293results about How to "Enhanced magnetic field" patented technology

The invention provides an electromagnetically-assisted laser drilling method. The method includes the steps of 1, clamping a workpiece to be processed onto an electromagnetically-assisted laser drilling device; 2, driving a fixture base to rotate by a motor so that a permanent magnet clamped on the fixture base rotates at high speed and forms a rotational magnetic field; meanwhile, allowing a mouse cage in the rotational magnetic field to produce electromagnetic force whereby the workpiece rotates in sync with the mouse cage; 3, after the speed of the motor stabilizes to a preset value, starting a laser, which generates a laser beam acting on the surface of the workpiece via a focusing lens so as to finish the electromagnetically-assisted laser drilling process. According to the method, the application of the operating method of rotating the workpiece enhances the assistance of the magnetic field in laser drilling; meanwhile, the rotational magnetic field can control motion of plasma and molten metal generated in the laser drilling process, so that laser drilling effect is optimized. The invention further provides the electromagnetically-assisted laser drilling device.

A windmill electric-generating unit improved in generated potential because of no interference with the captured wind, unlike large-capacity generator vulnerable to the interference with the capturedwind in the windmill. The permanent-magnet generator has a revolving shaft, at least three stage rotors of multiple disc constructions connected to the shaft in tandem an a lengthwise direction of theshaft and having mounted permanent magnets thereon, and stators of disc construction with stator windings of copper wires, which are isolated from the revolving shaft and laid in at least two gaps each of which is between any two adjacent rotors. The rotors and stators are arranged to alternate each other in the lengthwise direction of the shaft across five stages or more. Further, there is provided the windmill generator in which a propeller is coupled to the rotor shaft of the permanent-magnet generator constructed as stated earlier.

A single trigger / shunt coil is utilized for combined induced magnetic field triggering and shunt impedance. The single coil connected in parallel with the high temperature superconducting element, is designed to generate a circulating current in the parallel circuit during normal operation to aid triggering the high temperature superconducting element to quench in the event of a fault. The circulating current is generated by an induced voltage in the coil, when the system current flows through the high temperature superconducting element.

The invention discloses a vibrating ash removal device for removing ash inside an ash pipeline to be cleaned. The vibrating ash removal device comprises an annular frame fixed inside the ash pipeline to be cleaned and coaxial with the ash pipeline to be cleaned, at least one vibrating rod and at least one electromagnet arranged outside the ash pipeline to be cleaned. The annular frame is provided with at least one guide rail in an inclined state relative to the annular frame, the upper end portion of the guide rail is relatively close to the axis of the annular frame, and the lower end portion of the guide rail is relatively away from the axis of the annular frame. The vibrating rod can move along the guide rail and is made of a ferrous material, and one end of the vibrating rod is connected to the annular frame through a compression spring. When the electromagnet is electrified, attraction force is exerted onto the vibrating rod so as to enable the vibrating rod to knock on the inner wall of the ash pipeline to be cleaned. The vibrating rod is arranged inside the ash pipeline to be cleaned, the electromagnet provides drive force for the vibrating rod to enable the vibrating rod to knock on the inside of the ash pipeline to be cleaned, and accordingly the purpose of effective ash removal is achieved.

The invention relates to a magnetic roller used in a laser printer and a copier. An isotropic bonded NdFeB magnet used by the magnetic roller contains rare earth permanent magnetic powder and adhesive resin, wherein the rare earth permanent magnetic powder is a mixture of NdFeB magnetic powder and ferrit magnetic powder, and the formed magnet has the length of between 210 and 910mm. When the isotropic bonded NdFeB magnet is used to replace one or more ferrit permanent magnet poles in the magnetic roller, because the bonded NdFeB magnet has stronger magnetic performance than ferrit magnets, a strong magnetic filed can be formed on an outer surface taking the bonded NdFeB magnet as a pole so as to provide stronger magnetic filed adsorptive power, contribute to the size distribution of multiple kinds of color matching powder, and reduce the grey back of copying and printing to contribute to clear imaging.

