Showing papers on "Rotor (electric) published in 1983"

High Phase Order Induction Motors - Part I-Description and Theoretical Considerations

Abstract: The characteristics of induction motors having more than three phases are presented. The sequence sets of the symmetrical component method are used to determine the inductances with time harmonics in the source waveform such as for inverter sources. The effect of stator coil pitch on these inductances is explained. It is shown that some of these harmonics cannot induce rotor currents in motors having many phases, thereby reducing the torque pulsations and rotor I2R loss below the values for three-phase motors. Other advantages are lower current per phase and the ability of the motor to start and run with one phase open. Six and nine-phase motors are found to be especially attractive.

Analysis of the Isolated Induction Generator

Abstract: The increasing rate of depletion of conventional energy resources and the ability of induction generators to convert mechanical power over a wide range of rotor speeds have given rise to an interest in the possible contribution of wind energy to provide fuel displacement.

Wind powered system for generating electricity

Abstract: A fixed pitch wind turbine rotor (18) is teeter mounted (76, 78, 80) onto a low speed input shaft (44) which is connected to the input (58) of a step-up transmission (46). The output (48) of the transmission (46) is connected to a rotary pole amplitude modulated induction machine (42) which is operable as a generator at a plurality of discreet speeds of rotation and is also operable as a startup motor for the rotor. A switch (45) responsive to the rotational speed of the wind turbine rotor switches the generator from one speed of operation to the other. The rotor hub (72) and the inner body portions (71) of two blades (68, 70), which extend radially outwardly in opposite directions from the hub (72), are constructed from steel. The outer end portions (73) of the blade (68, 70) are constructed from a lighter material, such as wood, and are both thinner and narrower than the remainder of the rotor. The outer end section (73) of each blade (68, 70) includes a main body portion and a trailing edge portion (104) which is hinge-connected to the main body portion. Each blade (68, 70) includes a centrifugal force operated positioning means (98, 100) which normally holds the drag brake section (104) in a retracted position, but operates in response to a predetermined magnitude of centrifugal force to move the drag brake (104) section into its deployed position. Each blade has an airfoil cross section and each blade (68, 70) has a plus twist inner portion adjacent the hub (72) changing to first a zero twist and then a minus twist as it extends radially outwardly from the hub (72).

Control Methods for Good Dynamic Performance Induction Motor Drives Based on Current and Voltage as Measured Quantities

Abstract: A family of schemes for the control of torque and speed of the induction machine is described. It has been developed with the intention of closing the gap between high dynamic performance drives, requiring measurement of the rotor position or the field, and the simpler schemes with poor dynamic performance. Dynamic behavior and a static accuracy have been achieved which promise a broad range of applications. This is due also to the relative simplicity of the equipment and insensitivity to changes in resistance parameters. Implementation with a voltage source inverter and a current source inverter are shown.

Rotor for permanent magnet type synchronous motors

Abstract: This invention concerns an improvement for the structure of a rotor attachment in a permanent magnet type synchronous motor. This invention can effectively prevent axial displacement or peeling off of the magnets which might otherwise be caused by insufficient adhesion or deterioration of adhesives by the unique structure of attaching magnets to the rotor shaft as side plates having grooves are fixed to both sides of magnets adhered to a shaft to engage with at least one end face of magnets and the outer peripheries of the side plates and the magnets are wound with non-magnetic fibers for securing, thereby greatly enhancing the reliability of the motor.

Angular position sensor

Abstract: An angular position sensor comprising a generator coil driven by an oscillator to provide an alternating magnetic field which is symmetrical about an axis, an annular rotor of electrically-conductive or magnetic material such that it distorts the magnetic field around it and arranged so that it is asymmetrical about its axis of rotation and lies outside the equatorial plane of the magnetic field and two sensing coils disposed within the magnetic field. As the rotor 16 rotates about its axis the emfs induced in the sensing coils vary in dependence upon the angular position of the rotor relative to the axis of the undistorted magnetic field.

Vibration control of multi-mode rotor-bearing systems

Abstract: This paper presents a computationally fast and efficient least-squares method to minimize the vibration of any general rotor-bearing system by the application of external control forces. The D-optimality concept is used to optimize the force locations. The proposed method provides a wide range of statistical information, and the sensitivity of the optimum response to changes in the control forces. Magnetic bearings can be applied to implement the open-loop adaptive vibration control strategies outlined in the paper. These components can also be used to inject a multi-frequency test signal as required for identi­fication studies.

