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Introduction. The presence of broad-spectrum and high-amplitude electromagnetic interference (EMI) within a single-phase induction motor (SPIM) drive poses a significant threat to both the system and other electronic equipment. High-frequency (HF) models of electrical motors play a critical role in overcoming these challenges, as they are essential for characterizing electromagnetic compatibility (EMC) in drives and designing effective EMI filters. The novelty of this study proposes an enhanced HF motor model based on transfer functions (TFs) to accurately represent the motor’s behavior at HFs for frequency-domain analyses in the range of 100 Hz to 30 MHz. Purpose. The equivalent HF model for a SPIM is discussed in this paper. The suggested equivalent circuit describes a motor’s common-mode (CM) properties. Methodology. HF model was developed by a frequency-domain analysis utilizing an experimental setup and MATLAB software. The motor impedance analysis is based on the measurement of variations in motor characteristics as a function of frequency in the CM setup. Originality. TF has been tuned using an asymptotic identification method of Bode to match the behavior of the real impedances of the motor parameters as a function of the frequency in the CM configuration. This tuned TFs are then synthesized into a comprehensive wideband EMC equivalent circuit model using the Foster network technique, which can be then simulated in any Spice-based simulator tools. Results. The proposed mathematical model was employed to conduct simulations, and the resulting predictions were validated against experimental data. CM response of the EMC equivalent circuit at low, medium, and HFs were compared between simulations and experimental measurements using Lt-Spice simulator software. Practical value. It is observed that results show satisfactory agreement with the measurements over a large frequency bandwidth [100 Hz–30 MHz], and the equivalent model of SPIM can be cascaded with other electronic and electrical modules to form a complete single-phase electric drive system model for fast analysis and prediction of system level EMI and electromagnetic sensitivity. [ABSTRACT FROM AUTHOR]

Introduction. The presence of broad-spectrum and high-amplitude electromagnetic interference (EMI) within a single-phase induction motor (SPIM) drive poses a significant threat to both the system and other electronic equipment. High-frequency (HF) models of electrical motors play a critical role in overcoming these challenges, as they are essential for characterizing electromagnetic compatibility (EMC) in drives and designing effective EMI filters. The novelty of this study proposes an enhanced HF motor model based on transfer functions (TFs) to accurately represent the motor’s behavior at HFs for frequency-domain analyses in the range of 100 Hz to 30 MHz. Purpose. The equivalent HF model for a SPIM is discussed in this paper. The suggested equivalent circuit describes a motor’s common-mode (CM) properties. Methodology. HF model was developed by a frequency-domain analysis utilizing an experimental setup and MATLAB software. The motor impedance analysis is based on the measurement of variations in motor characteristics as a function of frequency in the CM setup. Originality. TF has been tuned using an asymptotic identification method of Bode to match the behavior of the real impedances of the motor parameters as a function of the frequency in the CM configuration. This tuned TFs are then synthesized into a comprehensive wideband EMC equivalent circuit model using the Foster network technique, which can be then simulated in any Spice-based simulator tools. Results. The proposed mathematical model was employed to conduct simulations, and the resulting predictions were validated against experimental data. CM response of the EMC equivalent circuit at low, medium, and HFs were compared between simulations and experimental measurements using Lt-Spice simulator software. Practical value. It is observed that results show satisfactory agreement with the measurements over a large frequency bandwidth [100 Hz–30 MHz], and the equivalent model of SPIM can be cascaded with other electronic and electrical modules to form a complete single-phase electric drive system model for fast analysis and prediction of system level EMI and electromagnetic sensitivity. References 37, table 5, figures 13.