The invention provides an antenna device and a mobile terminal with the same. The antenna device comprises at least two layers of stacked coils; a second feed point electrically connected to an NFC (Near Field Communication) chip or an RFID (Radio Frequency Identification) chip is respectively arranged on the coils, and a first feed point electrically connected to a WPC (Wireless Power Consortium) chip or an FM (Frequency Modulation) chip is respectively arranged on the two coils of the surface; and the two adjacent layers of coils are isolated by an isolating unit, and the isolating unit is configured to isolate working signals of the NFC chip or the RFID chip. The antenna device realizes superposition of effective area of antennas via multilayer superposed coils, the coils can be connected or isolated to support two different functions, and multiplexing of the antenna device is realized; meanwhile, in the NFC or RFID working mode, the intensity of the radiation electromagnetic field can be improved, and the NFC or RFID communication performance is optimized.

The invention discloses a linear permanent-magnet generator, which comprises a primary iron core, a primary coil, a secondary iron core and a non-magnetic material shaft. The primary iron core, the primary coil, the secondary iron core and the non-magnetic material shaft are arranged in turn from the outside to inside; the primary coil is wound on the interior of the primary iron core; the non-magnetic material shaft is embedded in the secondary iron core; and a permanent magnet of a Halbach array is also sleeved outside the secondary iron core, and the permanent magnet enhances the magnetic field outside the permanent magnet and weakens the magnetic field inside the permanent magnet. The Halbach permanent-magnet array is applied to the linear generator and has the advantages of improving the power density of the generator, improving the utilization rate of the permanent magnet and simultaneously reducing eddy-current loss in the secondary iron core; therefore, the structure of an electric motor is simplified, the electric motor runs more stably, and the volume and weight of the generator are reduced.

A coil used for fast pulse superconducting magnet winding structure has an epoxy gasket (5) arranged on a frame (4) with a hole; a first layer of superconducting winding (6) is winded on the epoxy gasket (5); a layer of epoxy glass ribbon (7) is winded between the first layer of the superconducting winding (6) and a second layer of superconducting winding (8) which are bonded together by low-temperature epoxy resin; and epoxy glass steel strips (9) are distributed on the surface of the second layer of the superconducting winding (8) at equal intervals along the circumference direction of the winding. The superconducting wire used by the superconducting winding of the coil is formed by coating a composite matrix (2) consisting of CuNi and copper outside a superconductor (1), wherein an insulating layer (3) is coated on the composite matrix (2). The coil has higher mechanical stability and better heat transfer characteristics, and is suitable for a fast-excitation large-scale superconducting coil with high energy-storing density and high magnetic field.

The invention discloses a high-temperature superconductive magnetic levitation system introduced with ferromagnetic substances. The system is characterized by comprising rails and a low-temperature container, the rails comprise permanent magnets, magnetic accumulation materials and the like, the low-temperature container is fixed into a vehicle body frame, a high-temperature superconducting bulk layer composed of superconducting bulks is fixed in the low-temperature container, and the ferromagnetic substances are arranged on the superconducting bulks corresponding to a horizontal magnetic field dominant area in the high-temperature superconducting bulk layer. The ferromagnetic substances are introduced above vehicle-mounted high-temperature superconductors, so that stable levitation performance of an original high-temperature superconductive magnetic levitation system can be remarkably enhanced, the high-temperature superconductive magnetic levitation system introduced with the ferromagnetic substances is simple in structure, easy to process, convenient to popularize and the like and can be suitable for places with higher requirements on guide performance of a high-temperature superconductive magnetic levitation vehicle in practical application, such as occasions in curve operation.

Disclosed are a dynamic wireless power supply system for a tramcar and an efficiency optimization control method of the system. The system device comprises a first transmitting terminal circuit and a second transmitting terminal circuit on the ground, and a receiving terminal circuit mounted on the tramcar. First and second transmitting coils and a receiving coil of the system adopt a winding mode of 8-shaped coil rows, and two sub-coils of each 8-shaped coil have opposite winding directions. The first transmitting coil (LPl) and the second transmitting coil (LP2) are completely overlapped in the width direction, and overlapped in an offset manner in the length direction, and the offset distance is one quarter of the length of one single 8-shaped transmitting coil. According to the invention, the ratio of the effective values of currents of the two transmitting coils can be adjusted in real time, and the ratio of the effective values of the currents of the transmitting coils is the ratio of the system at optimum efficiency, so as to improve the efficiency of the system. By applying the method, the transmission efficiency of the dynamic wireless power supply system for the tramcar provided with the 8-shaped coil rows can be effectively improved through simple and convenient control, the power supply capacity of the system is reduced, reliability is high, and control is easy.

