Frequency Power Supply Research Articles

Retraction: Application of LSTM algorithm combined with Kalman filter and SOGI in phase-locked technology of aviation variable frequency power supply.

Retraction: Application of LSTM algorithm combined with Kalman filter and SOGI in phase-locked technology of aviation variable frequency power supply.

A Multi-Polarized Reconfigurable Plasma Antenna Array

Research on antenna reconfiguration is important in antenna applications. We present design of a multi-polarized plasma antenna with 40.68 MHz radio frequency (RF) power supplies and several discharge tubes filled with argon (neon) and mercury. Furthermore, self-made regulating circuits among the vibrators are introduced for the antenna array system. It can not only make the length of the dipole controllable but also improve the antenna gain and circular polarization (CP) performance under different lengths. Antenna arrays can be classified into linear and circular polarization by quickly adjusting the phase difference between vibrators. Both the experimental and simulation results indicate that the plasma antenna can realize impedance, pattern, and polarization reconstruction expediently. In addition, the linear polarization (LP) and CP can be transformed into each other quickly by adjusting the discharge conditions and regulating circuits. Moreover, compared with a symmetrical cross vibrator plasma antenna and a metal antenna of the same size, the proposed antenna array shows a certain gain and good reconfigurable performance within the frequency band of 150–250 MHz.

Motor Current Model for Detecting Localized Defects in Planet Rolling Bearings

A motor current model for the diagnosis of localized defects in planet rolling bearings (PRBs) is proposed in this study. A dynamic analysis of the motor-driven planetary gearbox system is conducted, and a translational-torsional vibration model of the system is developed. Both the additional time-varying impact caused by localized defects and the influence of the Hertzian contact and radial clearance on the translational support forces of PRBs are considered in the model. Based on the magnetic equivalent circuit network model, vibrational-electromagnetic coupling analysis is performed with the aid of the air-gap permeance and electromagnetic torque. By iteratively solving the nonlinear algebraic differential equations describing the dynamic characteristics of the coupling system, the motor current variation curve with localized defects in the PRB is obtained. Taking a typical motor-driven planetary gearbox system as the object, electromagnetic finite element calculations and dynamic response tests are performed to verify the proposed motor current model. The results show that the characteristic motor current frequencies are a combination of the fault passing frequency and power supply frequency when the inner race of the PRB has a localized spall fault. When the outer race (or roller) has a localized spall fault, the combination of current characteristic frequencies, which generally consists of the fault passing frequency, power supply frequency, and PRB outer-race rotational frequency (outer-race spall) or cage revolution frequency (roller spall), become complex. By discussing the effect of the spall width on the motor current spectra in detail, the characteristic frequencies sensitive to defects are extracted, providing a theoretical basis for the quantitative diagnosis of PRB-localized defects.

Capacitor‐voltage‐balancing control for isolated medium‐voltage AC‐DC modular matrix converter

AbstractThis paper presents a capacitor‐voltage‐balancing control scheme for an isolated medium‐voltage AC‐DC converter using level‐shifted pulse width modulation (PWM) control of a modular matrix converter (MMxC). The proposed isolated AC‐DC converter is composed of the primary MMxC with level‐shifted PWMcontrol, high‐frequency transformer, and secondary H‐bridge circuits. The high‐frequency transformer of the proposed circuit can be downsized because the level‐shifted PWM control scheme makes the rated frequency of the high‐frequency transformer equal to the switching‐frequency. The proposed capacitor‐voltage‐balancing control can compensate for the capacitor voltage imbalance of the MMxC using the positive‐sequence and negative‐sequence circulating‐currents with a power supply frequency and high‐frequency voltage. In the proposed control system, the three feedback control systems with DC control variables can be developed to compensate for the capacitor voltage imbalance. The effectiveness of the proposed capacitor‐voltage‐balancing control scheme and the control systems is verified by experiments using a 200 V, 5‐kW laboratory prototype.

