Carrier Pulse Research Articles

Analysis of Cascaded H Bridge Multilevel Inverter for Three-Phase Induction Motor Drive

The last ten years have seen a rise in the usage of multilayer inverters. Because they can produce waveforms with a greater harmonic spectrum and reliable output. Several high voltages and high-power applications are suitable for these new inverters. A multilayer converter not only produce high power ratings, but it also saves time and money and enhances the system performance in terms of harmonics, dv/dt strains, and pressures on the motor bearings. Owing to its flexibility and modularity, the possible topology for a power application is the cascaded H-bridge multilevel inverter (CMI) with separated DC sources. This study investigates a cascade H bridge multilevel inverter, such as a Three, Five, Seven, Nine and Eleven level inverter in order to drive a three phase AC induction motor. A Level shifted Pulse Width Modulation (LSPWM) technique was applied for the CHBMLI. Specific emphasis is given to aspects like modulation and total harmonic distortion that are preferable or necessary for multi-level converters. For both intellectual and scientific considerations, investigating sine triangle carrier pulse width modulation is deemed to be the most auspicious approach. Analysis of the many performance parameters, including load torque, motor speed, and efficiency, an extensive survey is conducted. MATLAB / Simulink is built into the entire system, and simulation results are developed. The purpose of this research is to demonstrate the performance of 9-level and 11-level fed induction motor driving results for Electric Vehicle applications. CHBMLI fed motor drive is better suitable for Induction Motor Drives.

A carrier pulse width modulation for asymmetric three-level NPC inverter

A carrier pulse width modulation for asymmetric three-level NPC inverter

Object detection based deinterleaving of radar signals using deep learning for cognitive EW

In a real-world environment, multifunction radars (MFRs) pose major challenges to the electronic support system that is a part of cognitive electronic warfare. One of the main problems is deinterleaving of signals belonging to MFRs. The ability of MFRs to change their carrier frequency, pulse width, and pulse repetition interval (PRI) from pulse to pulse makes the deinterleaving task challenging. In this paper, an object detection based deinterleaving approach exploiting amplitude patterns caused by radar beam motions, which are determined based on radar antenna scan types, is proposed to deinterleave MFR signals. Amplitude patterns are created in two-dimensional images using amplitude (AMP) and time of arrival (TOA) parameters obtained from radar pulses. Deinterleaving is performed using a deep learning algorithm applied to these images. To the best of the authors’ knowledge, object detection based deinterleaving of radar signals using AMP-TOA images has not been considered so far. Contrary to the common approaches, in which searching for PRI patterns is required, amplitude patterns formed by the radar beam motions on the electronic support system are used in the proposed method. This enables robust identification of signals of MFRs having PRI, carrier frequency, and pulse width agility. With the proposed method, the intention of the radar, i.e., search or tracking, can be acquired in the deinterleaving stage, which ensures earlier situational awareness. The performance of the method is evaluated for varying number of radar signals from one to five through simulations, in which scenarios with missing pulses at different rates are considered. Simulation results demonstrate that, on the average, more than 0.98 mean average precision (mAP50) is achieved at 30% missing pulse rate. The performance of the method for search radar signals is slightly lower compared to that achieved for tracking radar signals due to the lower number of pulses received by the system. However, more than 0.93 AP50 is achieved for search radar signals in the presence of five radar signals with different missing pulse rates. Besides, real-time performance can be achieved using the proposed method on the GPU platform.

Carrier Transport and Pulse Compression of an Opposed-Contact GaAs Photoconductive Switch at Low-Energy Optical Excitation

Carrier Transport and Pulse Compression of an Opposed-Contact GaAs Photoconductive Switch at Low-Energy Optical Excitation

Nonreciprocal propagation of optical pulses in a one-dimensional photonic crystal with two Weyl semimetal-based defects

We investigated the nonreciprocal propagation properties of an optical pulse in a one-dimensional photonic crystal containing Weyl semimetal-based defect layers. High optical nonreciprocity, without the need for high-intensity input light sources or external magnetic fields, is the most essential property of the Weyl semimetal. The transfer matrix and Fourier transform techniques are used to obtain the time envelopes of the transmitted pulses. It is demonstrated that the transmitted pulse may attain two different time envelopes by reversing the impinging direction of the input pulse. Then, the effects of the input pulse carrier frequency and time width on the characteristics of the transmitted pulse are presented and shown that reversing the impinging direction of the input pulse has a significant effect on the length and energy of the transmitted pulse. The results may have applications in designing pulse-shaping filters and transferring digital data.

