Showing papers on "Magnetic core published in 2012"

Single-Phase Improved Active Clamp Coupled-Inductor-Based Converter With Extended Voltage Doubler Cell

Abstract: In this paper, A single-phase improved active clamp coupled-inductor-based converter with extended voltage doubler cell is proposed for large-voltage conversion ratio applications. The secondary winding of the coupled inductor is inserted into the half-wave voltage doubler cell to extend the voltage gain dramatically and decrease the switch voltage stress effectively. By combining the coupled inductor and voltage doubler cell structure, the disadvantage of the potential resonance between the leakage inductance and the diode stray capacitor is cancelled, and the unexpected high pulsed current in the voltage doubler cell is decreased due to the inherent leakage inductance of the coupled inductor. Meanwhile, the active clamp scheme is employed to recycle the leakage energy, suppress the switch turn-off voltage spikes, and implement zero-voltage-switching turn-on operation. In addition, there is only one magnetic component in the proposed converter and the coupled inductor operates not only as a filter inductor, but also as a transformer when the main switch is in the ON state, which reduces the volume of the magnetic core and improves the power density of the converter. A 500 W prototype operating at 100 kHz with 48 V input and 380 V output is built to verify the analysis. The maximum efficiency of the prototype is nearly 97% and the efficiency is higher than 96% over a wide load range.

A 2.5D integrated voltage regulator using coupled-magnetic-core inductors on silicon interposer delivering 10.8A/mm 2

Abstract: Energy consumption is a dominant constraint on the performance of modern microprocessors and systems-on-chip. Dynamic voltage and frequency scaling (DVFS) is a promising technique for performing “on-the-fly” energy-performance optimization in the presence of workload variability. Effective implementation of DVFS requires voltage regulators that can provide many independent power supplies and can transition power supply levels on nanosecond timescales, which is not possible with modern board-level voltage regulator modules (VRMs) [1]. Switched-inductor integrated voltage regulators (IVRs) can enable effective implementation of DVFS, eliminating the need for separate VRMs and reducing power distribution network (PDN) impedance requirements by performing dc-dc conversion close to the load while supporting high peak current densities [2–3]. The primary obstacle facing development of IVRs is integration of suitable power inductors. This work presents an early prototype switched-inductor IVR using 2.5D chip stacking for inductor integration.

Effect of surface modification on magnetization of iron oxide nanoparticle colloids

Abstract: Magnetic iron oxide nanoparticles have numerous applications in the biomedical field, some more mature, such as contrast agents in magnetic resonance imaging (MRI), and some emerging, such as heating agents in hyperthermia for cancer therapy. In all of these applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration, and add functionality. However, the coatings may interact with the surface atoms of the magnetic core and form a magnetically disordered layer, reducing the total amount of the magnetic phase, which is the key parameter in many applications. In the current study, amine and carboxyl functionalized and bare iron oxide nanoparticles, all suspended in water, were purchased and characterized. The presence of the coatings in commercial samples was verified with X-ray photoelectron spectroscopy (XPS). The class of iron oxide (magnetite) was verified via Raman spectroscopy and X-ray diffraction. In addition to these, in-house prepared iron oxide nanoparticles coated with oleic acid and suspended in heptane and hexane were also investigated. The saturation magnetization obtained from vibrating sample magnetometry (VSM) measurements was used to determine the effective concentration of magnetic phase in all samples. The Tiron chelation test was then utilized to check the real concentration of the iron oxide in the suspension. The difference between the concentration results from VSM and the Tiron test confirmed the reduction of magnetic phase of magnetic core in the presence of coatings and different suspension media. For the biocompatible coatings, the largest reduction was experienced by amine particles, where the ratio of the effective weight of magnetic phase reported to the real weight was 0.5. Carboxyl-coated samples experienced smaller reduction with a ratio of 0.64. Uncoated sample also exhibits a reduction with a ratio of 0.6. Oleic acid covered samples show a solvent-depended reduction with a ratio of 0.5 in heptane and 0.4 in hexane. The corresponding effective thickness of the nonmagnetic layer between magnetic core and surface coating was calculated by fitting experimentally measured magnetization to the modified Langevin equation.

