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In this thesis the compounds Fe5SiB2 and Fe5PB2 have beensynthesized via high temperature synthesis, including arc melting anddrop synthesis. The structure for both compounds are of Cr5B3 typewith the space group I4/mcm. The cell parameters were refined toa = 5.5533 Å and c = 10.3405 Å for Fe5SiB2 and a = 5.4903 Å andc = 10.3527 Å for Fe5PB2. The saturation magnetization at roomtemperature for Fe5SiB2 has been measured to 138.8 Am2/kg and theanisotropy constant has been estimated to 79 kJ/m3. Theferromagnetic properties and the high anisotropy constant makesthese materials promising as permanent magnet materials, but moreinvestigations are necessary.

A permanent magnet synchronous motor is traditionally controlled from measured values of the angular velocity and position of the rotor. However, there is a wish from SAAB Avitronics to investigate the possibility of estimating this angular velocity and position from the current measurements. The rotating rotor will affect the currents in the motor’s stator depending on the rotor’s angular velocity, and the observer estimates the angular velocity and angular position from this effect. There are several methods proposed in the article database IEEE Xplore to observe this angular velocity and angular position. The methods of observation chosen for study in this thesis are the extended Kalman filter and a phase locked loop algorithm based on the back electro motive force augmented by an injection method at low velocities. The extended Kalman filter was also programmed to be run on a digital signal processor in SAAB Avitronics’ developing hardware. The extended Kalman filter performs well in simulations and shows promise in hardware implementation. The algorithm for hardware implementation suffers from poor resolution in calculations involving the covariance matrices of the Kalman filter due to the use of 16-bit integers, yielding an observer that only functions in certain conditions. As simulations with 32-bit integer algorithm performs well it is likely that a 32- bit implementation of the extended Kalman filter would perform well on a motor, making sensorless control possible in a wide range of operations.

The researchers at the Department of Electricity at Uppsala University has recently entered the field of electric motor design, however no real knowledge of motor control of salient pole permanent magnet motors exists in the department. This thesis will present a general description of the control method of motors that exist today, this has been done by reviewing existing literature. The literature review has shown that there are at least three control methods with a significant different in their control approach, Scalar-, Field Oriented- and Direct Torque- Control. The two last methods were chosen by the author as the most useful and was implemented and simulated together with the newly developed motor in MATLAB Simulink to evaluate their performance. The simulation results show that there is no difference in performance of the two methods, but they show a difference in efficiency. The results show that it's worth to develop both methods further, mainly for reducing the torque and current ripple. This result was not expected according to literature, which suggests that the Field Oriented Control has a lower torque ripple. This could be caused by the choice of hysteresis control for inverter switching, instead of more sophisticated methods with a proportional integral derivative controller (PID) together with Sinusoidal Pulse Width Modulation (SPWM) or Space Vector Modulation (SVM).

Sliding mode controllers (SMC) with time delay and a rotor position observer are designed for the sensorless speed control of permanent magnet synchronous motor (PMSM) are proposed in this paper. Based on field-oriented principle, a flux SMC is designed to achieve quick flux control. And then a speed SMC with time delay is presented and compared with PI controller in the direct torque control framework. The effectiveness of the proposed control scheme under the load disturbance and parameter uncertainties is verified by simulation results.

This thesis presented a sensor-less permanent magnet synchronous motor (PMSM) driver for controlling air-conditioner rotary compressor speed. In this thesis, a quasi-sine pulse-width modulation (PWM) driving method was proposed. Furthermore, the current feedback control scheme and rotor magnet pole position detection were included. The system structure was implemented by using a digital signal processing (DSP) platform. The proposed driving scheme was compared with the square-wave driving without current feedback and six-step square-wave driving method with current feedback. Moreover, the passive and shunt semi-active power factor correction (PFC) technique were researched for the air-conditioner application. Experimental results demonstrated that the system power factor could be improved by the proposed shunt semi-active PFC method. Besides, the proposed sensor-less quasi-sine PWM driving method implemented in an air-conditioner compressor driver was capable of reducing the magnitude of rotational speed ripples, compressor vibration, and system power consumption.

