Frequency Modulation Method Research Articles

Efficient power conversion with four switch soft-switching boost integrated half-bridge dual-output series resonant converter

Soft switching reduces voltage and current stress during transitions, smoothing and quieting operations and reducing electromagnetic interference while also increasing efficiency and equipment lifespan. Circuit design, component selection, and switching frequency optimization affect power electronics soft switching. This paper proposes boost integrated half-bridge dual-output series resonant (BIHBDOSR) converter, a novel converter design and control method to increase series resonant converter performance by reducing storage element size, switch count, and switching losses. This methodology relies on soft-switching technologies like zero-voltage switching (ZVS) and zero-current switching (ZCS). These methods use class-D, class-E, series, parallel, and series–parallel resonant converter circuits to increase efficiency and minimize component stress. The proposed converter is ideal for constant voltage, constant power, and current-controlled loads with the output voltage being regulated by a closed-loop PI controller. The output voltages for two loads in the simulation depart from reference values. V01 changes from 14 to 20 V and V02 from 18 to 15 V at 300 ms owing to switching variances. The proposed converter utilizes gate driver circuits, resonant tank circuit, current sensor, FPGA board for closed-loop control, and current sensor for stability, ensuring converter stability. The proposed converter closed-loop control method modifies PWM signals to regulate both loads independently and ensure steady output voltage. Additionally, to validate the effectiveness of proposed converter, a 50-W driver circuit is designed, delivering two independent outputs of 20 W and 30 W. Frequency modulation (FM) and duty cycle control methods are employed to obtain the desired outputs.

Resonance-driven microwave heating for improved methane conversion to hydrogen

Efficient hydrogen production through methane pyrolysis is hindered by high temperature required and frequent catalyst deactivation due to carbon deposition. This study proposes a novel use of variable-frequency microwave heating to enhance the efficiency and stability of methane pyrolysis by leveraging the resonance effects between microwave frequencies and dielectric properties of activated charcoal (AC). A solid-state variable-frequency microwave reactor was employed to modulate microwave frequencies to match the dielectric properties of AC, with a peak tanδ of 0.19 at 4600 MHz. Experimental results showed that at a resonance frequency of 4650 MHz and a microwave power of 100 W, the reaction temperature of AC reached 960 °C within 2 min, achieving a 100% methane conversion rate. However, carbon deposition reduced the conversion rate to 35.1% after 150 min. By cyclically adjusting the microwave frequencies between 4650 MHz and 4640 MHz, the catalyst was successfully reactivated, restoring the conversion rate to 100%. This frequency modulation method enabled continuous methane pyrolysis for 1300 min, highlighting the potential of variable-frequency microwave heating as a novel and efficient approach for a sustainable production of green hydrogen.

Optimization of such strategy as frequency modulation for grid-side energy storage control-terminal in response to frequency fluctuations in the new power system grid

Abstract This paper focuses on the refinement of the control strategy for grid-side energy storage systems as they engage in primary and secondary frequency modulation within an emerging smart grid. To attain an optimal outcome, traditional frequency modulation methods, which often require high-precision operations and extended adjustment periods, fall short of the stringent demands posed by modern power systems for swift and responsive frequency modulation. Under such circumstances, the grid-side energy storage control-terminal system presents a viable solution for managing energy storage, thereby providing rapid and precise assistance to the power system’s frequency modulation. By implementing a control mechanism that can adaptively switch between ARR signal-based and ACE signal-based frequency adjustments, a segmented parallel control approach ensures that the energy storage system can promptly and effectively modify the power within the grid system, facilitating swift frequency modulation.