Generating power from wind

Abstract: A wind machine turns a shaft to activate a multistage positive displacement pump having intake and discharge means respectively coupled to intake and discharge fluid lines in a recirculating hydraulic system. Control means regulates the operative positions of the intake means, dis­ charge means or separate idling means to remove selected stages from effective pumping while at the same time fluid passes into and from the selected stages. The stages can be of different capacities and selected groups or all of them may be periodically idled by a common or individual idling means. Constricting means is located in the common dis­ charge line from all stages and can be additionally located in each discharge line from each stage. Automatic control of torque on the wind rotor shaft by the idling and constricting means permits the rotor to start to rotate, continue to rotate at a speed for maximum efficiency conversion of the wind power into hydraulic power over any desired range of wind speeds, rotate as limited to any specified maximum rates rotation during high wind speeds, and to stop and lock if the wind speed becomes excessive. The hydraulic system can parallel-connect a number of wind machines to drive a sin­ gle turbine installation to produce useful power.

Easy load peristaltic pump

Abstract: There is provided a peristaltic pump which has a base member and a rotor attached to the base member. The rotor is adapted to receive a resilient collapsible tube. The pump further includes a stator having a fixed member disposed in a permanent position relative to the rotor. A door stator is connected to the fixed stator, and the entire stator will confront the periphery of the rotor over at least uninterrupted 180° concave surface. A latch is provided on the door stator, so that it may pivot outward for ease of removal of the tubing.

Surgically-implantable stepping motor

Abstract: A stepping motor isolated physically from electrical power sources and powered by the influence of a magnetic field applied from outside the apparatus, the stepping motor including a rotor and one or more stator elements, the stator elements being composed of magnetically soft and permeable material shaped and positioned with respect to the rotor so that when magnetized under the influence of the external field the stator elements strengthen and orient the magnetic field in their vicinities so as to cause movement of the rotor.

Control device for brushless motor

Abstract: A control device for brushless motor comprises an inverter (3), a control circuit (8) and a rotor position detecting circuit (9). In the rotor position detecting circuit (9), voltage induced in stator coils (U, V and W) due to rotation of a rotor (7) and neutral voltage at a virtual neutral point (25) are compared by comparators (CU, CV and CW) so that polarity changing points can be detected. The control circuit (8) controls the inverter (3) based on the above stated polarity changing points so as to control changeover of the modes for conducting to the stator coils (U, V and W). As a result, rotation of a brushless motor can be controlled without using Hall elements.

Brake rotor with vibration harmonic suppression, and method of manufacture

Abstract: A ventilated disc brake rotor in which spacing between and/or radial length of cooling fins are varied around the rotor for frequency and/or amplitude modulated damping of vibration harmonics, and for balancing the rotor.

Soft inplane bearingless helicopter rotor

Abstract: This invention relates to helicopter rotors and more particularly to rotor mounting involving a composite fiber-reinforced unitary yoke with resilient inplane restraints.

Formulation and solution of rotary-wing aeroelastic stability and response problems

Abstract: The state of the art in the formulation and solution of rotary-wing aeroelastic stability and response problems is reviewed in detail. The approximations used in the structural, inertia and aerodynamic operators are discussed. The important role of geometric nonlinearities, due to moderate deflections, and aerodynamic stall in the aeroelastic stability and response problem are identified. It is also shown that geometric nonlinearities are of primary importance in aeroelastic stability calculations, and have a more limited, though important, role in response calculations. Next, formulation of coupled rotor/fuselage problems is described, for both air and ground resonance type problems. Both topics, the isolated blade problem and the coupled rotor/fuselage problem, are treated for both hover and forward flight. Solution of aeroelastic stability and response problems proceeds in two stages. First, the spatial dependence is eliminated by using Galerkin's method, or by using the finite element method. Next the nonlinear, or linear, ordinary differential equation with periodic coefficients have to be solved for stability or response. Efficient numerical methods for accomplishing these objectives are presented in a comprehensive manner. The paper contains a number of illustrative numerical results which are intended to clarify various aspects of the modeling process and serve as representative results for both aeroelastic stability and response calculations for a variety of blade and rotor configurations.

Modeling and Analysis of Induction Machines Containing Space Harmonics Part I: Modeling and Transformation

Abstract: The coupled-circuit approach is used to derive a mathematical model of a general m-n winding machine in which all MMF harmonics are taken into account. The model, which is applicable to both squirrel cage and phase- wound rotors, has provision for cage rotors with non-integral number of rotor bars per stator pole-pair. The effects of the transformations from polyphase to a-P-0 and to d-q-0 on the machine equations are analyzed. It is shown that the polyphase to a-P-0 transformation, when applied to the stator and rotor of the m-n winding machine, divides the harmonics into different groups of harmonics with possible interaction, whereupon each group of harmonics can then be represented by an a-P or a zero component circuit. This result shows that the usual assumption of representing the cage rotor by independent harmonics circuits is, in general, not valid. It is also shown that the polyphase to rotating d-q transformation is applicable when only one harmonic from each a-P component is to be considered, otherwise a new problem of separating the harmonic voltages within each a-P component is created.

