97 results about "Ac resistance" patented technology

The invention relates to a semi-analytical calculation method for loss of a Litz wire winding of a high-frequency transformer, and the method comprises the steps: extracting equivalent electromagnetic parameters of a single-turn Litz wire through finite element simulation software, taking the equivalent electromagnetic parameters as the calculation premise of an AC resistance coefficient of a homogenized Litz wire winding, and accurately improving the calculation precision for a complex Litz wire winding. Compared with three-dimensional finite element simulation, the method has the advantages that calculation speed is increased and calculation power resources are saved while calculation precision is considered, so that calculation support is provided for prediction of winding loss in subsequent optimization design of the high-power high-frequency transformer; the technical problem that in the prior art, it is difficult to balance the balance between the calculation precision and the speed due to the complex multi-strand structure of the litz wire is solved.

The invention belongs to the technical field of high-frequency magnetic devices, and particularly relates to a circular litz wire winding alternating current resistance coefficient analytical calculation correction method. The method comprises the following steps: step 1, folding each turn of circular litz wire winding into a square litz wire winding; 2, folding each layer of square litz wire winding into a long foil type litz wire winding with the same height as the iron core window; step 3, according to a principle that effective resistance is equal, calculating a conductivity conversion coefficient of the winding before and after conversion; 4, correcting the permeability of the circular litz wire winding according to the conductivity conversion coefficient; and step 5, in a circular litz wire winding alternating current resistance coefficient analytical calculation formula, adopting the corrected winding permeability parameter to obtain a corrected winding alternating current resistance coefficient analytical calculation formula. The high-frequency magnetic device loss evaluation method is a key for carrying out loss evaluation on the high-frequency magnetic device, is beneficial to technical popularization and application of the high-frequency magnetic device, and has relatively high accuracy and relatively high universality.

The invention belongs to the technical field of high-frequency electromagnetic devices, and particularly relates to a circular litz wire alternating current resistance coefficient optimization calculation method based on a winding shape, which comprises the following steps of: 1, fitting a winding external magnetic field analytical expression of a circular litz wire under a rectangular coordinate system according to the winding shape; 2, converting the winding external magnetic field analytical expression under the rectangular coordinate system into a cylindrical coordinate system for expression; 3, deriving an external proximity effect loss analytical expression of the single-turn circular litz wire by adopting a winding external magnetic field analytical expression under a cylindrical coordinate system; 4, deriving a winding alternating-current resistance coefficient analytical expression corresponding to the external proximity effect of the circular litz wire winding by adopting a single-turn circular litz wire external proximity effect loss analytical expression; and 5, superposing the alternating current resistance coefficient analytical expressions corresponding to the external proximity effect of the winding, the skin effect and the internal proximity effect to form an alternating current resistance coefficient analytical calculation improved formula of the circular litz wire winding.

The invention provides an MCR-WPT system tiny planar coil structure parameter optimization method based on a spot turner optimization algorithm, and the method comprises the steps: deducing an MCR-WPT system energy transmission efficiency form through analyzing a compensation structure network; analyzing physical structure parameters in the tiny planar coil, and calculating self-inductance, mutual inductance and alternating-current resistance; calculating a theoretical self-inductance value of the micro planar coil; calculating a mutual inductance coefficient value between the coupling coils; a Litz wire is adopted to wind a coupling coil; calculating the alternating current resistance of the Litz wire under the high-frequency alternating current; the coils of the transmitting end and the receiving end have the same specification and parameter; establishing a coupling coil structure optimization model; setting upper and lower boundaries of parameter variables; adding constraint conditions; taking the energy transmission efficiency as an optimization target of the target function; and carrying out optimization calculation on the coupling coil structure optimization model by using a kirschner optimization algorithm. The method is shorter in average operation time and higher in operation speed.