The invention discloses a wide-beam ion source device used for an ion implanter. The device comprises a source magnetic field iron core, a source magnetic field coil, an arc chamber and an extraction electrode, one end of the arc chamber is provided with a first filament and a first cathode, the other end of the arc chamber is provided with a second filament and a second cathode, the first filament and the second filament are connected with filament power supplies respectively, a first bias power supply is connected between the first filament and the first cathode, a second bias power supply is connected between the second filament and the second cathode, a first arc voltage power supply is connected between the first cathode and the arc chamber, and a second arc voltage power supply is connected between the second cathode and the arc chamber. Since the arc chamber adopts an indirect-heating type double-cathode structure with double filaments and double cathodes, so that a gas medium and hot electrons emitted by the cathodes fully collide, and a relatively wide ion beam and relatively high beam intensity can be generated, thereby facilitating increase of the width of the ion beam, and directly obtaining a parallel wide-band beam that covers the width of a target implantation silicon wafer.

The invention discloses an electrical inductance in an integrated circuit and a manufacturing method, comprising the following steps: 1, a metal layer is deposited on a dielectric layer; 2, the diagram of the electrical inductance is defined through adopting photoetching technology; 3, the etching is conducted on the metal layer, and the optical resist is removed, and a metal coil is formed; 4, the dielectric layer continues to be deposited, and a through hole is formed at the dielectric layer; 5, the filling metal is filled in the through hole; 6, step 1-step 5 are repeated to increase the number of layers of the electrical inductance, until the last layer of metal coil is formed. The electrical inductance in the integrated circuit contains a plurality of layers of metal coils in parallel, and the adjacent metal coils are connected through connecting contact holes. The electrical inductance of the integrated circuit which is manufactured through utilizing the manufacturing method of the invention comprises the plurality of metal coils, and increases the magnetic-field strength of the electrical inductance.

The invention discloses a low current electric arc magnetic blow-out device and an arc-blowing method of a medium-pressure direct current breaker. According to the device, a V-shaped arc extinguish chamber grid sheet is adopted, a magnet exciting coil is arranged on the side surface of an arc extinguish chamber shell, which is parallel to the grid sheet, the magnet exciting coil is externally connected with a low current detecting and judging system, and a piece of Y-shaped magnetism enhancing armature iron is arranged at each of the two sides of the arc extinguish chamber shell, which correspond to the regions of movable and fixed contacts and an arc running channel. According to the magnetic blow-out device, the magnetic fields of the regions of the contacts and the arc running channel are effectively enhanced, thereby playing obvious effects on the facts that lower current electric arcs in the contact region can fast enter the grid sheet, the electric arcs can be broken successfully, and the fault probability of the device can be reduced. In addition, the device is compact in structure, can reasonably utilize optimizable breaker spatial layout and results in the reduction of the volume.

The invention relates to the field of domestic appliance, in particular to a magnet drive electric shaver. The magnet drive electric shaver solves the problem of waterproof sealing difficulty and thetransmission structure without overload protection function in an electric shaver with a current transmission structure. The magnet drive electric shaver comprises a main body assembly and a cutter head assembly; the cutter head assembly is arranged on the main body assembly; the main body assembly comprises a main body and a driving unit arranged in the main body; the cutter head assembly comprises a movable cutter unit and a shell used for supporting the movable cutting tool unit; the driving unit comprises a motor, a driving magnetic body arranged in the main body and a driven magnetic bodyarranged in the shell; the driving magnetic body and the driven magnetic body are arranged to be multipole magnetization magnetic bodies; and the movable cutting tool unit is driven to rotate by themotor, the driving magnetic body and the driven magnetic body. Excellent waterproofing effect is achieved and overloading protection is achieved by magnet drive.

The invention relates to a multi-surface cylinder type hybrid excitation switch magnetic flux linear motor. A multi-stator modularized structure is designed, so that the machining and assembling of the motor are more convenient and simple; magnetic steel and windings are arranged on stators of the linear motor, so that the material consumption and the cost of the linear motor are reduced; a motor rotor only has movable sub-tooth rings, so that the linear driving robustness of motor is high, and the response is rapid. According to the invention, the excitation windings are set, so that the magnetic field of the motor is adjusted, and the low-speed loading and high-speed feeding performance of the linear motor is improved; in addition, a cooling liquid circulation system is arranged, the magnetic steel, an armature winding and the excitation windings are enabled to dissipate heat together, and the operation load and stability of the linear motor are substantially improved, so that compared with an existing linear motor, the linear motor serving as a servo direct driving force source of a main shaft large thrust axial driving type has more advantages, and the working performance is better.