Circulating current suppression for ground tied variable frequency to constant frequency converter system in aircraft

This paper presents a solution to the circulating current fault of aircraft power supply. The DC-link type Variable Frequency to Constant Frequency (VFCF) converter system is the preferred scheme to feed the constant 400 Hz load in an aircraft with a variable frequency power supply. Due to the requirement of aircraft standards, both grounds of the rectification and inversion stage are tied to the metal frame of the aircraft. With such a tied ground, the DC bus voltage rises greatly, and a large circulating current appears in the casing as the ground, which leads to equipment failure and potential safety hazards. According to the existing methods of circulating current fault suppression, this paper analyzes the causes of the above faults and the harmonic components of circulating current and points out the limitations of the existing methods. Therefore, a Common-Mode (CM) choke-based method is proposed to provide a high impedance in the path of the CM circulating current. By doing so, the circulating current can be suppressed without the additional burden of the hardware and control algorithm, which is quite friendly for quality control of mass-production aircraft. Moreover, a simplified mathematic model of the VFCF converter system is derived to calculate the minimum inductance value reference of the CM choke, which saves the weight of passive devices to the greatest extent. Finally, simulation and experimental results are studied to verify the effectiveness of the proposed method.

Capacitor-Voltage-Balancing Control for Isolated Medium-Voltage AC-DC Modular Matrix Converter

This paper presents a capacitor-voltage-balancing control scheme for an isolated medium-voltage AC-DC converter using level-shifted PWM control of a modular matrix converter (MMxC). The proposed isolated AC-DC converter is composed of the primary MMxC with level-shifted PWM control, high-frequency transformer, and secondary H-bridge circuits. The high-frequency transformer of the proposed circuit can be downsized because the level-shifted PWM control scheme makes the rated frequency of the high-frequency transformer equal to the switching-frequency. The proposed capacitor-voltage-balancing control can compensate for the capacitor voltage imbalance of the MMxC using the positive-sequence and negative-sequence circulating-currents with a power supply frequency and high-frequency voltage. In the proposed control system, the three feedback control systems with DC control variables can be developed to compensate for the capacitor voltage imbalance. The effectiveness of the proposed capacitor-voltage-balancing control scheme and the control systems is verified by experiments using a 200V, 5-kW laboratory prototype.

Design of VHF micro-EDM discharge state detection method based on energy coupling detection

Because the pulse frequency of VHF micro-EDM power supply (30–300 MHz) is higher than that of traditional EDM power supply and the pulse has two characteristics of positive and negative bipolar, it is impossible to use traditional discharge state detection technology to meet the requirements of VHF discharge state detection. And during the experiment, it was found that the resonant frequency of the VHF pulse would migrate with the change of circuit impedance, leading to the change of pulse voltage amplitude. In order to break through the limitations of traditional detection method, this paper combined the technology of EDM discharge state recognition and microwave detecting technology, based on the principle of electrode impedance change, put forward a discharge condition detection method of VHF pulse source based on energy principle of coupling detection, the method using a double-directional coupler and rf receiver device for detecting pulse energy. It can detect the inter-electrode power of a VHF pulse source with a frequency range from 30 to 300 MHz and a power range below 100 W and realize accurate discharge status identification of VHF micro-EDM.

Improving Sparrow Search Algorithm for Optimal Operation Planning of Hydrogen–Electric Hybrid Microgrids Considering Demand Response

Microgrid operation planning is crucial for ensuring the safe and efficient output of distributed energy resources (DERs) and stable operation of the microgrid power system. The integration of hydrogen fuel cells into microgrids can increase the absorption rate of renewable energy, while the incorporation of lithium batteries facilitates the adjustment of microgrid power supply voltage and frequency, ensuring the three-phase symmetry of the system. This paper proposes an economic scheduling method for a grid-connected microgrid that considers demand response and combines hydrogen and electricity. Based on the operating costs of renewable energy, maintenance and operation costs of nonrenewable energy, interaction costs between the microgrid and main grid, and pollution control costs, an optimization model for dispatching a hydrogen–electric hybrid microgrid under grid-connected mode is established. The primary objective is to minimize the operating cost, while the secondary objective is to minimize the impact on the user’s power consumption comfort. Therefore, an improved demand response strategy is introduced, and an enhanced sparrow search algorithm (ISSA) is proposed, which incorporates a nonlinear weighting factor and improves the global search capability based on the sparrow search algorithm (SSA). The ISSA is used to solve the optimal operation problem of the demand-response-integrated microgrid. After comparison with different algorithms, such as particle swarm optimization (PSO), whale optimization algorithm (WOA), sooty tern optimization algorithm (STOA), and dingo optimization algorithm (DOA), the results show that the proposed method using demand response and ISSA achieves the lowest comprehensive operating cost for the microgrid, making the microgrid’s operation safer and with minimum impact on user satisfaction. Therefore, the feasibility of the demand response strategy is demonstrated, and ISSA is proved to have better performance in solving optimal operation planning problems for hydrogen–electric hybrid microgrids.

