Indirect Vector Control of Linear Induction Motors Using Space Vector Pulse Width Modulation

Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.

Evolution of the Pulse Width in Dielectric Barrier Atmospheric Pressure Discharge

A study of the evolution of the pulse width in homogeneous dielectric barrier dis- charge at atmospheric pressure with helium as the working gas is reported by using a one- dimensional fluid model. In this paper, a new computational method is presented to estimate the pulse width through calculating the time interval between the breakdown voltage and the extinguishing voltage. The effects on the discharge characteristics of the applied voltage and exci- tation frequency are studied based on the computational data. The results of the simulation show that the pulse width is observed to be narrower and the time intervals between two consecutive current pulses decrease with increasing amplitude and excitation frequency, which indicates that the homogeneous discharge is susceptible to the filamentary mode. The simulation results support the conclusion that in order to restrain the transition from the glow mode to filamentary mode, the applied voltage and excitation frequency should be kept within an appropriate range.

Tunable and Switchable Narrow Bandwidth Semiconductor-Saturable Absorber Mirror Mode-Locked Yb-Doped Fiber Laser Delivering Different Pulse Widths

The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.

The 266-nm ultraviolet-beam generation of all-fiberized super-large-mode-area narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate

We report on a compact, stable, all-fiberized narrow-linewidth(0.045 nm) pulsed laser source emitting laser beam with a wavelength of 266 nm, and tunable pulse width and repetition rate. The system is based on all-fiberized nanosecond amplifier architecture, which consists of Yb-doped fiber preamplifiers and a super-large-mode-area Yb-doped fiber power amplifier. The fiber amplifier with a core of 50 μm is used to raise the threshold of the stimulated Brillouin scattering(SBS) effect and to obtain high output power and single pulse energy. Using lithium triborate(LBO) crystal and betabarium borate(BBO) crystal for realizing the second-harmonic generation(SHG) and fourth-harmonic generation(FHG),we achieve 17 μJ(1.73 W) and 0.66 μJ(66 mW), respectively, at wavelengths of 532 nm and 266 nm and a repetition rate of 100 kHz with pulse width of 4 ns. This source has great potential applications in fluorescence research and solar-blind ultraviolet optical communication.

Effect of Peak Power and Pulse Width on Coherent Doppler Wind Lidar’s SNR

The laser device is the core component of coherent Doppler wind lidar.The peak power and pulse width of laser transmitting pulse have important effects on SNR.Based on coherent Doppler wind pulse lidar,the peak power and pulse width influence on SNR is studied on the theoretical derivation and analysis,and the results show that the higher the peak power can realize the greater the signal-to-noise ratio of coherent Doppler wind lidar.But when the peak power is too large,the laser pulse may appear nonlinear phenomenon,which cause the damage of the laser.So,the peak power must be less than the stimulated brillouin scattering power threshold.Increasing the pulse width can make the laser device to output more energy,but it will also make the spatial resolution lower,and the influence of turbulence on SNR will be greater.After a series of simulation analyses,it can be concluded that when the peak power is 650W and the pulse width is 340ns,the SNR of the system can be maximized.In addition,the coherent Doppler wind lidar system is set up to carry out corresponding experimental verification.The experimental results are consistent with the theoretical analysis and simulation,which verifies the correctness of the theoretical analysis and simulation results.It provides theoretical basis and practical ex-perience for the design of laser transmitting pulse in coherent Doppler wind lidar system.

Effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier

The effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier is investigated theoretically and experimentally. The complex Ginzburg–Landau equation and adaptive split-step Fourier method are used to simulate the propagation of pulses with different pulse widths in the fiber amplifier, and the results show that a longer pulse is more profitable in near-infrared supercontinuum generation if the central wavelength of the input laser lies in the normal dispersion region of the gain fiber. A four-stage master oscillator power amplifier configuration is adopted and the output spectra under picosecond and nanosecond input pulses are compared with each other. The experimental results are in good accordance with the simulations which can provide some guidance for further optimization of the system.