The invention discloses a miniature circuit breaker with a high breaking capacity, which comprises a shell, wherein the shell is internally provided with a magnet yoke assembly, a moving contact assembly, an arc extinction system and an actuating mechanism. A magnet yoke, a wiring board and a connecting sheet in the magnet yoke assembly are designed into a whole to ensure that the structure of the magnet yoke assembly is simplified, the quantity of soldered dots of the magnet yoke assembly is reduced and the internal resistance of a circuit breaker is lowered; a moving contact in the moving contact assembly comprises a contact support and a contact which are connected, the specific gravity of the contact support is smaller than that of the moving contact, and a magnet conductive plate is additionally arranged on the back of the moving contact and used for accelerating the transfer of an electric arc, therefore, the breaking capacity of the circuit breaker is improved; and a plurality of linkage lug bosses used for multipolar linkage are arranged on a contact support body, thus the linkage performance of the multipole circuit breaker is effectively ensured. A coil is connected with the moving contact through an annealed copper wire in a spot welding manner, and the soldered spots are moved from the linkage lug bosses to the moving contact without influencing the linkage property of the multipole circuit breaker. The invention has the advantages of high breaking capacity, high consistency of the interelectrode linkage and good reliability performance.

The invention provides a superconductive magnetic field coil integrated with a Josephson junction and a preparation method thereof. The superconductive magnetic field coil comprises a plurality of bottom magnetic field coil layers, a plurality of top magnetic field coil layers and a second insulation material layer. The plurality of bottom magnetic field coil layers and the plurality of top magnetic field coil layers are separated by the second insulation material layer. Holes are arranged in the second insulation material layer. The holes are filled with third superconductive material layers. The top magnetic field coil layers are connected with two adjacent bottom magnetic field coil layers through the third superconductive material layers in the holes, thereby forming a whole superconductive magnetic field coil. According to the superconductive magnetic field coil prepared by the invention, a magnetic field can be produced at the Josephson junction. An introduced current numerical value is smaller than the value of a current required by the prior art, a magnetic field range of the Josephson junction in magnetic field change measurement can be expanded, and the measurement efficiency is improved.

The invention discloses a method for producing castings by utilizing waste scrap iron and waste steel. The method comprises the following steps of: paving a layer of scrap iron at the bottom of an intermediate frequency furnace; injecting a furnace bottom carburant; adding scrap returns; filling gaps with the scrap iron; adding the waste steel; filling the gaps among the waste steel with the scrap iron; turning on power for preheating; increasing power to full load; when furnace burden at a furnace mouth descends, poking the furnace and charging until all taken raw materials are added into the intermediate frequency furnace; when all taken components are molten and the distance from the surface of molten iron to the furnace mouth is 10 to 15cm, sampling the molten furnace and performing forehearth laboratory analysis; adjusting elements in the molten iron according to an analysis result to make the content of the elements in the molten iron meet a requirement; pouring the adjusted molten iron by a method for producing gray iron castings or nodular iron castings to prepare the gray iron castings and the nodular iron castings. By using the method, the castings of which the chemical components, the metallographic structures and the mechanical properties meeting requirements can be produced; and the difficulty in adjusting the chemical components in a melting process can be reduced.

A single trigger / shunt coil is utilized for combined induced magnetic field triggering and shunt impedance. The single coil connected in parallel with the high temperature superconducting element, is designed to generate a circulating current in the parallel circuit during normal operation to aid triggering the high temperature superconducting element to quench in the event of a fault. The circulating current is generated by an induced voltage in the coil, when the system current flows through the high temperature superconducting element.

