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Showing papers on "Rotor (electric) published in 1992"


Journal ArticleDOI
TL;DR: In this paper, an experimental study of the acoustic noise emitted from an inverter-driven doubly salient variable-reluctance motor (VRM) is presented, and a list of possible noise sources is given.
Abstract: An experimental study of the acoustic noise emitted from an inverter-driven doubly salient variable-reluctance motor (VRM) is presented. A list of possible noise sources is given. Through a series of experiments, all but one source is eliminated as being important, and the remaining source is shown to be dominant. The dominant noise source is the ovalizing deformation of the stator due to its radial magnetic attraction to the rotor. The emitted noise is particularly strong when the frequency of deformation coincides with that of a natural mechanical resonance of the stator. Several methods of reducing acoustic noise emission are studied. One successful method is the introduction of dither into the control of the motor in order to spread the spectrum of noise excitation and reduce its coupling to the mechanical resonance of the stator. >

406 citations


Journal ArticleDOI
TL;DR: In this paper, the phase rotor filter is described as an optical element whose complex transmittance depends in a linear fashion on the azimuth angle, and relationships are given that describe the scalar diffraction of coherent light by the rotor filter.
Abstract: We report creation by photolithography techniques of the phase rotor filter, an optical element whose complex transmittance depends in a linear fashion on the azimuth angle. Relationships are given that describe the scalar diffraction of coherent light by the rotor filter. The results of the numerical simulation and experiments are discussed.

301 citations


Proceedings ArticleDOI
04 Oct 1992
TL;DR: In this paper, a method for real-time estimation of the parameters and fluxes of induction motors is presented, based on a standard model of the induction motor, expressed in rotor coordinates.
Abstract: A novel method for the real-time estimation of the parameters and fluxes of induction motors is presented. The method is based on a standard model of the induction motor, expressed in rotor coordinates. It is assumed that current and position (or velocity) measurements are available. The interesting features of the method are: that it does not rely on special tests such as the locked rotor test or the no-load test (instead, a broad range of motor responses can be used); the method provides estimates of the rotor fluxes together with the estimates of the parameters; and measures of the uncertainties in the estimated motor parameters are provided. Results for both simulated and experimental data are provided. >

274 citations


Journal ArticleDOI
TL;DR: In this paper, the stator includes a piezoelectric film in which bending is induced in the form of a traveling wave, and a small glass lens placed upon the stators becomes the spinning rotor.
Abstract: The authors have begun research into piezoelectric ultrasonic motors using ferroelectric thin films. The authors have fabricated the stator components of these millimeter diameter motors on silicon wafers. Ultrasonic motors consist of two pieces: a stator and a rotor. The stator includes a piezoelectric film in which bending is induced in the form of a traveling wave. A small glass lens placed upon the stator becomes the spinning rotor. Piezoelectric micromotors overcome the problems currently associated with electrostatic micromotors such as low torque, friction, and the need for high voltage excitation. More importantly, they may offer a much simpler mechanism for coupling power out. Using thin films of lead zirconate titanate on silicon nitride membranes, various types of actuator structures can be fabricated. By combined new robot control systems with piezoelectric motors and micromechanics, the authors propose creating micromechanical systems that are small, cheap and completely autonomous. >

261 citations


Journal ArticleDOI
TL;DR: A method for predicting the cogging torque in radial-field permanent magnet brushless motors, based on the analytical calculation of the airgap field distribution and the net lateral force acting on the stator teeth is developed and validated.
Abstract: A method for predicting the cogging torque in radial-field permanent magnet brushless motors, based on the analytical calculation of the airgap field distribution and the net lateral force acting on the stator teeth, is developed and validated. The technique is applicable to both internal and external rotor motor topologies, modeled in a cylindrical coordinate system. It can also be applied to variants of the basic motor topologies, such as those with shifted magnets (i.e. spaced unsymmetrically) or unevenly distributed stator slots, and thus it can enable design features aimed at reducing the level of cogging torque to be evaluated. Based on the proposed analytical model, the effects of varying the leading design parameters on the cogging torque can be investigated. Hence, an optimal combination of design parameters can be identified to enable low cogging torque motors to be designed. >

