1463results about "Magnetic bodies" patented technology

A motor drive circuit comprises positive and negative input terminals for connection of the motor circuit to a DC supply, a DC link filter connected between the input terminals: an electric motor having at least two phases, a plurality of motor drive sub-circuits, each connected to a respective phase of the electric motor and which each control the flow of current into or out of the respective phase of the motor that has been drawn from the supply through the DC link filter, and a switching means provided in the electrical path between the DC link filter and the electric motor drive sub-circuits, the switching means being movable between a closed position in which it connects the DC link filter to the motor drive sub-circuits, and an open position which isolates the DC link filter from the motor drive sub-circuits.

Methods, system and apparatus are provided for sensorless control of a vector controlled motor drive system that includes an electric motor used to drive an auxiliary oil pump.

The invention provides an electrostatic chuck capable of widening a temperature range when the temperature of a flat substrate is controlled and reducing a variation in thermal conductivity between the electrostatic chuck and the flat substrate over time. According to an aspect of the invention, an electrostatic chuck includes: a body that has an internal electrode for attracting a flat substrate by an electrostatic force provided therein; a plurality of protrusions that are formed on one surface of the body, serving as an electrostatic attraction surface; and one or more minute projections that are provided on each of top surfaces of some or all of the plurality of protrusions. In the electrostatic chuck, a region of the top surface of each of the minute projections on which the flat substrate is loaded is referred to as a mounting surface, and the total area of the mounting surfaces of the minute projections is equal to or larger than 0.01% and equal to or smaller than 2% of the area of the electrostatic attraction surface.

A discharge control device in an electric power conversion system mounted to a motor vehicle turns off a relay in order to instruct an electric power conversion circuit to supply a reactive current into a motor generator, and thereby to decrease a capacitor voltage to a diagnostic voltage. After this process, the discharge control device outputs an emergency discharging instruction signal dis in order to turn on both power switching elements at high voltage side and a low voltage side in the electric power conversion circuit. This makes a short circuit between the electrodes of the capacitor in order to discharge the capacitor, and executes a discharging control to detect whether or not an emergency discharging control is correctly executed and completed. The discharge control device detects whether or not the electric power stored in the capacitor is discharged on the basis of the voltage of a voltage sensor.

A homopolar machine produces an axial counter force on the rotating shaft to compensate for the load on the shaft's thrust bearing to reduce wear and noise and prolong bearing life. The counter force is produced through magnetic interaction between the shaft and the machine's field coils and is created by changing the current excitation of the field coils, which results in a magnetic flux asymmetry in an inner flux return coupled to the shaft. The homopolar machine may also have a configuration that uses current collectors that maintain substantially constant contact pressure in the presence of high magnetic fields to improve current collector performance. The current collectors are flexible and may be made from either electrically conductive fibers or stacked strips such that they bear up against the armature so that the pressure is maintained by the spring constant of the current collector material. The homopolar machine may also have a configuration where the brushes are oriented so that the current is aligned as much as is practical with the local magnetic field lines so as to reduce the lateral electromagnetic forces on the brushes.

To suppress the magnetizing inrush current occurring when supplying power of three phases of the transformer are performed simultaneously using three single-phase circuit breakers or a non-phase segregated operation-type circuit breaker, without providing a circuit breaker with a resistor or other equipment. A magnetizing inrush current suppression method for transformer suppresses a magnetizing inrush current occurring at the start of energizing of a three-phase transformer 300, when a three-phase power supply 100 is input to a terminal of each phase by means of a three-phase circuit breaker 200. In the method, by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side when three-phase AC voltages are applied in a steady state to the transformer 300, steady-state magnetic flux 4, 5, 6 for each phase of the transformer is calculated, and the polarity and magnitude of the residual magnetic flux 7, 8, 9 of each phase of the transformer after the circuit breaker 200 shuts off the transformer are calculated, and the three-phase circuit breaker is caused to close simultaneously in a region 13 in which three phases overlap, each of the three phases having the polarity of the steady-state magnetic flux 4, 5, 6 equal to the polarity of the residual magnetic flux 7, 8, 9 for each phase of the transformer.

A control apparatus for master/slave outlets having a current sensor, a driver, a large current switch component and a direct-bucking type power supply such that the working power source required by the master/slave equipment can be supplied stably. Further, the control apparatus for master/slave outlets provides a most simplified circuit to perform a function that the slave outlet supplies a power at the time the master outlet is supplied the power.

