Showing papers on "Rotor (electric) published in 1985"

Detection of Rotor Position in Stepping and Switched Motors by Monitoring of Current Waveforms

Abstract: The paper describes new methods of detecting rotor position in stepping and switched motors, with chopper or series-resistance drives, by monitoring winding currents. In contrast to previous methods of waveform detection, the new techniques are reliable over the complete speed range. It is shown that the most useful indicators of rotor position are: i) current rise times arising from chopping an unexcited phase at low current and ii) the initial rate of current rise as a phase is switched on in a series-resistance drive. Implementation is via simple low-cost electronic circuits and the paper includes discussion of how the techniques can be applied to closed-loop stepping motor control, ministep drives, and optimization of step response.

Fluid powered electrical generator

Abstract: A fluid powered electrical generator having an impellor-rotor rotatively mounted on a central support structure. A toroidal outer support structure surrounds the impellor-rotor, with the impellor-rotor including a plurality of circumferentially spaced-apart fluid dynamic blades. The outward ends of the blades are connected together by a rotor rings which is coaxial with respect to the outer support structure. The central support structure is supported within the outer support structure by stanchions or the like so as to permit a fluid stream to flow therebetween past the fluid dynamic blades. A peripheral electrical generator having a rotor element secured to the rotor ring and a stator element secured to the outer support structure produces electrical energy as the impellor-rotor is driven by the fluid stream.

Prediction of No-Load Flux Density Distribution in Permanent Magnet Machines

Abstract: Both the average output torque as well as the output torque pulsations of permanent magnet (PM) motors depend on the air gap flux density waveform produced by the magnets. An analytical model is presented, which uses the two-dimensional field theory in polar coordinates to determine the flux density waveforms at the stator and rotor surfaces of PM machines and also the amount of magnetic flux entering these surfaces. The analysis is valid for dc as well as for synchronous brushless motors with magnets which are magnetized in either the radial or the parallel direction. The results obtained by the model are verified by comparison with results obtained by finite-element analysis as well as with test results.

Closed hemapheresis system and method

Abstract: A hemapheresis system and method in accordance with the invention comprises a stationary closed housing concentric about a central axis and a feed system that moves blood upwardly from the housing lower end toward an outlet port adjacent a substantially closed upper end. Within the stationary housing is a double walled rotor concentric with the housing and rotatable by magnetic means within the housing on sealed end bearings. The space between the rotor walls defines a centrifugation gap into which whole blood is passed and within which centrifugal separation takes place as the rotor is spun at a relatively low rate. Whole blood also seeks to flow upwardly in the space between the rotor and housing, but this path is arranged to have a substantially higher flow impedance, so that the preferential path is within the centrifugation gap. At the upper end of the rotor, lighter matter such as plasma rich in platelets passes continuously inwardly to a central lengthwise passageway leading to an outlet port coaxial with the central axis, while heavier central matter flows through apertures in the outer rotor wall to the upper outlet port. In one example the differential impedance is established by housing and rotor configurations which diverge outwardly with compound curvatures, and with the space between rotor and housing leading to a closed end. In another example the housing-rotor space is of restricted cross section and an opposing flow of compatible fluid is introduced in an intermediate region of the flow path.

Brushless direct current motor system

Abstract: The invention relates to a brushless direct current motor system that includes an outer rotor receiving a load member such as a fan wheel having a plurality of blades. An axial extension of the rotor functions as a drive boss whose diameter is independent of the diameter of the motor stator core and is step-wise smaller in diameter at its outer closed end than at its inner opened end.

Magnetic field analysis of a switched reluctance motor using a two dimensional finite element model

Abstract: This paper describes the application of two-dimensional finite element analysis of a doubly salient switched reluctance motor. The motor has six poles on the stator and four poles on the rotor. The magnetic field patterns are determined for varying excitations at different positions of the rotor. The flux levels through different magnetic paths are obtained. The flux that passes through the rotor and stator core, the flux that flows through the interpolar air gap linking only the excited winding and the flux that links both the excited and the adjacent pole windings are clearly identified. From the results obtained, the variation of inductance with rotor position can be predicted more accurately.

Electrical drive systems

Abstract: A direct current brushless electric motor has a rotor, and a stator with inwardly extending teeth, between each pair of which a winding slot is defined. The radially inward face of each tooth has a dummy slot shaped so the reluctance forces between rotor and stator due to the presence of the dummy slots are the same as those due to the winding slots. Motor control arrangement incorporates a current feedback loop based on the incoming phase of each phase combination in the phase energization sequence in a driving mode and phase changeover may be initiated by Hall devices, two for each transition point, underlying the axial ends of the rotor magnets. The control arrangement may incorporate a pulse width modulation power supply permitting the establishment of bias currents under motor standstill conditions.