Novel V2G regulation scheme using Dual-PSS for PV islanded microgrid

The incorporation of electric vehicles (EVs) into residential/industrial microgrids (MGs) presents some limitations such as fluctuations in voltage, frequency, and lack of power supply. According to the literature, the control methods for vehicle-to-grid (V2G) in MGs are insufficiently coordinated for charging and regulation, limited by narrow charging control constraints, complex, and computationally demanding. Moreover, the power system stabilizer (PSS) is employed only in the generation side. To this regard, a PSS is proposed in this paper along with the proportional-integral-derivative (PID) controller, which is tuned adaptively using Harris hawks optimizer (HHO) for frequency, voltage, and power-sharing regulations through the parked EVs. The considered islanded MG is consisting of a diesel generator as a backup generation source, dealing with the intermittent nature of the solar photovoltaic (PV) plant and residential load. It also includes an EV aggregator. In case of partial shading of the solar PV farm and triggering the load demand, the proposed control strategy provides a complementary signal to promote short response time during transients, boost the transient stability performance, and offer damping characteristics adequate for V2G regulation with the islanded residential MG. To examine the efficacy of the proposed scheme, a detailed simulation model using Matlab/Simulink was built. The final findings show that the proposed direct adaptive PID-PSS controller gives significantly enhanced voltage and frequency with spinning reserve compared to the conventional PI-controller both considering the inclusion of V2G on the MG regulation side and conventional controller without V2G and PSS on the regulation side. Also, it can provide power flow in a bi-directional way during the partial shading contingency that the residential MG may experience within 24 hr.

Combinatorial Synthesis of AlTiN Thin Films

Nitrides of aluminum (Al) and titanium (Ti) mixtures have long been studied and used as commercial coatings because of their high hardness and high oxidation resistance due to the formation of an alumina layer on the coating surface. To fully understand the contribution of Al and Ti to the properties of the film, a combinatorial deposition approach was employed using half-disk targets. Film growth was carried out using a magnetron sputtering system powered by a 13.56 MHz radio frequency power supply with varying argon (Ar) and nitrogen (N2) gas ratios. Depending on the location of the substrate relative to the target, atomic percent gradients of 0.60–0.70 Al and 0.30–0.40 Ti across the substrate surface were obtained from energy dispersive X-ray spectral analysis. X-ray diffraction peaks at 43.59°, 74.71° (face-centered cubic), and 50.60° (wurtzite) confirmed the presence of aluminum titanium nitride (AlTiN) mixtures, with an increasing amount of wurtzite phase at higher Al concentrations. For all samples, cauliflower-like nanograins were obtained and samples of the 80:20 Ar:N2 gas pressure ratio showed the smallest grain size among the three gas ratio combinations. The 80:20 Ar:N2 films revealed a relatively high hardness compared to the other gas ratios. All thin films exhibited good adhesion to 304 stainless steel substrates.

