EMI Performance Research Articles

Improving emi performance in automotive data transmission systems using spread spectrum modulation

This paper investigates the enhancement of electromagnetic interference (EMI) performance in automotive data transmission systems through the application of spread spectrum modulation techniques. The significance of this research lies in the growing complexity and density of electronic systems within modern vehicles, which increases the potential for EMI-related issues that can compromise the reliability and safety of automotive communication systems. The primary objective of this study is to evaluate the effectiveness of spread spectrum modulation in mitigating EMI and improving the overall performance of data transmission in automotive environments. To achieve this objective, the research utilizes both theoretical analysis and experimental validation. The methods include a detailed review of current EMI mitigation strategies, the design and implementation of spread spectrum modulation techniques in a controlled environment, and subsequent testing to measure the impact on EMI performance. Key metrics for evaluation include signal integrity, data transmission rate, and EMI reduction levels. The results of the study indicate a significant improvement in EMI performance when spread spectrum modulation is applied. The experimental data demonstrate a notable reduction in EMI levels, leading to enhanced signal integrity and more reliable data transmission. These findings suggest that spread spectrum modulation is a viable solution for addressing EMI challenges in automotive data transmission systems

Investigation of the radiated emission of honeycomb structured aluminum foam/cellular heatsinks at 1–10 GHz

Metal foams or cellular structures like honeycombs, can also be evaluated according to mechanical, acoustic, thermal, and chemical resistance parameters in terms of functionality. However, it is vital to investigate the performance of these cellular structures' radiated emission (RE), which can be used as PCB heatsinks. In this study, the radiated emission (RE) performance of honeycomb-structured aluminum foam (or cellular) heatsinks (AFH), which can be considered as unidirectional regular foam, is examined in the frequency range of 1–10 GHz as a novelty. Also, the effect of four primary variables (the geometry of AFH, honeycomb hole direction, honeycomb cell size, and honeycomb cell wall thickness) on the RE performance of AFH is investigated. Unlike classical honeycomb production methods, the investment flask mold casting (loss wax) method is preferred due to the complex offset strip geometry of designed honeycombs. The original design offset hexagonal honeycomb structures were successfully produced using this investment casting method with additive manufacturing technologies from molten metal. While all simulations are carried out using CST Studio Suite, the RE performance of the proposed AFHs is measured in a standard 3 m fully anechoic chamber using a reference horn antenna and vector network analyzer (VNA). When the results are examined, the measured and simulated results agree with each other quietly. Regarding RE, structures with a CPI value of 14 are better at low frequencies, while structures with a CPI value of 3.5 are better at high frequencies. Secondly, the honeycomb cell thickness value does not significantly affect EMI performance. Lastly, although there is no significant difference in EMI in the low-frequency region, it is better to use a directional structure with vertical holes in the high-frequency region. As a result, in the design of AFH, the RE performances of the heatsinks and their thermal performance should be considered.

Multifunctional and recyclable aerogel/fiber building insulation composites with sandwich structure

Fire, electromagnetic (EM) pollution, and sustainability require building insulation with fire resistance, EM interference shielding, and recyclability. However, fewer building insulation materials can fulfill these multifunctional requirements. Here, we report a multifunctional building thermal insulation material with a sandwich structure that uses SiO2 aerogel powder as the insulating filler phase, α-Al2O3 fiber as the refractory reinforcing phase, and carbon fiber mat (CFF) as the electromagnetic interference shielding layer prepared by the mixing-pressing-drying method. The effects of different SiO2 aerogel power contents on fire resistance, thermal insulation, and hydrophobicity, the effects of different carbon fiber contents on EMI performance, and the effects of CFF as an interlayer on compressive strength and recyclability were investigated. The results demonstrated exceptional fire resistance properties and low thermal conductivity (0.0529 W/m·K) with a SiO2 aerogel powder content of 11.2 wt%. Specifically, the structure of the aerogel/fiber composite remains intact and the temperature of the non-heated surface is lower than 75.8 ℃ after 4 min of continuous flame combustion. It can achieve a commercial shielding standard of 20 dB at a carbon fiber content of 5 wt%. In addition, CFF as interlayers can effectively improve the compression strength of the material and solve the problem of difficult recycling of carbon fiber. In conclusion, this sandwich structure of multifunctional aerogel/fiber composites provides new ideas for the manufacture of fire resistance, energy-saving, EM-protection, and recyclable building insulation materials.