The Electron Energy Corporation (EEC) along with the National Aeronautics and Space Administration (NASA) is researching magnetic bearings. The purpose of this research was to design and develop a high-temperature (1000�F) magnetic bearing system using High Temperature Permanent Magnets (HTPM), developed by the EEC. The entire system consisted of two radial bearings, one thrust bearing, one motor and 2 sets of catcher bearings. This high temperature magnetic bearing system will be used in high performance, high speed and high temperature applications like space vehicles, jet engines and deep sea equipment. The bearing system had a target design to carry a load equal to 500 lb-f (2225N). Another objective was to design and build a test rig fixture to measure the load capacity of the designed high temperature radial magnetic bearing (HTRMB) called Radial Bearing Force Test Rig (RBFTR). A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1000 �F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces even if half the coils have failed. The permanent magnet bias of the radial magnetic bearing reduces the amount of current required for magnetic bearing operation. This reduces the power loss due to the coil current resistance and also increases the system efficiency because magnetic field of the HTPM is used to take up the major portion of the static load on the bearing. The bias flux of the homopolar radial bearing is produced by the EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed using the Radial Bearing Force Test Rig (RBTFR) to measure actual load capacity of the designed bearing at the test rig. All the results obtained from the experiment were compiled and analyzed to determine the relation between bearing force, applied current and temperature.

This thesis provides a detailed field analysis of a specially designed axial-flow radial-flux permanent magnet motor for cooling fan applications. By implementing an iron strip segment at the stator base, this motor can provide a stable guidance force in its axial direction, such that the operational vibration effects can be minimized and the undesired forces applied onto associated bearing system can be alleviated. Supported by adaptive magnetic equivalent circuit and three-dimensional finite element analyses, the motor operational fluxes and forces can be analyzed. Results show that excellent performance and enhanced reliability objectives can all be achieved.

This dissertation presents a high-precision positioner with a novel superimposed concentrated-field permanent-magnet matrix. This extended-range multi-axis positioner can generate all 6-DOF (degree-of-freedom) motions with only a single moving part. It is actuated by three planar levitation motors, which are attached on the bottom of the moving part. Three aerostatic bearings are used to provide the suspension force against the gravity for the system. The dynamic model of the system is developed and analyzed. And several control techniques including SISO (single input and single output) and MIMO (multi inputs and multi outputs) controls are discussed in the dissertation. The positioner demonstrates a position resolution of 20 nm and position noise of 10 nm rms in x and y and 15 nm rms in z. The angular resolution around the x-, y-, and z-axes is in sub-microradian order. The planar travel range is 160 mm ?? 160 mm, and the maximum velocity achieved is 0.5 m/s at a 5-m/s2 acceleration, which can enhance the throughput in precision manufacturing. Various experimental results are presented in this dissertation to demonstrate the positioner??s capability of accurately tracking any planar trajectories. Those experimental results verified the potential utility of this 6-DOF high-precision positioner in precision manufacturing and factory automation.

The EEC (Electron Energy Corporation) in conjunction with the National Aeronautics and Space Administration is researching the magnetic bearings for an alternative to conventional journal or ball bearings. The purpose of this research was to design and develop a high-temperature (1000ºF) hybrid Magnetic Bearing using High Temperature Permanent Magnets (HTPM), developed by the EEC for high performance jet engines at high speeds that supply loads of 500 lbf. Another objective is to design and build a test rig fixture to measure the load capacity of the designed bearing. The permanent magnet bias of the Homopolar radial magnetic bearing reduces the amount of current required for magnetic bearing operation. This reduces the power loss due to the coil current resistance and improves the system efficiency because the magnetic field of the HTPM can suspend the major portion of the static load on bearing. A high temperature radial magnetic bearing was designed via an iterative search employing 3D finite element based electromagnetic field simulations. The bearing was designed to produce 500 lbf of force at 1000ºF and the design weight is 48 lbs. The bias flux of the Homopolar radial bearing is produced by EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed to measure actual load capacity of the designed bearing at the test rig. All the results obtained from the experiment were compiled and analyzed to determine the relation between bearing force, applied current and temperature.