1196 results about "Field coil" patented technology

An apparatus and method for controlling a hybrid motor, The hybrid motor, uses a permanent magnet instead of a field coil for a rotor, winds a coil round a stator in a multi-phase independent parallel manner, fixes a rectifying type encoder to the rotor and connects a sensor to a driving circuit. The apparatus comprises: an encoder attached to a rotor in cooperation with a pole sensor a speed input unit for generating a speed instruction signal a power switching circuit to generate motor driving signals; a drive module receiving the speed instruction signal and the sensor signal and outputting the speed instruction signal synchronized with the sensor signal as a driving motor signal; a power supply for applying a DC voltage to the power switching circuit; A logic power supply for converting the DC voltage into a logic voltage, and applying logic voltage to the drive module. The motor has n phases, n power switching circuits and n drive modules.

A low inductance electrical machine that may be used as an alternator or motor with low armature inductance is disclosed. Arrangements of complementary armature windings are presented in which the fluxes induced by currents in the armature windings effectively cancel leading to low magnetic energy storage within the machine. This leads to low net flux levels, low core losses, low inductance and reduced tendency toward magnetic saturation. The inclusion of additional gaps in the magnetic circuit allows for independent adjustment of air gap geometry and armature inductance. Separately excited field arrangements are disclosed that allow rotor motion to effect brush-less alternator or brush-less motor operation. An exemplary geometry includes a stator including two annular rings and a concentric field coil together with a rotor structure separated from the stator by four air gaps.

The invention relates to an oil and gas field coiled tubing paraffin removal and contaminant release process and a tool thereof. Paraffin removal is performed by using coiled tubing, and removed paraffin can be recycled to the ground, and therefore a wellbore cannot be blocked due to human factors. A flushing port is designed at the upper end of a flushing tool, and then paraffin remaining on mechanical scraping portions can be cleared. The coiled tubing is connected with the paraffin removal and contaminant release tool for paraffin removal and contaminant release. The flushing tool at the front end of a pipe string can first perform 360 degree hydraulic cleaning on the wellbore, and then along with descending of the pipe string, a paraffin remover in the pipe string performs mechanical cleaning on the wellbore, and therefore dual cleaning mode combining the hydraulic cleaning with mechanical scraping is achieved, removal effects are greatly improved, cost is saved, and work efficiency is improved.

An apparatus for generating electricity from aeolian oscilaltions caused by the flow of a fluid such as wind or water. An immobile beam extends between two piers, and a movable vane is disposed around the beam in parallel relation thereto. The vane is generally tubular, having a generally cylindrical or foil-shaped cross section. The movement of a fluid, such as wind or deep ocean tidal flow, past the vane induces aeolian oscillation in the vane, so that the vane moves to-and-fro, with respect to the beam, in a direction generally perpendicular to the direction of fluid flow. Rods and a crankshaft may connect the vane to a generator mounted upon the beam, so that the movement of the vane is converted into electricity. Alternatively, electricity can be generated from the movement of the vane by a field coil on the vane inducing electrical current in induction wires mounted upon the immobile beam.

A continuously variable ratio transmission including a planetary gear set having a sun gear, a ring gear, and a planet carrier having at least two planet gears carried thereon, a control element including a servogenerator capable of generating electric power, and at least one auxillary field coil adapted to be operatively connected to an output means to influence a power output level and AC power frequency of the output means, the at least one auxillary field coil being powered by the servogenerator and constituting a load to the servogenerator, the speed of the servogenerator being capable of being controlled by the load; and a means for controlling an electrical current to the at least one auxiliary field coil form the servogenerator; where the servogenerator is capable of being driven to produce electrical power by a rotation of one of the sun gear, the ring gear, and the planet carrier.

The invention relates to a method for refining a solidified structure of a laser cladding layer by using an alternating magnetic field and a device thereof, belongs to the technical field of laser processing. A compound coating is prepared on the surface of a substrate in a manner of conventional powder-feed laser cladding; the alternating magnetic field is applied to acting on a laser molten pool during the laser cladding; the powder-feed laser cladding process is carried out under the alternating magnetic field; and the direction of magnetic lines of force generated by the alternating magnetic field is perpendicular to the scanning speed direction of the laser cladding. The device for refining the solidified structure of the laser cladding layer by using the alternating magnetic field comprises a cooler, a CO2 laser, an argon protector, a synchronous powder feeder, a clamping device, an alternating magnetic field, a cladding substrate body and a numerical control operation floor. The method and the device provided by the invention are capable of obviously refining the solidified structure of the cladding layer; when alternating current with certain frequency is introduced into a coil, an alternating magnetic field can be generated between a metal melt and the magnetic field coil; and the intensity of the alternating magnetic field is controlled so as to change a form of the solidified structure of the cladding layer and refine crystalline grains through changing the intensity of an alternating magnetic field. The device provided by the invention is simple, low in investment cost, high in benefit, etc.

A drive control system, with PLL control, drives a rotatable multi-phase sensor-less motor by switching a current of a field coil of each phase depending on the rotating phase of the motor. When the moto is driven, a desired phase is selected as a datection phase, and a voltage induced on the coil of the detection phase is detected when power is fed for a predetermined time to the field coils other than the detection phase. A magnetic pole position is detected from the amplitude condition of the detected induced voltage. Based on this detection, the power-feeding phase of the motor drive is determined. Power feeding and pole position detection are performed alternately.