Suppression of leakage magnetic field from a wireless power transfer system using ferrimagnetic material and metallic shielding

Abstract: This paper describes a method to suppress the leakage magnetic field from a wireless power transfer (WPT) system through the use of a ferrimagnetic material and metallic shielding To demonstrate the advantages of the coil structure with the ferrimagnetic material and metallic shielding, magnetic field distributions and the electrical performance of three different coil structures are investigated via 3D electromagnetic (EM) field solver and SPICE simulation Results show that the suggested method considerably reduces the leakage magnetic field in the vicinity of the WPT system without significant loss of electrical performance The simulation results of the suggested coil structure are experimentally verified with a 100 W-class WPT system for an LED TV

Micro-magnetic simulation study on the magnetic particle imaging performance of anisotropic mono-domain particles

Abstract: The performance of magnetic mono-domain particles is of crucial importance in magnetic particle imaging (MPI). So far, the behavior of mono-domain particles has been modeled within the framework of Langevin theory. This theory predicts the dependence of the MPI signal on the particle core size, but cannot account for the influence of the shape, i.e. the anisotropy of the particle core. In this study we present the first micro-magnetic ab initio simulation of spectra of anisotropic particles with different core diameters in an oscillating magnetic field at 25 and 100 kHz. We find that the MPI signal strongly depends on the anisotropy of the magnetic core. Thus, a difference of 3 nm between the principal axes of a prolate ellipsoid with the volume of a 30 nm sphere can result in a complete loss of the MPI signal. Smaller anisotropies, however, can increase the MPI performance of the particle. The simulations show that the effect of the anisotropy on the MPI signal depends on the frequency of the oscillating magnetic field. At 100 kHz, the optimal signal is found at smaller anisotropies than at 25 kHz. Furthermore, the simulations show that experimental spectroscopic results for Resovist® can only be explained quantitatively by particles with a magnetic core size of at least 25 nm.

Design study and experimental analysis of wound field flux switching motor for HEV applications

Abstract: This paper presents design study, optimization and performance analysis of wound field flux switching machine with non-rare-earth magnet for hybrid electric vehicle drive applications. The stator of proposed machine consists of iron core made of electromagnetic steels, armature coils and field excitation coils as the only field mmf source. The rotor is composed of only stack of iron and hence, it is robust and suitable for high speed operation. The design target is a machine with the maximum torque and power density, and the maximum speed more than 210Nm and 3.5kW/kg, and 20,000r/min, respectively, which competes with interior permanent magnet synchronous machine used in an existing hybrid electric vehicle. Deterministic optimization method is applied to design the proposed machine until the target performances are achieved. Some experimental studies using a prototype of the finally designed machine are demonstrated to validate the effectiveness of the proposed machine.

Nanoparticle magnetization measurements by a high sensitive nano-superconducting quantum interference device

Abstract: A high sensitive nano superconducting quantum interference device (nanoSQUID) operating as a magnetic flux to critical current transducer with a suitable feedback circuit is employed to measure the magnetization of ferrimagnetic iron oxide nanoparticles An improved SQUID responsivity has been obtained by using a loop inductance asymmetry Iron oxide nanoparticles having a mean diameter of 8 nm have been excited by applying a polarizing field in the plane of the nanoSQUID loop The field dependence of the nanoparticle magnetization at T = 42 K shows magnetic hysteresis Magnetic relaxation measurements are reported and compared with those obtained by using a commercial measurement system

Rotary electric machine

Abstract: PROBLEM TO BE SOLVED: To achieve high efficiency and high torque of a rotary electric machine by a method with a low cost and high reliability.SOLUTION: In an inner rotor type rotary electric machine in which a stator iron core and a rotor iron core are opposed to each other, and rugged gaps are provided between both iron cores, at least, the stator iron core has an armature and is constituted by collecting a plurality of divided dust iron cores.

Rotor for electric rotating machine

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

Integrated on-chip inductors with electroplated magnetic yokes (invited)

Abstract: Thin-film ferromagnetic inductors show great potential as the energy storage element for integrated circuits containing on-chip power management. In order to achieve the high energy storage required for power management, on-chip inductors require relatively thick magnetic yoke materials (several microns or more), which can be readily deposited by electroplating through a photoresist mask as demonstrated in this paper, the yoke material of choice being Ni45Fe55, whose properties of relatively high moment and electrical resistivity make it an attractive model yoke material for inductors. Inductors were designed with a variety of yoke geometries, and included both single-turn and multi-turn coil designs, which were fabricated on 200 mm silicon wafers in a CMOS back-end-of-line (BEOL) facility. Each inductor consisted of electroplated copper coils enclosed by the electroplated Ni45Fe55 yokes; aspects of the fabrication of the inductors are discussed. Magnetic properties of the electroplated yoke materials are...