The invention relates to an ultra-low frequency alternating-current (AC) constant-current demagnetization device of a large transformer or mutual inductor, comprising a display (1) and a CPU control unit (2), wherein the CPU control unit (2) is connected with a power-frequency signal generator (3); the power-frequency signal generator (3) is connected with a voltage power amplifier (4); the voltage power amplifier (4) is connected with a voltage booster (5); the CPU control unit (2) is also connected with an ultra-low frequency signal generator (6); a switch is arranged between a transformer or a mutual inductor (8) to be tested and the voltage booster (5); and a switch is arranged between the transformer or the mutual inductor (8) to be tested and a current power amplifier (7). The invention overcomes the defects of long demagnetization time, easy transformer coil deformation, and the like of the traditional method and has the advantages of short demagnetization time, light equipment weight, and the like. The invention also discloses a demagnetization detection method adopting the demagnetization device.

Disclosed is an apparatus for destroying electronic memory media by use of a bi-directional degaussing device. The degaussing device utilizes an SCR gate controller to cause bi-directional polarity from a charged capacitor into a sealed chamber containing the magnetic media. The chamber has a movable steel plate cover and floor that encloses the chamber containing magnetic media during the degaussing stage. The cover and floor cause a reflective chamber that focuses and directs the flux level to the magnetic media. The gate controller allows the use of the same capacitor bank to power a coil in two different directions to obtain effective degaussing without multiple coils or directional capacitors.

A magnetizer for a rotor of an electrical machine is provided. The magnetizer includes a magnetizing yoke and coils wound around the magnetizing yoke. The magnetizing yoke includes multiple pole-pieces extending therefrom, and at least some of the pole-pieces include a cobalt alloy.

An inner magnetic transducer with multiple magnetic gaps and multiple coils, and a preparation method thereof. The inner magnetic transducer with multiple magnetic gaps and multiple coils includes a non-magnetic material frame and a non-magnetic material bearer frame. The inner magnetic transducer with multiple magnetic gaps and multiple coils includes two or more coaxial annular magnetic gaps with the same diameter value, two suits of symmetric magnetic paths, and a symmetric coil. In the transducer, enwinding direction, connection mode and parameters of coils are decided, in order to ensure that the value of the inductance of coils and the opposing electromotive force obtained during the process of moving to and fro are counteracted by each other. The inner magnetic transducer with multiple magnetic gaps and multiple coils has resistance load character or approximately has a resistance load character, simultaneously, has high sensitivity, high analytic capability, and high fidelity.

A motor control method that includes the steps of: rotationally driving a motor that is provided with a rotor having permanent magnet pieces, and a stator; and short circuiting a plurality of phases of the motor when the rotational frequency of the motor is equal to or greater than a predetermined rotational frequency.

The invention discloses a transformer remanence detection and demagnetization method which comprises the following steps: collecting residual flux content of a test transformer, and inputting the residual flux content into an intelligent analysis system; reading the residual flux content of the test transformer through a human-computer interaction interface, and inputting corresponding control instructions; controlling the output of a frequency conversion voltage-regulating unit through the control instructions; and outputting by the frequency conversion voltage-regulating unit a low-frequency AC voltage required for demagnetization, and carrying out demagnetization on the test transformer. The invention also discloses a transformer remanence detection and demagnetization device which comprises an AC power supply module, a power supply conversion module, a DC power supply module, a control acquisition module, the frequency conversion voltage-regulating unit, a man-machine interaction unit, a data acquisition module, the intelligent analysis system and the test transformer. The low-frequency AC voltage is utilized for demagnetization, thereby reducing power capacity and size of the demagnetization device; and through the man-machine interaction unit, operation personnel can obtain the demagnetization processing progress accurately and visually, and input the corresponding control instructions, thereby realizing thorough demagnetization of the test transformer.

A magnetizing coil unit and a method of making a magnetizing coil unit is provided. The coil includes a solenoid coil having a coiled copper sheet in which the width of the copper sheet is equal to the height of the solenoid coil. A magnetizing assembly includes a plurality of magnetizing coil units.