The invention discloses a conducting wire state evaluation method and device based on current-carrying capacity, terminal equipment and a storage medium, and belongs to the field of conducting wires, and the method comprises the steps: determining the conducting wire radiation heat dissipation power, conducting wire convection heat dissipation power and conducting wire sunlight heat absorption power of a target conducting wire according to an environment parameter, a physical attribute parameter and a real-time operation parameter; calculating the theoretical current-carrying capacity of the target wire according to the nominal alternating-current resistance value in the physical attribute parameters, the calculated convection heat dissipation power of the wire, the calculated radiation heat dissipation power of the wire and the calculated sunlight heat absorption power of the wire; and according to the theoretical current-carrying capacity, the load current, the wire convection heat dissipation power, the wire radiation heat dissipation power and the wire sunlight heat absorption power, calibrating the nominal alternating current resistance value to obtain a calibrated alternating current resistance value, and calculating the calibrated current-carrying capacity so as to evaluate the operation state of the target wire. According to the invention, the problem of inaccurate lead state evaluation in the prior art can be solved.

The application discloses a flyback transformer winding loss evaluation method, device, equipment and storage medium, and the method comprises the following steps: acquiring electrical data in a preset switching period, and actual primary side current waveform and actual secondary side current waveform of a to-be-tested flyback transformer under the electrical data, and constructing a current calculation model to obtain a primary side current change function and a secondary side current change function; then, the primary side current change function and the secondary side current change function are subjected to Fourier decomposition to obtain a primary side DC component, a primary side harmonic component, a secondary side DC component and a secondary side harmonic component; then, selected primary side harmonic components, selected primary side harmonic frequencies, selected secondary side harmonic components and selected secondary side harmonic frequencies are determined; subsequently, the primary side AC resistance, the primary side DC resistance, the secondary side AC resistance and the secondary side DC resistance of the flyback transformer are acquired; finally, the winding loss value of the to-be-tested flyback transformer is calculated. Through implementation of the application, the winding loss of the flyback transformer can be quantitatively calculated.

A vernier motor or generator is widely concerned due to low copper consumption, the end parts of all phases of windings of a conventional distributed winding are overlapped, the process is complicated, and the required investment of coil inserting equipment is large, the vernier motor or generator with the centralized winding comprises a stator and a rotor (mover) with the centralized winding, the number P of pole pairs of the stator winding is equal to Z1-Z2, Z1 is the number of pole pairs of the stator, and Z2 is the number of pole pairs of the rotor. And the rotor Z2 is the number of pole pairs of the rotor. The motor is mainly characterized in that each winding on the stator is wound in two adjacent winding grooves. In addition, due to the fact that the magnetic density fluctuation range of a notch winding area caused by rotor magnetic steel is too large, the winding generates large alternating current copper loss, the winding even alternating current resistance is far larger than direct current resistance, and a vernier motor or a generator with a magnetic slot wedge or a stator iron core semi-closed slot at the winding notch position is specially developed. After the magnetic slot wedge is used, harmonic waves can be reduced.

The invention discloses a corrugated seven-segment cable core structure, a cable structure and a production process, the corrugated seven-segment cable core structure comprises a central conductor and seven tile-shaped separation strand block conductors, and the seven tile-shaped separation strand block conductors are twisted around the central conductor to form a cable core with a circular cross section; the center conductor and the tile-shaped separation strand block conductors are isolated through graphene insulation paper, and the adjacent tile-shaped separation strand block conductors are isolated through graphene insulation paper. According to the invention, the current transmission channel is obviously increased. Meanwhile, the current transmission capability of the cable is improved by adopting a central conductor and seven-segment corrugated split conductor structure; the insulation paper doped with the graphene is used in the cable conductor, and the graphene has extremely low relative permeability, so that the magnetic flux density in the conductor is reduced, the heat energy generated by the action of a magnetic field is reduced, and the current-carrying capacity and the working efficiency of the cable are improved; and meanwhile, the current can be more uniformly distributed in the conductor, the alternating-current resistance and phase loss of the cable core are reduced, and the transmission efficiency of the cable is enhanced.