Design of coupled power inductors with crossed anisotropy magnetic core for integrated power conversion

Abstract: Design and partial microfabrication of a coupled power inductor is presented for use in high power-density integrated voltage regulators (IVR). The proposed inductor uses many laminations of uniaxial, high-permeability magnetic material where the orientation of anisotropy between successive laminations is rotated to provide an effectively isotropic core. The high permeability core allows for an inductance density of 200nH/mm2, while coupling between phases prevents magnetic saturation and allows a current density as high as 11A/mm2 according to quasi-static finite-element-analysis (FEA) simulations. The coupling factor, inductance and resistance of the device are optimized for operation in a four-phase integrated buck converter switching at 100MHz.

Three-Level Forward–Flyback Phase-Shift ZVS Converter With Integrated Series-Connected Coupled Inductors

Abstract: In this paper, a novel three-level Forward-Flyback phase-shift converter is proposed for high-input voltage and high-efficiency applications. The primary-side structure of this converter is similar to that of the conventional three-level phase-shift converters, which makes the switch voltage stress only half of the input voltage and the voltage on the capacitor divider autobalanced. There are only two coupled inductors in this converter and each coupled inductors has two windings. The primary windings of the two coupled inductors are in series to achieve buck-type conversion. And their secondary windings operate in the interleaved mode to sustain the large current. The coupled inductors operate in Flyback and Forward modes to enhance the magnetic core utility rate. Furthermore, the two coupled inductors can be integrated into a magnetic core to further improve the power density. In addition, zero-voltage-switching performance of the inner switches at light load condition can be provided because the magnetizing current can be employed to charge and discharge the parallel capacitors. As a result, the switching losses are minimized at a wide load range. A 500 V prototype is tested to verify the advantages of the proposed converter.

Luminescent and Magnetic Properties of Fe3O4@SiO2@Y2O3:Eu3+ Composites with Core–Shell Structure

Abstract: Multifunctional Fe3O4@SiO2@Y2O3:Eu3+ composites were prepared with a facile solvothermal method followed by a subsequent heat treatment. Their structure and magnetic and luminescent properties were analyzed and discussed. Y2O3:Eu3+ phosphor as a shell was coated on the surface of Fe3O4@SiO2 as the core to form Fe3O4@SiO2@Y2O3:Eu3+ composites. The particle size of the composites is 262.36 nm which consists of the magnetic core with about 210 nmin diameter and a silica shell with an average thickness of about 20 nm. It exhibits ferromagnetic behavior with the special saturation magnetization Ms of 12.62 emu/g, the negligible coercivity Hc, and remanence Mr at room temperature and exhibits a strong red emission peak originating from the electric–dipole transition 5D0 → 7F2 of Eu3+ ions at 611 nm. The current and potential biomedical uses include biological imaging, cell tracking, and magnetic bioseparation.

Integrated RF On-Chip Inductors With Patterned Co-Zr-Ta-B Films

Abstract: Integrated on-chip inductors with boron-incorporated amorphous Co-Zr-Ta-B films for reducing the size of the inductor and increasing the quality factor are presented. A 3.5-fold increase in inductance and a 3.9-fold increase in quality factor over inductors without magnetic films are measured at frequencies as high as 1 GHz. The Co-Zr-Ta-B films are patterned into the shape of fingers in the magnetic via region to improve the on-chip inductors, high frequency response. Compared with nonpatterned films, finger-shaped magnetic vias result in at least a 30% increase in quality factor in the gigahertz range. It is also demonstrated that by using laminations, an up to 9.1X inductance increase with good frequency response up to 2 GHz can be achieved.

