Sensorless Control of Switched-Flux Permanent Magnet Machines

This thesis investigates the sensorless control strategies of permanent magnet synchronous machines (PMSMs), with particular reference to switched-flux permanent magnet (SFPM) machines, based on high-frequency signal injection methods for low speed and standstill and the back-EMF based methods for medium and high speeds

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

Modelagem dinâmica e acionamento de atuadores eletromagnétcos lineares de imãs permanentes

Este trabalho apresenta um estudo teórico, computacional e experimental sobre o desempenho dinâmico e o acionamento elétrico de atuadores lineares síncronos de ímãs permanentes. Inicialmente, uma modelagem dinâmica genérica de atuadores lineares é realizada no referencial trifásico e em função do número de condutores ativos da armadura. Assim, o modelo proposto é diretamente aplicável em máquinas com topologias planas ou tubulares e para diversos arranjos de ímãs permanentes utilizados no sistema de excitação de campo. Na sequência, através de uma transformação de coordenadas, um modelo não linear é expresso no referencial bifásico síncrono. A seguir, esse modelo é linearizado em torno de um ponto de operação. Um atuador de topologia tubular é escolhido para validação da modelagem matemática. Simulações computacionais via método de elementos finitos e testes experimentais são realizados, sendo os resultados obtidos comparados aos fornecidos pelos modelos analíticos desenvolvidos. Dessa forma, o equacionamento apresentado é validado no domínio do tempo e no domínio da frequência. Por fim, um acionamento em malha fechada baseado em orientação de campo é implementado no atuador tubular. Os ganhos proporcional e integral do controlador são calculados a partir da resposta temporal desejada e da constante de força do dispositivo.This work presents a theoretical, computational and experimental study on the dynamic performance and the electric drive of linear permanent magnet synchronous actuators. For this purpose, a generic dynamic modeling of linear actuators is performed initially on the three-phase reference frame as a function of the number of active conductors in the armature. Thus, the proposed model is directly applicable in flat or tubular machines with different arrangement of end magnets used in the field excitation system. Then, by a coordinate transformation, a non-linear model is expressed in the synchronous reference frame. This model is then linearized around an operating point. A tubular topology was chosen to validate the mathematical modeling. Numerical simulations using finite element method and experimental tests are performed and their results are compared to analytical models. Thus, the presented modeling is validated both in the time domain and in the frequency domain. Finally, a closed loop electric drive based on field orientation is implemented in the tubular actuator. The controller gains are calculated by means of the desired time response and the force constant of the device

Detent Force Reduction of an Arc-Linear Permanent-Magnet Synchronous Motor by Using Compensation Windings

© 2016 IEEE. An arc-linear permanent-magnet synchronous machine (AL-PMSM) is a kind of servo machine used for a scanning system to meet the requirements of high positioning accuracy, high response performance, and wide scanning range. To reduce the detent force and increase the travel range of the AL-PMSM, a novel hybrid excited AL-PMSM with a normal armature winding and compensation windings is proposed and investigated. The compensation windings are installed on the end teeth of the primary side. The influence of a compensation direct current is analyzed by a finite element method (FEM). Based on the result of the analysis, a proper compensation current is proposed to reduce the detent force. The result after the compensation is simulated by the FEM. In addition, a combination of primary length optimization and current compensation is proposed, the proper formula for the compensation current is deduced, and the result calculated by the FEM is provided. To reduce the detent force of the travel end, a proper current is supplied into the compensation winding, the detent force during the both end of the travel range is much reduced, so the smooth travel range is increased. Finally, prototypes of AL-PMSM are manufactured and experiments are conducted to validate the proposed compensation method

Magnetic Field and Force Calculation in Linear Permanent-Magnet Synchronous Machines Accounting for Longitudinal End Effect

© 1982-2012 IEEE. This paper presents an improved analytical method for predicting the magnetic field and forces in linear permanent-magnet synchronous machines (LPMSMs) accounting for both the primary end effect and secondary end effect. So far, the magnetic field calculation of LPMSM in most studies is conducted in Cartesian coordinate, whereas the end effect is neglected by applying periodic boundary. In this paper, to implement the analytical model, a polar presentation of the machine geometry is proposed and the subdomain method is applied to calculate the magnetic field. Then, according to the developed model, the tangential thrust and normal forces are calculated based on the Maxwell stress theory. Numerical results are subsequently obtained by finite-element method and employed to validate the analytical model. Finally, an LPMSM prototype is manufactured and experiments are conducted. The results show that the developed analytical model has high accuracy for predicting the magnetic field and forces

Analysis and minimization of detent end force in linear permanent magnet synchronous machines

© 1982-2012 IEEE. In this paper, the end forces caused by the longitude end effects in linear permanent magnet synchronous machines (LPMSMs) are analyzed and minimized. First, the left/right-end forces are calculated based on an analytical model and the Maxwell stress tensor, in which the optimal integration surfaces are investigated. Then, based on the spectrum analysis of the left/right-end forces, two different methods are adopted to minimize the fundamental and high-order harmonics, respectively. The optimal length of the primary iron is obtained from the phase difference of the fundamental and a two-step iteration instead of the trial-and-error with the finite element method. Furthermore, step-skewed auxiliary irons are added to the primary end to eliminate the high-order harmonics. Third, to reduce the secondary end effect when the primary moves to the secondary end, a compensation method of adding mirror permanent magnet is proposed and good results are obtained. Finally, an LPMSM prototype is manufactured and experiments are conducted. The experimental results verify the theoretical study

Power quality improvement utilizing photovoltaic generation connected to a weak grid

Microgrid research and development in the past decades have been one of the most popular topics. Similarly, the photovoltaic generation has been surging among renewable generation in the past few years, thanks to the availability, affordability, technology maturity of the PV panels and the PV inverter in the general market. Unfortunately, quite often, the PV installations are connected to weak grids and may have been considered as the culprit of poor power quality affecting other loads in particular sensitive loads connected to the same point of common coupling (PCC). This paper is intended to demystify the renewable generation, and turns the negative perception into positive revelation of the superiority of PV generation to the power quality improvement in a microgrid system. The main objective of this work is to develop a control method for the PV inverter so that the power quality at the PCC will be improved under various disturbances. The method is to control the reactive current based on utilizing the grid current to counteract the negative impact of the disturbances. The proposed control method is verified in PSIM platform. Promising results have been obtaine