The embodiment of the invention provides a cable alternating current resistance measuring system, method and equipment. The system comprises a power supply unit, a zero-phase closing switch unit, a transition loop unit, a to-be-measured cable and a cable measurement loop unit, and the zero-phase closing switch unit is connected with the transition loop unit and the cable measurement loop unit and used for controlling connection or disconnection between the transition loop unit or the cable measurement loop unit and the power supply unit. The power supply unit is connected with the zero-phase closing switch unit and is used for supplying power to the transition loop unit or the cable measurement loop unit, and the transition loop unit is connected with the zero-phase closing switch unit and is used for stably transitioning closing overvoltage generated by the power supply unit to preset voltage; and the cable measurement loop unit is connected with the zero-phase closing switch and the cable to be measured and is used for determining the alternating-current resistance of the cable to be measured. According to the technical scheme, the influence of switching-on overvoltage in a loop can be avoided, and the alternating-current resistance of the to-be-tested cable can be accurately obtained.

The application provides an MCR-WPT system micro-plane coil structure parameter optimization method based on a kingfisher optimization algorithm, which comprises the following steps: analyzing a compensation structure network, deducing an energy transmission efficiency form of the MCR-WPT system; analyzing physical structure parameters in the micro-plane coil, calculating self-induction, mutual induction and alternating current resistance; calculating a theoretical self-induction value of the micro-plane coil; calculating a mutual induction coefficient value between the coupling coils; winding the coupling coils with Litz wires; calculating the alternating current resistance of the Litz wires under high-frequency alternating current; making the coils at the transmitting end and the receiving end have the same specifications and parameters; establishing a coupling coil structure optimization model; setting the upper and lower limits of the parameter variables; adding constraint conditions; taking the energy transmission efficiency as an optimization target of the objective function; and performing optimization calculation on the coupling coil structure optimization model by using the kingfisher optimization algorithm. The method has shorter average running time and faster operation speed.

The invention discloses a transformer winding loss calculation method and a related device. The method comprises the steps of obtaining harmonic current of an environment where a transformer winding is located; calculating the AC resistance of the transformer winding according to the harmonic current through a skin effect and a proximity effect; acquiring a non-sine-wave current of an environment where the transformer winding is located, and decomposing the non-sine-wave current into a plurality of harmonic components; after the height of the transformer winding is adjusted to be equal to the height of the magnetic core window based on a preset transformer winding design method, the frequency of each harmonic component is calculated, and the total winding loss is calculated according to the frequency of the harmonic component and the alternating-current resistance. By optimizing the structure of the winding and the loss calculation method, the operation efficiency and reliability of the medium-frequency transformer are effectively improved, and energy loss caused by the high-frequency electromagnetic effect is reduced. Therefore, the problems of loss increase caused by inaccurate winding loss calculation and winding height mismatching in a high-frequency environment and complex loss caused by harmonic current in the prior art are solved.

This application provides a method for determining a filtering device, a storage medium, and a filtering device. The method includes acquiring a first test result, which is obtained by conducting conducted EMI interference testing on a first domain controller based on a current method. Based on the first test result, a first out-of-range frequency point of the first domain controller is determined. The rated current of a common-mode inductor is determined based on the actual input current of the first domain controller. A first AC resistance of the common-mode inductor is determined based on the out-of-range value corresponding to the first out-of-range frequency point and the first out-of-range frequency point. A target size of the common-mode inductor is determined based on the spatial dimensions of the first domain controller. The common-mode inductor is then designated as the first filtering device for the first domain controller, thereby performing conducted EMI filtering on the first domain controller. This embodiment enables rapid, effective, and low-cost conducted EMI interference testing through a domain controller.