A permanent magnet field type rotor structure for an electric machine

Abstract: A rotor structure comprising a shaft and a magnetic pole assembly comprising radially disposed permanent magnets and yokes. The magnetic pole assembly is supported by the shaft through end plates. The end plate has a recess to receive the end of the magnetic pole assembly. The magnetic pole assembly can be fit into the end plates.

Progress in rotor broadband noise research

Abstract: The current status of research on various rotor broadband noise sources is reviewed Theoretical modeling techniques which appear to have the most promise in the development of successful noise prediction capabilities are emphasized The types of noise considered include: turbulence ingestion noise, blade self-noise due to turbulence passing the trailing edge, blade self-noise due to separated flow, and blade self-noise due to vortex shedding Comparisons with experimental results are given, and present theoretical and experimental limitations are delineated to help identify areas of needed research

Ventilated end turns for rotor windings of a dynamoelectric machine

Abstract: A ventilation scheme for rotor windings in a dynamoelectric machine includes passages axially extending through the axial end turn conductors of the windings. Each axially extending conductor is an integral, single bar of metal having a groove thereon which defines the passages in cooperation with the turn insulation interposed between each conductor and the underlying and overlaying conductors. Circumferential end turn conductors are mechanically and electrically attached to the axial end turn conductors by reinforcing plates. Circumferential passages through the circumferential end turn conductors allow gas to flow between an end turn region and an isolated low pressure area. The centrifugal pumping action developed by the rotation of the rotor draws gas from the end turn region through the passages and to the periphery of the rotor body.

Optimization of Darrieus turbines with an upwind and downwind momentum model.

Abstract: This paper presents a theoretical inviscid aerodynamic optimization method for straight-bladed Darrieus wind turbines. First, a generalized Betz limit has been derived for an arbitrary number of actuator disks in series. Then a momentum-type velocity model is introduced with separate cosine-type interference coefficients for the upwind and downwind half of the rotor. The cosine-type velocity interference permits the rotor blades to become unloaded near the junction of the upwind and downwind rotor halves. A closed-form solution for the optimum and off-design value of the interference coefficients has been obtained by equating the jc component of force on each of the rotor halves to that on each of two semicylindrical actuators in series. The values for the optimum rotor efficiency, solidity, and corresponding interference coefficients have been obtained in a closed-form analytical solution by maximizing the power extracted from the downwind rotor half as well as from the entire rotor. The Betz limit for two uniformly loaded actuator disks in series is shown to equal CP = 0.64 and for two cosine loaded semicylindrical actuators in series Cp = 0.617 and for a straight-bladed Darrieus rotor CP = 0.610.

Motor control apparatus with rotor heating protection

Abstract: A microprocessor controlled motor starter is utilized in which the short term temperature differential between the rotor bars and the rotor end bells is accounted for by the microprocessor-based system as a function of operator programmed stall time and locked rotor current for the particular rotor in question The latter information is supplied to the operator by the manufacturer of the motor The foregoing takes into account a slight deviation between the shutdown temperature, which should be predicted as a function of the manufacturer's data, and the actual shutdown temperature as expressed by an exponential In the event that the short term temperature differential is exceeded, the microprocessor will enter a TRIP routine causing the motor controller to shut the motor down, thus preventing serious damage to the motor

Turbo-molecular pump

Abstract: A turbo-molecular pump characterized in that three out of five degrees of freedom except the rotation around the rotational axis of a shaft are actively controlled constrainingly by a pair of magnetic radius direction bearings and a pair of magnetic axial bearings, a bell-shaped rotor provided to cover the whole of magnetic bearing and a shaft which is supported by a magnetic bearing passively constraining the remaining two degrees of freedom, and said rotor is rotated at high speed by an inner-rotor type of a driving motor provided between a radius direction bearing and axial bearing.

An Investigation of Ingress for an “Air-Cooled” Shrouded Rotating Disk System With Radial-Clearance Seals

Abstract: In order to model the flow between an air-cooled gas turbine rotor and its stationary casing, a simple isothermal plane rotating disk and stator are used. In tests reported earlier, the cavity between the rotor and stator was sealed by a stationary cylindrical shroud, and the dimensionless minimum amount of “coolant,” Cw, min , necessary to prevent a radial inflow (or ingress) of “hot gas” through the axial clearance between the shroud and the rotor, was determined. In the current tests, a number of seals with a radial clearance between the cylindrical shroud and the rotor are tested. Unlike their axial-clearance counterparts, radial-clearance seals can exhibit a pressure-inversion effect, where the pressure inside the cavity increases, rather than decreases, with increasing rotational speed. Using pressure measurements and flow visualization, correlations showing the variation of Cw, min with clearance ratio and rotational Reynolds number are presented, and it is shown that — under equivalent conditions — a seal with a radial clearance can be much more effective than one with an axial clearance.