221 citations



Journal ArticleDOI
TL;DR: The viscous, three-dimensional flowfield of a lifting helicopter rotor in hover is calculated by using an upwind, implicit, finite-difference numerical method for solving the thin layer Navier-Stokes equations as discussed by the authors.
Abstract: The viscous, three-dimensional flowfield of a lifting helicopter rotor in hover is calculated by using an upwind, implicit, finite-difference numerical method for solving the thin layer Navier-Stokes equations. The induced effects of the wake, including the interaction of tip vortices with successive blades, are calculated as part off the overall flowfield solution without using any ad hoc wake models. Comparison of the numerical results for the subsonic and transonic conditions show good agreement with the experimental data and with the previously published Navier-Stokes calculations using a simple wake model. Some comparisons with Euler calculations are also presented, along with some discussions of the grid refinement studies.

208 citations


Journal ArticleDOI
TL;DR: In this article, the aerodynamic performance and flow fields of Savonius rotors at various overlap ratios have been investigated by measuring the pressure distributions on the blades and by visualizing the flow fields in and around the rotors with and without rotation.

205 citations


Journal ArticleDOI
TL;DR: In this article, the working principle of traveling wave ultrasonic motors is reviewed and the main phenomena are mathematically modelled, and a detailed mathematical description of the stator vibration and a first model of the contact problem is given.

198 citations


Proceedings ArticleDOI
04 Oct 1992
TL;DR: In this paper, the main problems related to the design of a synchronous reluctance servomotor are examined and a simplified but general algorithm is found for calculating the internal optimized anisotropy ratio.
Abstract: The main problems related to the design of a synchronous reluctance servomotor are examined. The most suitable rotor structure is identified among different alternatives. A simplified but general algorithm is found for calculating the internal optimized anisotropy ratio. Optimization algorithms are given regarding minimization of the q-axis magnetic flux and maximization of torque for given outside diameter and power dissipation capability. A maximum torque design is illustrated in the general case, practical involvements of this design are pointed out and discussed. >

172 citations


Journal ArticleDOI
TL;DR: A way to understand mechanical characteristics of an ultrasonic motor is presented and the calculated and the measured efficiency of the motor also agree.
Abstract: A way to understand mechanical characteristics of an ultrasonic motor is presented. First, the vibration mode of a stator is calculated using a finite-element method (FEM) code. The path of the elliptic motion of the stator's teeth is obtained. The computed vibration mode at the surface of the stator is compared with that measured by an electrooptical displacement transducer. Next, the contact condition of the rotor/stator is calculated. The displacement and velocity of the rotor/stator, the distortion of the stick/slip area, the rotational speed of the rotor, and the friction loss of the motor are obtained. The calculated rotor displacement and torque-rotational speed curve correspond closely to the experimentally measured ones. The internal loss of the rotor/stator and the loss of the supporting felt are measured. The total loss of these losses and the calculated friction loss agree with the measured total loss. The calculated and the measured efficiency of the motor also agree. >

Proceedings ArticleDOI
04 Oct 1992
TL;DR: In this article, the vector control of an induction motor by speed estimation using an extended Kalman filter (EKF) is described, where the rotor speed is regarded as a parameter, and the composite state is composed of the original state and the speed.
Abstract: The vector control of an induction motor by speed estimation using an extended Kalman filter (EKF) is described. The rotor speed is regarded as a parameter, and the composite state is composed of the original state and the rotor speed. The EKF is employed to identify the speed of an induction motor and rotor magnetic flux based on the measured quantities such as stator currents and DC link voltage. The estimated speed is used for vector control and overall speed control. The current control is performed in the synchronous rotating reference frame, and the estimated speed information is used for reference frame transformation of the current controller. Computer simulation of the speed control has been carried out to confirm the usefulness of the speed estimation algorithm. The error between the real speed and the estimated speed is within a few RPM even in the low speed range of about 20 RPM. >