The Effect of Gate Drive Resistance on the CM EMI Performance of the Balanced Inverter with Asymmetrical Parasitic Impedance Distribution

The Effect of Gate Drive Resistance on the CM EMI Performance of the Balanced Inverter with Asymmetrical Parasitic Impedance Distribution

Facile synthesis and characterization of polymer composites with cobalt ferrite and biomass based activated carbon for microwave absorption

In this work, flexible EMI shield materials have been prepared by the solution cast technique using AC-STG {activated carbon derived from Sal tree's gum}, CoFe2O4 nanoparticles and a polymer electrolyte {P(VDF-TrFE) + 15 wt% LiTFSI + 50 wt% EMIMTFSI}. The prepared polymer composites have been characterized for structural, morphological, thermal, ionic conductivity, dielectric, and magnetic properties. EMI shielding effectiveness has been obtained in the X-band (8.2–12.4 GHz). AC-STG particles have been characterized using XRD, FESEM EDX with elemental mapping, FTIR and RAMAN techniques. The CoFe2O4 (CF) nanoparticles have been prepared using the hydrothermal method. The highest ionic conductivity of ∼ 3.24х10−3 S.cm−1 for polymer electrolyte (PE15IL50) has been obtained at room temperature. On addition of AC-STG and CF particles to the polymer electrolyte, enhanced EMI shielding effectiveness and thermal stability of the composite films has been achieved. Also, FTIR results give the confirmation of interaction between the polymer electrolyte, AC-STG and CF particles. This study demonstrates that the EMI shielding properties of the polymer composite (PE15IL50AC-STG4CF5) get improved owing to the synergy between the properties of AC-STG and CF nanoparticles resulting in EMI shielding of ∼ 49.6 dB at 8.2 GHz (absorption ∼ 99.99%). There are three factors, viz., dielectric losses, magnetic losses and interfacial polarization which contribute majorly to this much desirable EMI performance. The studies being reported indicate PE15IL50AC-STG4CF5 polymer composite to be an excellent biomass-based composite for EM wave absorption.

A fully integrated half-bridge driver circuit in All-GaN GAN-IC technology

To unlock the full potential of fast switching GaN technology, monolithic integration of power circuit is crucial. GaN-IC ensures a fast efficient switching operation by reducing the parasitic inductance of interconnections significantly. In this paper, we demonstrate a monolithically integrated half-bridge power switch with its corresponding driving stage and the protection circuits that is realized by using our GAN-on-SOI technology. A low gate threshold voltage along with a low gate overdrive makes the driving of a GaN HEMT difficult. An optimized gate driver design is important to fully utilize a GaN power switch. This is also crucial for overall system efficiency, robustness, and EMI performance. Along with the design description this paper discusses the challenges and the design considerations of the GaN power IC.

Aerogels containing ionomers and microwave assisted growth of carbon nanostructures on carbon urchins for multifunctional electromagnetic interference shielding