The application discloses a large-section conductor alternating current resistance automatic testing system and method, and relates to the electrical testing field.The system comprises a computer, an FPGA / real-time system, a D / A converter 1, a D / A converter 2, a D / A converter 3, an A / D converter, a voltage-controlled current source, electrodes, a GIL conductive pipe sample, a through-type high-precision current transformer, a high-precision resistor R, a lock-in amplifier and a coupling transformer with a load Z.The application eliminates the mutual inductance between a current loop and a voltage testing loop and the influence of the self-inductance of a sample, generates a 90-degree leading current voltage based on an equivalent circuit model through the FPGA and the D / A converter, and is used for compensating the voltage on the self-inductance of the sample and the mutual inductance in the voltage testing loop, reducing the phase angle between the voltage on the measured conductor and the exciting current, solving the precision problem of the large-section conductor alternating current resistance testing, and realizing the accurate and automatic measurement of the large-section conductor alternating current resistance.

The purpose of the present invention is to reduce AC resistance. In a multilayer substrate (100), a plurality of ground electrodes (41-44) are separated from each other in the thickness direction (D1) of a laminated substrate (1), and are adjacent to a plurality of signal lines (21-24) in the width direction of the plurality of signal lines (21-24). In a first transmission line region where the maximum line width of the plurality of signal lines (21-24) is minimum, the plurality of signal lines (21-24) do not overlap with any one of the plurality of ground electrodes (41-44) in the thickness direction (D1) of the laminated substrate (1). In a second transmission line region (102) in which the maximum line width of the plurality of signal lines (21-24) is the largest, one ground electrode (41) among the plurality of ground electrodes (41-44) overlaps with signal lines (22-24) other than the signal line (21) adjacent to the one ground electrode (41) among the plurality of signal lines (21-24).

The utility model discloses a low-temperature-rise inductor, which belongs to the technical field of inductors and comprises a magnetic core, a wire body and a shell, the inductor is novel in design and ingenious in device, heat can be conducted and dissipated more effectively by introducing high-heat-conductivity materials into the magnetic core and the wire body, the magnetic core and the wire body are made of high-heat-conductivity copper alloy materials, the temperature rise of the inductor is reduced, the wire body adopts the flat winding or Litz wire winding design, the surface area of the winding is increased, the heat dissipation efficiency of the winding is improved, and the service life of the inductor is prolonged. The flat winding and the Litz wire can reduce the skin effect and the proximity effect and reduce alternating current resistance, so that heating is reduced, a special heat dissipation channel is designed in the inductor, it is ensured that heat can be rapidly conducted to the outside, the heat dissipation channel can effectively guide heat to flow, heat is prevented from being accumulated in the inductor, and therefore the heat dissipation effect of the inductor is improved. By improving materials and structural design, the low-temperature-rise inductor can effectively reduce temperature rise under the high-current condition, and the overall performance and reliability are improved.

The application discloses a kind of litz wire winding intelligent design optimization methods, and the litz wire winding ac resistance and porosity are obtained by neural network and hfss, the model of litz wire winding is constructed using hfss simulation software to simulate the ac resistance of litz wire winding under different materials, different number of turns, different litz wire winding radius and different frequency, to complete the training data and test data used to litz wire winding neural network model. Manual grid division is used to simplify the solving steps and time, and the accuracy is ensured. The litz wire winding neural network model is used to automatically train and test using particle swarm optimization algorithm to improve the network model, and finally the litz wire winding neural network model can quickly and accurately obtain the required litz wire winding ac resistance. The application can be used to quickly and accurately obtain the litz wire winding ac resistance under different requirements, reduce the amount of calculation and working time, greatly improve the efficiency.