The invention provides automatic magnetizing apparatus and method of two poles of a magnetic sheet. The magnetizing apparatus comprises a main stand, a charging part, a feeding part, a loading magnetic head fixing part, an upper magnetic head fixing part and a taking-out part, wherein the main stand is used for supporting each part of the apparatus; the charging part is installed on the main stand and is used for storing the magnetic sheet to be magnetized; the feeding part is installed on the main stand and is used for conveying the magnetic sheet to be magnetized to a magnetizing region from the charging part; the loading magnetic head fixing part is installed on the main stand and is provided with a lower magnetic head, and the magnetizing region for magnetizing the magnetic sheet to be magnetized is arranged at the middle part of the lower magnetic head; the upper magnetic head fixing part is provided with an upper magnetic head and is used for pressing the magnetic sheet conveyed by the feeding part between the upper magnetic head and the lower magnetic head, and the magnetic sheet to be magnetized can be magnetized in the state; and the taking-out part is used for taking out the magnetized magnetic sheet through a taking-out apparatus and putting the magnetized magnetic sheet into a storing apparatus of the loading magnetic head fixing part. The invention realizes the automatic magnetization of the two poles of the magnetic sheet, improves the production efficiency, and saves the manual labor and the cost.

A method for assembling rotors which is applicable to a large axial gap type permanent magnet rotating machine is provided.

A permanent magnet rotating machine comprising: a rotating shaft; at least two rotors comprising a table-like structure and permanent magnets attached thereto, the table-like structures being connected to the rotating shaft and being disposed in an axial direction of the rotating shaft; and a stator comprising a table-like structure and stator coils around which a copper wire is wound, said stator being disposed in a gap formed by the rotors so that the stator being separated from the rotating shaft, is manufactured by the following steps of: assembling the two rotors such that a predetermined gap is formed therebetween; and mounting the magnets on the table-like structures by inserting the magnet from the radially outer side of the table-like structures towards the center of the rotation with the assembled state being maintained.

The invention provides an iron core remanent magnetism elimination and measurement method based on a polarity-reversal DC voltage source. The iron core remanent magnetism elimination and measurement method is characterized in that the iron core remanent magnetism elimination and measurement method comprises the step 1, applying a negative voltage (-VDC) to enable an iron core to achieve a negative saturation point, and then calculating a winding direct current resistance RDC according to the voltage and current data of the saturation point; and the step 2, changing the power source polarity at two ends of the winding when the current value applied to the winding achieves the negative saturation current (-Is), thus applying a positive direct current voltage (VDC) to the winding to enable the iron core to achieve the positive saturation point, and at the same time recording the time T and the like from the negative saturation point to the positive saturation point. The iron core remanent magnetism elimination and measurement method has the advantages that a single test can measure the remanent magnetism (remanent magnetism coefficient) and eliminate the remanent magnetism; the measuring time is short; the measuring efficiency is high; the demagnetization effect is excellent; the test is simple in operation; and the polarity-reversal direct current source for an electronic power switch is used to realize demagnetization, so that the waveform is well and the power is low and the test cost is low.

In methods and arrangements for concentrating stray magnetic fields, a pair of permanent magnets is employed in combination with a magnetic flux circuit, the permanent magnets in the pair having respective magnetizations that are oriented oppositely to each other. The permanent magnets produce a stray magnetic field that adds to a magnetic field produced by the magnetic flux circuit.

This invention is a back EMF permanent electromagnetic motor generator and method using a regauging process for capturing available electromagnetic energy in the system. The device is comprised of a rotor with magnets of the same polarity; a timing wheel in apposition to a magnetic Hall Effect pickup switch semiconductor; and a stator comprised of two bars connected by a permanent magnet with magnetized pole pieces at one end of each bar. There are input and output coils created by wrapping each bar with a conducting material such as copper wire. Energy from the output coils is transferred to a recovery rectifier or diode. The magnets of the rotor, which is located on a shaft along with the timing wheel, are in apposition to the magnetized pole pieces of the two bars. The invention works through a process of regauging, that is, the flux fields created by the coils is collapsed because of a reversal of the magnetic field in the magnetized pole pieces thus allowing the capture of available back EMF energy. Additional available energy may be captured and used to re-energize the battery, and/or sent in another direction to be used as work. As an alternative, the available back EMF energy may be dissipated into the system.

The invention discloses a large-scale power transformer residual magnetism detection method. Comparison between curves of forward and reverse charging currents of a transformer is utilized to detect residual magnetism, whether there is residual magnetism is judged, and when a charging current is about 100 mA, the transformer without the residual magnetism is little affected; and after a forward and reverse charging test, current wave forms influenced by the residual magnetism is relatively visually represented, and whether there is residual magnetism is relatively visually represented. The transformer residual magnetism detection method has the technical effects that the universality is relatively good, the detection accuracy and effect are relatively good, and demagnetization is available.