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

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

Traction control in electric vehicles

Tese de Mestrado Integrado. Engenharia Electrotécnica e de Computadores. Área de Especialização de Automação. Faculdade de Engenharia. Universidade do Porto. 201

Comparison of shaft position estimation and correction techniques for sensorless control of surface mounted PM synchrononous motors

This thesis is a detailed study of how two error correction schemes affect the precision of shaft position estimation in state-observer techniques for sensorless control surface-mounted Permanent Magnet Synchronous Motors (PMSM), variance correction and variable PI regulation. A novel sensorless estimation technique based on Linear Kalman Filter (LKF) through constant variance correction is proposed and compared with the conventional Flux Linkage Observer (FLO) method and other state-estimation sensorless control techniques namely, Extended Kalman Filter (EKF), variable variance correction, Single Dimension Luenberger (SDL) observer and Full-Order Luenberger (FOLU) observer both through variable PI regulation. These five sensorless control techniques for PMSM are successfully implemented in the same lab-based hardware platform, i.e. full digital float-point-type DSP control inverter-fed PMSM system. Experiments are reported on each sensorless method covering position estimation, speed response, self-startup and load behaviour. Intensive analysis has also been carried out on the impact of error correction of estimated position on the steady/dynamic PMSM characteristics with different sensorless approaches. The experiment demonstrates that the novel Linear Kalman Filter can achieve the minimum average position estimation error throughout the electrical cycle of the five sensorless estimation techniques during no load operation at rated speed and also makes PMSM capable of self-startup for any initial rotor position except the dead area. A speed response experiment for LKF shows that individual speed estimation can be extracted directly from LKF state estimation for sensorless control PMSM. Experiments on the five sensorless methods proves that position error correction scheme is the dominating factor for state estimation sensorless control PMSM and better dynamic/steady control performance can be achieved using a variance correction scheme applied in EKF/LKF than with variable PI regulation applied in SDL/FOLU. The thesis also concludes that the novel Linear Kalman Filter is an optimised cost-effective sensorless estimation method for the PMSM drive industry compared with classic and Flux Linkage observers/Extended Kalman Filters

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

Modelling and practical set-up to investigate the performance of permanent magnet synchronous motor through rotor position estimation at zero and low speeds

This thesis provides a study for the rotor position estimation in SM-PMSMs, particularly at zero and low speeds. The method for zero rotor speed is based on injection of three high frequency voltage pulses in the motor stator windings. Then, the voltage responses at the motor terminals are exploited to extract the rotor position. Two approaches, modelling and practical implementations, are presented. The obtained results have showed a verification of a high-resolution position estimation (a position estimation of 1 degree angle), a simplicity and cost effective implementation and a no need for current sensors is required to achieve the estimation process. It should be noticed that the implementation of rotor position estimation at zero speed is only attended when the rotor is at standstill or very low speed. Therefore, the motor driver is not expected to be active at this condition. Thereby, the zero speed estimation does not provide a robust torque control. In future, this should be taking into consideration to overcome this drawback and to make the estimator more reliable. At low speed running, the primary goal is to start spinning the under test motors, and then the rotor position estimation is achieved. The motor spinning is based on adopting a virtual injected signal to generate the voltage components, Vα and Vβ, of the space vector pulse width modulation technique. Then, generating the eight space vectors is conducted through storing the standard patterns of the six space vector sectors in a memory structure together with the timing sequences of each sector. The presented strategy of motor running includes a proposed motor speed control scheme, which is based on controlling the frequency of the power signal, at the inverter output, through controlling the timing period of execution the power delivery program. The thesis presents a proposed method to achieve the estimation goal depends on tracking the magnetic saliency on one motor line voltage. Thereby, the rotor position estimation The introduced proposed method, for rotor position estimation at zero speed, verifies the following contributions: - Presents a simple and cost effective zero speed rotor position estimator for the motor under test. - The aimed resolution in this thesis is an angle 1 degree. IV - Adopting solely the measuring of motor terminal voltages. Eliminating the detection of the rotor magnet polarity as a necessary technique for completing the position estimation. At low speed running, the following contributions are verified: - Rather than a real frequency signal, a virtual injected signal is adopted to generate the voltage components, Vα and Vβ of the space vector pulse width modulation technique. - The proposed method for generating the eight space vectors is based on storing the standard patterns of the six sectors in a memory structure together with the timing sequence. - The strategy of motor speed control is based on controlling the period of execution the power delivery program. - The strategy of low speed rotor position employs one motor line voltage from which the low speed estimation is achieved