Patent
11 May 1992
TL;DR: In this paper, the axial flow blood pump for intracorporeal or extracorporeal use pumps blood axially through a cylindrical conduit disposed in the bloodstream of a patient.
Abstract: An axial flow blood pump for intracorporeal or extracorporeal use pumps blood axially through a cylindrical conduit disposed in the bloodstream of a patient. The pump further includes a pump stator mounted in the conduit and a motor stator located either externally or internally of the conduit which applies a magnetic flux in the conduit. A rotor located in the conduit carries permanent magnets which interact with the applied magnetic flux to rotate the rotor. The rotor also carries impeller blades which, during rotation, produces an axial flow of blood through the conduit. During rotor rotation, the rotor is radially suspended solely by one or more hydrodynamic bearings formed by blood flowing through the conduit, with the location of at least one hydrodynamic bearing defined by a radial gap between the inside surface of the conduit and the rotor. By radially suspending, or floating, the rotor on blood in the conduit, the size of the pump may be reduced and the need for radial bearings, radial bearing seals and/or a supply of purge fluid is eliminated.

Journal ArticleDOI
TL;DR: In this article, the equations of motion for a simple rotor with a breathing crack are derived based on fracture mechanics, and the breathing crack model is further simplified to a switching crack model, the conditions for crack opening and closing are derived, and can provide useful information for crack identification.

Proceedings ArticleDOI
04 Oct 1992
TL;DR: In this article, a new method of indirect rotor position sensing for switched reluctance motor (SRM) drives is described based on measuring the mutually induced voltage in an inactive phase which is either adjacent or opposite to the energized phase of an SRM.
Abstract: This paper describes a new method of indirect rotor position sensing for switched reluctance motor (SRM) drives. The principle is based on measuring the mutually induced voltage in an inactive phase which is either adjacent or opposite to the energized phase of an SRM. The mutual voltage in the "off" phase, induced due to the current in the active phase, varies significantly as the rotor, corresponding to the energized stator, moves from its unaligned position towards complete alignment. This mutually induced voltage variation is captured by a simple electronic circuit and then processed in a microcontroller to determine the commutation instants, thereby eliminating the need for direct rotor position sensors in an SRM. Successful operation of a four-phase SRM drive has been demonstrated in the laboratory using the mutual voltage (MV) technique of indirect rotor position sensing. The theoretical aspects of mutually induced voltages in an SRM and the relevant experimental results are presented in this paper. >

Proceedings ArticleDOI
04 Oct 1992
TL;DR: In this article, the development of a knowledge base branch related to rotor electrical faults in squirrel cage machines, to be implemented in an expert system (ES), utilizing instantaneous values as input data, is considered.
Abstract: The authors consider the development of a knowledge base branch related to rotor electrical faults in squirrel cage machines, to be implemented in an expert system (ES), utilizing instantaneous values as input data. The knowledge base is organized in two levels: in the first level diagnostic indexes for the orientation of the ES inference engine toward the appropriate branch of the fault tree are utilized. The second level includes the deep knowledge with a data set obtained on the basis of a complete faulty machine model. The diagnostic indexes of the first level concern how to distinguish faulty events from the healthy signals due to the unavoidable manufacturing asymmetries. They are pointed out through a simplified model of a faulted rotor that needs few machine parameters. Some diagnosis examples are reported to describe the sequence of operations of the diagnostic system. >

Proceedings ArticleDOI
TL;DR: In this article, a short duration turbine test facility was used to measure the heat transfer on a fully cooled transonic turbine stage, which simulates full engine non-dimensional conditions.
Abstract: Time-resolved measurements of heat transfer on a fully cooled transonic turbine stage have been taken in a short duration turbine test facility, which simulates full engine nondimensional conditions. The time average of this data is compared to uncooled rotor data and cooled linear cascade measurements made on the same profile. The film cooling reduces the time-averaged heat transfer compared to the uncooled rotor on the blade suction surface by as much as 60 percent, but has relatively little effect on the pressure surface. The suction surface rotor heat transfer is lower than that measured in the cascade. The results are similar over the central 3/4 of the span, implying that the flow here is mainly two dimensional. The film cooling is shown to be much less effective at high blowing rations than at low ones

Patent
09 Sep 1992
TL;DR: In this paper, a test assembly for testing regulators and rectifiers is presented, which consists of two main components: a modified alternator and a test board, and the test board has a regulator test station and a rectifier test station.
Abstract: A test assembly for testing regulators and rectifiers. The assembly includes two main components: a modified alternator and a test board. The test board has a regulator test station, which is electrically connected to the rotor of the modified alternator, and it has a rectifier test station, which is electrically connected to the stator of the modified alternator. The modified alternator is run on a conventional alternator tester and its meter observed. This testing assembly allows regulators and rectifiers to be tested individually at a high amperage (full load) before they are assembled into an alternator.