Introduction. Most electromagnetic compatibility studies carried out in the context of power switch research are generally valid for low frequencies. This frequency restriction appears to be too restrictive for a complete analysis of the electromagnetic interference conducted. The novelty of this work lies in the load-dependent an optimal selection of IGBTs and MOSFETs for least-disturbance power switching in the frequency range from 150 kHz to 30 MHz, based on an optimal experimental selection procedure and show the impact of load value on switch switching and noise generation. Purpose. Analysis of the fundamental possibility of selecting a switching device with a power supply based on an experimental measurement which allows to increase the reliability of the entire mechanism operation and significantly simplify the design. Methods. In this paper, the proposed study is used and compared with experimental results at low and high frequencies. Then, a comparison is made for conducted electromagnetic interference (common-mode and differential-mode) generated by IGBT and MOSFET for different loads, and the proposed methodology is verified on an experiment suitable for predicting terminal overvoltage analysis and conducted electromagnetic interference problems. Practical value. The primary method for establishing a conducted electromagnetic interference source for switching devices is based on IGBT and a MOSFET depending on the resistive load. References 22, figures 17.

Introduction. Most electromagnetic compatibility studies carried out in the context of power switch research are generally valid for low frequencies. This frequency restriction appears to be too restrictive for a complete analysis of the electromagnetic interference conducted. The novelty of this work lies in the load-dependent an optimal selection of IGBTs and MOSFETs for least-disturbance power switching in the frequency range from 150 kHz to 30 MHz, based on an optimal experimental selection procedure and show the impact of load value on switch switching and noise generation. Purpose. Analysis of the fundamental possibility of selecting a switching device with a power supply based on an experimental measurement which allows to increase the reliability of the entire mechanism operation and significantly simplify the design. Methods. In this paper, the proposed study is used and compared with experimental results at low and high frequencies. Then, a comparison is made for conducted electromagnetic interference (common-mode and differential-mode) generated by IGBT and MOSFET for different loads, and the proposed methodology is verified on an experiment suitable for predicting terminal overvoltage analysis and conducted electromagnetic interference problems. Practical value. The primary method for establishing a conducted electromagnetic interference source for switching devices is based on IGBT and a MOSFET depending on the resistive load. [ABSTRACT FROM AUTHOR]

Machine stator winding insulation degradation is one of the main results of machine aging. It is non-negligible once this degradation process becomes asymmetric between phases. The traditional way to determine the insulation state of health is a partial discharge test. However, this method requires the system offline, which causes production loss and extra administrative burden. This paper presents an idea for better characterizing the insulation machine’s state of health using common-mode (CM) behavior in the machine-drive system. With the help of circuit decomposition methods and modeling tools, the CM quantities due to asymmetric aging show a unique characteristic that distinguishes itself from other differential-mode (DM) quantities in the equivalent circuit. It is shown effective to represent the asymmetric aging effect from the detection of system leakage current. This paper provides an analytical method to quantify this characteristic from mathematical approaches, and a proper approximation has been made on the CM equivalent model (CEM) such that the CM behavior is accurately characterized. The proposed method will serve the purpose of predicting machine abnormal behavior using the simple RLC circuit. Researchers can adapt this method to quantify and characterize the machine insulation state of health (SOH).

In this paper, CM noise suppresion and magnetic elements winding loss optimization design of a cascade power module based on GaN design are carried out (the front stage is buck converter, the second stage is LLC resonant converter). To suppress CM noise, the front buck converter adopts planar stagger reverse coupling inductance, by establishing reverse stagger coupling buck converter CM noise model and conduction path model, the equivalent capacitance can effectively reduced, thus further reducing CM noise current. A staggered winding structure is proposed for second stage LLC resonant converter, compared and calculated LLC resonant transformer winding electromagnetic field characteristics with different structure. a novel shielding and cancellation technique is proposed for LLC resonant converter, by establishing LLC converter CM noise shielding model and the equivalent capacitance can effectively reduced, thus further reducing CM noise current. In order to improve the LLC resonant converter efficiency, winding copper foil optimal thickness is proposed. Experimental results show that power module with winding optimization and shielding technology can effectively suppress the CM noise and improve efficiency, CM noise can reduced 12-20dB, the peak efficiency improved about 1% after copper foil thickness is optimized.