The utility model provides an antenna module and an electronic terminal device, the antenna module comprises a first radiation antenna, a second radiation antenna, a feed assembly, a grounding assembly and a substrate, the feed assembly and the grounding assembly are electrically connected with the first radiation antenna and the second radiation antenna; the first radiating antenna and the second radiating antenna are arranged on the substrate; the second radiation antenna is arranged around the first radiation antenna; the first radiation antenna comprises a first coil and a second coil, the first coil and the second coil are attached to the two faces of the substrate respectively, the first coil and the second coil are connected in series, and the second radiation antenna surrounds the first coil and / or the second coil. The antenna module provided by the utility model not only can simplify the overall circuit of the antenna and effectively improve the net space of the antenna, but also can effectively avoid the overall resistance of the antenna by changing the wiring connection of the coil, so that the first radiating antenna can obtain larger inductance under the condition of lower alternating-current resistance.

The invention provides an overhead conductor alternating current resistance measuring method which comprises the following steps: S1, arranging a Rogowski coil on an overhead conductor, acquiring current flowing through the overhead conductor based on electromagnetic induction, sampling induced current of the Rogowski coil through a current sampling circuit, and outputting the sampled induced current to a processing unit; s2, a voltage transformer is arranged on the overhead conductor and used for obtaining the alternating voltage of the overhead conductor, and a voltage sampling circuit determines a voltage sampling signal and outputs the voltage sampling signal to a processing unit; s3, detecting the environment temperature of the current overhead conductor and outputting the environment temperature to a processing unit; and S4, the processing unit obtains the AC resistance of the current overhead conductor according to the current sampling signal, the voltage sampling signal, the conductor temperature and the environment temperature by adopting a least square method.

The embodiment of the invention provides a stator winding, a motor and a motor optimization method, the stator winding comprises a multi-phase winding structure, each phase winding structure comprises at least one stator slot, each stator slot comprises at least one copper flat wire and at least one aluminum flat wire, and the copper flat wire is arranged at the notch of the corresponding stator slot; the aluminum flat wires are arranged at the bottoms of the corresponding stator grooves. Therefore, the copper flat wire and the aluminum flat wire which are connected in series and in parallel are arranged in the stator slot of each phase winding structure, the copper flat wire is arranged corresponding to the slot opening of the stator slot, and the aluminum flat wire is arranged corresponding to the slot bottom of the stator slot, so that the problem that the alternating current resistance of a copper flat wire motor in the prior art rises quickly along with the rotating speed is solved; and the motor has the characteristics of low winding resistance and high working condition efficiency in a wide speed domain range, so that the energy consumption of the motor is effectively reduced.

The utility model discloses a special alternating current resistance box for detecting a conductivity meter, which relates to the technical field of alternating current resistance boxes and comprises a resistance box main body, wiring grooves are arranged on the back of the resistance box main body at equal intervals, a wiring mechanism is arranged on the outer side of the resistance box main body, and the wiring mechanism comprises a bearing assembly and a pressing assembly. The bearing assembly and the pressing assembly are used in cooperation, the bearing assembly comprises rotating shafts, the rotating shafts are symmetrically and rotatably connected to the outer side of the resistance box body, and rotating ends are fixedly connected to the outer sides of the two rotating shafts. According to the alternating-current resistance box special for detecting the conductivity meter, due to the arrangement of the ground wiring mechanism, it can be ensured that electric wires are arranged in the wire grooves of the bearing columns in order, the electric wires are kept stable and prevented from loosening or falling off through the tension of the tension springs, the situation that the electric wires are not attached due to the toughness of the electric wires is avoided, the structure is simple, and the practicability is high. And the practicability is high.

The application relates to a flat wire stator with multi-parallel winding, comprising a stator core and a flat wire winding, the stator core has a plurality of stator slots, the number of layers of the flat wire winding in the stator slots is ten, and the flat wire winding comprises a three-phase winding; the three-phase winding is three groups of parallel winding lines, each group of winding lines is five parallel branches, and each branch comprises a plurality of PIN wire conductors arranged in the stator slots and connected in series with each other. After the winding is divided into ten layers, the thickness direction size of each layer of conductors is relatively small, the increase of high-frequency alternating current resistance can be obviously inhibited, and the design of five parallel branches per phase makes the total current be uniformly shunted to the five branches, and the current borne by each branch is only 1 / 5 of the total current. This reduces the current stress of each PIN wire conductor, allows the use of a smaller cross-sectional area of the conductor, reduces the Joule heat concentration in the branch, and improves the motor temperature rise.

