18 research outputs found
Online Control of IPMSM Drives for Traction Applications Considering Machine Parameter and Inverter Nonlinearities
In this paper, an online control method of interior permanent magnet synchronous machine (IPMSM) drives for traction applications considering machine parameter and inverter nonlinearities is presented. It is shown that the conventional technique using parameter information instantly extracted from premeasured parameter look-up tables (LUTs) only determines the local maximum torque per ampere (MTPA) operating point associated with this specific parameter information without evaluating the global MTPA achievement. Therefore, global MTPA operation may not be achieved for conventional online control IPMSM drives with extreme nonlinear machine parameters (e.g., short-period overload operations). Thus, a model-based correction method using stator flux adjustment is proposed for an online quasiglobal MTPA achievement. It is also proven that in the flux-weakening (FW) region, due to the inverter nonlinearities, a lower than expected maximum achievable torque for a demanded speed and a higher than expected current magnitude for a demanded torque may be obtained. Hence, an inverter nonlinearity compensation (INC) method exploiting the voltage feedback (FB) loop is introduced and its advantages over the conventional INC scheme are demonstrated. The proposed online control method is validated via measurements on a 10-kW IPMSM
Design Optimization of Permanent Magnet Machines Over a Target Operating Cycle Using Computationally Efficient Techniques
The common practices of large-scale finite element (FE) model-based design optimization of permanent magnet synchronous machines (PMSMs) oftentimes aim at improving the machine performance at the rated operating conditions, thus overlooking the performance treatment over the entire range of operation in the constant torque and extended speed regions. This is mainly due to the computational complexities associated with several aspects of such large-scale design optimization problems, including the FE-based modeling techniques, large number of load operating points for load-cycle evaluation of the design candidates, and large number of function evaluations required for identification of the globally optimal design solutions. In this dissertation, the necessity of accommodating the entire range of operation in the design optimization of PMSMs is demonstrated through joint application of numerical techniques and mathematical or statistical analyses. For this purpose, concepts such as FE analysis (FEA), design of experiments (DOE), sensitivity analysis, response surface methodology (RSM), and regression analysis are extensively used throughout this work to unscramble the correlations between various factors influencing the design of PMSMs. Also in this dissertation, computationally efficient methodologies are developed and employed to render unprohibitive the problems associated with large-scale design optimization of PMSMs over the entire range of operation of such machines. These include upgrading an existing computationally efficient FEA to solve the electromagnetic field problem at any load operating point residing anywhere in the torque-speed plane, developing a new stochastic search algorithm for effectively handling the constrained optimization problem (COP) of design of electric machines so as to reduce the number of function evaluations required for identifying the global optimum, implementing a k-means clustering algorithm for efficient modeling of the motor load profile, and devising alternative computationally efficient techniques for calculation of strand eddy current losses or characterization of the mechanical stress due to the centrifugal forces on the rotor bridges. The developed methodologies in this dissertation are applicable to the wide class of sine-wave driven PM and synchronous reluctance machines. Here, they were successfully utilized for optimization of two existing propulsion traction motors over predefined operating cycles. Particularly, the well-established benchmark design provided by the Toyota Prius Gen. 2 V-type interior PM (IPM) motor, and a challenging high power density spoke-type IPM for a formula E racing car are treated
Advances in Rotating Electric Machines
It is difficult to imagine a modern society without rotating electric machines. Their use has been increasing not only in the traditional fields of application but also in more contemporary fields, including renewable energy conversion systems, electric aircraft, aerospace, electric vehicles, unmanned propulsion systems, robotics, etc. This has contributed to advances in the materials, design methodologies, modeling tools, and manufacturing processes of current electric machines, which are characterized by high compactness, low weight, high power density, high torque density, and high reliability. On the other hand, the growing use of electric machines and drives in more critical applications has pushed forward the research in the area of condition monitoring and fault tolerance, leading to the development of more reliable diagnostic techniques and more fault-tolerant machines. This book presents and disseminates the most recent advances related to the theory, design, modeling, application, control, and condition monitoring of all types of rotating electric machines
The investigation of electromagnetic radial force and associated vibration in permanent magnet synchronous machines
The rising public awareness of climate change and urban air pollution has been one
of the key drivers for transport electrification. Such trend drastically accelerates the
quest for high-power-and-torque-density electric drive systems. The rare-earth permanent
magnet synchronous machine, with its excellent steady-state and dynamic
characteristics, has been the ideal candidate for these applications. Specifically, the
fractional-slot and concentrated-winding configuration is widely adopted due to its
distinctive merits such as short end winding, low torque pulsation, and high efficiency.
