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.

A Pulse Width Modulation Scheme With Zero-sequence Voltage Injection for Single Phase Three-level NPC Rectifiers

直流侧中点电位电压偏移是多电平中性点钳位型变流器的主要缺点。以单相三电平NPC整流器为研究对象，以实现直流侧中点电位无漂移为控制目标，以传统的单相三电平单极性载波脉宽调制方法为基础，首先提出一种基于零序电压分量注入的载波脉宽调制算法；然后在此基础上给出基于零序电压分量极限值注入的载波脉宽调制算法；并给出这2种方法的零序电压分量的设计方案；最后，对这2种方法进行了详细的理论分析、计算机仿真和1kW样机实验对比验证。研究结果表明：所提出的2种算法都能有效实现直流侧中点电位平衡控制，其中基于零序电压分量极限值注入的载波调制算法的中点电位控制具有更快动态响应速度，且其网侧电流的高次谐波主要分布在开关频率附近；而基于零序电压分量注入的载波调制算法的网侧电流高次谐波主要分布在2倍开关频率附近。但是在一个调制信号周期内，基于零序电压分量极限值注入的载波调制算法的开关切换次数比基于零序电压分量注入的载波调制算法低25％左右。

An Optoelectronic Pulse Frequency Modulation Circuit for Retinal Prosthesis

A pulse frequency modulation（PFM） circuit for retinal prosthesis,which generates electrical pulses with frequency proportional to the intensity of incident light, is presented. The fundamental characteristic of the circuit is described and analyzed. The circuit is realized in 0.6μm CMOS process,and the simulation results testify to the possibility of sub-retinal implantation.

CONTROL STRATEGY FOR ELECTRO-HYDRAULIC POSITION SERVO SYSTEM WITH GENERALIZED PULSE CODE MODULATION

A hybrid control strategy has been designed and developed for the electro-hydraulic posi-tion servo control system with generalized Pulse code modulation （GPCM）, which is suitable for the area where the work condition is poor and a large flow rate is required. It is difficult to control the GPCM system because the system is discrete. With consideration of the stability and speediness of the GPCM position servo control system, a control strategy is developed through the theoretical and ex-perimental analyses. The control strategy integrates the merits of Bang-Bang control, PID control and fuzzy control. With this hybrid control strategy, the electro hydraulic control system has good per-formances, and the servo control is carried out with GPCM through on-off valves.

Operation Mode on Pulse Modulation in Atmospheric Radio Frequency Glow Discharges

The discharge operation regime of pulse modulated atmospheric radio frequency （RF） glow discharge in helium is investigated on the duty cycle and frequency of modulation pulses. The characteristics of radio frequency discharge burst in terms of breakdown voltage, alpha（s）- gamma（γ） mode transition voltage and current are demonstrated by the discharge current voltage characteristics. The minimum breakdown voltage of RF discharge burst was obtained at the duty cycle of 20% and frequency of 400 kHz, respectively. The α-γ mode transition of RF discharge burst occurs at higher voltage and current by reducing the duty cycle and elevating the modulation frequency before the RF discharge burst evolving into the ignition phase, in which the RF discharge burst can operate stably in the γ mode. It proposes that the intensity and stability of RF discharge burst can be improved by manipulating the duty cycle and modulation frequency in pulse modulated atmospheric RF glow discharge.

Ultra-low power anti-crosstalk collision avoidance light detection and ranging using chaotic pulse position modulation approach

A novel concept of collision avoidance single-photon light detection and ranging（LIDAR） for vehicles has been demonstrated, in which chaotic pulse position modulation is applied on the transmitted laser pulses for robust anti-crosstalk purposes. Besides, single-photon detectors（SPD） and time correlated single photon counting techniques are adapted, to sense the ultra-low power used for the consideration of compact structure and eye safety. Parameters including pulse rate, discrimination threshold, and number of accumulated pulses have been thoroughly analyzed based on the detection requirements, resulting in specified receiver operating characteristics curves. Both simulation and indoor experiments were performed to verify the excellent anti-crosstalk capability of the presented collision avoidance LIDAR despite ultra-low transmitting power.

A Novel Square-wave Pulse Rotation Modulation Strategy for Modular Multilevel Converters

悬浮直流电容电压的均衡问题是模块组合多电平变换器（modular multilevel converter,MMC）的关键问题之一。提出一种可实现MMC直流电容电压平衡的方波脉冲循环调制（square-wave pulse rotation modulation,SWPRM）策略,在保证合成的阶梯波输出波形不变的前提下,根据MMC的拓扑结构和工作原理,对传统方波脉冲列进行脉冲优化,并按照一定的次序和切换周期进行循环和判断反相调整,获得的循环方波脉冲列作为最终驱动脉冲用于实现对MMC的控制。实验结果表明,采用提出的方波脉冲循环调制策略无需任何电容电压控制措施,在较低开关频率下,实现了MMC各功率单元间有功能量的平均分配和直流电容电压的均衡。

Spectrum for Pulse Frequency Modulation

This paper gives a spectrum expression which is simple and has a clear physical conception for pulse frequency modulation signal, and has been confirmed by an experiment simultaneously.

Chaotic pulse position modulation ultra-wideband system based on particle filtering

Traditional chaotic pulse position modulation(CPPM)system has many drawbacks.It introduces delay into the feedback loop,which will lead to divergence of chaotic map easily.The wrong decision of data will cause error propagation.Mismatch of parameters and synchronization error between the receiver and transmitter will arouse high bit error rate.To solve these problems,a demodulation algorithm of CPPM based on particle filtering is proposed.According to the mathematical model of the system,it tracks the real signal by online separation in demodulation.Simulation results show that the proposed method can track the true signal better than the traditional CPPM scheme.What's more,it has good synchronization robustness,reduced error propagation by wrong decision and low bit error rate.