Such an apparatus, having a structure to measure a battery parameter of a battery of a plurality of batteries, can be implemented in a variety of applications. The apparatus can be configured to measure an alternating current (AC) electrical impedance of a battery cell by processing a difference between the battery cell and another battery cell. The battery cell under measurement experiences an AC excitation, while the other does not, with both battery cells sharing a common load current. This differential approach can reduce sensitivity to noisy battery load currents, which are common to both battery cells. This differential approach can also eliminate or substantially reduce a large direct current (DC) offset, i.e., the battery potential itself, under which AC signal measurements are burdened.

To provide a transformer with small AC resistance despite its low magnetic coupling.SOLUTION: A transformer 1 comprises: a primary winding 2; a secondary winding 3; and a core 7 that has a center leg part 71 where the primary winding 2 and the secondary winding 3 are wound with a gap therebetween, and a side leg part 72 provided on the outer peripheral side of the primary winding 2 and the secondary winding 3. The transformer comprises: a first magnetic member 21 that is arranged in contact with at least part of a surface of winding material of the primary winding 2, and is formed of magnetic composite material including magnetic powder and matrix material; a second magnetic member 31 that is arranged in contact with at least part of a surface of winding material of the secondary winding 3, and is formed of magnetic composite material including magnetic powder and matrix material; and a third magnetic member 4 that is arranged between the primary winding 2 and the secondary winding 3, and is formed of magnetic composite material including magnetic powder and matrix material.SELECTED DRAWING: Figure 1

The application discloses a cable conductor AC resistance testing device and method, which directly supplies a large current to a cable conductor, measures the temperature, current and voltage of the powered cable conductor, adopts the measured data and a function relationship between the interference voltage value and the cable conductor radius which is fitted in advance, and obtains the cable conductor AC resistance, so that the reverse current is not applied to the cable metal shielding layer, and the proximity effect between the cable conductor and the shielding layer is avoided to influence the test result.

The invention belongs to the technical field of computer-aided engineering and power electronics, and particularly relates to a rotating motor rotor overvoltage calculation method and system based on an industrial database, and the method comprises the steps: obtaining a preset motor design reference value, a preset material attribute parameter and a preset voltage change rate threshold value in the industrial database; monitoring the voltage at the input end of the motor in real time to obtain a real-time voltage change rate; performing spectral analysis on the transient voltage waveform, and calculating a dominant angular frequency; calculating dynamic alternating-current resistance and dynamic alternating-current inductance through a frequency self-adaptive parameter model; coupling the dynamic alternating-current resistor and the dynamic alternating-current inductor to an overvoltage propagation model, and calculating a rotor overvoltage waveform; generating a high-frequency impedance model, and providing the high-frequency impedance model to a frequency converter control system; according to the method, the self-adaptive model capable of adjusting the resistance and inductance parameters of the motor in real time according to the actual frequency characteristics of the transient event is constructed, so that the final overvoltage calculation result is highly consistent with the physical reality.

The invention belongs to the technical field of aviation, and particularly relates to an aviation high-power motor round wire alternating current copper loss evaluation and reduction method, which comprises the following steps of: based on a stator after wire embedding, measuring wire resistances at different frequencies and different rotor positions by adopting an alternating current resistance tester, further calculating alternating current copper loss again by using simulated phase current, and judging whether the alternating current copper loss is met or not; if yes, completing the design; and if not, optimizing the alternating current copper loss again, and repeatedly calculating the alternating current copper loss until the alternating current copper loss meets the requirement. MotorCAD software is adopted to calculate alternating current copper loss through finite elements, modeling is simple, winding subdivision is refined, and the difference between the calculation result and the actual result is small. The stator winding mode is optimized, and the ring current of the groove leakage flux on the same turn of wires located at different groove height positions is reduced; and the stator slot size is optimized, so that the slot size with relatively low alternating current copper consumption can be obtained. Part of tests prove that the alternating current copper consumption can be greatly reduced, and the motor efficiency is improved.

