established that in order to take into account the effect of current displacement in a massive rotor in the mathematical model of an asynchronous electric machine, it is necessary to use three circuits on the rotor.