Common-mode voltage and current in an electric machine are undesirable. Although the strategic placement of a common-mode inductor and dc input side capacitors may reduce the common-mode current produced by an electric drive system, the effectiveness of this mitigation is a function of machine parasitic capacitance. This engenders the need to insert another electrical component into the system to effectively mitigate the common-mode current. With this purpose, a common-mode shorting network for an inverter-based drive system is proposed in this work. This network, in conjunction with a common-mode inductor and dc input side capacitors, reduces the machine common-mode voltage and current. The proposed approach is experimentally demonstrated.

Introduction. Most electromagnetic compatibility models developed for the study of three-phase induction machines are generally valid for low and medium frequencies (<< 1 MHz). This frequency limit seems to be too restrictive for the overall study of conducted electromagnetic interference. In this paper, the model is using the proposed model and compared with experimental results in low and medium frequency. And then, the high-frequency modeling of induction motor is presented new method based on transfer function model. The proposed methodology is verified on an experimental and simulation, it’s suitable for prediction of the terminal overvoltage analysis and electromagnetic interference problems and common-mode and differential-mode currents. The novelty of the work consists to develop an improved high-frequency motor model based on transfer function to represent the motor high-frequency behavior for frequency-domain analyses in the frequency range from 40 Hz up to 110 MHz .The purpose of this work is to study the common-mode impedance and the differential-mode impedance of AC motor. The determination of these impedances is done for firstly both common and differential modes at low and medium frequency, and then common-mode and differential-mode characteristics at high frequency. Methods. For the study of the path of common-mode and differential-mode currents in typical AC motor (0.25 kW, 50 Hz) an identification method in high frequency for induction motor has been proposed based on the transfer function in differential-mode and common-mode configuration. The low and medium frequency model were presented in the first time based on equivalent circuit of electrical motor. Then, the common-mode and differential-mode impedances were defined in high frequency using asymptotic approach. This motor was studied by MATLAB Software for simulation and also experimental measurements. Results. All the simulations were performed using the mathematical model and the results obtained are validated by experimental measurements performed in the University of the Federal Armed Forces Hamburg in Germany. The obtained results of common-mode and differential-mode at low frequency, medium and high frequency are compared between simulation and experiment.

Ground fault tests of ultra-high voltage direct current (UHVDC) transmission line indicate that voltage differential protection of the other pole may be false tripped when the ground fault happens on the line of the pole with a larger number of operating valve groups. In order to solve this problem,it is pointed out that the transmission velocity of common-mode of the fault traveling wave is less than that of differential-mode,and there is a time difference between common-mode and differential-mode to reach the protection measurements. Then,it is analyzed that the cause of the voltage differential protection false tripping is that the time difference between common-mode and differential-mode to reach the protection measurements is longer than the setting time of the protection. In addition,the polarity of common-mode component is used as the criterion to identify the fault pole and the protection of voltage mutation is improved accordingly. Finally,a real-time digital simulation model of UHVDC transmission is established to verify the correctness of the analysis results for the impoved method.

Most electromagnetic compatibility models developed for the study of three-phase induction machines are generally valid for low and medium frequencies (<< 1 MHz). This frequency limit seems to be too restrictive for the overall study of conducted electromagnetic interference. In this paper, the model is using the proposed model and compared with experimental results in low and medium frequency. And then, the high-frequency modeling of induction motor is presented new method based on transfer function model. The proposed methodology is verified on an experimental and simulation, it’s suitable for prediction of the terminal overvoltage analysis and electromagnetic interference problems and common-mode and differential-mode currents. The novelty of the work consists to develop an improved high-frequency motor model based on transfer function to represent the motor high-frequency behavior for frequency-domain analyses in the frequency range from 40 Hz up to 110 MHz .The purpose of this work is to study the common-mode impedance and the differential-mode impedance of AC motor. The determination of these impedances is done for firstly both common and differential modes at low and medium frequency, and then common-mode and differential-mode characteristics at high frequency. Methods. For the study of the path of common-mode and differential-mode currents in typical AC motor (0.25 kW, 50 Hz) an identification method in high frequency for induction motor has been proposed based on the transfer function in differential-mode and common-mode configuration. The low and medium frequency model were presented in the first time based on equivalent circuit of electrical motor. Then, the common-mode and differential-mode impedances were defined in high frequency using asymptotic approach. This motor was studied by MATLAB Software for simulation and also experimental measurements. Results. All the simulations were performed using the mathematical model and the results obtained are validated by experimental measurements performed in the University of the Federal Armed Forces Hamburg in Germany. The obtained results of common-mode and differential-mode at low frequency, medium and high frequency are compared between simulation and experiment. References 34, table 2, figures 14. [ABSTRACT FROM AUTHOR]