Hierarchal 3D porous carbon materials show huge potential for EMI shielding because of their adjustable pore structure, tunable morphology and high electrical conductivity. However, poor graphitic nature and improper contact between materials lead to reduce the inherent conductivity, which supress the EMI shielding performance. In this work, we designed a hierarchical Carbon–Carbon nanostructure, which resembles a ‘sea-urchin’, exhibiting high shielding performance. A facile strategy of microwave assisted growth of carbon nanofiber (CNF) on the ‘self-assembled’ carbon urchin (CU) holds the rank of hierarchy, which enhance the electrical contact between the urchins. In order to obtain a 3D construct, a classical Ionomers pair-PEDOT:PSS was chosen as the matrix and CNF@CU was infused and subjected to freeze-drying to design ultra-light aerogel. The morphological assessment reveals that CNF@CU in the aerogel offers trapping centers by providing multiple interfaces. The aerogels exhibited two orders of jump in electrical conductivity and showed excellent thermal stability. The high limiting oxygen index value begins to suggest that these aerogels can extend their utility to flame retardant materials. The EMI shielding properties of the construct were studied in the X-band (8.2–12.4 GHz). The aerogel with 1.7 wt% of CNF@CU exhibited −50.8 dB of shielding efficiency (representing 99.999% blocking). The excellent EMI performance achieved here is mainly due to the conductive losses, dipole polarization, interface polarization, and wave trappers. These wave trappers are extremely beneficial for shielding EM radiations through multiple scattering. The utility of these materials were further evaluated using a Bluetooth module, wherein the aerogel potentially blocked all the transmitting Bluetooth signals confirming the quick shielding quality of the proposed aerogel. Taken together, this work provides a facile approach for designing and developing lightweight aerogel based EMI shielding materials.

Investigation of ZVS Criteria and Optimization of Switching Loss in a Triple Active Bridge Converter Using Penta-Phase-Shift Modulation

Triple active bridge (TAB) as an isolated multiport dc–dc converter is a promising solution for integrated energy management systems to maintain an efficient power flow between the ports. This article presents the design, modeling, and switching loss optimized phase-duty-controlled PWM modulation scheme of a TAB converter composed of three full-bridge modules and a high-frequency planar transformer. The work aims at the derivation and analysis of the zero-voltage switching (ZVS) conditions for a TAB, where the turn-on switching loss is mitigated along with attaining an improved EMI performance, comprising of reduced noise peaks. Moreover, an optimized five-variable control-based TAB PWM modulation technique is proposed in this article in order to achieve minimized switching loss and the overall system loss for a wide voltage gain and load range. The instantaneous switching currents, responsible for the switching losses at the devices, are derived from the transformer winding current expressions, formulated employing the generalized harmonic approximation (GHA) technique. The various loss minimization techniques and the theoretically obtained criteria for ZVS are experimentally verified using a laboratory-developed prototype of an 800-W TAB converter. With the implementation of the proposed optimal phase-duty control, the experimental results show a nonunity gain light-load efficiency increment up to 10% compared to the conventional phase-shift modulation alone.

A sandwich-structured ultra-flexible Pva-co-PE/Cu nanofiber composite film with excellent electrical conductivity, electromagnetic shielding properties, and environmental stability

A sandwich-structured ultra-flexible copper clad film based on nanofiber film has been successfully prepared via plasma induction, which combines super flexibility, low resistivity, hydrophobicity and outstanding electromagnetic shielding properties with potential applications in wearable circuit substrate boards. Acrylic acid was grafted onto Pva-co-PE nanofiber film by plasma irradiation induction, and silver ions were loaded on the surface of fiber film by electrostatic coordination between silver ions and carboxylic acid particles. Then copper was deposited on the surface of fiber film by chemical reduction reaction to obtain flexible copper-clad film. The resistivity of the obtained flexible copper-clad film is only 42.7 μΩ*cm, which is as good as that of the conductor. The EMI performance is above 55 dB, and the film has good hydrophobicity (150.6°). After 100 cycles of compression, the flexible copper-clad film still possessed outstanding performance. The flexible copper-clad film exhibited super stability and had broad application prospect in the flexible intelligent wearable field that will be popularized soon.

