367 results about "Magnetic potential" patented technology

The invention relates to a method for suppressing the torque ripple of a permanent-magnet motor based on space vector modulation. The method comprises the following steps of: adopting a vector control strategy that a permanent-magnet motor has a zero direct axis current so that electromagnetic torque and a quadrature axis armature current form a linear connection; and solving an additional quadrature axis injection harmonic current according to the linear connection of the electromagnetic torque of the permanent-magnet motor and the quadrature axis armature current so that an additional electromagnetic torque high-harmonic component generated by coupling the quadrature axis injection harmonic current and the direct axis permanent-magnet chain and fundamental and high-harmonic components in the orientation torque of the permanent-magnet motor have identical amplitude and opposite phases and can be mutually counteracted to suppress the torque ripple. The invention adopts the permanent-magnet motor as an implementation object, and the motor of the type can adopt advanced control protocols of vector control, direct torque control, and the like so that the method is simple and practical by editing control software without increasing the hardware cost of a control system and can obviously suppress the torque ripple of the motor and remain the constant motor characteristics of idling magnetic potential, torque output capability, and the like.

The present invention discloses a DC curren sensor. In said sensor a detection coil is added, said sensor adopts single-core three-winding structure, when a DC bias magnet is existed in the magnetic core, the induced potential obtained by detection coil can produce positive-negative half-wave unsmmetrical waveforms, said waveforms can be converted into the voltage signal of difference of positive-negative half-wave effective values, after voltage/current conversio, said signal can be fed into feedback winding, said feedback winding cap produce the DC magnetic potential whose direction is opposite to that of magnetic patential produced by detected direct current to balance the bias magnetic potential produced by detected direct current to form 'null-flux' state, so that it can obtain the detected direct current intensity so as to implement the detection of direct current.

A magnetic write head having independent trailing and side magnetic shields. The side shields and trailing shields are independently of one another so that they can have throat heights that are different from one another. This advantageously allows the magnetic potential between the write pole and side shields to be controlled independently of one another without relying on the side gap and trailing gap thicknesses. Furthermore, magnetic performance of the write head can be improved because the side shields can be constructed with varying tapered throat heights, while the throat height of the trailing shield can remain constant.

The invention discloses a Hall phase sequence detecting method of a brushless direct-current motor, relating to the technical field of the brushless direct-current motor. Based on the operating principle of the brushless direct-current motor and the magnetic potential synthesis principle, the method adopts the magnetic potential of a fixed stator to position a rotor, and obtains the position of the rotor by reading a signal of a Hall position sensor, thus determining the relation of the magnetic potential of a stator and the position of the rotor. The invention also discloses a phase sequence detecting device of the brushless direct-current motor, comprising a computational processing module, a motor-driven module and a man-machine interface module, wherein the man-machine interface module comprises an input unit and an output display unit; a motor-driven unit is in a three-phase inverse bridge-type structure; and the calculated processing module is respectively connected with the motor-driven module, the input unit and the output display unit by signals. Compared with the prior art, the detecting device has the advantages that the structure is simple, the use is convenient, the cost is low and the like.

The invention discloses a method for estimating a rotor position of a three-stage brushless AC synchronous motor. A main exciter of the three-stage brushless AC synchronous motor is a three-phase field winding, and a three-phase alternating current is connected to the three-phase field winding, wherein the three-phase alternating current acts as the three-phase exciting current of the main exciter; the slip frequency of exciting magnetic potential and motor rotors is set as one-sixth of the high-frequency signal frequency that is expected to be injected; and after the alternating current induced at the rotor side passes a rotary rectifier, a DC current with high-frequency harmonic components is generated so as to provide excitation for the main generator field winding, detect output current of the main generator, and realize the determination of the initial motor rotor position and the estimation of the rotor position during the starting operation. By use of the method for estimating the position disclosed by the present invention, a more accurate position estimation value can be obtained, and the method is insensitive to the accuracy of the injected high-frequency signal frequency and phase, and has certain anti-interference ability.