Wind turbine rotor

Abstract: A fixed pitch wind turbine rotor (18) is teeter mounted (76, 78, 80) onto a low speed input shaft (44) which is connected to the input (58) of a step-up transmission (46). The output (48) of the transmission (46) is connected to a rotary pole amplitude modulated induction machine (42) which is operable as a generator at a plurality of discreet speeds of rotation and is also operable as a startup motor for the rotor. A switch (45) responsive to the rotational speed of the wind turbine rotor switches the generator from one speed of operation to the other. The rotor hub (72) and the inner body portions (71) of two blades (68, 70), which extend radially outwardly in opposite directions from the hub (72), are constructed from steel. The outer end portions (73) of the blade (68, 70) are constructed from a lighter material, such as wood, and are both thinner and narrower than the remainder of the rotor. The outer end section (73) of each blade (68, 70) includes a main body portion and a trailing edge portion (104) which is hinge-connected to the main body portion. Each blade (68, 70) includes a centrifugal force operated positioning means (98, 100) which normally holds the drag brake section (104) in a retracted position, but operates in response to a predetermined magnitude of centrifugal force to move the drag brake (104) section into its deployed position. Each blade has an airfoil cross section and each blade (68, 70) has a plus twist inner portion adjacent the hub (72) changing to first a zero twist and then a minus twist as it extends radially outwardly from the hub (72).

Method and system for starting a motor-commutated SCR inverter

Abstract: Highly reliable and consistent starting is achieved by first initializing the rotor position, namely establishing the rotor in a known starting position. This is accomplished by gating on two pairs of SCRs in sequence and supplying current pulses through the gated SCRs to the stator of the motor to rotate the rotor to a first position and then to a second position, the rotor coming to a complete stop in each of those positions. The rotor aligns itself with the magnetic field created by the stator in each position and any ambiguity in the rotor position is eliminated. Thereafter, the inverter is operated asynchronously in a second mode with predetermined pairs of the inverter SCRs being sequentially gated into conduction at an increasing frequency to current pulse energize the motor to effect step-by-step rotation of the rotor at a faster and faster rate, the motor current being reduced to zero at the termination of each energizing pulse to force commutate the conducting pair of SCRs. After the motor has reached a preset speed, operation in a third mode occurs and the inverter is synchronized with the motor, gating of the SCRs being controlled by the motor voltage in order that the rotor position will be synchronized to the revolving magnetic field created by the stator. During this third operating mode the motor speed continues to increase and the SCRs are forced commutated, as a result of which the rotor follows the stator magnetic field very closely and synchronization will be perfected. When the motor subsequently reaches a given speed sufficiently high to permit motor commutation exclusively, the starting system switches to a fourth and normal running mode wherein the gating of the inverter SCRs continues to be synchronized with the motor and controlled by the motor voltage, but the SCRs will now be commutated only by the motor voltage. Operation in the third mode provides a buffer and ensures a very smooth, reliable, consistent and a relatively short transition from asynchronous, forced-commutation operation to synchronous, motor-commutated operation.

Froth flotation apparatus and method

Abstract: In froth flotation apparatus for separating solid particle impurities from a liquid suspension stock in a flotation cell, provision is made for aerating the stock flowing through the inlet conduit leading to the cell by positioning a drum-shaped rotor having an irregular outer surface in the conduit on an axis extending transversely of the conduit, directing a supply of air against the rotor surface on the upstream side of its rotational axis, and causing the rotor to rotate at a linear speed of its outer surface which is substantially higher than the linear flow rate of the stock in the conduit so that the rotor surface breaks up the air impinging thereon into bubbles and distributes those bubbles in the stock flowing therepast to create foam within the cell.

In-flight monitoring of composite structural components such as helicopter rotor blades

Abstract: The apparatus comprises one or more acoustical transducers associated with a particular interchangeable rotor blade for monitoring acoustic emissions emitted by the rotor blade under operating stress. The output of the transducers is connected to a computer associated with the particular aircraft. The transducer output signals are processed by the computer and filtered to allow real time stress return level readings so as to accumulate a count of critical acoustic emissions which are indicative of progressive irreversible structural fatigue or damage to the interchangeable rotor blade.