Bearing Fault Detection in Three-Phase Induction Motors Using Support Vector Machine and Fiber Bragg Grating

Due to its robustness and cost-effectiveness, the three-phase induction motor (TIM) has become the most widespread electric machine today. However, like any other equipment, it is vulnerable to a fault, and about 52% of these are related to bearings. This work presents the detection of flaws in the outer bearing’s raceway from the measurement of motor dynamic strain signals collected from sensors based on fiber Bragg grating (FBG). Three different degrees of severity were considered for faults in the outer bearing’s raceway. The tests were carried out on the motor operating under no-load conditions, with 47 different power supply frequencies. This work proposes a support vector machine (SVM) classifier to identify fault severity levels. Feature extraction was performed using two techniques: selecting the four highest peaks in the frequency spectrum and principal component analysis (PCA). The supervised SVM classifiers show that the dataset formed from the PCA presented a higher hit rate than the dataset constituted by the four highest peaks, with 99.82% and 92.73%, respectively. Based on the methodology presented in this work, it was possible to validate the use of FBG to detect bearing faults. Regardless of the degree of severity of the fault analyzed, the sensor detected its characteristic frequency. Based on the methodology presented in this work, it was possible to validate the use of FBG to detect bearing faults. Regardless of the degree of severity of the flaw analyzed, the sensor detected its characteristic frequency.

Simulation and validation of the effective power absorbed by a non-equilibrium plasma flow inside the medium-power inductively coupled plasma wind tunnel

A non-equilibrium magneto-hydrodynamic model coupled with a power absorption model was established to calculate the effective power absorbed by the plasma flow inside a 110 kW medium-power inductively coupled plasma wind tunnel. This magneto-hydrodynamic model takes into account the coupling of Navier–Stokes equations, electromagnetic field equations, five species and eight chemical reactions of nitrogen, and a four-temperature model. Moreover, the power absorption model not only considers the power loss from the power supply system but also the coupling efficiency between plasma and the inductive coils. First, the anode loss of an electronic tube and its oscillator circuit efficiency is calculated, respectively, to obtain the total power loss from a radio frequency power supply system. Second, a transformer circuit model of the inductively coupled plasma (ICP) is established to calculate the coupling efficiency between the coil and plasma. Third, the effective power absorbed by the plasma flow and the pathways of the power losses of a medium-power ICP wind tunnel are obtained and discussed. Finally, the flow-field properties of the plasma flow, which are simulated by solving the Navier–Stokes equations coupled with the power absorption model, are obtained and analyzed. Furthermore, the simulated results are compared with corresponding experimental data, and they agree well with each other. It is found that the power loss of the electron tube oscillator accounts for 40%. It is the most dominant part of the total power loss. The effective power absorbed by a plasma flow is about 33.6% for the 110-kW inductively coupled plasma wind tunnel.

An Efficient Resonant Pole Inverter With Reliable Elimination of Switching Loss of Main Switches

The brief presents a novel resonant pole inverter for the efficient operation of the inverter. Its design process can be summarized briefly as follows: three sets of identical auxiliary circuits are respectively connected in parallel with each bridge arm of the three-phase hard-switching inverter and each set of auxiliary circuits only contains two auxiliary switches, two resonant capacitors and one resonant inductor; when the auxiliary circuits work, the current will flow through the antiparallel freewheeling diode of main switches periodically before main switches are switched on or off. Thus, the outstanding advantage of the novel inverter is that main switches can acquire zero-voltage switching-on and zero-current switching-off, making for more reliable elimination of switching loss. The brief elaborates each working state in a switching cycle. Experimental waveforms imply that switches can attain soft-switching. Moreover, the efficiency of the novel inverter achieves 99.1% at rated output power and the value marks an increase of 0.5 percentage points at the same rated output power, compared with the most recent topology in another literature. Thus, the novel inverter can have efficiency superiority over other soft-switching inverters when it is applied as the variable frequency power supply in the electric drive system.