The invention discloses a control method for compensating location torque of permanent-magnet motor by injecting current harmonics; in the method, harmonic current is injected to interact with the fundamental wave permanent magnetic potential to generate an additional torque component, so that the additional torque can be equal to the amplitude of the fundamental wave and the ultra-harmonics component in the directional torque and the phase positions thereof are opposite and can be offset, thus achieving the aim of compensating the location torque. In the method, firstly harmonic analysis is carried out on the location torque of the permanent-magnet motor by using finite element simulation result or observed data and adopting the Fourier series approximation approaching method; secondly the aero load counter electromotive force of the permanent-magnet motor is analyzed and the corresponding mathematical expression is written out; and finally the injected harmonic current is worked out according to the principle that additional torque and location torque can offset each other.

The invention relates to a circuit for checking on-site accuracy of a current transformer under the condition of underload operations, comprising a test power supply, a voltage regulator, a power current transformer, a current transformer to be tested, a standard current transformer, a comparison type current transformer checking meter, a current comparator, a load box and a null indicator. In the circuit for checking the on-site accuracy of the current transformer under the condition of the underload operations, the on-site accuracy of the current transformer under the condition of the underload operations is checked by utilizing a magnetic potential balance method, therefore, a measurement error of the current transformer which works below 1% of rated current can be accurately measured, and the defect of the traditional method is effectively compensated. The circuit provided by the invention has the advantages of simple structure and convenience for use, and the measurement error of the current transformer can be directly read through the comparison type current transformer checking meter.

When an accelerating voltage and operating distance are changed, an excitation current and a pole voltage of an aberration corrector must also be changed. Moreover, different multipole voltages or currents must be added individually for each pole in order to superpose multipoles. In view of overcoming the problems explained above, the charged particle optical apparatus of the present invention comprises an excitation device including, to give excitation to form a multipole field to each pole of the multipole lens, electromagnetic type quadrupole of four stages arranged along an optical axis of charged particle beam, electromagnetic type quadrupole of two stages for superposing distribution of voltage similar to distribution of magnetic potential of the electromagnetic type quadrupole of two stages at the center of the electromagnetic type quadrupole of four stages, and electromagnetic type octupole for superposing magnetic potential at least to three multipoles among that of four stages and also comprises a first power supply group for driving the same excitation device and a second power supply group for impressing voltages.

Belonging to technical area of electrical motor and equipment of automobile, the mixed excitated voltage stabilized generator includes assembly of rotor, assembly of stator, front end cover, back end cover, and electronic controller. Characters are that tangential type rotor in permanent magnet and salient pole type electricity excitated rotor are installed on shaft. The said tangential type rotor and electricity excitated rotor share one armature winding. Magnetic potentials generated by them are synthesized in parallel in magnetic circuit. In operation, adjusting magnitude and direction of current in salient pole type electricity excitated rotor can adjust magnetic field of superposed magnetic field of permanent magnetism and electricity excitated magnetic field so as to guarantee stable outputted voltage when in state of variational rotation speed and variational load. Features of the generator are: compact structure, safety and reliable.

On a charged-particle optical system for achieving optimum aberration correction and obtaining a minimum probe diameter, the optical system focuses a beam of charged particles onto a surface of a specimen, and has four stages of multipole elements arranged along the optical axis of the beam, power supplies capable of supplying five or more independent octopole electric or magnetic potentials, and a control portion for correcting third-order aperture aberrations by adjusting the five or more independent octopole electric or magnetic potentials independently. The power supplies apply normal octopole electric or magnetic potentials to at least three of the four stages of multipole elements independently and apply skew octopole electric or magnetic potentials to at least two of the multipole elements independently.

Particle-beam apparatus is realized which is equipped with an aberration corrector capable of controlling the angular aperture of a particle beam after performing aberration correction. The corrector comprises four stages of electrostatic quadrupole elements, two stages of magnetic quadrupole elements for superimposing a magnetic potential distribution analogous to the electric potential distribution created by the two central stages of the electrostatic quadrupole elements, and four stages of electrostatic octupole elements for superimposing an octupole electric potential on the electric potential distribution created by the four stages of electrostatic quadrupole elements. An objective lens is located downstream of the corrector. An objective aperture is located upstream of the corrector. An angular aperture control lens is located downstream of the objective aperture to control the angular aperture of the probe hitting a specimen surface.