The invention belongs to the technical field of busbar current carrying capacity calculation, and discloses a method for quickly calculating the current carrying capacity of a copper / aluminum busbar conductor. The method comprises the steps of inputting copper / aluminum busbar size information and temperature information; obtaining an additional loss coefficient K by looking up a table; S , conductor resistivity p c and temperature coefficient a; calculate the DC resistance R0 and AC resistance R at the operating temperature t ; Calculate the heat dissipation P of the conductor Z ; Calculate the current carrying capacity of copper and aluminum bars I = [(P r +P c ) / R t ] 1 / 2 The present invention combines the actual engineering needs to look up the table to obtain the additional loss coefficient K affected by the skin effect and proximity effect S , making the calculation results more accurate, the heat dissipation is divided into surface radiation heat P r and natural convection heat dissipation P c , respectively calculated and added to get the heat dissipation P Z , and the calculation results thus obtained are more in line with the actual situation.

The invention discloses a method and a system for predicting coil parameters of a wireless power transmission system, and relates to the technical field of coil electrical parameter calculation, finite element simulation is performed based on an established two-dimensional parameterized geometric model of a circular coil to obtain training data, and the training data is used to train an improved Gaussian process regression model to obtain a prediction result. The method comprises the steps of obtaining a coil parameter prediction model, constructing an integrated learning correction model based on the coil parameter prediction model, predicting coil geometric parameters to be predicted based on the coil parameter prediction model and the integrated learning correction model, and obtaining coil electrical parameters including alternating-current resistance, self-inductance and mutual inductance. According to the method, the coil parameters under different working conditions are efficiently predicted, the time consumption of traditional finite element simulation is reduced, the accuracy of coil alternating current resistance, self inductance and mutual inductance obtained through prediction is more effectively ensured, and therefore the coil parameters of the wireless power transmission system are accurately and efficiently predicted.

An inductor has a main magnet core, a coil mounted around the main magnet core, and a residual magnet encapsulating the main magnet core and partially encapsulating the coil. The main magnet core is made of a main magnet core powder containing amorphous iron base material and nickel base material powders. The residual magnet is made of a residual magnet powder containing a main magnet powder and a soft magnet powder including an iron-silicon-chromium alloy powder and a carbonyl iron powder. Thus, through a low-loss feature of the amorphous iron base material and nickel base material powders, a loss of the main magnet core is reduced. Furthermore, a magnetic permeability of the residual magnet matches a magnetic permeability of the main magnet core. A magnetic leakage is further avoided, and the alternating current resistance is reduced. A quality factor and a conversion efficiency are enhanced.

The invention discloses a thermal evaluation method and device for a double-spliced cable line laid in a pulling and jacking pipe, and the method comprises the steps: obtaining the first AC resistance of a core wire and the second AC resistance of a metal sheath of each cable at the initial temperature of the core wire; actual transmission capacity data and thermal resistance parameters are obtained; obtaining core wire loss and circulating current loss of each cable; obtaining the mutual heating temperature rise of the kth cable to the pth cable; obtaining the self-heating temperature rise of each cable; obtaining a core wire calculation temperature of each cable according to the mutual heating temperature rise, the self-heating temperature rise and the environment boundary temperature of each cable; acquiring a temperature difference value between the core wire initial temperature and the core wire calculation temperature of at least one cable; when the temperature difference value is smaller than or equal to a preset difference value and each core wire calculation temperature is smaller than a first preset temperature, determining the core wire calculation temperature of each cable as a core wire steady-state temperature of each cable; otherwise, determining the core wire calculation temperature of each cable as the core wire initial temperature of each cable; and returning to execute the steps.