Passively synchronized dual-color soliton fiber laser based on single-walled carbon nanotubes

In this work, we propose a uniquely designed fiber laser to generate dual-color soliton molecules, which are stable bound states made up of solitons with different carrier frequencies, pulse widths and soliton energies. This fiber laser consists of two resonators, which are cascaded by a pair of wavelength division multiplexers (WDMs), and a single-walled carbon nanotube saturable absorber (SWCNT-SA) is placed in the common branch shared by two sub-cavities to achieve optical soliton mode-locking. The optical solitons generated by this laser have central wavelengths of 1530.43 nm and 1547.62 nm with pulse widths of 0.832 ps and 1.198 ps, respectively. The synchronous mode-locked operation of the two sub-cavities can be easily achieved by adjusting the optical delay line (DL) in one of the resonant cavities. When the synchronized state is reached, two solitons with different central wavelengths operate synchronously and stably at a consistent repetition frequency of ∼8.1505 MHz and dual-color soliton molecules are generated. The fiber laser has the advantages of simple structure and controllable generation of soliton molecules, which provide a new idea for the design of soliton molecule ultrafast fiber laser.

Experimental demonstration of dyed water aerosol fluorescence stimulated by femtosecond laser postfilaments propagating in air.

We present the fluorescence spectra of single millimeter water droplets and micron-sized dyed water aerosol (rhodamine 6G) stimulated by a high-intensity femtosecond Ti:sapphire-laser pulse (carrier wavelength 792nm) upon its nonlinear propagation in air. The distinctive feature of our experimental measurements is that the droplet fluorescence is obtained in the area of plasma-free pulse propagation after the pulse filamentation has already been terminated (postfilamentation region). Our results significantly expand the working area of femtosecond laser-induced fluorescence spectroscopy for remote diagnostics of atmospheric aerosols.

A Method for Suppressing False Target Jamming with Non-Uniform Stepped-Frequency Radar

Stepped-frequency radar can increase the degree of freedom of the range dimension by adding a tiny stepping frequency between neighboring pulse carrier frequencies, which has a clear advantage in countering range false target jamming. However, when the jamming is released by a self-defense jammer carried by the target, the range information is coupled to the Doppler frequency. This makes it impossible for a stepped-frequency radar to extract the range information accurately. In this paper, we derive the correlation between the phase difference of adjacent pulses and range information and the Doppler frequency when the frequency is uniformly stepped, as well as the error caused by the Doppler frequency in range estimation. Then, we propose a decoupling method based on a waveform design and the corresponding suppression method of range false target jamming. Simulation results show that the proposed method can effectively suppress the jamming of self-defense range false targets.

Surpassing the classical limit of the microwave photonic frequency fading effect by quantum microwave photonics

With energy–time entangled biphoton sources as the optical carrier and time-correlated single-photon detection for high-speed radio frequency (RF) signal recovery, the method of quantum microwave photonics (QMWP) has presented the unprecedented potential of nonlocal RF signal encoding and efficient RF signal distilling from the dispersion interference associated with ultrashort pulse carriers. In this paper, its capability in microwave signal processing and prospective superiority are further demonstrated. Both QMWP RF phase shifting and transversal filtering functionality, which are the fundamental building blocks of microwave signal processing, are realized. Besides good immunity to the dispersion-induced frequency fading effect associated with the broadband carrier in classical MWP, a native two-dimensional parallel microwave signal processor is provided. These results well demonstrate the superiority of QMWP over classical MWP and open the door to new application fields of MWP involving encrypted processing.

A new generalized floor function based high switching frequency modulation and control technique: Multilevel inverters

SummaryA new generalized floor function (F2) based single carrier pulse width modulation (F2SC‐PWM) technique has been proposed in this paper by considering a single‐phase 9‐level T‐type packed U‐cell (PUC) inverter topology. In literature, the conventional level‐shifted PWM technique requires (level‐1) carriers, and the unipolar phase disposition (UPD) PWM technique requires (level‐1)/2 carriers to produce a particular level of output. To reduce the complexity of control, the authors have developed single‐carrier‐based PWM techniques. However, these are not generalized in a simple manner and are especially applicable only to particular inverter topologies. In this paper, a new F2SC‐PWM technique with a single modulating signal has been introduced that is applicable to any multilevel inverter (MLI) topology. This technique is very simple to implement, and it does not internally require any large number of mathematical operations and if‐else loops. Finally, a laboratory prototype has been used to verify the operation of the 9L‐TPUC topology considering R and RL loads with respect to step change of load, step change of modulation index (MI), and step change of modulation frequecy (MF) via with new proposed control technique (PCT).