The spinning rotor gauge

Abstract: The determination of pressure in a high vacuum from the gaseous drag of a freely rotating sphere was already proposed in 1946 by Beams and co‐workers. On the basis of novel techniques, this method was developed from its original bulky and delicate experimental state to a practicable, compact instrument for widespread laboratory and industrial use. The present paper gives a detailed description of the gauge head functions, and of the method of evaluation of the rotor deceleration rate. The predictability of the gaseous drag is discussed in view of absolute pressure gauging. The feasibility of extending the measurement range up to atmospheric pressure is demonstrated on the basis of experimental results.

An Inviscid Blade-to-Blade Prediction of a Wake-Generated Unsteady Flow

Abstract: This paper describes a time-marching calculation of the unsteady flow generated by the interaction of upstream wakes with a moving blade row. The inviscid equations of motion are solved using a finite volume technique. Wake dissipation is modeled using an artificial viscosity. Predictions are presented for the rotor mid-span section of an axial turbine. Reasonable agreement is found between the predicted and measured unsteady blade surface static pressures and velocities. These and other results confirm that simple theories can be used to explain the phenomena of rotor stator wake interactions. © 1985 by ASME.

Turbocharger for internal combustion engines

Abstract: A turbocharger for an internal combustion engine is disclosed, including a turbine drivable by the exhaust energy of the internal combustion engine, and an air compressor coupled by a shaft to an impeller of the turbine for charging air into engine cylinders in response to rotation of the shaft. A rotor is mounted on the shaft and stator cores and coils are disposed around the rotor. The rotor and the stator cores and coils jointly constitute a motor-generator which operates as a motor or a generator dependent on operating conditions of the internal combustion engine.

Brushless electrical machine for use as motor or generator

Abstract: A brushless electrical machine has a stator assembly with spaced coils and a rotor assembly with spaced permanent magnets and with axial air gaps between the assemblies. The magnets define rotatable flux-producing modules and the coils are in positions adjacent to the paths of travel of the magnets. The machine can be operated as a low speed, high torque motor or as a low speed, high power output generator with output characteristics proportional to the number of axially interleaved stator and rotor assemblies.

An Experimental Investigation Into the Effect of Wakes on the Unsteady Turbine Rotor Flow

Abstract: Detailed measurements were carried out near and within a turbine rotor using the Laser-2-Focus velocimeter. Testing was performed in a single stage cold air turbine at off-design conditions with a stator outlet Mach number of approximately 0.8. Instantaneous and averaged results of the velocity, the yaw angle, and the turbulence intensity provided information on the rotor flow field. This report describes the periodical and random unsteady effects of the stator wakes impinging on the rotor blades. In particular the constant unsteadiness contours clearly disclose the development of the wakes cut by the rotor blades. The objective of the study was to gain more insight into unsteady flow phenomena affecting losses, heat transfer, and related problems.

Parameters and performance of a high-field permanent-magnet synchronous motor for variable-frequency operation

Abstract: The paper studies the application of conventional two-axis machine theory to the performance analysis of modern permanent-magnet synchronous motors. A representative motor with radially-oriented samarium-cobalt magnets in a rotor of interior type is considered as an example. Full performance data are measured for the full 360° range of load angles at various supply frequencies. Performance computations using constant motor parameters show significant discrepancies when compared with measurements, particularly at low supply frequency. Detailed determinations of parameter values reveal an important variation of quadrature-axis reactance as a function of quadrature-axis current, owing to magnetic saturation on this axis. When this variation is included within the analysis, together with temperature variation of stator resistance, excellent correlation is shown in all respects.

Permanent magnet rotor type synchronous motor

Abstract: PURPOSE:To enable to readily control the rotating direction at the starting time by controlling so that the magnetic force applied to a rotor becomes the prescribed direction from a magnetic relationship between the rotor and a stator during the prescribed time after a power source is turned ON CONSTITUTION:When a power source is turned ON, time measuring means 13 does not output information to normal operation control means 14 until a predetermined time T1 is elapsed after the power source is turned ON Accordingly, logic sum information output means 15 transmits information of initial operation control means 11 to power source current control means 16 The means 11 judges the steady state of a rotor 1 to a stator 3 on the basis of the information from magnetic field direction detecting means 10 to control stator poles 3a, 3b and the pole generated at an auxiliary stator 18, ie, the direction of the current flowed to an armature winding 4 and an auxiliary winding 19 When the time T1 is elapsed, the means 14 output information preferential to the information of the means 11

Hybrid excited generator with flux control of consequent-pole rotor

Abstract: An electrical machine utilizes a consequent pole rotor with a polyphase stator assembly and a control coil to produce a widely variable voltage output. Either constant-speed--variable-voltage performance, or variable-speed--constant-voltage performance may be easily achieved by varying the magnitude and level of D.C. current supplied to the control coil. Single and double rotor embodiments are disclosed, with cogging being easily suppressible in the double rotor embodiments.