Multi-Objective Optimization of the Ultrasonic Scalpel Rod and Tip with Improved Performance: Vibration Frequency, Amplitude, and Service Life

Ultrasonic scalpel design for minimally invasive surgical procedures is mainly focused on optimizing cutting performance. However, an important issue is the low fatigue life of traditional ultrasonic scalpels, which affects their long-term reliability and effectiveness and creates hidden dangers for surgery. In this study, a multi-objective optimal design for the cutting performance and fatigue life of ultrasonic scalpels was proposed using finite element analysis and fatigue simulation. The optimal design parameters of resonance frequency and amplitude were determined. By setting the transition fillet and keeping the gain structure away from the node position to enable the scalpel to have a high service life with excellent cutting performance. The frequency modulation method of setting the vibration node bosses at the node position and setting the vibration antinode grooves at the antinode position was compared. Then, the mechanism of the influence of various design elements, such as tip, shank, node position, and antinode position, on the resonance frequency, amplitude, and fatigue life of the ultrasonic scalpel was analyzed, and the optimal design principles of the ultrasonic scalpel were obtained. The proposed ultrasonic scalpel design was confirmed by simulations, impedance measurements, and liver tissue cutting experiments, demonstrating its feasibility and enhanced performance. This research introduces innovative design strategies to improve the fatigue life and performance of ultrasonic scalpels to address an important issue in minimally invasive surgery.

Study on primary frequency modulation control strategy based on wind-fire cooperation

Abstract Due to the increasing proportion of wind power in the power system, the wind turbine should have the ability of primary frequency modulation when integrated into the power system. At the wind turbine level, different methods are adopted according to different wind speeds, which can get the wind turbine fully joined in the system. Secondly, this paper gives full consideration to the characteristics of thermal and wind power units and proposes a joint primary frequency modulation method between the thermal and wind farms. The output of wind and thermal power is determined by adding a frequency divider. The system stability and reaction speed are effectively enhanced.

Chaff Cloud Integrated Communication and TT&C: An Integrated Solution for Single-Station Emergency Communications and TT&C in a Denied Environment

In response to potential denial environments such as canyons, gullies, islands, and cities where users are located, traditional Telemetry, Tracking, and Command (TT&C) systems can still maintain core requirements such as availability, reliability, and sustainability in the face of complex electromagnetic environments and non-line-of-sight environments that may cause service degradation or even failure. This paper presents a single-station emergency solution that integrates communication and TT&C (IC&T) functions based on radar chaff cloud technology. Firstly, a suitable selection of frequency bands and modulation methods is provided for the emergency IC&T system to ensure compatibility with existing communication and TT&C systems while catering to the future needs of IC&T. Subsequently, theoretical analyses are conducted on the communication link transmission loss, data transmission, code tracking accuracy, and anti-multipath model of the emergency IC&T system based on the chosen frequency band and modulation mode. This paper proposes a dual-way asynchronous precision ranging and time synchronization (DWAPR&TS) system employing dual one-way ranging (DOWR) measurement, a dual-way asynchronous incoherent Doppler velocity measurement (DWAIDVM) system, and a single baseline angle measurement system. Next, we analyze the physical characteristics of the radar chaff and establish a dynamic model of spherical chaff cloud clusters based on free diffusion. Additionally, we provide the optimal strategy for deploying chaff cloud. Finally, the emergency IC&T application based on the radar chaff cloud relay is simulated, and the results show that for severe interference, taking drones as an example, under a measurement baseline of 100 km, the emergency IC&T solution proposed in this paper can achieve an accuracy range of approximately 100 m, a velocity accuracy of 0.1 m/s, and an angle accuracy of 0.1°. In comparison with existing TT&C system solutions, the proposed system possesses unique and potential advantages that the others do not have. It can serve as an emergency IC&T reference solution in denial environments, offering significant value for both civilian and military applications.

Magneto-acousto-electrical tomography using nonlinearly frequency-modulated ultrasound.

