Calculation Of Switching Times Research Articles

Simulation of 3D-space vector modulation for neutral point clamped inverters

This paper gives an idea to simulation of three-dimensional space vector modulation for neutral point clamped multilevel inverter. Three dimensional-space vector modulation (3D-SVM) algorithm is progressed method of two dimensional-space vector modulation (2D-SVM) algorithm; it leads to reduce the complexity in reference vector identification and switching time calculation, also it includes the various advantages of 2D-SVM like minimized total harmonic distortion, reduced EMI issues. A simple system for the assortment of switching state vectors to track the reference voltage vectors without using any redundant switching vectors. This proposed method tracks the reference vector by identifyinglsubcubes and prisms by using mathematicallconditions. Here the cost of the proposedltechnique is independentlof voltagellevels oflinverter. This paper realizes the accomplishment of 3D-SVM using a neutral point clamped inverter. The simulation results of the proposed method are verified using MATLAB/Simulink.

Comparative analysis of 3D‐SVM and 4D‐SVM for five ‐phase voltage source inverter

Pulse width modulation (PWM) methods play a major role to control the various power electronic converters to progress the recital of the system. In this paper, a comparative analysis is done for three dimensional space vector modulation (3D-SVM) and four dimensional space vector modulation (4D-SVM) for five-phase voltage source inverter. 3D-SVM method comprises all qualities of conventional SVM; switching time calculation is simple and much suitable for three-phase system; where in five-phase system, it has redundant switching state vectors. 4D-SVM includes advantages of 3D-SVM and other conventional methods, it employs only nonredundant switching state vectors; it directs to diminish the intricacy in switching time calculations and avoids trigonometric calculations and look up tables for reference vector identification. The various parameters such as total harmonic distortion, improved output voltage, minimized common mode voltage and switching time calculation are analyzed and compared for 3D-SVM and 4D-SVM techniques. Simulation and hardware results are acquired and established using matlab simulink and FPGA processor, respectively.

A Comparative Analysis of Hysteresis Current Control SVM and 3D-SVM for 3-Level NPC Inverter

This paper elucidates a comparative analysis of hysteresis current control space vector modulation (HCC-SVM) and 3-dimensional space vector modulation (3D-SVM) for control of 3-level neutral point clamped (NPC) inverter. The NPC inverter topology is much suitable for single input applications and medium and high power applications. The detailed comparative analysis of total harmonic distortion (THD) for both modulation control strategies is analyzed. Among various modulation strategies, these two control strategies increased more attention due to the improved output compared to the other conventional methods. The simulation and hardware results are evident that 3D-SVM is the most efficient controller for capacitor balancing, common mode voltage minimization, THD minimization and attain low voltage stress across switch, but in terms of system design and complexity in switching time calculation is simple in the HCC-SVM method. The simulation and hardware results are verified using simulink and FPGA processor, respectively.

Modified digital space vector pulse width modulation realization on low-cost FPGA platform with optimization for 3-phase voltage source inverter

The realization of power electronic applications on hardware is a challenging task. The digital control circuit strategies are used to overcome the analog control strategies by providing great flexibility with simple equipment and higher switching frequencies. In this manuscript, an area optimized, modified digital space vector (DSV) pulse width modulation is designed and realized on low-cost FPGA. The modified digital space vector pulse width modulation (DSVPWM) uses a phase-locked loop (PLL) to generate clocks using the digital clock manager (DCM). These DCM clocks are used in the DSVPWM module to synchronize the other sub-modules. The voltage generation unit generates the three-phase (3-Ф) voltages and is used in the alpha-beta generation and sector determination unit. The reference active vectors are made by the reference generation unit and used in switching time calculation. The PWM pulses are generated using switching time generation, and lastly, the dead time occurrence unit generates the final SVPWM gate pulses. The modified DSVPWM is synthesized and implemented on Spartan-3E FPGA. The modified DSVPWM utilizes 17% slices, works at 102.45 MHz, and consumes 0.070 W total power. The simulation results and the resource utilization of modified DSVPWM are represented in detail. The modified DSVPWM is compared with existing PWM approaches on different Spartan-series FPGAs with better chip area improvement

An adaptive, observer-based switching method for B4 inverters feeding three-phase induction motors

Abstract A four-switch inverter called the B4 inverter is a reconfigured topology of a B6 inverter, one leg of which is damaged. The four-switch topology provides the overall system with fault-tolerant characteristics. However, this reconfiguration will not only change the system dynamics but also degrade the system performance. For overcoming with these issues, this paper presents an adaptive switching method based on DC-link voltage control. In the proposed method, the selection of active vectors and the calculation of switching times are made according to an adaptive, observer-based algorithm which will reduce DC-link voltage oscillations and adjust unbalanced currents fed to induction machines. In this algorithm, an online, designed observer is utilized so as to estimate the DC amount of the DC-link voltage. Applying this method, we will decrease flux and torque ripples as well as increase the inverter efficiency and performance. The simulation results presented in the MATLAB environment evaluate and validate the performance and effectiveness of this approach.