A machine includes a shaft adapted to rotate about a longitudinal axis and formed of a magnetic material and a rotor assembly rotationally engaged with the shaft The rotor assembly includes a pair of rotor disks comprising a magnetic material, each of the rotor disks having a number of magnetic poles, the magnetic poles being spaced apart circumferentially. The rotor disks are coupled to the shaft for rotation about the shaft and generation of a rotating permeance wave. The machine further includes a stator assembly that includes a magnetic core stator disposed between the rotor disks, a number of armature windings supported on the magnetic core stator, and a stationary superconducting field coil disposed between the magnetic core stator and the shaft. The stationary superconducting field coil is configured as a stationary magneto-motive force (MMF) source for the rotating permeance wave produced by the rotor assembly to produce a rotating magnetic field.

To reduce vibration and noise generated in supplying pulsatile current to the gradient magnetic field coil for driving that coil in a MRI apparatus, an active shielded gradient magnetic field coil is used, in which the gradient magnetic field coil is supported by and fixed to the static magnetic field generating magnet. The supporter for supporting this gradient magnetic field coil in non-contact does not prevent the interventional procedure performed by a doctor. Further, an eddy current generated on the surface of the static magnetic field generating magnet near the periphery of the gradient magnetic field coil, when supplying the pulsatile current to the gradient magnetic field coil, can be reduced.

In an aspect of this invention, a fixing device includes a heating member including a first area and a second area formed of conductive members (e.g., aluminum and iron) having different magnetic permeability ratios, and an induction heating unit which generates a magnetic field from a coil to induction-heat this heating member, and the fixing device changes a frequency of a high-frequency current to be supplied to the coil to thereby control a heating area of the heating member.

An MRI apparatus having an open structure includes a static magnetic field generating magnet including magnetic field generating sources arranged above and below an imaging space and magnetic field fluctuation reducing plates arranged inside the magnet. Gradient magnetic field coils are fixed to the static magnetic field generating magnet so as to not be in contact with the magnetic field fluctuation reducing plates. When the strength of the magnetic field generated by the static magnetic field generating magnet fluctuates due to vibration of the gradient magnetic field coils or other devices during an imaging operation of the MRI apparatus, an eddy current is generated on the magnetic field fluctuation reducing plates in response to the magnetic field fluctuation components. Magnetic flux which cancels the static magnetic field fluctuation components is generated due to this eddy current, and consequently, a time-sequentially stable static magnetic field can be obtained.

A hand-held power tool (1) includes a linear motor (2) having a rotor (3) which is movable along a percussion axis (A) in an axially limited manner between two reversal points (W) and which can be driven by the striking piston (5) of the power tool with the intermediary of an air spring (4), sensors designed for determining the actual state of the rotor (3) and connected to a computer (9) connected via power electronics (33) to at least one field coil (10) of the linear motor (2), with the rotor (3) being displaced against a contact element (11a, 11b) at least at one reversal point (W) and being pressed against the contact element electromagnetically; and a control process for the hand-held power tool.

A superconducting magnet configuration (4; 14) for generating a homogeneous magnetic field B0 in an examination volume (4b), has an interior radial superconducting main field coil (1) which is disposed rotationally symmetrically about an axis (z-axis) and an oppositely driven coaxial radially exterior superconducting shielding coil (2) is characterized in that the magnet configuration (4; 14) consists of the main field coil (1), the shielding coil (2), and a ferromagnetic field formation device (3; 18), wherein the ferromagnetic field formation device (3; 18) is located at the radially inside of the main field coil (1), the main field coil (1) consisting of an unstructured solenoid coil or of several radially nested unstructured solenoid coils (15, 16) which are driven in the same direction, the axial extent Labs of the shielding coil (2) being smaller than the axial extent Lhaupt of the main field coil (1), wherein the axial magnetic field profile (5) generated by the main field coil (1) and the shielding coil (2) during operation has a minimum of the field strength along the axis (z-axis) in the center (4a) and a maximum of the field strength on each side of the center (4a), and wherein the axial magnetic field profile (6) generated by the ferromagnetic field formation device (3; 18) during operation has a maximum of the field strength along the axis (z-axis) in the center (4a) and a minimum of the field strength on each side of the center (4a). The magnet configuration in accordance with the invention has a very simple structure.

An alternator has a field coil that produces a magnetic field which induces electricity in an coil arrangement. A field coil excitation system includes a generator with an output coil assembly for producing alternating electricity. A rectifier converts the alternating electricity into voltage and direct current at two nodes. A capacitor, between the nodes, has capacitance that forms a resonant circuit with inductance of the output coil assembly. Due to that resonant circuit, the voltage and direct current oscillate in a predefined phase relationship. A switch and the field coil are connected in series between the nodes. A controller renders the switch conductive for a time period specified by a received control signal. The switch is rendered non-conductive at the first occurrence of a minimum current level after the time period ends. The predefined phase relationship enables the minimum current level to be detected by sensing the voltage.

A drive motor assembly for a power driven wheelchair comprises: a stator housing for containing field coils of a stator of the motor assembly; at least one sensor disposed in the stator housing for sensing rotation of the motor; a memory storing motor error parameter data including data of errors of the at least one sensor, the memory being embedded in the stator housing; and a connection for accessing the error parameter data of the memory from the stator housing. The motor error parameter data may be accessed from the embedded memory of the drive motor by a programmed motor controller for use in controlling the drive motor. Also, the motor error parameter data may be embedded in the drive motor by the steps of: controlling the motor through at least one predetermined drive pattern; sensing motor rotation during the drive pattern and generating signals representative thereof; deriving error parameter data of the drive motor from the generated signals; programming a memory with the derived error parameter data; and embedding the memory in the drive motor.