Objective. In this study, nonlinearly frequency-modulated (NLFM) ultrasound was applied to magneto-acousto-electrical tomography (MAET) to increase the dynamic range of detection.Approach. Generation of NLFM signals using window function method-based on the principle of stationary phase-and piecewise linear frequency modulation method-based on the genetic algorithm-was discussed. The MAET experiment systems using spike, linearly frequency-modulated (LFM), or NLFM pulse stimulation were constructed, and three groups of MAET experiments on saline agar phantom samples were carried out to verify the performance-respectively the sensitivity, the dynamic range, and the longitudinal resolution of detection-of MAET using NLFM ultrasound in comparison to that using LFM ultrasound. Based on the above experiments, a pork sample was imaged by ultrasound imaging method, spike MAET method, LFM MAET method, and NLFM MAET method, to compare the imaging accuracy.Main results. The experiment results showed that, through sacrificing very little main-lobe width of pulse compression or equivalently the longitudinal resolution, the MAET using NLFM ultrasound achieved higher signal-to-interference ratio (and therefore higher detection sensitivity), lower side-lobe levels of pulse compression (and therefore larger dynamic range of detection), and large anti-interference capability, compared to the MAET using LFM ultrasound.Significance. The applicability of the MAET using NLFM ultrasound was proved in circumferences where sensitivity and dynamic range of detection were mostly important and slightly lower longitudinal resolution of detection was acceptable. The study furthered the scheme of using coded ultrasound excitation toward the clinical application of MAET.

Optical parametric-assist frequency modulation for FMCW Lidar enabling double-range velocity measurement

Frequency-modulated continuous waves (FMCW) Lidar functioned as simultaneous measurement of velocity and distance has shown promising prospects in many applications. Direct modulation on semiconductor lasers is a common approach to achieve linear optical frequency scanning in FMCW Lidar for the simple configuration and easy implementation. However, the directly-modulated laser used to suffer from the limited scanning bandwidth, resulting in poor range resolution and limited velocity measurement range of FMCW Lidar. In particular, the issue becomes critical in the case of high velocity measurement over short distance. Here, we propose an optical parametric-assist frequency modulation (OPAFM) method to improve the velocity and distance measurement of FMCW Lidar simultaneously. Firstly, a chirp rate doubled idler light is generated via the four-wave mixing of a frequency-swept pump with a continuous-wave signal. The idler light then serves as a linear frequency swept laser source in the FMCW Lidar to double the range of velocity measurement and improve ranging resolution. We experimentally demonstrated the chirp rate improvement of frequency-swept light from 80.75 MHz/μs to 163.75 MHz/μs. To apply the idler light to the FMCW Lidar, the maximum measurable velocity can be doubled from 2.13 m/s to 4.41 m/s for a target at 5.2 m. Moreover, ranging measurement with improved resolution of 117 mm is also achieved, compared to the 234 mm ranging resolution by using the traditional FMCW Lidar solely. The maximum range can reach 41.54 m. The precision of velocity and distance measurement are 0.1 m/s and 3.5 cm, respectively. The method provides a promising solution to enhance the velocity and distance measurement of FMCW Lidar, enabling diverse applications in sensing and mapping.

Corrosion inhibition properties of perimidin-10-one derivatives for steel reinforcement in acidic environments: Experimental and theoretical insights

Perimidin-10-one derivatives are environmentally benign corrosion inhibitors that prevent steel reinforcement from corroding in acidic environments. The inhibitory impact of 8-(2-Hydroxybenzoyl)-7 H-9-(3-methylphenylhydrazono)-pyrrolo[1,2-a] perimidin-10-one and 8-(2-Hydroxybenzoyl)-7 H-9-phenylhydrazono-pyrrolo[1,2-a] perimidin-10-one on steel-reinforced corrosion in an acidic media (2 M HCl) were explored using chemical technique, (TP) Tafel polarization, (EIS) electrochemical impedance spectroscopy, and (EFM) electrochemical frequency modulation method, as well as theoretical research (quantum chemistry analysis and molecular dynamic studies). Also Energy dispersive X-ray and scanning electron microscopy (EDX–SEM) were used to examine the morphology of shielded steel-reinforced concrete. The inhibition efficiency of the inhibitors with increasing inhibitor concentration and reaches a maximum of 89.68 percent at a concentration of 11×10−6 M at 55° C, according to the findings. The examination of potentiodynamic polarization revealed that the two compounds act as a mixed category of inhibitor. The Langmuir and Henry adsorption isotherms were followed by inhibitors adsorption on steel reinforcement surface. Quantum chemical calculations based on density functional theory (DFT) were used to investigate the manner of adsorption of the two compounds on reinforced surface. Molecular dynamic studies were used to determine the adsorption energy of the inhibitors at different temperatures. Also the comparison between the experimental parts was applied. The results clearly show that the two compounds work well as corrosion inhibitors for steel reinforcement in an acidic media. Compound (1) > compound (2) are the percent IE orders of Perimidin-10-one derivatives.