This paper presents a novel scheme based on the Crosstalk Harnessed Signaling (CHS) technique for parallel high-speed interfaces. The proposed scheme, called Asymmetric Crosstalk Harnessed Signaling (ACHS), provides a robust and consistent eye opening for all the transmitted bits in the interface. The Hadamard matrix employed for CHS encoding has been modified to a non-square format in order to either eliminate the common eigenmode or turn it differential. This in turn results in a signaling scheme that converts a binary data array to a slightly larger signal/interconnect array. The resulting signaling and routing overhead translates into a comparable eye opening across all the bits inside the encoded bus, overcoming the crosstalk sensitivity associated to the common mode present in the original CHS scheme. Both CHS and the proposed ACHS are implemented on a 16-bit source-synchronous bus wired through 3-dimensional interconnect arrangements in a multi-stripline stackup, in order to compare performances in very aggressive crosstalk environments. Simulation results show a consistent eye opening across all data bits when ACHS is applied, rendering a fully functional bus with only 11% routing overhead, against a practically inoperable bus in the CHS case, due to the eye collapse for the common-mode encoded bit. [ABSTRACT FROM AUTHOR]

The high frequency PWM voltage pulses from a two-level six-switch inverter produce a common-mode voltage in an electric machine's windings, a fraction of which appears on the machine shaft due to electrostatic (capacitive) coupling. When the shaft voltage exceeds the dielectric strength of the bearing lubricating grease, electric discharge machining (EDM) electrostatic discharges occur within the bearing, which can lead to premature failure. According to pulsed dielectric theory, the breakdown voltage across a dielectric increases with an increase in voltage slew rate (dv/dt). Therefore, the faster voltage rise times of wide bandgap devices are expected to produce higher magnitude shaft voltages and EDM bearing currents. This paper presents circuit modeling of EDM currents and compares the shaft voltage and bearing current amplitudes of silicon- and silicon carbide-based PWM inverters through experimental measurements and a statistical analysis using probability density functions. The statistical analysis provides insights regarding the correlation between bearing failure and the number of damage causing discharges over time which is a key step in developing bearing lifetime prediction models. [ABSTRACT FROM AUTHOR]

We present a time-domain numerical method for calculating the current propagating through coaxial lines including the radiation effect. In previous studies of transmission lines using the retarded potential integral equations (RPIE), the so-called thin-wire approximation to the RPIE has been mainly used. However, the thin-wire approximation has the problem that the unphysical oscillation occurs when the spatial mesh size is smaller than the radius, even for one-conductor line. In addition, the application of the thin-wire approximation in multi-conductor coaxial lines causes a problem in the formulation. We solve these problems by developing a numerical method using the exact RPIE. We perform numerical calculations in the time-domain for two-conductor coaxial lines and obtain numerical solutions even for the very small common-mode current that causes radiation emission.