Impacts of laser pulse width and target thickness on laser micro-propulsion performance

In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions,which employs a micro semiconductor laser,the impacts of pulse width and glycidyl azide polymer(GAP)thickness on thrust performance were researched.The results showed that with a GAP thickness of 200μm,the single-pulse impulse(I)increased gradually with the increase in the laser pulse width from 50 to 800μs,while the specific impulse(I_(sp)),impulse coupling coefficient(Cm)and ablation efficiency(η)all reached optimal values with a 200μs pulse width.It is worth noting that the optimal pulse width is identical to the ignition delay time.Both Cmandηpeaked with a pulse width of 200μs,reaching 242.22μN W^(-1)and 35.4%,respectively.With the increase in GAP thickness,I and Cmincreased gradually.GAP of different thicknesses corresponded to different optimal laser pulse widths.Under a certain laser pulse width,the optimal GAP thickness should be the most vertical thickness of the ablation pit,and the various propulsion performance parameters at this time were also optimal.With the current laser parameters,the optimal GAP thickness was approximately 150μm,I_(sp)was approximately 322.22 s,andηwas approximately 34.94%.

Comparison of performance between bipolar and unipolar double-frequency sinusoidal pulse width modulation in a digitally controlled H-bridge inverter system

By deriving the discrete-time models of a digitally controlled H-bridge inverter system modulated by bipolar sinu- soidal pulse width modulation （BSPWM） and unipolar double-frequency sinusoidal pulse width modulation （UDFSPWM） respectively, the performances of the two modulation strategies are analyzed in detail. The circuit parameters, used in this paper, are fixed. When the systems, modulated by BSPWM and UDFSPWM, have the same switching frequency, the stabil- ity boundaries of the two systems are the same. However, when the equivalent switching frequencies of the two systems are the same, the BSPWM modulated system is more stable than the UDFSPWM modulated system. In addition, a convenient method of establishing the discrete-time model of piecewise smooth system is presented. Finally, the analytical results are confirmed by circuit simulations and experimental measurements.

All-fiberized very-large-mode-area Yb-doped fiber based high-peak-power narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate

We demonstrate an all-fiberized narrow-linewidth nanosecond amplifier with high peak power,tunable pulse width,and repetition rate.A fiber-coupled narrow-linewidth laser diode operating at 1064.1 nm is employed as the seed source,which is gain-switched to generate nanosecond pulses with tunable pulse widths of 1-200 ns and tunable repetition rates of10 Hz-100 kHz.By utilizing a very-large-mode-area Yb-doped fiber with a core diameter of 50 μm in the power amplifier,thresholds of the stimulated Brillouin scattering at different pulse widths and repetition rates are increased.The maximum average power reaches 30.8 W at the pulse width of 4 ns and a repetition rate of 100 kHz,corresponding to an optical-tooptical conversion efficiency of ~55.2%.Pulse energy and peak power are calculated to be 0.2 mJ and 50 kW,respectively,which are limited by stimulated Brillouin scattering.The 3-dB spectral linewidth remains around 0.05 nm during the power scaling process.The stimulated Brillouin scattering limited output powers at different pulse widths and repetition rates are investigated.Peak power of 47.5 kW(0.19 mJ) is obtained for the 4 ns pulses at a repetition rate of 50 kHz,which is nearly the same as that of 4 ns pulses at 100 kHz.When the pulse width of the seed source is increased to 8 ns,peak powers/pulse energies are decreased to 19.6 kW/0.11 mJ and 13.3 kW/0.08 mJ at repetition rates of 50 kHz and 100 kHz,respectively.

Research and Making of a High-Power Switching Supply Using Pulse Width Modulation

Compared with the traditional SCR phase-shift regulated power supply, a new type of power semiconductor , noncrystalline state magnetic material and pulse width modulation technology, high-power switching supply has many advantages： small volume, high converting efficiency, good dynamic performance, small harmonic componont and small pollution to AC supply.

Realization of Space Vector Pulse Width Modulation Method Based on DSP

In order to compensate for the deficiency of Sine Pulse Width Modulation（SPWM）, on the base of analyzing the principle of space w tot pulse width modulation and being compared with SPWM, the method of solving working time of adjacent vector and the method of generate space voltage vector were introduced. The experiment to the inverter which consists of IGBT proves that SVPWM centrol algorithm can reduce harmonic effectively, it is beneficial to enhancing the utilization rate of voltage source inverter direct current power supply.

