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A laminated core has advantages such as low loss, high permeability, and high saturation flux density. For inductor applications, an air gap has to be inserted into the magnetic circuit to avoid saturation at lower magnetic field strengths. However, when an air gap is inserted, fringing flux leaks out of the air gap and concentrates on the surface...
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Citations
... Adding discrete air gaps is always a promising method to reduce the effects of fringing flux on the winding loss and core loss [6]. Moreover, reshaping the air gaps can also achieve the same purpose [7]. Besides the manufacturing difficulties, the above methods both may cause short-circuit problems due to the thin metal ribbon of the nanocrystalline cores. ...
Abstract A simple method is proposed here to improve the gap loss concentration problem of a nanocrystalline core in an LCL filter inductor for high switching frequency converters using SiC devices. This alloy‐gapped inductor design aims to reach two primary goals. First, to reduce the concentrated gap loss in a nanocrystalline core. Second, decrease the maximum temperature around the gap region and lead to more even temperature distribution. A finite element (FE) power loss and thermal models, validated by experiment, have been created to evaluate the proposed design. Based on the FE model results, the eddy current loss on the surfaces, which used to have the most severe gap loss is reduced by either 70% or 40% for the two commonly used winding placements. The total eddy current loss can be reduced by 29% and 27% for those two winding placements. In addition, FEA thermal model indicates that the hotspot temperature can be significantly decreased, and the nanocrystalline core can achieve a more uniform temperature distribution by this design, which can be a potential downsize method for the nanocrystalline core inductor.
... It is possible to reduce the fringing flux effects and corresponding loss by distributing air gap and optimizing the shape of gap edges [3,4]. However, in addition to manufacturing difficulties, both methods would also cause potential short-circuits between lamination layers due to the extremely thin lamination thickness of nanocrystalline cores. ...
... Different approaches have been taken over the years in order to achieve larger inductance including the increases in permeability, higher saturation magnetization, higher frequency and lower loss magnetic materials for inductor cores [ 33] [ 34]. Also, improving the magnetic core structure such as in the use of multi-permeability cores which improves the utilization of the magnetic core material [ 35]- [ 39]. In addition to improving the winding structure to reduce the winding losses and increase the inductor power density [ 40] [ 41]. ...
Power electronics is an enabler for the low-carbon economy, delivering flexible and efficient control and conversion of electrical energy in support of renewable energy technologies, transport electrification and smart grids. Reduced costs, increased efficiency and high power densities are the main drivers for future power electronic systems, demanding innovation in materials, component technologies, converter architectures and control. Power electronic systems utilise semiconductor switches and energy storage devices, such as capacitors and inductors to realise their primary function of energy conversion. Presently, roughly 50% of the volume of a typical power electronic converter is taken up by the energy storage components, so reducing their weight and volume can help to reduce overall costs and increase power densities. In addition, the energy storage densities of inductors are typically much lower than those of capacitors, providing a compelling incentive to investigate techniques for improvement. The main goal of this research was to improve the design of an inductor in order to achieve higher energy densities by combining significantly increased current densities in the inductor windings with the ability to limit the temperature increase of the inductor through a highly effective cooling system. Through careful optimisation of the magnetic, electrical and thermal design a current density of 46 A/mm2 was shown to be sustainable, yielding an energy storage density of 0.537 J/ kg. A principal target for this enhanced inductor technology was to achieve a high enough energy density to enable it to be readily integrated within a power module and so take a step towards a fully-integrated “converter in package” concept. The research included the influence of the operating dc current, current ripple, airgap location and operating frequency on the inductor design and its resulting characteristics. High frequency analysis was performed using an improved equivalent circuit, allowing the physical structure of the inductor to be directly related to the circuit parameters. These studies were validated by detailed small-signal ac measurements. The large signal characteristics of the inductor were determined under conditions of triangular, high-frequency current as a function of frequency, current (flux) ripple amplitude and dc bias current (flux) and a model developed allowing the inductor losses to be predicted under typical power electronic operating conditions.
This paper examines the performance of a 13kW high-power inductive power transfer system utilising a hybrid core structure with novel nanocrystalline ribbon cores and nanocrystalline flake ribbons. Conventional laminated nanocrystalline ribbon cores exhibit excessive edge losses due to high flux density concentrated on the edge and high eddy current losses in the lateral wall, potentially causing partial thermal runaway. To mitigate this issue, the solution is proposed to employ nanocrystalline flake ribbons as a shielding material on the edge while maintaining the nanocrystalline ribbon core as the main magnetic coupler. The performance of the hybrid core is evaluated under different power levels up to 13.8 kW. Experimental results reveal a nearly 2% increase in peak efficiency compared to the ferrite DMR44 and a 1% increase compared to standalone nanocrystalline ribbon cores, bringing the peak DC-DC efficiency to over 96%. Moreover, under 6.6 kW output power, the temperature rise after 2-hour operation is significantly reduced to a maximum temperature of 76.5°C with the proposed hybrid core, compared to 96.4°C with the ferrite shield and 110.6°C without any edge shield. The design highlights using nanocrystalline material in inductive power transfer systems to improve efficiency and thermal performance.