Design and Fabrication of VHF Tapped Power Inductors Using Nanogranular Magnetic Films

Abstract: The design and fabrication of coupled inductors with low profile, low cost, and high power density for tapped-inductor high-step-down dc-dc power converters in the very-high-frequency (30-300 MHz) range are presented. The inductor consists of a multilayer thin-polyimide printed circuit board with nanogranular thin-film magnetic material deposited on both sides and on beveled cuts to form a fully linked closed core. The magnetic material Co-Zr-O has good soft magnetic properties, high resistivity, and high flux density capability. Multilayer Co-Zr-O/ZrO2 thin films are used to improve the performance of the magnetic core. A winding loss model of this coupled inductor is presented. Coupled inductors with turns ratios 2 and 10 for several different converter applications have been designed, fabricated, and measured. Loss in the magnetic material is investigated. Small-signal and large-signal measurements show good performance of the fabricated components with high-frequency, high-field excitation.

Comparison of soft magnetic composites (SMCs) and electrical steel

Abstract: This paper deals with a comparison of soft magnetic composites (SMCs) and electrical steel. At first the theory and practice of measuring of the magnetic properties with the ring core method are described. Next a comparison between electrical steel and SMC regarding different frequencies, flux densities and magnetic field strengths is given. The measurements have shown that SMCs have less iron losses, i.e. mainly hysteresis and eddy current losses, for high frequencies due to their low electrical conductivity. However the magnetic permeance of SMCs is less than that of electrical steel and consequently a higher magnetic field strength and thus a higher current is needed to obtain the same magnetic flux density. Since higher current increases the ohmic losses, an estimation of the total losses, i.e. the sum of iron and ohmic losses is given at the end.

A novel integrated magnetic structure suitable for transformer-linked interleaved boost chopper circuit

Abstract: A novel integrated magnetic structure suitable for the transformer-linked interleaved boost chopper circuit is proposed in this paper. The coupled inductor is known to be effective for miniaturization in high coupling area because the DC flux in the core can be canceled and the inductor current ripple become to high frequency. However, coupled inductor with E-E core and E-I core are realistically difficult to obtain necessary leakage inductance in high coupling area. The cause is fringing effect and the effects leads to complication of magnetic design. To solve this problem, novel integrated magnetic structure with reduction of fringing flux and high frequency ripple current performance, is proposed. Furthermore, the design method for novel integrated magnetic structure suitable for coupled inductor is proposed from analyzing of the magnetic circuit model. Finally, effectiveness of reduction of fringing flux and design method for novel coupled inductor are discussed from experimental point of view.

Core loss behavior in high frequency high power transformers—II: Arbitrary excitation

Abstract: High frequency high power transformers used in power electronic converters are frequently subjected to non-sinusoidal excitations. The main purpose of this paper is to study the effects of some general arbitrary waveforms on magnetic core loss in these transformers. First, using well-known empirical equations, general expressions were derived based on the parameters of the waveforms. Second, the impacts of different orders of voltage harmonics were investigated. Finally, capabilities of nanocrystalline and amorphous magnetic materials were compared. It is shown that the loss inside the core is highly sensitive to the rise time and duty cycle of trapezoidal and rectangular waveforms, respectively. Furthermore, although amorphous materials have higher saturation flux density, the total core loss inside the transformer designed using nanocrystalline material is considerably lower than the similar transformer with amorphous materials.

Transient simulation of magnetic circuits using the permeance-capacitance analogy

Abstract: When modeling magnetic components, the permeance-capacitance analogy avoids the drawbacks of traditional equivalent circuits models. The magnetic circuit structure is easily derived from the core geometry, and the energy relationship between electrical and magnetic domain is preserved. Non-linear core materials can be modeled with variable permeances, enabling the implementation of arbitrary saturation and hysteresis functions. Frequency-dependent losses can be realized with resistors in the magnetic circuit. The magnetic domain has been implemented in the simulation software PLECS. To avoid numerical integration errors, Kirchhoff's current law must be applied to both the magnetic flux and the flux-rate when solving the circuit equations.

On the performance of a dual-mode non-linear vibration energy harvesting device

Abstract: The research trend for harvesting energy from the ambient vibration sources has moved from using a linear resonant generator to a non-linear generator in order to improve on the performance of a linear generator; for example, the relatively small bandwidth, intolerance to mistune and the suitability of the device for low-frequency applications. This article presents experimental results to illustrate the dynamic behaviour of a dual-mode non-linear energy-harvesting device operating in hardening and bi-stable modes under harmonic excitation. The device is able to change from one mode to another by altering the negative magnetic stiffness by adjusting the separation gap between the magnets and the iron core. Results for the device operating in both modes are presented. They show that there is a larger bandwidth for the device operating in the hardening mode compared to the equivalent linear device. However, the maximum power transfer theory is less applicable for the hardening mode due to occurrence of the ...