The traction network design of the new three‐phase 3‐kV traction power supply system based on the limits of receiving‐end voltages and negative sequence voltage unbalance factor

AbstractThe characteristics of traction network (TN) of the three‐phase 3‐kV traction power supply system (TPSS) are: three‐phase conductors are flat layout (layout‐1, layout‐2); the material and cross‐section of conductors are ferromagnetic and irregular, respectively. So the phase impedance matrix (PIM) is unbalanced and the closed‐form formula for conductor impedance is hard to get. To address these issues, firstly, the PIM is derived, and the cause of unbalance is revealed. From the perspective of structure optimization, a new flat layout (layout‐3) and an equilateral triangle layout (layout‐4) is proposed. Then, to calculate the wideband frequency self‐ and mutual impedances of the special phase conductors, a frequency‐ and current‐dependent closed‐form formula based on 4‐parameters equivalent tubular conductor (ETC) model is proposed. Furthermore, an equivalent TN circuit model at 50 Hz is established to calculate the receiving‐end voltage and its negative sequence voltage unbalance factor (NSVUF). Finally, using these two indexes, the performances of the layout‐1 to 4 are evaluated and compared. The results show that the conductor spacing and power supply frequency affect the two indexes much while the dimension of the power supply rail (PSR) not; layout‐4 can completely balance the receiving‐end voltage and improve its magnitude which can enhance the power supply capability.

Active signal-generating spacer-fabric-type continuous touch/pressure sensor

Attention toward automated driving has recently increased. This has also increased the need to monitor drivers’ actions, such as finger touch/pressure sensing on the steering wheel. This study demonstrates an active signal-generating spacer-fabric-type continuous touch/pressure sensor comprising five yarn layers: surface-insulating cotton, upper conductive, monofilament spacer, lower conductive and bottom-insulating cotton yarn. The sensor actively generates signals, and the magnitude of the voltage output through a diode bridge and capacitor circuit determines if the fingers are ‘not touching’, ‘touching’, ‘pushing’ or ‘pushing hard’. This demonstrates that the proposed sensor can be operated as an active signal-generating touch/pressure sensor and can also detect ‘pushing hard’ actions. Furthermore, the active signal-generating operation originates from the electromagnetic waves emitted by electrical appliances and cables powered by a commercial power supply frequency in the environment. The proposed sensor will contribute to developing high-cushioning touch/pressure sensors with low power consumption and excellent air permeability that can be used in electric and autonomous vehicles.

An EMI susceptibility study of different integrated operational transconductance amplifiers

Abstract This paper presents a comparative EMI susceptibility study of different integrated operational transconductance amplifier (OTA) topologies. We analyzed conventional well-known amplifier topologies based on the Miller OTA and folded cascode concepts with lower power consumption. The output dc voltage shifts induced by power supply and input common mode high frequency disturbances are presented. On top of the EMI susceptibility comparison, we discuss PSRR and CMRR within large and small excitation signal with a new simulation setup. Even more, the back-gate connections of differential MOS pair in OTA input stage are investigated for EMI susceptibility impact as well.

Power Transmission Characteristics in Commercial Frequency of Wireless Power Transfer System for Railway Vehicles Using High Temperature Superconducting Coil

This study investigated experimentally and analytically the power transmission characteristics of High Temperature Superconducting (HTS) coils at commercial power supply frequency (50 Hz) to realize highly efficient power transmission in wireless power transfer systems for railway vehicles. We proposed a solenoidal coil with a thin magnetic core as an HTS coil structure suitable for lower frequencies and investigated its effectiveness by finite element analysis. The analysis results showed that the proposed coil can significantly suppress the current increase due to the low frequency of the wireless power transfer system. We also investigated the core shape to reduce the losses of the proposed coil and found that the loss in the coil can be reduced by increasing the length and thickness of the magnetic core. Furthermore, we compared the power transmission characteristics between the proposed coil and the conventional spiral coil and showed that the proposed coil could improve the overall efficiency by about 10 %. The power transmission characteristics at 50 Hz were also measured using the scaled-down model coil. As a result, we demonstrated that highly efficient power transmission could be achieved at 50 Hz by using the proposed solenoidal coil with a magnetic core.

Internet connectivity and power outages in university electronic libraries in Nigeria

This paper focuses on the role of power supply to e-library equipment most especially as it affects internet connectivity for effective library utilization in Delta State University E-libraries. A survey was carried out on the number of e-library equipment of the operating points of the Delta State University Libraries as well as the frequency of power supply in one of her campuses at Oleh. The results revealed that in Abraka main campus, out of 150 Internet connected computer systems, only 30 were Internet active. In the teaching hospital e-library, out of 20 Internet connected computer systems, only 15 were Internet active while in Oleh campus e-library out of 62 Internet connected computer systems, only 20 were Internet active. Also, power availability at Oleh Campus E-library is put at an average of 2.2 hours while non-availability is at an average of 5.8 hours out of the Eight (8) hours considered. This results indicate poor performance of equipment and operations of e-library in Oleh Campus. Solutions towards improvement and long serving equipment are proffered.