Magnetic-drive centrifugal pump

Abstract: A magnetic-drive centrifugal pump comprises a driving motor, a pump shaft, an impeller, a rotor with a sleeve portion to which is connected the impeller, the rotor and impeller being rotatably mounted on the pump shaft, and a pump casing consisting of a front casing and a rear casing. The impeller is driven by a magnetic coupling formed by a driving magnet provided on a magnet holder connected to the driving motor and an impeller magnet provided in the rotor. The sleeve portion has an outer diameter smaller than an outer diameter of a main portion of the rotor. The rear casing has at a location opposite to the sleeve portion a first inner diameter enabling an outer circumference of the main portion of the rotor to slide therein, and at a location opposite to the main portion of the rotor a second inner diameter larger than the first inner diameter. One end of the pump shaft is journaled in a boss in an inlet of the front casing and the other end of the pump shaft is journaled in a rear wall of the rear casing. With this arrangement, the pump according to the invention is very easy to assemble and disassemble to facilitate its maintenance and inspection of parts.

Vehicle actuated, roadway electrical generator

Abstract: The present invention transforms the vast amount of existent vehicular travel into an equally-vast alternative energy resource employable for the generation of electricity. This transformation is achieved by means of a novel system which generally includes a momentum-conversion assembly configured to convert available vehicle momentum into operational momentum for an associated momentum-referenced electricity generator. The conversion assembly is accordingly structured to be responsive to the passage along an associated roadway of vehicles having predeterminable roadway-traversal momentum, with a portion of this momentum then being that which is cooperatively applied to the generator. The resulting double utilization of associated energy resources for both vehicle motion and electricity generation constitutes an effective increase in resource conversion efficiency. In a convenient specific embodiment, the generator is of the rotor-and-stator variety and the conversion assembly is companionably configured to convert a given vehicular-momentum portion into rotational momentum for the associated rotor. For an embodiment of this nature, the conversion may then be more-specifically achieved by the particular means of an externally-threaded spindle mechanized to axially reciprocate through a matingly-rotated yoke carried on the interior of the rotor. The reciprocations of the spindle, and hence the rotations of the rotor, are induced by overpassing vehicles encountering a spindle-end which is interceptingly disposed in the vehicle roadway. The invention yet-more-specifically provides that the subject system may be realized in a modular form entailing a plurality of readily-replaceable and conveniently-transported foldable roadway sections.

Rotatable electrical connector for coiled telephone cord

Abstract: The low friction rotatable electrical connector is for use with a coiled telephone cord to prevent the cord from becoming twisted or tangled during use. This connector is generally of insulating material formed with a hollow housing for supporting a rotor assembly therein. This rotor assembly is a hollow cylinder that is positioned within the housing for relative rotation therein. One end wall of the housing has a circular opening in which one end of the rotor assembly is supported for rotation. The rotor assembly has a single longitudinal split for nearly the entire length thereof, but the split does not include the journal at one end that is located within the circular opening or bearing in the end wall of the housing. The rotor assembly supports a plurality of continuous conductive rings on the exterior thereof, and there is an insulating washer positioned between each pair of conductive rings to serve as a spacer between adjacent rings. Each conductive ring includes a separate insulated conductor on the underside that extends through the split in the rotor. There are several modifications of this invention, but each modification includes a plurality of spring wire contact elements mounted within the housing in a parallel array, where each wire contact element has a portion biased into continuous wiping contact with one of the continuous conductive rings for making a reliable electrical connection. The housing includes partitions interposed between the wire contact elements so as to stabilize and space them apart.

Method for manufacturing a composite sleeve for an electric motor

Abstract: In an electric motor having a plurality of magnets bonded to a rotor hub, a composite sleeve is disposed over the rotor hub and magnets. The composite sleeve may be wound directly upon the rotor hub, or the composite sleeve may be wound upon a mandrel and slid over the rotor hub.