The invention discloses a novel magneto-rheological damper, which comprises a working cylinder body, a piston rod and a piston arranged in the working cylinder body, wherein the piston is coaxially sleeved outside the piston rod; the piston rod drives the piston to move in the working cylinder body; two sealing bodies are arranged in the working cylinder; the region between the two sealing bodies forms a motion region of the piston; the motion region of the piston is filled with a magneto-rheological fluid; two axially distributed piston annular grooves are circumferentially arranged on the piston; a permanent magnetic ring is arranged in the piston annular groove; an annular insulating layer is arranged outside the permanent magnetic ring; an excitation coil is wound outside the annular insulating layer; and the outer circumference of the excitation coil is in contact with the inner circumferential wall of the working cylinder body. The novel magneto-rheological damper has the advantages that by arranging the permanent magnetic rings in the piston grooves of the piston, and by further arranging the excitation coils outside the permanent magnetic rings, the magnetic field generated when electric current passes through the excitation coils during the operation of the magneto-rheological damper can be effectively enhanced, thus the damping force of the magneto-rheological liquid at a controllable state in the working cylinder body can be increased.

The invention provides an opto-isolator, whichcomprises a pipe, an isolator core arranged inside the pipe, and an input collimator and an output collimator which are arranged at two ports of the pipe, wherein the isolator core comprises a first magnet ring, a second magnet ring, a third magnet ring and an isolation device; and the isolation device comprises a pair of birefringent chips and a Faraday rotation chip arranged between the pair of birefringent chips. The opto-isolator has a structure that the three magnet rings are combined, so that a magnetic field in a light passing area on the Faraday rotation chip in the isolation device is in a saturated state; and therefore, the radiating capacity of the Faraday rotation chip can be enhanced and heat on the core part of the opto-isolator is more easily dissipated; and moreover, two temperature sources in the opto-isolator are separated by a distance, so that the two temperature sources do not interfere each other, and the heat dissipation of the opto-isolator is facilitated.

The invention relates to a wireless charging device, and belongs to the technical field of wireless charging. The wireless charging device comprises a wireless charging coils which comprises an excitation layer, a first coil annular loop and a second coil annular loop. The first coil annular loop is arranged in parallel on the upper end surface of the excitation layer. The periphery of the first coil annular loop is provided with an electromagnetic shielding plate formed by magnetic conductive materials.The electromagnetic shielding plate is fixed on the upper end surface of the excitation layer, and the height of the electromagnetic shielding plate on the upper end surface of the excitation layer is higher than that of the first coil annular loop and the third coil annular loop on the upper end surface of the excitation layer. The second coil annular loop is arranged around the upper and lower end surfaces and two side surfaces of the excitation layer. The side of the second coil annular loop on the upper end surface is disposed adjacent to the side of the first coil annular loop. The wireless charging device can improve the wireless charging efficiency and can also shield the radiation scattering generated by the charging coil in the process of transmitting energy and has a good electromagnetic shielding effect.

The invention provides an annular micro-flow channel oil liquid detection device and a manufacturing method thereof. The device comprises a micro-fluidic sensor and a measuring unit. According to different magnetization effect mechanisms of ferromagnetic particles and non-ferromagnetic particles in a spatial magnetic field, the device is used for detecting solid pollutants in oil liquids such as hydraulic oil, lubricating oil and the like. The attributes of the pollutants are distinguished by utilizing an inductance detection method. An annular micro-flow channel is designed for the first time, so that the flux of a to-be-detected oil sample is increased, and the detection time is shortened; and a silicon steel sheet is placed in the micro-flow channel, and the spatial magnetic field of adetection area is gathered, so that the magnetic field intensity of the detection area is increased, and the detection precision of the sensor is improved. The method and the process have the advantages that the manufacturing is simple and reliable, and the cost is reduced. An effective method is provided for oil liquid online monitoring of machine equipment, and fault diagnosis can be carried outon the machine equipment.

The invention provides a single coil and characteristic frequency-based non-contact acute cerebral ischemia detection device. The single coil and characteristic frequency-based non-contact acute cerebral ischemia detection device includes a vector signal source which outputs sine wave excitation signals in a certain frequency range, a signal separation module which separates two paths of signals outputted by the vector signal source and separates excitation signals and detection reflected signals, and extracts out the detection reflected signals, a detection module which is a single annular coil, a signal acquisition module which acquires reflected signals outputted by the detection device and reference signals outputted by the vector signal source, and a signal processing module which processes detection signals and reference signals which are received by the signal acquisition module; a detected skull is arranged at the axial center of the single annular coil. The single coil and characteristic frequency-based non-contact acute cerebral ischemia detection device of the invention has high detection sensitivity and can distinguish different ischemia levels. An experiment carried out by using the detection device has high repeatability.

