7 research outputs found
Influence of skew and cross-coupling on flux-weakening performance of permanent-magnet brushless AC machines
A method is proposed for predicting the flux-weakening performance of permanent-magnet (PM) brushless ac machines accounting for skew and d-q axis cross-coupling. The method is based on a d-q-axis flux-linkage model, a hybrid 2-D finite-element (FE)-analytical method being used to predict the d- and q-axis inductances. However, it only requires 2-D FE analysis of the magnetic field distribution over a cross section of the machine. The developed method is used to predict the torque-speed characteristic of an interior PM brushless ac machine with one stator slot-pitch skew. This is compared with predictions from a direct FE analysis of the machine and validated by measurements
Design and performance analysis of a novel synchronous reluctance machine
© 2020 - IOS Press and the authors. All rights reserved. To improve output torque ability and reduce torque ripple in traditional synchronous reluctance motor (TSynRM), a new synchronous reluctance motor (NSynRM) is proposed in this paper. The rotor of NSynRM is composed of both grain-oriented silicon steel and non-oriented silicon steel. With the reasonable design of rotor structure, the torque of NSynRM has been improved and its torque ripple has been reduced greatly. Firstly, TSynRM and NSynRM are qualitatively compared by using the magnetic network method. Secondly, the main parameters of these two machines are optimized by using finite element method (FEM). Then the performance comparison between two optimized machines are carried out. Finally, the equivalent stress of these two machines at the maximum speed are analyzed. It can be seen that NSynRM can have 6.8% higher torque under rated load, 8% higher torque under maximum load, 17.5% wider constant torque operation region, and lower torque ripple compared with the TSynRM
Predictive Stator Flux and Load Angle Control of Synchronous Reluctance Motor Drives Operating in a Wide Speed Range
This paper presents a new simplified finitecontrol-
set model predictive control strategy for synchronous
reluctance motors operating in the entire speed
range. It is a predictive control scheme that regulates the
stator flux and the load angle of the synchronous reluctance
motor, incorporating the ability to operate the drive in the
field-weakening region and respecting the motor voltage
and current limits as well as the load angle limitation
needed to operate this type of motor in the maximum
torque per voltage region. The proposed control strategy
possesses some attractive features, such as no need for
controller calibration, no weighting factors in the cost function,
good robustness against parameter mismatch, and
smaller computational cost compared to more traditional
finite-control-set model predictive control algorithms.
Simulation and experimental results obtained using a
high-efficiency synchronous reluctance motor demonstrate
the effectiveness of the proposed control scheme.info:eu-repo/semantics/publishedVersio
An Advanced Model Predictive Current Control of Synchronous Reluctance Motors
Synchronous reluctance motors (SynRMs) have, in recent years, attracted much
attention due to their high-efficiency output and nature of their construction denoted by
the lack of expensive magnetic materials, thus cheapening the overall cost whilst
increasing in robustness. These benefits have made the SynRM a strong contender
against other established electric motors in the market. Similarly, model predictive
current control (MPCC) has recently become a powerful advanced control technology in
industrial drives, being, therefore, a suitable choice for SynRM drives granting overall
high control performance and efficiency. However, current prediction in MPCC requires
a high number of voltage vectors (VVs) synthesizable by the converter, being therefore
computationally demanding.
Accordingly, the main goal of this work is the development and analysis of a more
efficient and advanced MPCC for SynRMs whilst reducing the computational burden and
delivering good control performance in contrast with the standard MPCC. Therefore, to
achieve the intended levels of efficiency and control performance in SynRM drives, a
combination of two control strategies is developed, which combines hysteresis current
control (HCC) and MPCC, dubbed in this work HCC-MPCC. Furthermore, the SynRM
dynamic model equations comprising the magnetic saturating effects and iron losses are
presented through a detailed theoretical and computational analysis of the drive’s
control. Conclusively, the developed HCC-MPCC for SynRM drives is analyzed through
thorough and rigorous experimental tests alongside the standard MPCC, whose obtained
results are detailed comprehensively.Os motores sÃncronos de relutância (SynRMs) têm, nos últimos anos, atraÃdo muita
atenção devido à s suas caracterÃsticas construtivas, designadamente pela falta de
materiais magnéticos caros, depreciando assim o custo em geral; e simultaneamente pelo
aumento em robustez. Esses benefÃcios tornaram o SynRM num forte concorrente face a
outros motores elétricos existentes no mercado. Da mesma forma, o modelo preditivo de
controlo de corrente (MPCC) tornou-se recentemente numa poderosa estratégia de
controlo avançado em acionamentos industriais, sendo, portanto, uma escolha adequada
para acionamentos envolvendo SynRMs, garantindo elevado desempenho e eficiência de
controlo. No entanto, a previsão da corrente no MPCC requer um grande número de
vetores de tensão (VVs) sintetizáveis pelo conversor, sendo, portanto, exigente
computacionalmente.