On-Load Electromagnetic Compatibility Test and Simulation Closed-Loop of the Electric Drive System of New Energy Vehicles

In order to solve the problem of high-amplitude and high-frequency interference generated by the electric drive system of new energy vehicles, the author proposes a closed-loop research method for on-load electromagnetic compatibility testing and simulation for electric drive systems of new energy vehicles. The method includes EMC design of the electric drive system on-load test equipment, establishment of a conducted EMI simulation platform for the electric drive system under load conditions, and optimization of the conducted EMI performance of the electric drive system based on key parameters and PWM control. Experimental results show that if the parasitic inductance of the IGBT gate increases, the conducted emission level in the frequency range of 2∼30 MHz will increase, and there is basically no change at the low frequency, and the position of each resonance point shifts to the relatively low frequency. The experiment was replaced with the DPWM3 modulation mode, and the conducted emission amplitude was reduced by about 2 dBμV in the range of 200 kHz∼2 MHz, and there was basically no change on the whole. Conclusion. It is proved that the electromagnetic compatibility closed-loop development technology of the electric drive system of new energy vehicles under load conditions can meet the development needs of new energy vehicles in the environment where energy problems and air pollution problems are becoming more and more serious.

Promoting the electromagnetic interference shielding of Ti3C2T flakes by loading Fe3O4 nanoparticles: Insights into the performance of oligo-layers exposed to microwave interferences

This study aims to provide insights into the absorption and shielding performances of Fe 3 O 4 modified oligo-layered Ti 3 C 2 T x towards microwave electromagnetic interference. Oligo-layered Ti 3 C 2 T x was modified by Fe 3 O 4 nanoparticles (60 nm) via a facile electrostatic assembly approach at different loading rates. This composite was shown to have high dielectric constant and high permeability compared with oligo-layered Ti 3 C 2 T x . The microwave electromagnetic absorbing and shielding performances were monitored through a vector network instrument with focuses on the EMI performance. The sample Ti 3 C 2 T x /Fe 3 O 4 with a 5:1 mass ratio of Ti 3 C 2 T x to Fe 3 O 4 displayed the optimized EMI shielding performance. The average SE value was 62.19 dB, and the maximum value was 68.72 dB at 18 GHz with a 2.6 mm thickness. The EMI shielding mechanism was understood based on the conductive loss, magnetic loss, dipole polarization, and multiple scattering. Results suggests that Ti 3 C 2 T x /Fe 3 O 4 composites are expected to be superior EMI shielding material.

Analysis and Design of a Nonisolated High Step-Down Converter With Coupled Inductor and ZVS Operation

This article presents a detailed analysis and design of a high step-down converter. The proposed converter achieves high step-down voltage gain without the need of extreme duty cycles by using coupled inductor. The converter features low switch stresses, which reduces the conduction loss by using low voltage MOSFETs. Moreover, the magnetizing current of the coupled inductor is zero, which reduces the magnetic size. The leakage energy of the coupled inductor is recycled. Zero voltage switching is achieved to reduce switching loss and improve the EMI performance. In addition, continuous output current is achieved; hence, small filtering capacitor can be used. A hardware prototype is built and experimental results verify the feasibility of the step-down converter.

Performance comparison of capacitive power transfer between matching resonant circuit π1a and π1b at 13.56 MHz operating frequency

This paper proposes current technique for wireless power transfer (WPT), which is capacitive power transfer (CPT). To date, inductive power transfer (IPT) remains the most popular technique for this technology. However, CPT has several benefits which make the development of this technique is growing up faster in industry and able to compete the IPT technology. A low number of components usage, simple topology, enhanced EMI performance, robustness to surrounding metallic elements are the benefits of CPT. In this work, the system is designed using class E power amplifier with the presence of impedance matching circuit. It assists the system to attain maximum power transfer. Two types of impedance matching are selected and compared in this work in order to understand the advantage and disadvantage of each in the framework of CPT system. MATLAB/Simulink software is used in this work to design and simulate the CPT system. This proposed system ables to generate 0.83W output power through a combined interface capacitance of 0.024nF at an operating frequency of 13.56 MHz, with 99.2% efficiency for both matching resonant circuits π1a and π1b. In the case for biomedical implantable device application, π1b is the superior matching resonant circuit since it requires smaller capacitance value and smaller size of receiver unit.