The emergence of fast-switching wide-bandgap (GaN, SiC) power electronics devices has enabled motor drive systems to achieve high efficiency, power density, control bandwidth and high-level of integration. However, the fast-switching speed and high switching frequency result in an increased level of motor overvoltage at both motor terminals and stator neutral. This overvoltage increases the stress across the motor winding insulation and bearings. This paper investigates three types of motor overvoltages, i.e., differential mode (DM) (phase-to-phase) motor terminal overvoltage, common mode (CM) (phase-to-ground) motor terminal overvoltage and CM stator neutral overvoltage (motor neutral to ground). Both the high switching speed (high dv/dt) effect and the high switching frequency effect on the motor overvoltage are investigated in this paper, where the high switching frequency effect has not been fully addressed in existing literature. Significant overvoltage is observed when the switching frequency or its multiples coincide with the cable or motor anti-resonant frequency. The anti-resonant behavior in the cable and motor impedance has been used to identify the overvoltage oscillation frequency and to explain the overvoltage observations for the three types of motor overvoltages. The analysis has been tested using a 7.5kW motor setup with and without a four-core cable, driven by a SiC or a GaN three-phase inverter with a switching frequency up to 250kHz and switching speed up to 40kV/ $\mu \text{s}$ . In addition, the motor bearing current, which is a main cause of bearing degradation, has also been tested and the increase of bearing current is observed due to the high frequency effect.

A compact balanced microstrip tri‐band bandpass filter (BPF) using short and open stubs loaded resonators (SOSLRs) is achieved in this article. Three differential‐mode (DM) passbands can be adjusted by properly controlling the dimensions of the loaded short and open stubs, and the first and third DM center frequencies can be implemented independently. By introducing interdigital coupling microstrip lines, five transmission zeros (TZ) are implemented to achieve a higher selectivity. The positions of TZs can be controlled by adjusting the coupling gaps between SOSLRs and interdigital coupling microstrip lines. In addition, balanced microstrip line to slotline transformation structures is introduced as the feed structure, which can be used to block the common‐mode (CM) transmission inherently. Therefore, the DM performances are independent from the CM responses, which can simplify the design procedure significantly. For demonstration, a balanced tri‐band BPF centered at 1.57, 2.45, and 3.5 GHz was fabricated and measured. Comparison with other reported balanced BPFs indicates that the proposed design exhibits the advantages of high selectivity and good CM suppression responses. [ABSTRACT FROM AUTHOR]

We derive the integro-partial differential equations with delay effect based on the Maxwell equations for a two-line system under the thin-wire approximation and the approximation of neglecting the interwire distance in the delay term. We introduce the normal- and common-mode and write the integro-partial differential equations in terms of these two modes. For the case of the same radius, we show that the equation of the normal-mode reduces to the Heaviside telegraph equation in the partial differential form and the equation of the common-mode becomes the Pocklington equation in the integro-partial differential form. We perform numerical calculations of the coupled integral and partial differential equations in the time domain and compare the results with those of various approximations. We show that the Heaviside telegraph equation is valid for the normal-mode, while the full treatment of the delay term in the integro-partial differential equations is necessary for the common-mode. [ABSTRACT FROM AUTHOR]

The high frequency PWM voltage pulses from a two-level six-switch inverter produce a common-mode voltage in an electric machine’s windings, a fraction of which appears on the machine shaft due to electrostatic (capacitive) coupling. When the shaft voltage exceeds the dielectric strength of the bearing lubricating grease, electric discharge machining (EDM) electrostatic discharges occur within the bearing, which can lead to premature failure. According to pulsed dielectric theory, the breakdown voltage across a dielectric increases with an increase in voltage slew rate (dv/dt). Therefore, the faster voltage rise times of wide bandgap devices are expected to produce higher magnitude shaft voltages and EDM bearing currents. This paper presents circuit modeling of EDM currents and compares the shaft voltage and bearing current amplitudes of silicon- and silicon carbide-based PWM inverters through experimental measurements and a statistical analysis using probability density functions. The statistical analysis provides insights regarding the correlation between bearing failure and the number of damage causing discharges over time which is a key step in developing bearing lifetime prediction models.