Patent
14 May 1992
TL;DR: In this paper, an optical table active leveling and vibration cancellation system is described, which consists of three active isolation devices connected to the optical table and one sole pneumatic device, such that the table is supported on all four corners.
Abstract: An optical table active leveling and vibration cancellation system is disclosed. The system includes an optical table with three active isolation devices connected to the optical table, and one sole pneumatic device, such that the table is supported on all four corners. Each of the isolation devices includes a pneumatic suspension device and an electromagnetic suspension device. The pneumatic suspension device includes a pressurized load chamber, a gimballed piston received in the pressurized load chamber and coupled to the walls of the pressurized load chamber by a thin walled diaphragm, and a support rod extending from the optical table to the floor level. The electromagnetic bearing suspension device includes a magnetic bearing rotor having two planar surfaces and a peripheral surface, and two magnetic bearing stators, the stators each defining a central aperture and each stator being in a spaced apart relationship from each of the rotor planar surfaces. The rotor is secured to the support rod. Each of the stators includes an annular coil of wire. The electromagnetic suspension system may also include four radial electromagnets spaced around the peripheral surface of the rotor. The radial electromagnets also include an annular coil of wire. The system also includes three proximity sensors mounted under the optical table to detect motion of the table in relation to the floor or another fixed reference, and generate a signal in response to the motion. The system also includes three accelerometers mounted underneath the optical table in a triangle. The accelerometers measure vibration of the table in relation to inertial space and generate a signal in response to the movement. A controller receives the signals from the sensors and accelerometers, and generates a second signal, used to activate the pneumatic and electromagnetic bearing suspension devices to provide active leveling and vibration cancellation of the optical table.

Journal ArticleDOI
TL;DR: A field-oriented control method based on a predictive observer with digital current regulation of an induction motor, without speed and voltage sensors, is proposed, and the resulting speed and rotor fluxes are estimated with low sensitivity to parameter variation.
Abstract: A field-oriented control method based on a predictive observer with digital current regulation of an induction motor, without speed and voltage sensors, is proposed. Measuring only stator currents and estimating motor speed and rotor fluxes by a predictive state observer with variable pole selection the stator currents are controlled to be exactly equal to the reference currents at every sampling instant. The resulting speed and rotor fluxes are estimated with low sensitivity to parameter variation, and the torque ripples are reduced. The proposed method consists of four parts: identification of the rotor speed, derivation of a digital control law, construction of a state observer that predicts the rotor flux and the stator currents, and derivation of field-oriented control. A theoretical analysis of the method, computer simulations, and experimental results are described. >

Patent
Hong Li1
15 Jan 1992
TL;DR: A body implantable lead including a sheath, an electrode sleeve, a rotor body positioned within the sleeve, fixing helix secured to a distal end of the rotor body, and a torsion spring secured at the proximal end of a proximal-end of a rotor is described in this paper.
Abstract: A body implantable lead including a sheath, an electrode sleeve secured at a distal end of the sheath, a rotor body positioned within the sleeve, a fixing helix secured to a distal end of the rotor body, a torsion spring secured to a proximal end of the rotor body, and a rotation guide formed between the electrode sleeve and the rotor body which includes a helical groove formed on either the rotor body or the electrode sleeve and at least one guide pin formed on the electrode sleeve or the rotor body, respectively.