Numerical optimization of non-equilibrium plasma source for surface processing of materials

Over the years, non-equilibrium plasma sources have emerged as a promising technology in surface processing of materials. Various strategies have been employed to make significant advancement in the technology. However, the process optimization is found to depend on different factors like power supply frequency, gas species and gas pressure. In order to control material processing outcome, it is necessary to control plasma parameters as per requirement. In the present work, a surface microwave generated non-equilibrium plasma source is proposed for material processing applications. The source comprises of rectangular waveguide system and a quartz tube, whose dimensions are optimized based on the electric field profile obtained within the plasma tube in the presence of the microwave (f = 2.45 GHz). Argon gas is allowed to flow through the discharge tube at a velocity of 10 m/s keeping its pressure at 1 torr. The microwave electric field within the discharge tube ionizes the argon gas medium resulting into plasma state whose properties are investigated using commercially available COMSOL Multiphysics® software. The inner surface of the discharge tube is then filled with dielectric beads (radius = 2 mm) and the effect of the dielectric constant on the plasma properties are studied. An investigation of ion flux at different positions in the plasma tube suggests that in the absence of dielectric beads, remote contact mode of operation can be preferred while in the presence of dielectric beads, direct contact mode of operation can be implemented. These results are of significance for direct as well as remote mode of surface processing of materials.

Spectral diagnosis of atmospheric pressure AC argon plasma jet at constant power

In the application of atmospheric pressure plasma jet, because the frequency of AC power supply is limited in the kHz range, the research on the influence of power supply electrical parameters on discharge is basically aimed at the variation of plasma jet characteristics with a single driving electrical parameter ( such as voltage and frequency). However, the discharge power usually changes with a single electrical parameter changing, which can undoubtedly affect the discharge performances including the plasma physical parameters and generated reactive species, resulting in the failure to reflect the influence of the single driving parameter on the discharge. In this study, an atmospheric pressure argon plasma jet is driven by a home-made AC power supply with adjustable pulse modulated duty cycle. And combining the diagnosis of the optical emission spectrum and the optical absorption spectrum, the influences of the voltage, frequency and pulse modulated duty cycle parameters on the gas temperature <i>T</i><sub>g</sub>, electron excitation temperature <i>T</i><sub>exc</sub>, electron density <i>n</i><sub>e</sub>, and OH radical particle number density of the plasma jet are studied under a constant discharge power of 2 W. The results show that at the constant power, the electron density n<sub>e</sub> does not change with the variation of electrical parameters as the linkage change of electrical parameters will offset the influence of a single parameter on the electron density, while the gas temperature <i>T</i><sub>g</sub>, electron excitation temperature <i>T</i><sub>exc</sub>, and OH radical particle density are most affected by the pulse modulated duty cycle, followed by driving voltage, and the frequency effect is the smallest. Under the constant power, as the frequency decreases, the voltage will increase, and also the gas temperature <i>T</i><sub>g</sub>, electron excitation temperature <i>T</i><sub>exc</sub>, and OH radical particle number density will increase. On the contrary, although the voltage also increases as the pulse modulated duty cycle decreases, the gas temperature <i>T</i><sub>g</sub>, electron excitation temperature <i>T</i><sub>exc</sub>, and OH radical particle number density are all reduced. In addition, the results indicate that reducing the duty cycle of AC power can make the atmospheric pressure plasma jet produce more OH radicals at lower gas temperature. This study provides a new insight into the influence of electrical parameters on the characteristics of atmospheric pressure plasma jets under constant power, and also presents a guidance for choosing power parameters of plasma jets with low gas temperature and high density of reactive species, which is conducive to the development of atmospheric pressure plasma jets in biomedicine and other fields.