In a multimodal volume coil, only one mode can generate homogeneous Radiofrequency (RF) field for Magnetic Resonance Imaging. The existence of other modes may increase the volume coil design difficulties and potentially decreases coil performance. In this study, we introduce common-mode resonator technique to high and ultrahigh field volume coil designs to reduce the resonant mode while maintain the homogeneity of the RF field. To investigate the design method, the common-mode resonator was realized by using a microstrip line which was split along the central to become a pair of parallel transmission lines within which common-mode currents exist. Eight common-mode resonators were placed equidistantly along the circumference of a low loss dielectric cylinder to form a volume coil. Theoretical analysis and comparison between the 16-strut common-mode volume coil and a conventional 16-strut volume coil in terms of RF field homogeneity and efficiency was performed using Finite-Difference Time-Domain (FDTD) method at 298.2 MHz. MR imaging experiments were performed by using a prototype of the common-mode volume coil on a whole body 7 Tesla scanner. FDTD simulation results showed the reduced number of resonant modes of the common-mode volume coil over the conventional volume coil, while the RF field homogeneity of the two type volume coils was kept at the same level. MR imaging of a water phantom and a kiwi fruit showing the feasibility of the proposed method for simplifying the volume coil design is also presented.

The use of a transformer in grid-connected photovoltaic (PV) generation systems provides isolation between the grid and the PV array, this increases the cost, weight, and the size of the system. However, the transformer elimination increases the efficiency and the security issues, these should be taken into account, but also to remove the isolation leads the apparition of a leakage current due to the PV parasitic capacitance to the ground. This paper presents a five-switch common-mode current-source inverter for grid-connected applications and a control scheme based on finite control set, where an additional force section is considered, in order to regulate the current injected to the grid. The proposed topology can reduce the leakage current in photovoltaic systems due to the common mode connection. The operation modes, consideration design, control technique, and the simulation results are presented.

A compact differential filter with ultra‐wide band common‐mode (CM) suppression is proposed. Ultra‐wide band property is achieved by the frequency‐selecting coupling structure (FSCS), which generates three transmission zeros in the passband of differential‐mode (DM) as well as in the stopband of CM. Moreover, the position of the transmission zeros, the CM insertion loss and the DM return loss can be customized by designing the parameters of the FSCS. To verify the concept, a filter has been designed, simulated and measured. The proposed filter shows the center frequency of 2.45 GHz with a DM 3 dB fractional bandwidth of 51% and a CM 20 dB fractional bandwidth of 108.6%. [ABSTRACT FROM AUTHOR]

Subsynchronous oscillation (SSO) of generators caused by high voltage direct current (HVDC) systems can be solved by applying supplemental subsynchronous damping controller (SSDC). SSDC application in mitigating SSO of single-generator systems has been studied intensively. This paper focuses on SSDC application in mitigating SSO of multi-generator systems. The phase relationship of the speed signals of the generators under their common mechanical natural frequencies is a key consideration in SSDC design. The paper studies in detail the phase relationship of the speed signals of two generators in parallel under their shared mechanical natural frequency, revealing regardless of whether the two generators are identical or not, there always exists a common-mode and an anti-mode under their common natural frequency, and the phase relationship of the speed signals of the generators depends on the extent to which the anti-mode is stimulated. The paper further demonstrates that to guarantee the effectiveness of SSDC, the anti-phase mode component of its input signal should be eliminated. Based on the above analysis, the paper introduces the design process of SSDC for multi-generator systems and verifies its effectiveness through simulation in Power Systems Computer Aided Design/Electromagnetic Transients including Direct Current (PSCAD/EMTDC).

Preprocessing is a mandatory step in electroencephalogram (EEG) signal analysis. Overcoming challenges posed by high noise levels and substantial amplitude artifacts, such as blink-induced electrooculogram (EOG) and muscle-related electromyogram (EMG) interference, is imperative. The signal-to-noise ratio significantly influences the reliability and statistical significance of subsequent analyses. Existing referencing approaches employed in multi-card systems, like using a single electrode or averaging across multiple electrodes, fall short in this respect. In this article, we introduce an innovative referencing method tailored to multi-card instruments, enhancing signal fidelity and analysis outcomes. Our proposed signal processing loop not only mitigates blink-related artifacts but also accurately identifies muscle activity. This work contributes to advancing EEG analysis by providing a robust solution for artifact removal and enhancing data integrity.•Removes blink•Marks muscle activity• Re -references with design specific enhancements., (© 2023 The Author(s).)