Diode Laser Frequency Stabilities Obtained by Frequency and Zeeman Modulation Methods

Diode Laser Frequency Stabilities Obtained by Frequency and Zeeman Modulation Methods

An Effective Modulation Technique for Multi Level Inverters

High frequency modulation techniques play very important role in multilevel inverters MLIs. These techniques have several advantages over low frequency modulation methods where they provide lower harmonic contents and higher performance in real time adaptation. Multicarrier sinusoidal pulse width modulation MCSPWM is a common high frequency technique and control method for MLIs. The synchronization of carrier signals, complexity of hardware components and high cost are very important issues when implementing multicarrier MCSPWM in real time. This paper presents an efficient approach that can overcome the problems of multicarrier signals. The proposed approach combines the advantages of low and high frequency modulation techniques. Real time adaptation of modulation index can be achieved easily, and harmonics contents are reduced to very low levels as well. Simulation and comparison of the proposed approach with MCSPWM are presented. The proposed approach is applied and tested effectively with different topologies of MLIs.

A Virtual Synchronous Generator Secondary Frequency Modulation Control Method Based on Active Disturbance Rejection Controller

In order to solve the frequency modulation (FM) problem caused by load in the virtual synchronous generator (VSG) system under an islanding state, this paper proposes a frequency modulation method based on active disturbance rejection control (ADRC). Firstly, design a nonlinear function using the design rules of nonlinear functions. Then, the extended state observer (ESO) and nonlinear feedback control law (NLSEF) of ADRC are designed based on the nonlinear function. By introducing ADRC into the power–frequency control loop of VSG, error-free frequency modulation of VSG is achieved. Finally, the superiority of the proposed method was verified through experimental comparison.

A new method for ultrasonic fatigue component frequency modulation: From ultrasonic horn to uniaxial and multiaxial specimens

Ultrasonic fatigue specimens require rigorous design. The entire machine and specimen setup must vibrate in resonance at high frequencies, with the desired mode shapes that produce the intended stresses. The connection between parts must be considered too as they should allow for the desired mode shape to vibrate in free-free conditions. Most published research uses an analytical method that works only for uniaxial tension–compression or pure torsion specimens. This limits the range of experiments. In this paper, a semi-analytical formulation that can model more complex ultrasonic specimen geometries for a variety of stress states is proposed, namely multiaxial tension–torsion. Comparing numerical simulations with the analytical method show a good correlation between results. This work can help other researchers to design and conduct more varied and efficient ultrasonic fatigue experiments.

A high-frequency SSVEP-BCI system based on a 360 Hz refresh rate.

Objective. Steady-state visual evoked potential (SSVEP) based brain-computer interfaces (BCIs) often struggle to balance user experience and system performance. To address this challenge, this study employed stimuli in the 55-62.8 Hz frequency range to implement a 40-target BCI speller that offered both high-performance and user-friendliness.Approach. This study proposed a method that presents stable multi-target stimuli on a monitor with a 360 Hz refresh rate. Real-time generation of stimulus matrix and stimulus rendering was used to ensure stable presentation while reducing the computational load. The 40 targets were encoded using the joint frequency and phase modulation method, offline and online BCI experiments were conducted on 16 subjects using the task discriminant component analysis algorithm for feature extraction and classification.Main results. The online BCI system achieved an average accuracy of 88.87% ± 3.05% and an information transfer rate of 51.83 ± 2.77 bits min-1under the low flickering perception condition.Significance. These findings suggest the feasibility and significant practical value of the proposed high-frequency SSVEP BCI system in advancing the visual BCI technology.