Modeling and Analysis of Pulse Skip Modulation

The state space average model and the large signal models of Pulse Skip Modulation （PSM） mode are given in this paper. Farther more, based on these models and simulations of PSM converter circuits, the analysis of the characteristics of PSM converter is described in this paper, of which include efficiency, frequency spectrum analysis, output voltage ripple, response speed and interference rejection capability. Compared with PWM control mode, PSM converter has high efficiency, especially with fight loads, quick response, good interference rejection and good EMC characteristic. Improved PSM slightly, it could be a kind of good independent regulating mode during the whole operating process for a DC-DC converter. Finally, some experimental results are also presented in this paper.

An Improved Submodule Unified Pulse Modulation Scheme for a Hybrid Modular Multilevel Converter

This paper presents an improved submodule unified pulse width modulation(SUPWM)scheme for a hybrid modular multilevel converter(MMC)composed of half-bridge submodules(HBSMs)and full-bridge submodules(FBSMs).The proposed SUPWM scheme can achieve an output voltage of(2N+1)(where N is the number of submodules in each arm)levels,which is the same as that of the carrier-phase-shifted PWM(CPSPWM)scheme.Meanwhile,the proposed SUPWM scheme can alleviate the uneven loss distributions between the left leg and right leg in FBSMs of the hybrid MMC.Moreover,the capacitor voltages of the sub-modules can be well balanced without complicated closed-loop voltage balancing controllers.The validity of the proposed SUPWM scheme is verified by both the simulated and experimental results.

Linear and nonlinear characteristics of time-resolved photoluminescence modulation by terahertz pulse

The linear and nonlinear characteristics of time-resolved photoluminescence （PL） of n-type bulk semiconductor GaAs modulated with terahertz （THz） pulse are studied by using an ensemble Monte Carlo （EMC） method. In this paper the center energy valley （Г valley） electron concentration changes with the pulse delay time, sampling time and the outfield are mainly discussed. The results show that the sampling time and the THz field should exceed certain thresholds to effectively excite photoluminescence quenching （PLQ）. Adopting a direct current （DC） field makes the sampling time threshold shortened and the linear range of THz field-modulation PL expanded. Moreover, controlling the sampling time and the outfield intensity can improve the linear quality： with forward time, the larger outfield is used; with backward time, the smaller outfield is used. This study can provide a theoretical basis of THz field linear modulation in a larger range for new light emitting devices.

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.

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.

Pulse Propagation with Self-Phase Modulation in Nonlinear Chiral Fiber and Its Applications

From Maxwell＇s equations and Post＇s formalism, a generalized chiral nonlinear Schr6dinger equation （CNLSE） is obtained for the nonlinear chiral fiber. This equation governs light transmission through a dispersive nonlinear chiral fiber with joint action of chirality in linear and nonlinear ways. The generalized CNLSE shows a modu- lation of chirality to the effect of attenuation and nonlinearity compared with the case for a conventional fiber. Simulations based on the split-step beam propagation method reveal the role of nonlinearity with cooperation to chirality playing in the pulse evolution. By adjusting its strength the role of chirality in forming solitons is demonstrated for a given circularly polarized component. The application of nonlinear optical rotation is also discussed in an all-optical switch.

Performance Comparison of PIN and APD based FSO Satellite Systems for various Pulse Modulation Schemes in Atmospheric Turbulence

In this paper, the performance of various Pulse Position Modulation (PPM) schemes has been analysed for PIN and APD receivers in the presence of atmospheric turbulence. It is observed that the performance of the APD receiver is always better than that of the PIN receiver as expected. Among the various modulation schemes, the performance of Differential Amplitude PPM (DAPPM) scheme with more number of amplitude levels is better than that of the other schemes for the same single level peak amplitude. Further, the optimum gain of APD receiver does not change substantially for different modulation schemes and turbulent conditions.

Digital Pulse Width Modulation Control in Power Electronic Circuits Design

The paper mainly focuses on the digital pulse width modulation (DPWM) control techniques for high performance power electronic circuit design. The problem to be solved in this study addresses the DPWM converter design for DC to DC conversion process. The control techniques have been utilized the Fuzzy Logic Rules Base method for proposed SIMULINK model of high performance power electronic circuit. The analytical calculations for real circuit design have been completed based on the mathematical modeling of the system. The results from the developed SIMULINK model confirm the target specifications of the high performance condition for power electronic circuit which was met the objective of this study. The numerical results have been carried out with the help of MATLAB/SIMULINK.

Spectrum for Pulse Interval Modulation Signal

A static approach method method is used to get the spectrum expression of the pulse interval modulation signal.The expression is simple,has a clear physical concept and it has been confirmed by a simultaneous experiment.

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.

Kinetic simulation of the transition from a pulse-modulation microwave discharge to a continuous plasma

The generation of a very strong peak current in the first period(PCFP)in a pulse-modulated microwave discharge has been discussed in previous studies.In this paper we focus on the transition process from a pulsed discharge to a fully continuous one driven by the pulsed microwave power source by means of a kinetic model.The computational results show that by increasing the duty cycle or voltage modulation rate(VMR).the discharge eventually becomes fully continuous and PCFP can no longer he observed.In the transition process,the distributions of the electric field,electron energy probability function(EEPF)and plasma density are discussed according to the simulation data,showing different discharge structures.The simulations indicate that many high-energy electrons with electron energy larger than 20eV and low-energy electrons with electron energy less than 3eV could he generated in a pulsed microwave discharge,together with a reversal electric field formed in the anode sheath when PCFP occurs.However,only medium-energy electrons could be observed in a fully continuous discharge.Therefore,by investigating the transition process the pulse-modulated microwave discharges can be further optimized for plasma applications at atmospheric pressure.