Hybrid excitation generator with permanent and electromagnetic series magnetic fields

Abstract: The invention provides a hybrid excitation generator with permanent and electromagnetic series magnetic fields, and belongs to the technical field of automobile motor electric appliances. The hybrid excitation generator consists of a rotor, a stator, a front end cover, a back end cover and an electronic voltage regulation controller, wherein a radial permanent magnetic field and a salient pole electromagnetic field share the same rotor iron core; a generated magnetic field is formed through series connection in an air gap of the generator, the magnetic field intensity is high, and the power density of the generator is high; and during operation, the magnitude and the direction of the energization current of a salient pole electrical excitation rotor are adjusted to ensure that the magnetic field which is formed by superimposing the permanent magnetic field and an electrical excitation magnetic field is adjustable, the output voltage in a wide rotating speed and wide load range is kept stable, and a direct current power supply is provided for modern automobile electrical equipment.

Multi-phase air-cored tubular permanent magnet linear generator for wave energy converters

Abstract: Direct driven permanent magnet linear generators (PMLGs) are an alternative solution for wave energy converters (WECs). Generally, problems such as high magnetic attraction forces between the permanent magnets and the magnetic core are associated with direct driven PMLG. To eliminate the attraction, air-cored generators can be used. They do not contain any stainless steel in either the stator or the rotor and therefore there is no magnetic attraction between the moving and the stationary parts. In this study, a novel design of multi-phase air-cored PMLG is proposed. The main advantage of the generator is the reduction in the Lorentz forces acting on the bearings by addressing the force in the direction parallel to the motion axis and elimination of cogging forces. Additionally, in the study a new system bypassing inactive coils is proposed and simulated as part of the grid integration system. The system achieves implementation of a small number of elements connected in series with the coils and hence the thermal losses in the grid integration system are reduced. All simulations are made by means of finite-element (FE) software working simultaneously with Matlab/Simulink.

Effective Combination of Soft Magnetic Materials for Magnetic Shielding

Abstract: This study proposes an effective method in the arrangement of layers of high permeability materials for shielding power frequency magnetic field. The side of a neutral ground reactor was blocked with one or two layers of grain-oriented electrical steel (GO), nonoriented electrical steel (NGO), and permalloy (PC). In a weak magnetic field, PC showed the highest shielding performance, whereas GO was the best in a strong magnetic field. NGO had a lower shielding performance than GO, but was better than PC in a very strong magnetic field. When shielding with two layers directly adjacent to each other, the performance level of GO/PC combination (GO is closer to the field source) was between that of GO/GO and PC/PC combinations. When the two layers were slightly separated, on the other hand, GO/PC was most effective in a wide range of magnetic fields. These results are due to the shunt effect of high permeability materials and change of rank of permeability with magnetic field strength between different magnetic materials. Closely adjacent layers act as one body under the regime of shunt mechanism of magnetic shielding. Once the layers are separated, the GO sheet effectively reduces the strong magnetic field first, and then the PC sheet effectively shields the weakened field.

Core loss behavior in high frequency high power transformers—I: Effect of core topology

Abstract: This two-part paper presents an overview of core loss computations performed in both time and frequency domains in order to evaluate their behavior in single phase transformers with different core topologies. Moreover, the effects of non-sinusoidal waveforms on well-known core loss calculation methods are investigated with both analytically and finite element calculations. Three well-known configurations of transformers utilized in high frequency high power applications are investigated, namely, the core type, the shell type, and the matrix transformer. Based on the results obtained from a large number of FEM simulations for different operating conditions, the efficiencies of the transformers are compared in terms of distribution of magnetic flux density, loss density, total core loss, and weight. The analysis shows that for lower range of frequency and power, the shell type core could be the favorable option, and on the other hand, core type seems to be an appropriate solution for higher values of the operating frequency and nominal power.

Computation of 3-D Magnetic Leakage Field and Stray Losses in Large Power Transformer

Abstract: A time-stepping finite element method combining analytical and numerical solutions for laminated-material homogenization is proposed to calculate 3-D magnetic leakage field and its structural parts stray losses in a 380 000 kVA/500 kV single-phase power transformer, and the high-order harmonics of field components can be considered. To verify the method and computation code, a supplementary model of Team Problem P21C-M1 is made. Measured and computed results to the model indicate the validity of the method proposed.