A Simplified Sensorless Synchronous Rectification Method for Inner Phase Shift Control in CLLC Converters

The CLLC converter is a promising topology for bidirectional power conversion applications, such as vehicle-to-grid and battery energy storage systems. In these applications, wide output voltage range is needed. However, traditional pulse frequency modulation method is not suitable for wide output range because of wide switching frequency range. Inner phase shift (IPS) control is a good solution for this issue. In CLLC converters, to further increase the efficiency, synchronous rectification (SR) is required. In this paper, a simplified sensorless SR method is proposed for IPS control. A comprehensive operation mode analysis and an accurate operation mode model is established for IPS control in CLLC converters. With the operation mode model, waveform of secondary side current is simplified. As a result, only a standard quadratic-root formula needs to be calculated to generate SR drive signal, and no extra sensors are needed. The method is low cost and is suitable to implement in embedded systems. A prototype is built to verify the proposed simplified sensorless SR method. The proposed method achieves an obvious efficiency improvement (up to 1.88%) over uncontrolled rectification, and the effect of the proposed method is nearly the same as that of complete SR (maximum efficiency difference is 0.40%).

Comparative Study of Protection Efficiency of C-Steel Using Polystyrene Clay Nanocomposite Coating Prepared from Commercial Indian Clay and Local Khulays Clay

This work aimed to compare the coating protection efficiency of C-steel using two kinds of clay: a local Khulays clay (RCKh) from Saudi Arabia and a commercial clay (CCIn) from India. Clay-based polymer nanocomposites have a unique layered structure, rich intercalation chemistry, and availability at low cost. They are promising reinforcements for polymers. The raw clay for both clay types was washed before being treated with NaCl to produce sodium clay (NaC). The cationic surfactant cetylpyridinium chloride (CPC) was then used to convert the NaC into the organoclay (OC) form. Polystyrene/organoclay nanocomposites (PCNs) were prepared by combining different concentrations of organoclay (1%, 3%, and 5% OC) in toluene solvent and polystyrene (PS) as the matrix. To ensure the success of the PCN modification process, the organoclay and PCN films were characterized using a variety of techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The shifts in the FT-IR spectra after the CPC treatment of NaC confirmed the presence of CPC in the organoclay samples and the presence of OC in the PCNs. The exfoliated structure was obtained from the XRD spectrum for low clay loading (1–3% PCN), while the intercalated structure was the dominant form for the 5% PCN. The XRD results were confirmed by TEM images. To calculate the coating efficiency of the PCNs, various electrochemical methods were used. The electrochemical measurements included electrochemical impedance spectroscopy (EIS), the electrochemical frequency modulation (EFM) method, and Tafel plots. The PCN with a concentration of 1 wt.% OC has a fully exfoliated structure and higher coating efficiency than the PCNs with partially exfoliated structures (3 wt.% and 5 wt.%). It was found from the Tafel plots that commercial Indian clay has better corrosion protection (81.4%) than local Khulays clay (60.2%). A comparison with other studies using current density values shows that our results are superior to those of many studies.

Ultralinear 140-GHz FMCW signal generation with optical parametric wideband frequency modulation enabling 1-mm range resolution.

We demonstrate ultralinear and ultrawideband frequency-modulated continuous-wave (FMCW) signal generation using an optical parametric wideband frequency modulation (OPWBFM) method. The OPWBFM method optically expands the bandwidths of FMCW signals beyond the electrical bandwidths of optical modulators via a cascaded four-wave mixing (FWM) process. Compared to the conventional direct modulation approach, the OPWBFM method simultaneously achieves high linearity and a short measurement time of the frequency sweep. On the other hand, it is also known that the OPWBFM method expands the phase noise of idlers as well as their bandwidths if an input conjugate pair has different phase noise. To avoid this phase noise expansion, it is crucial to synchronize the phase of an input complex conjugate pair of an FMCW signal using an optical frequency comb. For demonstration, we successfully generated an ultralinear 140-GHz FMCW signal by using the OPWBFM method. Moreover, we employ a frequency comb in the conjugate pair generation process, leading to the mitigation of phase noise expansion. By using a 140-GHz FMCW signal, we achieve a range resolution of ∼1 mm through fiber-based distance measurement. The results show the feasibility of an ultralinear and ultrawideband FMCW system with a sufficiently short measurement time.