Consequentemente, o objetivo principal deste trabalho é o desenvolvimento e análise de
um MPCC mais eficiente e avançado para SynRMs, reduzindo a carga computacional e,
simultaneamente, demonstrando um bom desempenho de controlo em contraste com o
MPCC clássico. Portanto, para atingir os nÃveis pretendidos de eficiência e desempenho
de controlo em acionamentos com SynRMs, uma combinação de duas estratégias de
controlo é desenvolvida, combinando o controlo de corrente de histerese (HCC) e MPCC,
denominado neste trabalho HCC-MPCC. Além disso, as equações do modelo dinâmico
do SynRM, compreendendo os efeitos de saturação magnética e as perdas de ferro, são
apresentadas através de uma análise teórica e computacional detalhada do controlo do
acionamento. Conclusivamente, o HCC-MPCC desenvolvido para acionamentos com
SynRMs é analisado por meio de testes experimentais conjuntamente com o MPCC
padrão, sendo os resultados obtidos detalhados de forma abrangente
Predictive control of electrical drives
In this work, the application of the Predictive Control Technique to the electrical drives has been considered and discussed, especially in comparison with the employment of the traditional control techniques. First of all, a predictive control algorithm for the Brushless DC drive is developed with the aim of improving the traditional current commutation as best as possible. Then, a novel predictive control algorithm is proposed by imposing both the reference torque value and the minimum Joule losses condition. Then, several predictive control algorithms are proposed for the Synchronous Reluctance Machine, taking into account the magnetic saturation effects too. They are based either on the traditional control strategy or on optimization criteria, such as the minimum steady state Joule losses condition and the fastest achievement of the reference torque value. Finally, a novel predictive Direct Torque Control algorithm is synthesized for the Asynchronous Machine, by taking into account both voltage saturation and current limitation constraints. The synthesizing procedure adopted is also shown by an interesting graphical representation. The effectiveness of all the proposed algorithms has been properly tested by appropriate simulation studies, performed in the Matlab Simulink environment. The corresponding results have highlighted how the employment of the Predictive Control Technique allows better performances compared to those achievable by the traditional control ones
Synchronous reluctance motors with fractional slot-concentrated windings
PhD ThesisToday, high efficiency and high torque density electrical machines are a growing research
interest and machines that contain no permanent magnet material are increasingly sought.
Despite the lack of interest over the last twenty years, the permanent magnet-free synchronous
reluctance machine is undergoing a revival and has become a research focus due
to its magnet-free construction, high efficiency and robustness. They are now considered a
potential future technology for future industrial variable speed drive applications and even
electric vehicles. This thesis presents for the first time a synchronous reluctance motor
with fractional slot-concentrated windings, utilizing non-overlapping single tooth wound
coils, for high efficiency and high torque density permanent magnet-free electric drives.
It presents all stages of the design and validation process from the initial concept stage
through the design of such a machine, to the test and validation of a constructed prototype
motor. The prototype machine utilizes a segmented stator core back iron arrangement for
ease of winding and facilitating high slot fill factors. The conventional synchronous reluctance
motor topology utilizes distributed winding systems with a large number of stator
slots, presenting some limitations and challenges when considering high efficiency, high
torque density electrical machines with low cost. This thesis aims to present an advancement
in synchronous reluctance technology by identifying limitations and improving the
design of synchronous reluctance motors through development of a novel machine topology.
With the presented novel fractional slot concentrated winding machine design,
additional challenges such as high torque ripple and low power factor arise, they are explored
and analysed - the design modified to minimise any unwanted parasitic effects.
The electrical and electromagnetic characteristics of the developed machine are also explored
and compared with that of a conventional machine. A novel FEA post-processing
technique is developed to analyse individual air-gap field harmonic torque contributions
and the machines dq theory also modified in order to account for additional effects. The
developed machine is found to be lower cost, lower mass and higher efficiency than an
equivalent induction or conventional synchronous reluctance motor, but does suffer higher
torque ripples and lower power factor. The prototype is validated using static and dynamic
testing with the results showing a good match with finite element predictions. The work
contained within this thesis can be considered as a first step to developing commercial
technology based on the concept for variable speed drive applications.Financial assistance was provided by was provided by the
UK Engineering and Physical Sciences Research Council (EPSRC) in the form of a Doctoral
Training Award and additional financial assistance was kindly provided by Cummins
Generator Technologies, Stamford, UK, through industrial sponsorship of this wor
Fault tolerant vector control of five-phase permanent magnet motors
Equipped with appropriate control strategies, permanent magnet (PM) machines are becoming one of the most flexible types of actuators for many industrial applications. Among different types of PM machines, five-phase BLDC machines are very interesting in fault tolerant applications of PM drives.
Torque improvement in five-phase BLDC machines can be accomplished by optimizing their mechanical structure or by enhancing their controlling methods. New current controllers are proposed in this thesis to improve the quality of generated torque under normal operations of five-phase BLDC machines. Proposed current controllers are based on combination of predictive deadbeat controlling strategy and Extended Kalman Filter estimation. These controllers will be the basis for accurate faulty operation of the motor.
Operation of five-phase BLDC machines under faulty conditions has also been considered in this study. To improve the generated torque under faulty conditions, both amplitude and phase angle of fundamental and third current harmonics are globally optimized for the remaining healthy phases.
Under faulty conditions, appropriate reference currents of a five-phase BLDC machine have oscillating dynamics both in phase and rotating reference frames. As a result, the implemented current controllers under these conditions should be robust and fast. Predictive deadbeat controllers are also proposed for faulty conditions of five-phase BLDC machines.
Fault tolerant five-phase BLDC machines are very interesting in automotive applications such as electrical vehicles and more electric aircraft. In addition, these devices are gaining more importance in other fields such as power generation in wind turbines. In all of these applications, the efficiency of PM machine is of most importance. The efficiency of a typical five-phase BLDC machine is evaluated in this thesis for normal and different faulty conditions.
Experimental evaluations are always conducted to verify the theoretical developments. These developments include proposed controlling methods, optimized reference currents, and simulated efficiency of five-phase BLDC machine under different operational conditions