Real-Time Implementation of a Seven-Level Multilevel DC Link Inverter for Solar PV System during Partial Shading

An innovative control system for multilevel DC link inverters (MLDCLI) overcomes the insolation under partial shading of individual photovoltaic (PV) modules. This algorithm employs a combined MPPT and pulse width pulse generation technique to control a MLDCLI. in the presence of irregular sun solar energy. MLDCLI is evaluated with phase opposite disposition (POD) multiple of carrier pulse width modulation (MCPWM). Instead of affecting other PV sources, this method recovers maximum power from each shaded PV source without affecting others. Microcontroller-based prototypes validated with MATLAB/SIMULLINK system generators for typical output levels show drastic improvements in voltage quality. Inverter output is received through the filter for grid-connected applications.

Correlation analysis of frustrated tunneling ionization

We visualize frustrated tunneling ionization (FTI) using the correlation function analysis outlined in our preceding works [I. Ivanov and K. T. Kim, J. Phys. B 55, 055001 (2022); Sci. Rep. 12, 19533 (2022)]. We apply this technique to the hydrogen atom subjected to a strong laser field. Our analysis supports the basic premises of the theory of FTI and demonstrates its sensitive dependence on the laser pulse duration and carrier envelope phase.

A New Model-Based Dead-Time Compensation Strategy for Cascaded H-Bridge Converters

Cascaded H-bridge multilevel converter can generate high-voltage and high-power output with low harmonics. However, the error voltage caused by dead time effect will distort the output waveform, which depends on the phase current polarity. Since the normal dead time compensation method based on current sampling is often disturbed by sampling error and transmission delay, a novel current prediction method is proposed for dead time compensation of cascaded H-bridge converter in this paper. This method, based on phase shift carrier pulse width modulation, reconstructs the switch pattern, and combined with the system model, can easily predict the phase currents. Excellent compensation performance can be obtained by dead time compensation according to the predicted current. Simulation and experiments are built to validate the excellent performance of the proposed method applied to cascaded H-bridge converters.

Optimized Synchronous Pulse Width Modulation Strategy Based on Discontinuous Carriers

This article proposes a new technique called optimized discontinuous carrier pulse width modulation (ODCPWM), whose main objective is to solve the issue of significant output voltage harmonics of conventional synchronous carrier modulation at low carrier wave ratios. Based on the symmetry principle, the fundamental wave period is divided into regions; the carriers in adjacent regions are flipped, and the carrier width is changed symmetrically in each region to generate an unequal-width optimized discontinuous carrier pulse width modulation. In addition, using the weighted total harmonic distortion (WTHD) of the line voltage as an evaluation index, an optimized multi-mode PWM strategy is proposed to satisfy the system to operate stably in the whole speed range. The experimental results verify the effectiveness of the proposed strategy. The results show that ODCPWM proposed in this article can eliminate harmonics and multiples of three harmonics in line voltage harmonics. The VWTHD is lower, which improves the quality of the output waveform and makes the system operation more stable and reliable. The proposed multi-mode PWM strategy is smooth and shock-free during switching.

Super-conformal TiN thin film deposition by carrier pulse purge atomic layer deposition system: Chamber design optimization with computational fluid dynamics

Owing to the increase in demand for the shrinkage of semiconductor design rules and the advent of the three-dimensional structure of semiconductor devices, atomic layer deposition (ALD) has emerged as an attractive alternative to conventional chemical vapor deposition techniques. Although the development of precursors and characterization of ALD films have been widely studied, few studies have been conducted on the modification of ALD parameters and optimization of the ALD process. In this study, an advanced ALD titanium nitride (TiN) system was designed using a pumping and purging simulationBased on the simulation results, we adopted a carrier pulse purge method, where TiCl4 fed, purge N2, pulse purge N2, purge N2, NH3 fed, purge N2, pulse purge N2, and purge N2 were alternatively injected into the chamber in the ALD cycle. Compared to the conventional purge method, the carrier pulse purge method can reduce the ALD cycle time by 18.27% and yields a high-quality (high step coverage, 98 %) TiN film with lower electrical resistivity and chlorine impurity. This carrier pulse purge method can ultimately lead to improved throughput and productivity in the semiconductor industry by reducing the ALD cycle time.