Improved Protein Transfer Efficiency and Signal Intensity in BlotMan Using Pulse Width Modulation

BlotMan is a protein blotting device that allows generating multiple membranes from a single polyacrylamide gel. To transfer all proteins uniformly with the same efficiency regardless of protein size, BlotMan employs pulse-width-modulated (PWM) voltage that applies a higher average voltage to a larger protein species. BlotMan can be controlled not only by its custom-made interface but also by a smart phone via Bluetooth technology. In this study, we examined effects of PWM signals (50%, 60%, and 80% duty cycle) on transfer efficiency and signal intensity in comparison to a constant voltage signal (100% duty cycle). The result revealed that in response to the same average voltage of 150 V, a lower duty cycle with a higher maximum voltage increased transfer efficiency as well as sharpness of transferred proteins. We validated BlotMan’s capability using a chondrosarcoma cell line (SW1353 cells) and a breast cancer cell line (MDA-MB231 cells) in response to antitumor chemical agents. BlotMan successfully generated 5 membranes from a single gel and detected 5 protein species such as c-Src, eukaryotic translation initiation factor 2 alpha (eIF2), phosphorylated eIF2, lamin B, and actin. Collectively, we demonstrated herein that BlotMan reduces an amount of protein samples by generating multiple membranes from a single gel and improving signal intensity with PWM voltage signals.

Spectral Calculation of the Output Voltage of an Inverter with Bipolar Pulse Width Modulation

Converters with pulse width modulation are used for connections between the direct current （DC） and alternating current （AC） networks, e.g., in uninterrupted power supply systems, AC electromotor drives, for powering induction furnaces, in audio technique. Spectrum of signals sampled by pulse amplitude modulation and output voltage spectrum of the converter with pulse width modulation have similar properties. Spectrum of signals sampled by pulse amplitude modulation contains a harmonic of frequency equal to the frequency of the modulating signal and the harmonics of frequencies equal to the sum of frequency of the modulating signal and multiples of the sampling frequency. The output voltage spectrum of the converter with bipolar pulse width modulation contains harmonic of frequency equal to the frequency of the modulating signal and harmonics of frequencies equal to sum of the frequency of the modulating signal and multiples of the frequency of the carrier signal. It also contains harmonics of frequencies equal to the sum of the multiples of the frequency of the modulating signal and the multiples of the carrier signal. The comparison analysis was carried out for the harmonics of the output voltage of the converter with bipolar pulse width modulation in time domain. The dependency of the amplitudes and frequency spectrum on the wave forms of the carrier signal and modulating signal was shown. Similarity of the output voltage spectrum of the converter and signal spectrum sampled by the pulse width modulation was also shown. Key words： Output voltage converter with bipolar pulse width modulation, spectral analysis, Fourier series, carrier signal, reference signal.

Capacitor Pattern H-Bridge Multilevel Inverter (CPHMLI) Using Phase Diposition Pulse Width Modulation for Grid Applications

This work presents an implementation of an innovative single phase multilevel inverter using capacitors with reduced switches. The proposed Capacitor pattern H-bridge Multilevel Inverter (CPHMLI) topology consists of a proper number of Capacitor connected with switches and power sources. The advanced switching control supplied by Pulse Width Modulation (PDPWM) to attain mixed staircase switching state. The charging and discharging mode are achieved by calculating the voltage error at the load. Furthermore, to accomplish the higher voltage levels at the output with less number of semiconductors switches and simple commutation designed using CPHMLI topology. To prove the performance and effectiveness of the proposed approach, a set of experiments performed under various load conditions using MATLAB tool.

Global synchronous discontinuous pulse width modulation method with fast calculation capability for distributed three-phase inverters

When multiple distributed converters are integrated, the high frequency harmonics will randomly accumulate at the point of common coupling(PCC). This paper proposes a new fast global synchronous discontinuous pulse width modulation(GSDPWM) method of threephase inverters to effectively attenuate the high frequency current harmonics at PCC. Firstly, the basic principle and the realization method of GSDPWM for three-phase inverters are explained, which can be employed for different modulation types. Then a fast calculation method,which can equally derive the minimized total harmonic distortion(THD) of total current, is proposed to release the calculation burden. Finally, MATLAB simulations and experimental results are presented to verify the performance of GSDPWM.