01 Jan 1992
TL;DR: In this paper, an unstructured-grid solver for the unsteady Euler equations has been developed for predicting the aerodynamics of helicopter rotor blades, which is a finite-volume scheme that computes flow quantities at the vertices of the mesh.
Abstract: An unstructured-grid solver for the unsteady Euler equations has been developed for predicting the aerodynamics of helicopter rotor blades. This flow solver is a finite-volume scheme that computes flow quantities at the vertices of the mesh. Special treatments are used for the flux differencing and boundary conditions in order to compute rotary-wing flowfields, and these are detailed in the paper. The unstructured-grid solver permits adaptive grid refinement in order to improve the resolution of flow features such as shocks, rotor wakes and acoustic waves. These capabilities are demonstrated in the paper. Example calculations are presented for two hovering rotors. In both cases, adaptive-grid refinement is used to resolve high gradients near the rotor surface and also to capture the vortical regions in the rotor wake. The computed results show good agreement with experimental results for surface airloads and wake geometry.

Patent
02 Mar 1992
TL;DR: In this article, a wind turbine cross wind machine is described, which comprises a circumferential arrangement of guide vanes around a centrally located rotor, including a central aperture in the middle of the rotor blades, where the vanes are capable of guiding the wind falling upon counter acting rotor blades towards the direction of rotor rotation, whatever direction the wind may be coming from.
Abstract: A wind turbine cross wind machine is disclosed, which comprises a circumferential arrangement of guide vanes (1) around a centrally located rotor (2) including a central aperture (3) in the middle of a circumferential arrangement of blades (2), where the guide vanes are capable of guiding the wind falling upon counter acting rotor blades towards the direction of rotor rotation, whatever direction the wind may be coming from, thereby offering a substantial improvement in this wind machine efficiency. Alternatively, the guide vanes (2 in FIG. 7) being of a uniform airfoil type they divert the airstream path by acting like an aerodynamic lens causing a uniform concentration of it within the encircled area, thus producing twin symmetrically convergent airpaths passing through the engine and causing a horizontal venturi effect to appear across the rotor blades with advantageous results on engine performance.

Journal ArticleDOI
TL;DR: In this paper, a dynamic model was developed that includes an electrostatic drive term, a velocity-dependent viscous drag term, and a Coulomb friction term that is dependent on the square of the drive voltage and the sign of the velocity.
Abstract: The dynamometry technique uses a strobe flash which is triggered from a phase excitation signal after a known time delay. This acts essentially as a video shutter allowing the position of the rotor as a function of the time delay to be recorded and measured. A dynamic model is developed that includes an electrostatic drive term, a velocity-dependent viscous drag term, and a Coulomb friction term that is dependent on the square of the drive voltage and the sign of the velocity. From the position-versus-time data, coefficients for this model are estimated using nonlinear least square error estimation. It is shown that both viscous drag and Coulomb friction terms are required if the model is to closely fit all the experimental data. The motor dynamics are shown to have a weak, if any, dependence on the rotor-bushing apparent area of contact. >

Patent
04 Mar 1992
TL;DR: In this paper, a composite stator construction for a downhole drilling motor which provides improved sealing and distortion properties is presented. But the elastomer which maintains the sealing/pumping action of the motor is applied in a uniform thickness to a rigid metallic form.
Abstract: A composite stator construction for a downhole drilling motor which provides improved sealing and distortion properties. The elastomer which maintains the sealing/pumping action of the motor is applied in a uniform thickness to a rigid metallic form. In the stator, the rigid former has the basic configuration of the stator and is mounted within the casing of the motor. In the rotor, the elastomer can be applied directly to a metallic rotor core. The basic geometry is provided by the metallic former thereby reduces distortion of the lobes under increased torsional forces.

Journal ArticleDOI
TL;DR: In this article, the authors derived an abstract model of resonant capture by using perturbation theory and elliptic functions, which predicts which initial conditions lead to capture in a given system.
Abstract: This work concerns the phenomenon of resonant capture, i.e. the failure of a rotating mechanical system to be spunup to a desired terminal state, due to its resonant interaction with another system or with itself. The phenomenon is important in the dynamics of dual-spin spacecraft. Starting from a simple mechanical system consisting of an unbalanced rotor attached to an elastic support and driven by a constant torque, we derive an abstract model of resonant capture. The model is investigated by using perturbation theory and elliptic functions. For a given system, the analysis predicts which initial conditions lead to capture. These predictions are shown to compare reasonably with the results of numerical integration.