A 93.4% efficiency 42cc type-C power delivery adaptor with PMOS integration power line extension method

This paper presents a dc-link capacitor reduction method with P-MOS integrated control method. When compared with SCR chopping method, this novel method can easily integrate the auxiliary switch and control function circuits into one simple chip. Furthermore, the P-MOS control ground can be directly connected onto bus ground. This connection method is convenient to integration and easy drive. The theoretical analysis and detailed control method is given. Furthermore, one ultra-high efficiency GaN-based 65W prototype is made to verify it. The results show that with 27uF*4 bulk caps and integration control method, efficiency can achieve 93.4% at 90VAC with the PCB size 44*31*31mm, 42.3cc under the same dc-link capacitance. Dynamic and EMI performance are also verified. This method is suitable to commercial controller integration for ultra-density and high-efficiency type-c power delivery (PD) applications.

Tunable high-performance electromagnetic interference shielding of intrinsic N-doped chitin-based carbon aerogel

Heteroatom doping of carbon aerogels is a promising strategy to dissipate electromagnetic waves (EMWs) and it is still a daunting challenge to establish the relationship between heteroatomic structure and EMI shielding performance. In our work, intrinsic N-doped biomass-based carbon aerogel was successfully prepared by freeze-drying and a specific two-stage pyrolysis using chitin and chitosan as carbon and nitrogen source. The content and type of doping elements and electrical conductivity could be accurately manipulated by controlling the content of precursors and carbonization temperature. The intrinsic N-doped induced a dipole polarization, and the unique three-dimensional porous architecture of biomass-based carbon aerogel was conducive to multiple reflection/scattering of EMWs. The as-prepared biomass-based carbon aerogel at 1300 °C exhibited an optimal EMI performance of 82 dB, and the absorption coefficients could be tuned in the range of 0.31–0.88. The excellent EMI performance originated from a variety of mechanisms involving conduction loss, dipole polarization loss, and interface polarization loss. The novel heteroatomic doping strategy not only provides new insight into the contribution of heteroatomic structure to EMI shielding performance, but also opens a new avenue to develop biomass-based carbon aerogels with tunable EMI shielding performances.

Experiment and simulation of flexible CNT/SA/PDMS electromagnetic shielding composite

Flexible electromagnetic shielding composites have a great potential for wide range applications. In this study, two flexible composites were produced by plating Ni nanoparticles on carbon nanotubes (CNTs) or infiltrating carbon nanofibers/polydimethylsiloxane (CNF/PDMS) polymer into CNT/sodium alginate (CNT/SA) sponge skeleton (CNT/SA/CNF/PDMS composites). The composites are tested under the X band in the frequency range of 8.2 – 12.4 GHz, the electromagnetic interference shielding effectiveness (EMI-SE) values of the above two composites are almost as twice as that of CNT/SA/PDMS composite at a same CNT loading. Introducing nano-sized Ni particles on CNT improved the microwave absorption capacity of the composite, while adding CNF on the PDMS matrix enhanced the conductivity of these composites. Under 10% strain, both flexible composites show stable conductivity. Simulation and calculation results shown that increasing the cladding rate of Ni nanoparticles on the surface of CNT, reducing the average size of Ni particles, and increasing the loading of CNF in PDMS matrix can significantly improve conductivity and then EMI performance of the materials. All of these could benefit for the design of flexible electromagnetic shielding composites.

New EV Battery Charger PFC Rectifier Front-End Allowing Full Power Delivery in 3-Phase and 1-Phase Operation