An improvement of a standard fully differential class-AB symmetrical operational transconductance amplifier (OTA) topology is proposed in this brief to enhance the common-mode behavior. Common-mode behavior could be critical in fully differential class-AB OTAs, where the total current is not fixed and differential to common-mode conversion could therefore be present. A signal proportional to the input common-mode component is generated through a simple low-current auxiliary amplifier and used to modulate a bias voltage, achieving cancellation of the output common-mode component. Simulations in 40-nm CMOS technology show a net improvement of common-mode rejection ratio without affecting differential-mode behavior; the increase in area and power consumption is minimal, with a tradeoff between power and settling time. Simulations of a sample-and-hold exploiting the proposed OTA are presented. [ABSTRACT FROM AUTHOR]

In this paper, an approach to 1-to- 2^n ( n = 2, 3, 4,\ldots ) way microstrip balanced power divider is proposed for the first time. This approach is realized by one balanced-to-single-ended power divider, 2^{n-1} single-ended-to-balanced power dividers, and 2^{n-1}-2 single-ended power dividers. The function of differential-mode power dividing and common-mode suppression can be ensured by the balanced-to-single-ended and single-ended-to-balanced power dividers. The advantage of this approach is that it can reduce the circuit size effectively when comparing with the approach using all the balanced-to-balanced power dividers. The analysis of the balanced-to-single-ended power divider and the single-ended-to-balanced power divider is realized by combining the standard S -parameters, the mixed-mode S -parameters, and the odd- and even-mode equivalent circuits. To verify the theoretical prediction, three prototypes (one balanced-to-single-ended power divider, one single-ended-to-balanced power divider, and one 1-to-4 way balanced power divider) are fabricated and measured. The fabricated 1-to-4 way balanced power divider with the size of shows an insertion loss of 0.45 dB at 1.8 GHz, a fractional bandwidth for a 15-dB return loss of 29%, a 20-dB common-mode suppression of 74.6%, and a 20-dB differential-mode isolation ( \vert S\mathrm{ dd32}\vert and \vert S\mathrm{ dd42}\vert ) of 15.1% and 100%, respectively. [ABSTRACT FROM AUTHOR]

In a multimodal volume coil, only one mode can generate homogeneous Radiofrequency (RF) field for Magnetic Resonance Imaging. The existence of other modes may increase the volume coil design difficulties and potentially decreases coil performance. In this study, we introduce common-mode resonator technique to high and ultrahigh field volume coil designs to reduce the resonant mode while maintain the homogeneity of the RF field. To investigate the design method, the common-mode resonator was realized by using a microstrip line which was split along the central to become a pair of parallel transmission lines within which common-mode currents exist. Eight common-mode resonators were placed equidistantly along the circumference of a low loss dielectric cylinder to form a volume coil. Theoretical analysis and comparison between the 16-strut common-mode volume coil and a conventional 16-strut volume coil in terms of RF field homogeneity and efficiency was performed using Finite-Difference Time-Domain (FDTD) method at 298.2 MHz. MR imaging experiments were performed by using a prototype of the common-mode volume coil on a whole body 7 Tesla scanner. FDTD simulation results showed the reduced number of resonant modes of the common-mode volume coil over the conventional volume coil, while the RF field homogeneity of the two type volume coils was kept at the same level. MR imaging of a water phantom and a kiwi fruit showing the feasibility of the proposed method for simplifying the volume coil design is also presented.