Proceedings ArticleDOI
29 Jun 1992
TL;DR: In this paper, a method for minimizing the instantaneous torque ripple in switched reluctance (SR) machines is investigated and implemented based on estimating the instantaneous SR motor torque from the flux linkage versus current and rotor position characteristic curves via a bi-cubic spline interpolation.
Abstract: A method for minimizing the instantaneous torque ripple in switched reluctance (SR) machines is investigated and implemented. The method is based on estimating the instantaneous SR motor torque from the flux linkage versus current and rotor position characteristic curves via a bi-cubic spline interpolation. These coefficients are computed offline, stored in a given memory location of the control processor, and used by two routines that are capable of estimating the rotor position and electromagnetic torque from the phase voltages and currents. The estimated output torque is then compared to a constant reference value, and the result of this comparison drives a current regulator that generates the proper motor phase currents. The ripple minimization scheme is simple and does not require a very fast processor. Its feasibility is confirmed via simulation and some preliminary experimental results. >

Patent
01 Sep 1992
TL;DR: In this paper, a regenerative braking system in a motor vehicle is presented, which determines a state of deceleration on the basis of the number of revolutions of a motor and an accelerator signal.
Abstract: A regenerative braking system in a motor vehicle determines a state of deceleration on the basis of the number of revolutions of a motor and an accelerator signal and performs a regenerative braking according to the state of deceleration. The regenerative braking system includes a revolution sensor for detecting;the number of revolutions of a rotor of a vehicle driving motor and an accelerator opening sensor in a RAM stores discrimination data for discriminating between a regenerative braking mode and a drive mode on the basis of the number of revolutions of the rotor and the accelerator opening and also stores on-off duty ratio data of FETs in the regenerative braking mode and that in the drive mode. A CPU retrieves on-off duty ratio data corresponding to the number of revolutions of the rotor and the accelerator opening in the regenerative braking mode when the regenerative braking mode is determined on the basis of the rotor revolutions and the accelerator opening, and controls the FETs at an on-off duty ratio corresponding to the retrieved on-off duty ratio data. The power unit for the motor vehicle is an electric motor mounted in unit cases using at least a portion of the unit cases as a motor case. In the power unit of such construction, a heat sink is attached to the motor case. Switching elements are provided for controlling an electric current to be supplied to the electric motor. The switching elements are mounted to the heat sink.

Journal ArticleDOI
TL;DR: In this paper, a reluctance motor drive with high dynamic performances is proposed, which is sinusoidally wound and the rotor belongs to the axially laminated type, and the vector control technique used (utilizing a flux observer) is described.
Abstract: A reluctance motor drive giving high dynamic performances is proposed. The machine is sinusoidally wound, and the rotor belongs to the axially laminated type. The vector control technique used (utilizing a flux observer) is described. A prototype system has been realized, and the practical results obtained are given. >

Patent
24 Feb 1992
TL;DR: In this paper, a variable speed, reversible, brushless, direct current motor consisting of a rotor, electromagnets, a switching transistor module and an electronic controller module is described.
Abstract: The variable speed, reversible, brushless, direct current motor comprises a rotor, electromagnets a switching transistor module and electronic controller module. The rotor is mounted on a shaft with bearings at each end, with a plurality of permanent magnets symmetrically placed thereon in an alternating field pattern. Each electromagnet invokes a magnetic field at two permanent magnet positions to cause rotation of the rotor. The switching transistor module receives power from two power sources to conduct current and energize the electromagnets. The electronic control module supplies alternating voltage to points on the transistor module. The switching waveform is triggered by infra-red pick-ups mounted next to the rotor. In operation, each time an electromagnet is switched in polarity, the rotor rotates thirty-six degrees until the permanent magnets are aligned with the electromagnet. Each time the polarity is switched, the permanent magnet that is aligned is repelled, while the permanent magnet approaching is attracted. The infra-red pick-ups switch at such a time to continue the rotation.