A power generator is provided which, when used at an electric power generating facility such as a wind power plant, etc., would not be bulky and would not impede wind capture by a wind turbine; instead, it can raise the generated voltage without impeding wind capture. The invention provides a permanent magnet generator comprising a generator shaft; at least three rotors, which are secured with the generator shaft, constituted by a plurality of a plate-shaped structure having a permanent magnet attached thereto, and each disposed in the longitudinal direction of said generator shaft; and a stator, which is plate-shaped structures with a stator coil of a wound copper wire disposed in at least two gaps formed by said rotors, evenly-spaced apart from said generator shaft. The rotors and stators are disposed alternately in the longitudinal direction of said generator shaft, with a total of not less than five stages. Furthermore, a wind power generator obtained by installing a propeller on the shaft of this permanent magnet generator is provided.

The invention provides a melt testing apparatus having an elevating chassis. The melt testing apparatus is characterized in that the melt testing apparatus comprises a water cooling cannula (1), an induction heating coil, and a chassis system, and the water cooling cannula (1) and the chassis system form a cold crucible, wherein the chassis system comprises an elevating system (8). According to the melt testing apparatus, multiple melt-related testing researches can be developed, after the test is finished, a molten pool and a casing layer structure at an upper part of the molten pool are completely removed.

The invention provides an experimental apparatus for researching microstructure and magnetic field relation of magnetic fluid. The experimental apparatus consists of a video optical microscope 1, a double-loop liquid-cooling constant-temperature even magnetic field generating device 2, a bottom light source bracket 3, a computer 4, a programmable power supply 5, a light source 6, a water cooling liquid circulating radiating device 7, a transformer oil circulating radiating device 8 and a gauss meter 9, wherein the double-loop liquid-cooling constant-temperature even magnetic field generating device can provide large magnetic field stably for a long time without affecting ambient environment thereof; the observation is realized by moving the video optical microscope 1 right above the bottom light source bracket 3 and then adjust the focal length; the magnetic field parallel to or vertical to a magnetic fluid sample can be generated by simultaneously using the bottom light source bracket 3 and the double-loop liquid-cooling constant-temperature even magnetic field generating device 2, so as to research the microstructure of the magnetic fluid in multiple magnetic field directions.

The invention discloses a greenhouse gas conversion device and method utilizing a magnetic field to strengthen a blade gliding arc. The device comprises a blade gliding arc stabilization system and areactor. The blade gliding arc stabilization system comprises a first DC power supply, a second DC power supply, an inductance coil, a diode and an electromagnetic relay switch. The voltage of the second DC power supply is greater than that minimum breakdown voltage between two electrodes of the reactor. The voltage of the first DC power supply is 1 / 8-1 / 2 of the minimum breakdown voltage between the two electrodes of the reactor. The second DC power supply provides breakdown voltage, and the first DC power supply maintains power feeding. The reactor consists of an encloser, two electrodes, twoflat magnets and a nozzle. The encloser is a straight quadrangular prism structure with a rectangular cross section, and the two flat magnets are arranged outside the encloser parallel to each other.The invention improves the traditional blade reactor, utilizes the dual driving of the magnetic field and the airflow field, significantly improves the treatment capacity on greenhouse gas, and greatly prolongs the reactor lifetime.

The invention relates to a disc type permasyn motor for an electric car hub, which comprises a fixed mandrel, a rotor outer casing and a stator armature disc, wherein the rotor outer casing is supported on the fixed mandrel; the stator armature disc is fixedly connected with the fixed mandrel. The left and right sides of the rotor outer casing are symmetrically fixedly connected with parallel magnetic steel discs. A circular air gap of which the cross section is in a rectangle shape is formed between the magnetic steel discs. The stator armature disc is arranged in the circular air gap and is provided with an outgoing line. The stator armature disc has no core, and is directly formed by injection molding. The magnetic steel disc adopts a Halbach type permanent magnet array structure. The invention adopts the stator armature disc without a core for direct injection molding, and the magnetic steel disc with the Halbach type permanent magnet array structure, therefore the motor can greatly enhance power density of the motor, decrease the wear and tear of the motor and has the advantages of small volume, compact structure, stable low-speed running, good controllability, light weight, small vortex consumption of the rotor, small rotating inertia, large power density, small electromechanical time constant and the like.