The invention provides a coupling inductor and a power converter. The coupling inductor comprises at least two input ends, an output end, a common magnetic core, at least two first windings and at least two second windings, wherein the common magnetic core comprises at least two magnetic columns; the number of the magnetic columns corresponds to that of the input ends; each of the at least two magnetic columns is wound with a first winding and a second winding in parallel; the first windings and the second windings on the at least two magnetic columns are connected with each other between the at least two input ends and the output end to form mutually coupled inductors, so that when currents flowing into the at least two input ends are equal, the first winding and the second winding on each magnetic column generate opposite magnetic potentials. According to the technical scheme, when the currents flowing into the at least two input ends are equal, the first winding and the second winding on each magnetic column generate the opposite magnetic potentials, so that magnetic potentials generated by a common mode current offset each other, and leakage flux is reduced.

The invention discloses a modeling method of an axial permanent magnetic motor equivalent magnetic circuit model. The modeling method includes the following steps of judging the topological structure which an axial permanent motor belongs to, determining the sizes of a stator, a rotor, a permanent magnet and an air gap of the motor, carrying out three-dimensional limiting element analysis on the axial permanent magnetic motor by means of limiting element simulation software to obtain magnetic flux density distribution of all portions of the motor, averagely dividing the axial permanent magnetic motor into N sections in the diameter direction, calculating equivalent magnetic resistance of the stator and the rotor according to magnetic flux density distribution obtained through limiting element analysis and magnetization curves of iron core materials of the stator and the rotor, calculating equivalent magnetic potential and equivalent magnetic resistance of the permanent magnet according to residual magnetism density of permanent magnetic materials and relative recoil permeability, dividing the air gap into a plurality of small areas according to the relative position of the stator and the rotor to calculate the equivalent magnetic resistance of all the portions, building the axial permanent magnetic motor equivalent magnetic circuit model according to modeling of all the portions. According to the modeling method, an accurate and quick magnetic circuit calculating method is provided for initialization and optimal design of the axial permanent magnetic motor.

The invention discloses a solving method electromagnetic design used for a surface-mounted permanent magnet motor. The solving method comprises the following steps: (1) based on an improved subdomainmethod, establishing a vector magnetic potential expression of a permanent magnet, an air gap and a stator slot, and obtaining current magnetic field distribution of three subdomains according to thevector magnetic potential expression, wherein an equivalent current sheet is added into the stator slot as a boundary condition, the vector magnetic potential expression of the stator slot is relatedto the current density of the equivalent current sheet; (2) according to the obtained current magnetic field distribution, using a magnetic circuit method to solve and obtain the magnetic voltage dropof each part of a stator core, and converting the magnetic voltage drop into the current density of the equivalent current sheet inside the stator slot; (3) through mutual iteration of the improved subdomain method and the magnetic circuit method, solving the magnetic field distribution of the three subdomains; and (4) calculating permanent magnet motor magnetic flux linkage, counter electromotive force and cogging torque. By using the solving method, the magnetic field distribution of the motor and the electromagnetic performance of the motor under the condition that a saturation effect is considered can be calculated accurately, and optimal opinions are provided for motor design.

An aberration correction method and charged-particle beam instrument with four stages of multipole units. The two central stages of multipole units function as two stages of magnetic quadrupole components for superimposing a magnetic potential distribution analogous with an applied electric potential distribution on this electric potential distribution. The instrument further includes an objective lens, an objective aperture mounted in the optical path for a beam of charged particles, an operation portion for varying the accelerating voltage or the working distance between the objective lens and a specimen, and a control portion for controlling the multipole units according to an operation of the operation portion. When the accelerating voltage or working distance is varied, the resultant magnification of the four stages of multipole units and objective lens mounted behind the units is adjusted to maintain constant at least one of octupole component-activating potentials for correcting third-order aperture aberrations.

The invention relates to a sectional type Halbach array permanent magnet motor magnetic field calculation method. The sectional type Halbach array permanent magnet motor magnetic field calculation method comprises the steps of determining solution areas, respectively building Laplace's equations or Poisson's equations for the different solution areas, calculating the interval between magnetic blocks of a sectional type Halbach array, solving the radial and tangential component amplitudes under each order of harmonic waves of residual magnetization intensity of a permanent magnet, solving the built Laplace's equations or Poisson's equations, obtaining an expression of a scalar magnetic potential in the solution areas, and further obtaining radial and tangential components of flux densities of the areas. The sectional type Halbach array permanent magnet motor magnetic field calculation method can accurately solve the magnetic field of an inner and outer rotor sectional type Halbach array permanent magnet motor with any magnetic block number of each pole and any number of pole pairs.

