An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

This paper reviews the current technologies used in high-speed electrical machines through an extensive survey of different topologies developed and built in the industry and academia for several applications. Developments in materials and components, including electrical steels and copper alloys, are discussed, and their impact on the machines' operating physical boundaries is investigated. The main application areas pulling the development of high-speed machines are also reviewed to better understand the typical performance requirements.

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High-Speed Electrical Machines: Technologies, Trends, and Developments

This book equips the reader to understand every important aspect of the dynamics of rotating machines. Will the vibration be large? What influences machine stability? How can the vibration be reduced? Which sorts of rotor vibration are the worst? The book develops this understanding initially using extremely simple models for each phenomenon, in which (at most) four equations capture the behavior. More detailed models are then developed based on finite element analysis, to enable the accurate simulation of the relevant phenomena for real machines. Analysis software (in MATLAB) is associated with this book, and novices to rotordynamics can expect to make good predictions of critical speeds and rotating mode shapes within days. The book is structured more as a learning guide than as a reference tome and provides readers with more than 100 worked examples and more than 100 problems and solutions.

/pdf/dynamics-of-rotating-machines-499re2kizd.pdf

Dynamics of rotating machines

Online estimation of the frequency of a sinusoidal signal is a classical problem in systems theory that has many practical applications. In this paper the authors provide a solution to the problem of ensuring a globally convergent estimation. More specifically, they propose a new adaptive notch filter whose dynamic equations exhibit the following remarkable features: 1) all signals are globally bounded and the estimated frequency is asymptotically correct for all initial conditions and all frequency values; 2) the authors obtain a simple tuning procedure for the estimator design parameters, which trades-off the adaptation tracking capabilities with noise sensitivity, ensuring (exponential) stability of the desired orbit; and 3) transient performance is considerably enhanced, even for small or large frequencies, as witnessed by extensive simulations. To reveal some of the stability-instability mechanisms of the existing algorithms and motivate our modifications the authors make appeal to a novel nonlinear (state-dependent) time scaling. The main advantage of working in the new time scale is that they remove the coupling between the parameter update law and the filter itself, decomposing the system into a feedback form where the required modifications to ensure stability become apparent. Even though they limit their attention here to the simplest case of a single constant frequency without noise the algorithm is able to track time-varying frequencies, preserve local stability in the presence of multiple sinusoids, and is robust with respect to noise.

/pdf/a-globally-convergent-frequency-estimator-55p3afkx1e.pdf

A globally convergent frequency estimator

Unbalance of magnetically levitated rotors causes undesirable synchronous vibrations which may lead to saturation of the magnetic actuator. To avoid this problem we propose a generalized narrow-band notch filter which is inserted into the multivariable feedback without destabilizing the closed loop. The parameters of the generalized notch filter strongly depend on the inverse sensitivity matrix evaluated at rotational speed. This matrix is easily measured a priori and stored in a look-up table. It is shown that a decentralized notch is feasible for weakly gyroscopic rotors. The proposed notch filter approach has advantages in terms of run-time complexity and analytical verification of closed-loop stability. Results from the implementation of the proposed unbalance compensation in industrial magnetic bearing systems are included.

Unbalance compensation using generalized notch filters in the multivariable feedback of magnetic bearings

Active magnetic bearings (AMBs) are an example for industrial applications of digital signal processors (DSPs). The complex control functions involved include multichannel control in a delay-time sensitive system. DSPs are well suited for this challenging application. Hardware and software issues are discussed. Unbalance compensation and other additional functions of the controller are presented. An industrial milling spindle with AMBs and DSP control is discussed in detail. A section on AMB research projects with DSP control indicates future trends. >

Application of digital signal processors for industrial magnetic bearings

A magnetic bearing device (1) for rotatably supporting a shaft (20) for rotation about a rotation axis (101) is dis­closed. The device (1) comprises a first active radial bear­ing (5), one or more first radial displacement sensors (81), and an axial bearing (6, 7). At least a part of the axial bearing (6, 7) is disposed between the first active radial bearing (5) and the first radial displacement sensors (81) if viewed in an orthogonal projection onto the rotation axis (101). Also a vacuum pump comprising such a magnetic bearing device (1) and a multiple-sensing unit (8) are disclosed.

Magnetic bearing device and vacuum pump

A method and a controller for controlling a magnetic bearing device, in which a rotor is suspended for rotation around a shaft, are disclosed. Sensor signals are transformed to yield tilt displacement signals (Sθx, Sθy) which correspond to tilting displacements of the shaft in predetermined directions (x, y). From the tilt displacement signals (Sθx, Sθy), tilt control signals (Aθx, Aθy) are derived; these are transformed to yield actuator control signals for driving electromagnetic actuators in the magnetic bearing device. According to the invention, tilting displacements for which the tilt vector rotates about the device axis (z) with a first predetermined sense of rotation are controlled separately from tilting displacements for which the tilt direction vector rotates about the device axis (z) with a second sense of rotation opposite to the first predetermined sense of rotation. In this way, control of nutation and precession can be achieved without influence from blade vibrations or shaft bending modes.

Method and Apparatus for Controlling a Magnetic Bearing Device

A magnetic bearing device (1) with an improved vacuum-tight electrical feedthrough through its housing (10) is disclosed. The feedthrough (30) comprises a flat connection element (31) such as a rigid or flexible printed circuit board extending through the wall of the housing (10), preferably all the way along an inner circumference of the housing. The connection element is sealed in a gas-tight manner to the housing. The element preferably has a central opening (36) for receiving the rotor shaft. Connections to the bearing units and sensors may be achieved by flat-ribbon cables (51) or flexprints. The sensors are preferably also implemented as printed sensors. Thus a very compact and cost-efficient magnetic bearing device can be obtained. An alternative embodiment uses a connection element on a side wall of the housing as a feedthrough to the bearing components.

René Larsonneur

Papers

Unbalance compensation using generalized notch filters in the multivariable feedback of magnetic bearings

Application of digital signal processors for industrial magnetic bearings

Magnetic bearing device and vacuum pump

Method and Apparatus for Controlling a Magnetic Bearing Device

Magnetic bearing device with an improved vacuum feedthrough