94results about How to "Prevent magnetic saturation" patented technology

An axial gap rotating electrical machine is provided with permanent magnets and cores in a rotor. The permanent magnets are oriented such that magnetization surfaces face in the circumferential direction of the rotor. The cores are arranged alternately with the permanent magnets in the circumferential direction of the rotor. The amount of magnetic flux on the outside in the radial direction of the rotor is made greater than the amount of magnetic flux on the inside in the radial direction of the rotor. As a result, the magnetic flux density at the rotor cores can be made substantially constant in the radial direction of the rotor and torque output with respect to the size of the permanent magnets is improved by preventing magnetic saturation of the cores.

A magnetic field shielding sheet includes: at least one layer thin magnetic sheet made of a Fe-based amorphous alloy and flake-treated so as to be separated into a plurality of fine pieces; a protective film that is adhered on one surface of the thin magnetic sheet via a first adhesive layer provided on one side of the protective film; and a double-sided tape that is adhered on the other surface of the thin magnetic sheet via a second adhesive layer provided on one side of the double-sided adhesive tape, wherein the thin magnetic sheet is obtained by heat treating an amorphous ribbon sheet made of the Fe-based amorphous alloy at a temperature of 300° C. to 480° C. A method of manufacturing the magnetic field shielding sheet, and a portable terminal device using the magnetic field shielding sheet are disclosed.

A current sensor for measuring an electric current flowing through a current bus bar includes: a magnetic core with an opening, through which the current bus bar passes with a predetermined interval; and a first magnetic sensor for detecting magnetic flux density in the magnetic core, the magnetic flux density generated by the electric current passing through the current bus bar. The magnetic core has a first gap and a second gap. The first magnetic sensor is disposed in the first gap. The second gap is capable of preventing magnetic saturation of the magnetic core.

A reactor that can be disposed between stacked coolers, the reactor includes a flat case, a pair of coils, and core material. The pair of coils is (i) located in the flat case, (ii) wound in opposite directions from each other, and (iii) disposed adjacent to each other in a radial direction of the coils. The core material is covering the coils in the flat case.

A thin film magnetic head has a configuration in which a main magnetic pole film having a magnetic pole end portion on a medium opposing surface (ABS) side facing a magnetic disk, a write shield film facing the magnetic pole end portion so as to form a recording gap film on the medium opposing surface side, and a thin film coil wound around at least a part of the write shield film are laminated. Further, the thin film magnetic head has an upper yoke magnetic pole film whose size is larger than that of the main magnetic pole film at a part more distant from the ABS than the recording gap film, and this upper yoke magnetic pole film is bonded to the side of the main magnetic pole film close to the thin film coil. In the upper yoke magnetic pole film, an end portion on the ABS side is retracted in a direction apart from the ABS in accordance with an increase in film thickness which is measured from the surface of the main magnetic pole film.

In a capacitor charger, a transformer has a primary winding connected between an input voltage and a switch for generating a primary current flowing through the primary winding by switching the switch to thereby induce a secondary current flowing through a secondary winding of the transformer and a secondary voltage tapered from the secondary winding, a control apparatus and method adjusts the on-time period for the switch in response to the input voltage. The charging time and charging current are independent of the input voltage, and there is no power loss resulted from current sense to the primary current.

The invention relates to a rotor for an electric rotating machine. An iron rotor core includes a first permanent magnet in an outer peripheral portion of the iron rotor core, second permanent magnets on both circumferential sides of the first permanent magnet and arranged in a generally V-shaped configuration opening radially outward, and a first region provided opposite to the first permanent magnet radially inside the region between the second permanent magnets and having a low magnetic permeability. A q-axis magnetic flux path is formed in an iron core region among the first permanent magnet, the second permanent magnets and the first region, and a central portion thereof is formed between the first permanent magnet and the first region, and entrance / exit portions of the q-axis magnetic flux path formed between the second permanent magnets and second regions provided on both circumferential sides of the first permanent magnet and having a low magnetic permeability with generally the same width.

A bicycle hub dynamo 1 comprises a hub spindle 5 adapted to be mounted to a frame of the bicycle; a hub body 6 disposed around the hub spindle 5, wherein the hub body 6 has a pair of axially spaced hub flanges 12a, 12b; a plurality of bearings 7, 8 disposed between the hub body 6 and the hub spindle 5 for rotatably supporting the hub body 6 relative to the hub spindle 5; and a generator 9 disposed between the hub body 6 and the hub spindle 5, wherein the generator generates electricity in response to rotation of the hub body 6 relative to the hub spindle 5. A freewheel 10 is disposed on a first side of the hub body 6, wherein the freewheel 10 is adapted to mount a plurality of sprockets 54.

A magnetic structure for use in a magnetic head for avoiding stray field writing. The magnetic structure can be for example a magnetic shield or could be a magnetic pole of a write head and is particularly advantageous for use in a perpendicular recording system, because such perpendicular recording systems are especially susceptible to stray field writing. The magnetic structure includes a forward protruding portion that extends toward the air bearing surface (ABS) of the head also includes first and second wing portions that extend laterally from the forward protruding portion. The wing portions each have includes an inner constant recess portion, and an outer tapered portion. The inner constant recess portion of each wing prevents stray field writing while also preventing magnetic saturation, the outer tapered portions, which taper away from the ABS as they extend laterally outward, further prevent stray field writing by removing the outer corners of the shield away from the ABS.

A method of controlling a brushless motor that includes rectifying an alternating voltage to provide a rectified voltage having a ripple of at least 50%, exciting a winding of the motor with the rectified voltage, and performing a first process or a second process in response to current in the winding exceeding a threshold that is proportional to the rectified voltage. The first process includes freewheeling the winding, while the second process includes continuing to excite the winding for an overrun period and freewheeling the winding at the end of the overrun period. Additionally, a control system that implements the method, and a motor system that incorporates the control system.