A new universal front-end PFC rectifier topology of a battery charger for Electric Vehicles (EVs) is proposed, which allows fast charging at rated and/or full power level in case of 3-phase (Europe) as well as 1-phase (USA) mains supply. In this regard, a conventional 3-phase PFC rectifier would facilitate only one-third of the rated power in case of 1-phase operation. The new topology is based on a two-level six-switch (2LB6) 3-phase boost-type PFC rectifier, which is extended with a diode bridge-leg and additional windings of the Common-Mode (CM) chokes of the EMI filter. Besides this extension of the power circuit, the general design of the new converter is explained, and the generated Differential Mode (DM) and Common Mode (CM) EMI disturbances are investigated for 3-phase and 1-phase operation, resulting in guidelines for the EMI filter design. The EMI performance (CISPR 11 class-B QP) is experimentally verified for 1-phase and 3-phase operation at an output power of 4.5 kW, using a full-scale hardware prototype that implements the proposed extensions for a 2LB6 3-phase boost-type PFC rectifier and that is designed for output power levels of 22 kW and 19 kW in case of 3-phase and 1-phase operation, respectively. Compared to a conventional 2LB6 PFC rectifier, the volume of the extended system increases from 2.7 dm3 to 3.4 dm3, of which 0.5 dm3 is due to the additional dc-link capacitance for buffering the power pulsation with twice the mains frequency occurring for 1-phase operation.

In-situ Growing Carbon Nanotubes on Nickel Modified Glass Fiber Reinforced Epoxy Composites for EMI Application

Glass fiber (GF) reinforced polymer composites have attracted increasing attention due to their excellent performance. In this study, GF was coated by a thin layer of nickel, and then grafted carbon nanotubes (CNTs) array by a chemical vapor deposition method (CVD). The CNT contents can be varied by changing the CVD conditions. Three types of fillers, nickel coated GF (GF@Ni), GF with CVD grown CNTs (GF-CNTs) and nickel-coated GF with CVD grown CNTs (GF@Ni-CNTs), were used to prepare the epoxy composites. The electromagnetic interference shielding performances were investigated as a function of CNT contents. The GF@Ni-CNTs reinforced epoxy composites, which had the CNTs mass ratio of 9.2 wt% to the hybrids, showed the best EMI shielding performance among the composites. Their total EMI shielding effectiveness (SE) was higher than 35 dB in the range of 1–18 GHz, and above 50 dB in the X band. By incorporating the nickel layer on the GF surface, the same EMI performance can be achieved with lower CNTs content. For achieving a SE value of 35 dB in the X band, it needed GF@Ni-CNTs/epoxy with CNTs mass ratio of 3.8 wt% to the hybrids, instead of GF-CNTs/epoxy composites with CNTs mass ratio of 5.2 wt% to the hybrids.

Operating principles and practical design aspects of all SiC DC/AC/DC converter for MPPT in grid-connected PV supplies

A 20 kW, 20 kHz high frequency (HF) link maximum power point tracking (MPPT) converter for a grid-connected PV supply, based on all silicon carbide (SiC) power semiconductors, is presented. In the developed converter, SiC power MOSFETs are used in the low-voltage PV panel side and SiC Schottky diodes on the high-voltage DC output, in order to maximize the power conversion efficiency and the power density. Operating principles of the resulting dual H-bridge MPPT converter and the practical aspects of the converter design and its circuit layout, are described in detail. The implemented converter performance is compared with that of a classical Si-IGBT and hybrid-IGBT based MPPT converter in terms of efficiency. This configuration can compete with the non-isolated MPPT converter topologies, such as the boost converter commonly used in grid-connected PV systems, since it allows the possibility of using a conventional two-level, three-phase grid-connected inverter. This is due to the enhanced common-mode EMI performance as compared to non-isolated MPPT topologies, resulting in a competitive high efficiency PV converter design with galvanic isolation. It has been shown that the converter size can be shrinked up to a power density of 1.6 kW/lt, with a DC-DC converter full-load efficiency of 98%. The resulting compact and highly efficient SiC power MOSFET based HF link MPPT converter is suggested to be a part of grid-connected, multi-string PV supplies with simple inverter topologies in the future.

Conducted EMI performance comparison of Si and SiC MOSFETS in a CCM boost PFC converter for MIL-STD-461F CE102

Conducted EMI performance comparison of Si and SiC MOSFETS in a CCM boost PFC converter for MIL-STD-461F CE102