Effects of microwave pulse-width damage on a bipolar transistor

This paper presents a theoretical study of the pulse-width effects on the damage process of a typical bipolar transistor caused by high power microwaves（HPMs） through the injection approach.The dependences of the microwave damage power,P,and the absorbed energy,E,required to cause the device failure on the pulse width τ are obtained in the nanosecond region by utilizing the curve fitting method.A comparison of the microwave pulse damage data and the existing dc pulse damage data for the same transistor is carried out.By means of a two-dimensional simulator,ISE-TCAD,the internal damage processes of the device caused by microwave voltage signals and dc pulse voltage signals are analyzed comparatively.The simulation results suggest that the temperature-rising positions of the device induced by the microwaves in the negative and positive half periods are different,while only one hot spot exists under the injection of dc pulses.The results demonstrate that the microwave damage power threshold and the absorbed energy must exceed the dc pulse power threshold and the absorbed energy,respectively.The dc pulse damage data may be useful as a lower bound for microwave pulse damage data.

Wide Pulse Width Electroacupuncture Ameliorates Denervation-Induced Skeletal Muscle Atrophy in Rats via IGF-1/PI3K/Akt Pathway

Objective:To evaluate the effect of the pulse width of electroacupuncture(EA)in the treatment of denervation-induced skeletal muscle atrophy in rats and examine the role of insulin-like growth factor 1(IGF-1)/phosphatidylinositol 3-kinase(PI3 K)/Akt signaling pathway during EA.Methods:Sciatic nerve functional index(SFI),muscle wet weight and the cross-sectional area(CSA)of the gastrocnemius muscle were analyzed after treatment in model rats with EA of various pulse widths(0.5,50,100 and 200 ms).The apoptosis index(AI)and paired box(PAX)3 and PAX7 protein expression were also determined.Further,the mRNA and protein expressions of components of IGF-1/PI3 K/Akt pathway and their downstream targets were determined,along with the inhibiting effect of the pathway with a PI3-specific inhibitor.Results:EA with a pulse width of 200 ms was found to have the best effect with regard to increasing SFI,CSA and muscle weight,decreasing AI,and increasing the expression of PAX3 and PAX7.The IGF-1/PI3 K/Akt pathway was found to be activated by denervation,although the downstream forkhead box O(FoxO)pathway was not suppressed by its activation.The PI3 K/Akt pathway and its downstream molecule mammalian target of rapamycin(mTOR)were up-regulated further by EA to promote muscle protein synthesis.Meanwhile,the expressions of downstream FoxO and F-box protein 32(ATROGIN-1)were down-regulated to reduce protein degradation.Conclusions:EA with 200-ms pulse width was found to have a more significant effect than 0.5-ms EA.The positive effects of EA disappeared after inhibition of the PI3 K/Akt pathway.

Pulsed LD side-pumped MgO：LN electro-optic cavity-dumped 1123 nm Nd： YAG laser with short pulse width and high peak power

We report a cavity-dumped 1123 nm laser with narrow pulse width and high peak power by an Mg O: LN crystal electrooptic(EO) modulator. Based on the structural optimization design of a folded biconcave cavity using the 808 nm pulsed laser diode(LD) side-pumped ceramic Nd: YAG rod, output pulses with maximum pulse energy and peak power up to39.6 m J and 9.73 MW were obtained, corresponding to 100 Hz repetition rate and 4.07 ns pulse width. The instabilities of pulse width and pulse energy were ±1.55% and ±2.06%, respectively. At the highest repetition rate of 1 kHz, the pulse energy, pulse width, and peak power were 11.3 mJ, 5.05 ns, and 2.24 MW, respectively. The instabilities of pulse width and pulse energy were ±2.65% and ±3.47%, respectively.

Pulse width reduction in diode-pumped,doubly Q-switched Nd:GdVO_4/KTP green laser

Using both acoustic-optic (AO) Q-switeh and GaAs saturable absorber, a diode-pumped doubly Q-switehed Nd:GdVO4/KTP green laser is realized. This laser can generate a shorter and more symmetric pulse in comparison with purely AO and passively Q-switched lasers. In the meantime, the rate equations describing the operation of a diode-pumped, AO and GaAs doubly Q-switched Nd:GdVO4/KTP green laser are introduced. These equations are solved numerically and the dependence of pulse width on incident pump power is obtained. The numerical solutions are in agreement with the experimental results.