Magnetic structure and magnetic air-conditioning and heating device using same

Abstract: A magnetic structure includes: a magnetocaloric material that changes in temperature due to application and removal of a magnetic field; and a high heat conduction member that is in contact with the magnetocaloric material and has higher heat conductivity than the magnetocaloric material. A magnetic heating and cooling apparatus includes: the plural magnetic structures; a heat switch interposed between the magnetic structures to perform heat conduction and heat insulation; and a magnetic field increasing-decreasing unit that applies or removes a magnetic field to or from each of the magnetic structures. Since the magnetic structure is provided therein with the high heat conduction member having higher heat conductivity than the magnetocaloric material, all of or part of heat produced in the magnetocaloric material can rapidly be transmitted in the magnetic structure.

Magnetic structure and magnetization process of the glass-coated Fe-based amorphous microwire

Abstract: Magnetic structure of amorphous Fe73,9B13,2Si10,9C2 microwires was studied. The magnetic structure of the as-prepared microwire was found to consist of a magnetic core and a ring-shaped surface magnetic layer made up by radially magnetized small ring domains. The geometric characteristics of microwire magnetic structure were first experimentally determined. The width of the surface ring domains is about 5 μm, and the thickness of the surface magnetic layer is 2 μm. The magnetic core of the as-prepared microwire has been shown to consist of extensive domains, no less than 500 μm in size, and their spontaneous magnetization vector deviating from the microwire axis. The effect of magnetostriction on magnetic structure and its changes induced by magnetization has been established. The magnetic structure model for microwires with positive magnetostriction constant is proposed.

Magnetic submicron composite core-shell particles, and preparation method and application thereof

Abstract: The invention discloses magnetic submicron composite core-shell particles. In the magnetic submicron composite core-shell particles, Fe3O4 particles with the particle size of between 80 and 800nm are taken as a magnetic core, amorphous SiO2 is taken as an immediate shell layer and a substance with heavy metal absorption performance is taken as an outer shell layer. The invention also discloses a preparation method for the magnetic submicron composite core-shell particles. The preparation method comprises the following steps of: preparing the Fe3O4 particles with the particle size of between 80 and 800nm by a solvothermal method and taking the Fe3O4 particles as magnetic cores, performing alkaline hydrolysis of a silicon source reagent on Fe3O4 and dehydrating and condensing hydroxy groups so as to obtain amorphous SiO2 immediate shell layers, and coating the substance with heavy metal absorption performance on obtained submicron spheres under chemical or physical action to obtain the magnetic submicron composite core-shell particles. The submicron material has high performance of absorbing heavy metal ions in the sewage; and the material has stable characteristics, can be magnetically recovered and meets environmental protection requirements, and secondary pollution is avoided.

Ni-free MnZn ferrite magnetic core with double characteristics and manufacture method

Abstract: The invention discloses a MnZn ferrite magnetic core with double characteristics and a manufacture method. The magnetic core consists of main components and auxiliary components. The main components consist of Fe2O3 54-56 mol%, ZnO 5-10 mol% and the balance manganese oxide, wherein the sum of the Fe2O3, the ZnO and the manganese oxide is 100 mol%. The auxiliary components comprise a first auxiliary material, a second auxiliary material, a third auxiliary material and a selectable fourth auxiliary material, wherein the first auxiliary material is an oxide of Co, the second auxiliary material is one of Ni2O3, NiO or Li2CO3, the third auxiliary material is selected from CaCO3 and Nb2O5, and the fourth auxiliary material is selected from SiO2, V2O5 and ZrO2. The shortcoming that a common MnZn power ferrite material cannot integrate multiple characteristics is overcome, the MnZn ferrite magnetic core has the double characteristics of high temperature and Bs and wide temperature and low loss, the unit volume loss Pcv (100kHz, 200mT) of the magnetic core at the temperature of 25 DEG C to 120 DEG C is smaller than 350 kW/m , the lowest loss at the temperature of about 90 DEG C is 300 kW/m , and the saturation magnetic flux density can reach to 450 mT at the temperature of 100 DEG C.