Trapezoidal reference-based single carrier pulse width modulation method for multilevel converters with novel FPGA implementation

Recent attention has focused on trapezoidal reference-based pulse width modulation (PWM) schemes in multilevel converters (MLCs) with easier implementation and better harmonic performance. Nevertheless, these studies utilize trapezoidal reference only for multi carrier PWM methods and details of FPGA implementation are not provided. This paper proposes a trapezoidal reference-based single carrier PWM (TSC-PWM) with its novel FPGA implementation. Design parameters of TSC-PWM is determined such that harmonic performance is maximized and architectural details of FPGA implementation of TSC-PWM are provided. Results reveal that TSC-PWM significantly reduces the resource utilization compared to other methods. Single-phase three-module cascaded H-bridge MLC (CHB-MLC) is established in both simulation and experimental platforms. Results indicate that the TSC-PWM provides better harmonic performance along with higher DC utilization ratio compared to other methods. Moreover, both half-wave and quarter-wave symmetries are ensured with TSC-PWM.

Tuning spectral properties of individual and multiple quantum emitters in noisy environments

A quantum emitter in a dynamic environment may have its energy levels drift uncontrollably in time with the fluctuating bath. This can result in an emission/absorption spectrum that is spread over a broad range of frequencies and presents a challenging hurdle for various applications. We consider a quantum emitter in an environment that alters the energy levels so that the emission frequency is represented by a Gaussian random distribution around a given mean value with given standard deviation and correlation time. We study the emission spectrum of this system when it is placed under the influence of a periodic sequence of finite width $\pi$ pulses. We show that this external field protocol can effectively overcome spectral diffusion in this system by refocusing the bulk of the emission spectrum onto the pulse carrier frequency. We further consider two such emitters in different noisy environments and find that the two-photon interference operation can be made efficient by the sequence of finite width pulses applied on both systems. Finally, we show that an ensemble of nominally similar emitters, each with its different environment, and thus randomly shifted emission frequency, can have its overall emission spectrum that would otherwise be inhomogeneously broadened according to the random distribution, refocused onto a lineshape with a well-defined central peak that has the linewidth of an individual isolated non-noisy emitter. These results demonstrate for this specific model of noisy environments, the protection of spectral properties by an external control protocol here represented by a periodic sequence of finite width pulses.

Analytical Model of an Energy Detector for Ultra-Wideband Chaotic Communications

For the ultra-wideband chaotic radio pulses an analytical model of an energy detector is designed and closed-form expressions for the optimal threshold and the detection probabilities are derived. The analytical solution is compared with the results of the numerical simulation. The model proves to be well-suited for the chaotic radio pulses with large base B (or processing gain, or the number of freedom degrees), namely, B ≥ 100. Potential applications areas of the proposed model are ultra-wideband communications with chaotic pulse carriers, e.g., ultra-wideband systems of 802.15.x standards, and multi-element chaotic communication systems.

An Optimized Carrier Phase-Shifted Modulation Strategy for Cuk PV Inverter

There exists the problems of output voltage zero-point drift and high even harmonic content of the three-phase Cuk liftable voltage photovoltaic (PV) inverter when it adopts the conventional carrier modulation method. In view of these, a new optimized Phase-Shifted Pulse Width Modulation (PSPWM) strategy is proposed. Firstly, the optimal zero-sequence component is determined based on the inverter topology and control objectives. Next, the zero-sequence component is injected into the sinusoidal signal and used as the new modulating signal so that the carrier pulse width modulation is equivalent to the space vector pulse width modulation. Finally, the carrier and modulating waveforms are blended in a superior manner, and a new logical operation is applied to generate the required switching drive signals for the control of the inverter switching tubes. In order to verify the effectiveness of the strategy, simulation and experimental platforms were constructed, and numerous simulations and experiments were done. The results show that the modulation strategy can solve the output voltage zero drift problem effectively, and suppress the even harmonics effectively, meanwhile, the harmonics are mainly concentrated near the primary frequency, which significantly reduces the total harmonic content and greatly improves the output voltage waveform. In addition, the modulation can be achieved by reducing one carrier signal, thus simplifying the modulation process and the design of the digital signal system.

A Sensor-less Surface Mounted PMSM for Electronic Speed Control in Multilevel Inverter

Recent advancements in power electronics technology evolves inverter fed electric motors. Speed signals and rotor position are essential for controlling an electric motor accurately. In this paper, the sensorless speed control of surface-mounted permanent magnet synchronous motor (SPMSM) has been attempted. SPMSM wants a digital inverter for its precise working. Hence, this study incorporates fifteen level inverter to the SPMSM. A sliding mode observer (SMO) based sensorless speed control scheme is projected to determine rotor spot and speed of the multilevel inverter (MLI) fed SPMSM. MLI has been operated using a multi carrier pulse width modulation (MCPWM) strategy for generation of fifteen level voltages. The simulation works are executed with MATLAB/SIMULINK software. The steadiness and the heftiness of the projected model have been investigated under no loaded and loaded situations of SPMSM. Furthermore, the projected method can be adapted for electric vehicles.