Measurement of remanent magnetic moment using a torsion pendulum with single frequency modulation method

In TianQin spaceborne gravitational-wave detectors, the stringent requirements on the magnetic cleanliness of the test masses demand the high resolution ground-based characterization measurement of their magnetic properties. Here we present a single frequency modulation method based on a torsion pendulum to measure the remanent magnetic moment m r of 1.1 kg dummy copper test mass, and the measurement result is (6.45±0.04(stat)±0.07(syst)) × 10−8 A⋅m2. The measurement precision of the m r is about 0.9 nA⋅m2, well below the present measurement requirement of TianQin. The method is particularly useful for measuring extremely low magnetic properties of the materials for use in the construction of space-borne gravitational wave detection and other precision scientific apparatus.

Frequency-Modulation-Based IPT With Magnetic Communication for EV Wireless Charging

In this article, a switching frequency-modulation-based inductive power transfer system that provides wireless charging of the scooters by magnetic in-band communication is newly proposed. Although the transmitter (Tx) and receiver (Rx) coils are misaligned, the scooters can be freely charged in the charging station by the proposed frequency modulation method without additional power converters in the Tx and Rx sides. In order to implement frequency modulation control, the Rx side can transmit the required information to the Tx side through the magnetic coupling between Tx and Rx coils, i.e., magnetic in-band communication, in the suggested approach. By virtue of the proposed magnetic in-band communication method, the switching frequency can be modulated so that the load power for charging the battery in the Rx side is appropriately controlled, considering the battery charging profile. Contrary to the Qi standard technology using both amplitude shift keying (ASK) and frequency shift keying, the proposed magnetic communication protocol is optimally and simply designed for targeting scooter wireless charging applications. Because the proposed communication method is based on only ASK technique for unidirectional information delivery, the coil misalignment sensitivity and the complexity of the communication process can be reduced, which guarantees the robust frequency modulation control for load power regulation. A 100 W power level prototype for the charging station and the scooters was fabricated and verified by simulations and experiments. The 97.3% of the coil-to-coil efficiency and 90.6% of the dc-to-dc efficiency were obtained at a nominal operating point of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> = <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nom</sub> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_L</i> = 100.8 W. As a result, the battery having 44.0–53.0 V and 13 Ah in the Rx side was charged under a wide range of battery charging conditions and coil misalignments.

Influence of Electrostatic Force Nonlinearity on the Sensitivity Performance of a Tapered Beam Micro-Gyroscope Based on Frequency Modulation.

Electrostatic force nonlinearity is widely present in MEMS systems, which could impact the system sensitivity performance. The Frequency modulation (FM) method is proposed as an ideal solution to solve the problem of environmental fluctuation stability. The effect of electrostatic force nonlinearity on the sensitivity performance of a class of FM micro-gyroscope is investigated. The micro-gyroscope consists of a tapered cantilever beam with a tip mass attached to the end. Considering the case of unequal width and thickness, the motion equations of the system are derived by applying Hamilton's principle. The differential quadrature method (DQM) was used to analyze the micro-gyroscope's static deflection, pull-in voltage, and natural frequency characteristics. We observed that from the onset of rotation, the natural frequencies of the drive and sense modes gradually split into a pair of natural frequencies that were far from each other. The FM method directly measures the angular velocity by tracking the frequency of the drive and sense modes. Then, based on the linear system, the reduced-order model was used to analyze the influence of the shape factor and DC voltage on the sensitivity performance. Most importantly, the nonlinear frequency of system was obtained using the invariant manifold method (IMM). The influence of electrostatic force nonlinearity on the performance of the FM micro-gyroscope was investigated. The results show that the different shape factors of width and thickness, as well as the different DC voltages along the drive and sense directions, break the symmetry of the micro-gyroscope and reduce the sensitivity of the system. The sensitivity has a non-linear trend with the rotation speed. The DC voltage is proportional to the electrostatic force nonlinearity coefficient. As the DC voltage gradually increases, the nonlinearity is enhanced, resulting in a significant decrease in the sensitivity of the micro-gyroscope. It is found that the negative shape factor (width and thickness gradually increase along the beam) can effectively restrain the influence of electrostatic force nonlinearity, and a larger dynamic detection range can be obtained.