Permanent magnet variable reluctance generator

Abstract: A variable magnetic reluctance generator is disclosed generally comprising a stator having pairs of spaced magnetic poles of opposite polarity. Like polarity poles are adjacent one another to define a gap having all poles of the same polarity on the same side, and permanent magnet means provide an essentially uniform magnetic field intensity along the length of the gap. The opposite polarity poles are connected by a magnetically permeable path that is surrounded by a stator winding. The rotor has alternating segments of high and low magnetic permeability and these segments move through the gap between the opposite polarity poles, which changes the magnetic permeability between them. This causes variations in the magnetic flux in the magnetically permeable path, which induces an electrical current in the surrounding stator winding. Output voltage may be controlled by auxiliary field coils on the stator or by other means.

Crop harvesting apparatus and methods

Abstract: An apparatus for harvesting crop including a rotor (11) mounted on a movable frame (12) and carrying a succession of transverse combs (14) each formed of an array of outwardly projecting teeth (15) traverse to the direction of movement of the apparatus through the crop Each tooth (15) is pointed with side edges diverging away from the distal tip of the tooth The rotor rotates in the overshot mode and the combs intrude into the crop and gather crop stems between adjacent pairs of teeth and detach grain and grain heads, or other required crop parts, by rubbing or breaking the parts free from the stems The junction of adjacent teeth (15) preferably has an enlarged aperture (21) to assist striping and to allow withdrawal of striped stems In other embodiments, the teeth may be replaced by a brush-like structure or by rods or other crop engaging elements, backed by plain transverse ribs for collecting and conveying detached crop parts

Multiple pass optical rotary joint

Abstract: The invention relates to a multiple pass optical rotary joint which can simultaneously transmit optical signals along two or more channels in either of two directions. The joint uses a rotor and a stator to each of which is connected a plurality of optical fibers. Within the joint reflecting mirrors are used to redirect off-axis optical signals onto the joint axis, with relative rotation occurring while the signals are on-axis. A rotating member for each channel has a mirror for reflecting the on-axis signal portion off-axis to a receptor fiber. Alignment between the rotating member and the receptor fiber, as well as drive for the rotating member, is provided by a pair of magnets of opposite polarity, one being secured to the rotating member and the other being secured to the rotor. The magnetic interaction ensures synchronous rotation of the rotor and the rotating member. Specific embodiments in which transmission losses can be minimized are also disclosed.

An electric power supply system for portable miniature size power consuming devices

Abstract: An electric power supply system for portable miniature size power consuming devices, comprising an AC generator, a rechargeable battery and a charging device to be fed from the AC generator and maintaining the battery charging level, the AC generator comprising a multi-polar rotor wheel having permanently magnetized poles, a stator having one or more windings providing the AC current and an eccentric mass driving the permanently magnetized rotor wheel; the rotor wheel, the stator and the eccentric mass being mounted coaxially, a transmission being arranged between the eccentric mass and the rotor wheel. According to the invention the transmission is a loose coupling means to be tightened by magnetic fields between the poles of the rotor wheel and the respective poles of the stator.

Vibration characteristics of the HPOTP (High-Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine)

Abstract: Attention is given to rotor dynamic problems that have been encountered and eliminated in the course of Space Shuttle Main Engine (SSME) development, as well as continuing, subsynchronous problems which are being encountered in the development of a 109-percent power level engine. The basic model for the SSME's High Pressure Oxygen Turbopump (HPOTP) encompasses a structural dynamic model for the rotor and housing, and component models for the liquid and gas seals, turbine clearance excitation forces, and impeller diffuser forces. Linear model results are used to examine the synchronous response and stability characteristics of the HPOTP, with attention to bearing load and stability problems associated with the second critical speed. Differences between linear and nonlinear model results are discussed and explained in terms of simple models. Simulation results indicate that while synchronous bearing loads can be reduced, subsynchronous motion is not eliminated by seal modifications.

Rotational position detection device

Abstract: The rotational position detection device comprises a stator section (1) including primary and secondary windings (W1, W2) and a rotor section (2) disposed in such a manner that it is capable of performing relative rotational displacement with respect to the stator section. A conductive substance portion (2b) is provided in the form of a predetermined pattern. The amount of flux passing through the conductive substance portion of the rotor section (2) changes in accordance with a relative rotational position of the rotor section with respect to the stator section (1) and therefore an eddy current flows through the conductive substance portion. Reluctance is caused to change by a loss due to this eddy current and a secondary output signal corresponding to the rotational position is produced in the windings of the stator section. The pattern of the conductive substance portion (2b) can be formed easily by using electro-plating or other surface processing technique. The rotor section (2) may be of a shape such that the rate of the reluctance change is enhanced by the combination of the magnetic substance portion (2a) and the conductive substance portion.