Inductive power transfer (IPT) systems have advantages of safety, flexibility, and convenience compared to plug-in charging systems. However, in practical applications, pad misalignment is still an almost inevitable issue which may cause variation in magnetic couplings, thus affecting the power transmission and reducing the system efficiency. Therefore, IPT systems are usually expected to achieve tolerance for misalignment. To fulfill this feature, a hybrid IPT system is proposed in this article. By adopting two coils compensated by different topologies in receiver side and an additional intermediate coil in transmitter side, load-independent constant output current with improved misalignment tolerance can be achieved. In addition, when the receiver pad is very far away from the transmitter pad, the proposed system can operate safely due to the inherent limitation ability of the primary inverter current. The design process is presented to optimize the misalignment performance. Based on the experimental results of a 3.3-kW prototype, the fluctuation of the output current is less than 5% within ±300-mm misalignment in
$y$
-axis, −30- to +60-mm misalignment in
$z$
-axis, and −80- to +60-mm misalignment in
$x$
-axis. The system efficiency is 96.7% at nominal operating point (NOP) and varies from 94.7% to 97.8% with variable loads and misalignment.
Recently, achieving carbon neutrality which means balancing CO2 emissions and absorption is a global concern. To realize carbon neutrality, developing power electronics technologies that significantly contribute to reducing the emission of CO2 are important issues. In addition, to smoothly develop next-generation power electronics technologies, interdisciplinary action and mutual understanding from the material, components, circuit, and system levels are important. Furthermore, magnetic components used in power converters are one of the basic and important components for improving power density and efficiency. Therefore, this paper presents the latest trend of power electronics technologies and applied technology of magnetic components for power electronics.
To reduce the dependence on oil and environmental pollution, the development of electric vehicles has been accelerated in many countries. The implementation of EVs, especially battery electric vehicles, is considered a solution to the energy crisis and environmental issues. This paper provides a comprehensive review of the technical development of EVs and emerging technologies for their future application. Key technologies regarding batteries, charging technology, electric motors and control, and charging infrastructure of EVs are summarized. This paper also highlights the technical challenges and emerging technologies for the improvement of efficiency, reliability, and safety of EVs in the coming stages as another contribution.
A two-phase buck–boost converter utilizing dual interleaving is presented in this paper. The dual interleaving consists of an interphase transformer that doubles the ripple frequency together with two conventional buck-boost switching arms, mitigating the inductor ripple current and aiding to increase the power density of the converter. A description of the design and selection of the power devices is presented for a 32 kW, 75 kHz dual-interleaved SiC prototype with an interphase transformer, such that a power density of 7.4 kW/kg is achieved. The principle of operation of the circuit is validated by measurements operating the prototype with a 315-385 V supply, a 350 V load and a 97.5% efficiency. The experiments reveal that the interleaved coupled currents are equalized without an active balancer.
Wireless power transfer (WPT) has attracted a lot of attention these years due to its convenience, safety, reliability and weather proof features. First and foremost, the consistency of mutual model and T model of Loosely Coupled Transformer (LCT) was deduced. The application scenarios of these two models were then concluded so as to choose suitable model in circuit analysis. Then a new WPT compensation topology, which is referred to as LC/S compensation topology and consists of one inductor and two capacitors, is proposed. The constant-current-output (CCOut) characteristic of the newly proposed topology is analyzed in detail on the basis of the discussion about LC and CL resonant tank. The equivalent resistance of the rectifier, filter and resistor circuit are also analyzed to simplify circuit analysis. Then the current and voltage stress on each component and the system performance under imperfect resonant condition are studied with the help of MATLAB. The LCT is deliberately designed by the finite element analysis software ANSYS Maxwell as well because the coupling coefficient, primary and secondary self-inductance have a significant impact on system efficiency, power level and density. The LCT design approach employed in this paper can be extended to magnetic design of almost all WPT systems. Theoretical analyses are verified by both Pspice simulation and practical experiments. Practical output currents with an transient loads show an excellent CCOut characteristic of LC/S compensation topology
Due to the continuing progress in power electronics technologies, a drive frequency of electrical machine such as a reactor and a transformer can be changed arbitrarily. Consequently, it is expected that a reactor or a transformer is downsized by higher frequency for saving space. When these electrical machines which have iron core are driven by high frequency, the iron losses of iron core increase by eddy current effects. In general, these electrical machines are designed by taking account of iron loss characteristics obtained from datasheet of electrical steel sheets. However, there is not the guarantee that the loss on datasheet is the same as the loss of actual machine because of the influence of leakage flux, stress and etc. Nevertheless, the actual machine loss under high frequency has been hardly evaluated in conventional research [1]-[3]. Therefore, it is necessary that a building factor of loss is evaluated on high frequency excitation.