The invention discloses a claw-pole motor, which comprises a rotor and a stator. The rotor of the claw-pole motor comprises a driving end claw pole, an electric end claw pole, a magnetic steel assembly, a magnet yoke coil and a magnet yoke die core, wherein the whole magnet yoke die core is used as an independent component, and the magnet yoke die core and the claw poles are assembled together. By adopting the claw-pole motor of the invention, because the air gap produced by the accessory assembly joints inside the rotor is in the radial direction, the size of the secondary air gap caused by a manufacturing process is reduced so as to reduce the magnetic potential drop and magnetic resistance and improve the performance of the claw-pole motor. Moreover, the invention discloses the claw-pole motor assembled by multiple structural compositions so as to simplify the machining and assembly processes of the claw-pole motor.

The present invention provides a kind of multilayer planar magnetic engaged wheel and multilayer spherical magnetic engaged wheel and magnetic transmission equipment adopting this magnetic engaged wheel. Said multilayer magnetic engaged wheel is formed from several rotatable bases, several spacing pieces rotatable together with bases, magnetic bodies distributed on the bases and rotating shaft. Its whose magnetic engaged wheel is made up by alternatively and axially coinciding bases with magnetic bodies and spacing pieces togehter. The magnetic bodies are uniformly-spaced and arranged on the graduated cycle of base and magnetic shaft directions are alternatively arranged, in the engaged position of two engaged wheels any magnetic body or magnetic pole of one magnetic engaged wheel is being in magnetic potential well formed from several magnetic bodies or magnetic poles of another magnetic engaged wheel.

The invention provides a spindle synchronous motor with a wide speed regulation range for a lathe. The spindle synchronous motor comprises a stator core, three-phase windings in stator grooves, a rotor core and permanent magnets which are embedded into the rotor core and are in special structures, wherein the stator core and the rotor core are formed by laminating silicon steel sheets and fixed by rivets; conductors in the stator grooves are the three-phase symmetrical windings; the permanent magnets are in layered and segmented structures; slender and nonuniform-width hollow holes are reserved into a rotor structure to form double-layer magnetic barriers; the hollow holes are symmetrically distributed on the two sides, close to the bottom of a rotating shaft, of each concave permanent magnet, and transversely arranged into quadrature axis magnetic circuits; a chamfered angle close to a stator side is larger; and a chamfered angle close to a rotating shaft side is smaller. According to the spindle synchronous motor, a new method of selecting the number of the stator conductors is provided, the magnetic potential of an armature reaction is improved by a novel rotor structure, the main magnetic flux is reduced, the output characteristic of the motor is optimized, and effects of improving the weak magnetism and increasing the maximum rotating speed are achieved, so that the speed regulation range of the spindle synchronous motor is greatly widened.

The invention provides a method for starting a doubly salient motor without position sensor control, which is characterized in that the method includes the following steps: applying a pulse voltage of the same time and equal amplitude to each stator winding combination through an inverter , the corresponding current value is detected at the end of each voltage, and the corresponding current value is a function of the equivalent inductance of each combination mode. There is a corresponding relationship between the inductance and the rotor position, and the initial position of the rotor can be obtained indirectly by comparing the current value; according to Turning to the corresponding switch of the conduction inverter, so that the stator magnetic potential generated by the corresponding stator winding current is ahead of the initial position by a certain angle range, ensuring that the synthetic magnetic potential generated by the stator winding current interacts with the permanent magnetic field to obtain the maximum average electromagnetic torque , to make the motor rotate towards a given direction. The present invention does not need a position sensor, and does not need to obtain motor parameters in advance, and the change of the motor parameters does not affect the realization of the method.

Conventional perpendicular writers that utilize an extended return pole are subject to large undershoot fields. This problem has been reduced by replacing the prior art extended return pole by one whose magnetic potential has been increased relative to both the main and return poles. In a first embodiment, a second non-magnetic gap is inserted between the extended return pole and the return pole. In a second embodiment, the extended return pole is made very thin, thereby increasing its reluctance, while a third embodiment combines both reluctance-increasing features in a single design.