A complementary-defected ground structure (DGS) common stopband filter is proposed. The filter uses two kinds of DGS patterns: a $\Pi$-shaped DGS pattern is used in both sides of the filter and a button-headed H-shaped DGS pattern is adopted at the middle of the filter. The filter utilizes the mutual inductance and mutual capacitance that exists among the DGS patterns to improve the in-band gain-flatness of the filter, which is useful to broaden the bandwidth and improve the rejection ratio in the low cutoff frequency. The simulated and measured results show that the differential signal under the DGS filter is nearly intact and the common-mode noise can be reduced by 15 dB from 3.2 to 12.4 GHz. The area of the filter is only 10 mm × 10 mm. The fractional bandwidth of the stopband can reach 118%. [ABSTRACT FROM AUTHOR]

The imbalance difference theory provides both physical insight and a powerful technique for modeling the conversion from differential-mode signals to common-mode noise, especially for radiated emission problems. Although the theory has been successfully used to model a wide variety of important EMC problems over the past 14 years, it has not been rigorously derived. This paper provides a strict derivation of the theory and carefully defines the important quantities. The derivation demonstrates that imbalance difference calculations are exact provided that the differential-mode propagation is TEM and the current division factor, h, represents the actual ratio of currents on the two transmission line conductors excited by a common-mode source. The paper also discusses the acquisition of the current division factor from 2-D calculations of the cross section of the transmission line. [ABSTRACT FROM AUTHOR]

Transformerless inverters are being widely used in grid-connected photovoltaic (PV) generation systems. Transformer elimination, in grid-connected PV systems, has many advantages. This not only reduces cost, size, and weight, but also increases the whole system efficiency. However, once the transformer is removed, there is no galvanic isolation between grid and PV array; as a consequence, leakage current appears due to parasitic capacitance to the ground, resulting in prohibitive electromagnetic interference and security issues. [ABSTRACT FROM PUBLISHER]

In this paper, it can be applied to a walkie-talkie, the RFID / USN 920 MHz band(917～923.5 MHz) and WiFi 2.4GHz band(2.4～2.483 5GHz) return loss is 10 dB over the band, on-board dual band with omni-directional radiation characteristics is proposed. The basic structure designed antenna is used meander monopole antenna. It was used as double stubs and tabs for antenna designs that meet the criteria proposed. The double stub and the tab affects the reactance of the antenna to form a common-mode and differential-mode in the stub to improve the antenna characteristics and return loss in the bandwidth, gain and radiation characteristics. The system size of walkie-talkie is 52×77 mm2, the size of the antenna is limited to 52×15 mm2, the thickness of FR4 dielectric substrate is 0.8 mm, FR4 dielectric constant 4.4 is used. For experimental results, the return loss is measured more than 10 dB, the maximum gain is measured 1.95 dB, the maximum bandwidth is measured 360 MHz, the radiation characteristic is measured omni-directional. By a walkietalkie terminal design applying the results of the paper, the handset"s price competitiveness and production efficiency can be improved. [ABSTRACT FROM AUTHOR]

This paper proposes a technique for reducing the leakage current flowing into a power source as a conducted noise. This leakage current may have an adverse effect on the peripheral equipment, e.g., causing malfunctions. The proposed technique requires us to add a zero-sequence voltage to the output voltage reference of the inverter. The zero-sequence voltage can be controlled without affecting the driving characteristics of the motor. In a motor drive range, a counter electromotive force increases with an increase in the motor speed. The proposed technique, therefore, controls the zero-sequence voltage as a function of the inverter output frequency; as a result, a stable motor drive and reduction in the common-mode current are realized simultaneously. Simulation and experimental results prove the validity of the proposed technique. [ABSTRACT FROM PUBLISHER]

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ABSTRACT Dual-mode defected ground structure (DGS) is presented to construct differential wideband bandpass filter (WBPF) with very compact size. This proposed DGS is composed of an etched rectangular loop with a central zigzag tapered structure on the bottom surface. Based on this DGS, the filter exhibits adjustable dual-mode resonant characteristics under differential mode (DM) operation and widebandstop filtering characteristics under common-mode (CM) operation. To verify the design concept, one filter to cover the UWB lower-band has been designed, fabricated, and measured. The fabricated differential WBPF demonstrates a DM 3 dB fractional bandwidth of 59% with lower passband insertion loss of 0.52 dB, wider CM suppression better than 10 dB from DC to 11.5 GHz, and very compact size of 0.08 [ABSTRACT FROM AUTHOR]