The vibration and the associated acoustic noise become one of the main
parasitic issues of high-performance permanent magnet synchronous drives. These
undesirable features mainly arise from mechanical connection failure, imperfect assembly,
torque pulsation, and electromagnetic radial and axial force density waves.
The high-power-and-torque-density requirement will only be ultimately fulfilled by
the reduction of both electromagnetic active material and passive support structure.
This results in inflated electromagnetic force density inside the electric machine.
Besides, the sti.ness of the machine parts can be compromised and the resultant
natural frequencies are significantly brought down. Therefore, the vibration and
acoustic noise that are associated with the electromagnetic radial and axial force
density waves become a burden for large deployment of these drives.
This study is mainly dedicated to the investigation of the electromagnetic radial
forced density and its associated vibration and acoustic noise in radial-flux permanent
magnet synchronous machines. These machines are usually powered by voltage
source inverter with pulse width modulation techniques and various control strategies.
Consequently, the vibration problem not only lies on the permanent magnet
synchronous machine but also highly relates to its drive and controller. Generally,
the electromagnetic radial force density and its relevant vibration can be divided
into low-frequency and high-frequency components based on their origins. The
low-frequency electromagnetic radial force density waves stem from the magnetic
field components by the permanent magnets and armature reaction of fundamental
and phase-belt current harmonic components, while the high-frequency ones are
introduced by the interactions between the main low-frequency and sideband highfrequency
magnetic field components.
Both permanent magnets and armature reaction current are the main sources of
magnetic field in electric machines. Various drive-level modeling techniques are first reviewed, explored, and developed to evaluate the current harmonic components
of the permanent magnet synchronous machine drive. Meanwhile, a simple
yet e.ective analytical model is derived to promptly estimate the sideband current
harmonic components in the drive with both sinusoidal and space-vector pulse
width modulation techniques. An improved analytical method is also proposed to
predict the magnetic field from permanent magnets in interior permanent magnet
synchronous machines. Moreover, a universal permeance model is analytically developed
to obtain the corresponding armature-reaction magnetic field components.
With the permanent magnet and armature-reaction magnetic field components, the
main electromagnetic radial force density components can be identified and estimated
based on Maxwell stress tensor theory.
The stator tooth structure has large impacts on both electromagnetic radial force
density components and mechanical vibration behaviors. The stator tooth modulation
e.ect has been comprehensively demonstrated and explained by both finite
element analysis and experimental results. Analytical models of such e.ect are developed
for prompt evaluation and insightful revelation. Based on the proposed
models, multi-physics approaches are proposed to accurately predict low-frequency
and high-frequency electromagnetic radial vibration. Such method is quite versatile
and applicable for both integral-slot and fractional-slot concentrated-winding
permanent magnet synchronous machines. Comprehensive experimental results are
provided to underpin the validity of the proposed models and methods.
This study commences on the derivations of the drive parameters such as torque angle,
modulation index, and current harmonic components from circuit perspective
and further progresses to evaluate and decouple the air-gap magnetic field components
from field perspective. It carries on to dwell on the analytical estimations of
the main critical electromagnetic radial force density components and stator tooth
modulation e.ect. Based on the stator mechanical structure, the corresponding electromagnetic
radial vibration and acoustic noise can be accurately predicted. Various
analytical models have been developed throughout this study to provide a systematic
tool for quick and e.ective investigation of electromagnetic radial force density,
the associated vibration and acoustic noise in permanent magnet synchronous machine
drive. They have all been rigorously validated by finite element analysis and
experimental results. Besides, this study reveals not only a universal approach for
electromagnetic radial vibration analysis but also insightful correlations from both
machine and drive perspectives
Design and Application of Electrical Machines
Electrical machines are one of the most important components of the industrial world. They are at the heart of the new industrial revolution, brought forth by the development of electromobility and renewable energy systems. Electric motors must meet the most stringent requirements of reliability, availability, and high efficiency in order, among other things, to match the useful lifetime of power electronics in complex system applications and compete in the market under ever-increasing pressure to deliver the highest performance criteria. Today, thanks to the application of highly efficient numerical algorithms running on high-performance computers, it is possible to design electric machines and very complex drive systems faster and at a lower cost. At the same time, progress in the field of material science and technology enables the development of increasingly complex motor designs and topologies. The purpose of this Special Issue is to contribute to this development of electric machines. The publication of this collection of scientific articles, dedicated to the topic of electric machine design and application, contributes to the dissemination of the above information among professionals dealing with electrical machines
Aspects of magnetisation and iron loss characteristics in switched-reluctance and permanent-magnet machines
In the first section, the magnetisation characteristics of the switched-reluctance motor are examined. Measurements have been carried out using both static and dynamic test methods. The test data has been compared with simulation results from analytical design programs and finite element models. The effects of mutual coupling on the magnetisation characteristics are investigated through measurement and simulation. Results show that the degree of mutual coupling is strongly dependent on the winding arrangement of the machine.
In the next section, the difficulties in measuring the properties of permanent-magnet machines are discussed in detail, and solutions to common problems proposed. The measurement and analysis methods used for the switched-reluctance motor are further developed for analysis of permanent magnet machines. Techniques for determining the variation in synchronous reactances and permanent magnet flux are presented. Finite element simulations are used to show the variation of magnet flux under loading, a condition ignored in classical analysis methods.
The final section discusses the analysis of magnetisation characteristics of electrical sheet steels. Comparison is made between measurements carried out on single sheet tester and Epstein square test rigs. The iron losses of a typical non-grain-orientated steel are measured under both sinusoidal and nonsinusoidal flux density conditions. The iron losses are shown to increase significantly when higher harmonic components are introduced to the flux density waveform. The difficulties in modelling the nonlinear iron loss characteristics of electrical steels are considered
Control strategies for the More Electric Aircraft starter-generator electrical power system
The trend towards development of More Electric Aircraft (MEA) has been driven by increased fuel fossil prices and stricter environmental policies. This is supported by breakthroughs in power electronic systems and electrical machines. The application of MEA is expected to reduce the aircraft mass and drag, thereby increasing fuel efficiency and reduced environmental impact. The starter-generator (S/G) scheme is one of the solutions from the MEA concept that brings the most significant improvement to the electrical power generation system. A S/G system is proposed from the possible solutions brought by the MEA concept in the area of electrical power generation and distribution. Due to the wide operating speed range, limited controller stability may be present. This thesis contributes to the control plant analysis and controller design of this MEA S/G system. The general control requirements are outlined based on the S/G system operation and the control structure is presented. The control plants are derived specifically to design the controllers for the S/G control scheme. Detailed small signal analysis is performed on the derived plant while taking into consideration the aircraft operating speed and load range. A safe range for the controller gains can then be determined to ensure stable operation throughout the S/G operation. Adaptive gain and a novel current limit modifier are proposed which improves the controller stability during S/G operation. Model predictive control is considered as an alternative control strategy for potential control performance improvements with the S/G system. The technical results and simulations are supported by Matlab®/Simulink® based models and validated by experimental work on a small scaled drive system