Reactive Power Control and Neutral Current Elimination of Four Wire Five Level NPC Inverter based STATCOM using 3D-SVPWM Technique

In this paper, three phase four wire five level Neutral Point Clamped Inverter (NPCI) based Static synchronous Compensator (STATCOM) is implemented for reactive power control and neutral current elimination. Three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) control strategy is developed to control this 5-level NPC inverter. The behaviour of static synchronous compensator is analyzed and reactive power control is done using constant DC voltage. The objective of this compensating method is to provide balanced and sinusoidal source currents under unbalanced and nonlinear load conditions and reactive power control. The 3D-SVPWM technique provides reduced harmonic content in output voltage and current, controlled source current, minimized common mode voltage and improved output voltage. In 3D-SVPWM, switching pulses are generated with non-redundant switching states, which lead to reduce the complexity in switching time calculation and computational time is less. The highlights of the paper includes the neutral current is reduced to 0.25A, source current harmonics is minimized and it provides balanced and sinusoidal source currents with help of STATCOM compensation. The simulation and experimental results demonstrates the sinusoidal and harmonics free source current and minimized neutral current for four wire five level NPCI based STATCOM.

SVPWM control strategy for a three phase five level dual inverter fed open-end winding induction motor

A Space Vector Pulse Width Modulation (SVPWM) control strategy is proposed for a three phase five level dual inverter fed open-end winding induction motor. This system includes 2 three level Neutral Point Clamped (NPC) inverters, which is supplied by two isolated dc power supplies. The conventional SVPWM has more complexity in reference vector identification and switching time calculation. The reference vector for proposed five level SVPWM scheme is tracked using three level voltage vector and offset voltage, where 5-level hexagonal region is divided into seven 3-level hexagonal regions. The proposed SVPWM leads to reduce the complexity in switching time calculation, Total Harmonic Distortion (THD) reduction, Minimization of Common Mode Voltage (CMV) and low voltage stresses across the switching devices. Also this system estimate the phase current of the five level dual inverter fed open-end winding induction motor. The results obtained using simulation and hardware are compared and verified using Digital Signal Processor.

Artificial Neural Network based SVPWM for Five Level Cascaded H-bridge Inverter fed Grid connected PV System

An Artificial Neural Network (ANN) based Space Vector Pulse Width Modulation (SVPWM) for five level cascaded H-bridge inverter (CHBI) fed grid connected photovoltaic (PV) system. The multilevel inverter topologies are offers better performance compare conventional two level inverter like reduced total harmonic distortion, less electromagnetic interferences and voltage stresses across switches are low. The ANN based SVPWM generates the switching pulses for cascaded H-bridge inverter; it improves the accuracy in reference vectors tuning and identification, which leads to improve the inverter output voltage, better utilization of dc-link voltage and controlled output current. The ANN control makes the implementation of SVPWM becomes simple and minimizes the intricacy in tracking reference vector and calculation of switching time; it is suitable for any type of non-linear systems. This proposed system is energized using PV system and it is boosted using dc-dc boost converter, and the output of CHBI is synchronized with grid connected system using coupled inductor. The simulation and experimental results of ANN based SVPWM for CHBI is verified using simulink-matlab and DSP processor.

Indirect Vector Controlled Asynchronous Motor Drive’s Dynamic Performance and Analysis with A New Modified MPPT Controller

Generation of electricity from the PV system has nowadays chosen as a best energy collecting source, due to its abundance availability and also to save the conventional energy sources to the future generation. Because all the conventional sources are coming to an extinct. That is the reason, everybody are looking towards the available renewable energy resources like wind, solar, bio mass, ocean, tidal and geothermal. But, upon those, solar and wind sources are maximum preferred sources, due to their easy availability and easy way of collection of energy. This paper presents a modeling of solar photovoltaic (PV) array with a new modified maximum power point tracking (MPPT) controller, which enhances the PV system performance even at abnormal weather conditions. That the existed MPPT controllers were developed based upon the ideal characteristics of constant irradiance with variable temperature and constant temperature with variable irradiance. To overcome the above problem a practical data is considered for designing of MPPT controller which is based upon variable irradiance. But here, it is developed with the variable irradiance and variable temperature with better performance of the system. The output obtained from the PV with a new modified MPPT is given to the boost converter with an inverter to find the dynamic performance of an indirect vector controlled asynchronous motor drive under different operating conditions. For inverter control, a space vector modulation (SVM) algorithm is used, in which the calculation of switching times is proportional to the instantaneous values of the reference phase voltages. The dynamic performance responses like phasor current, torque and speed of the drive by the new modified MPPT along with SVM controlling technique of the inverter are compared and analyzed with the existed method for different operating conditions.

Generalized Scalar PWM Algorithm for VSI Fed Induction Motor Drives with Reduced Complexity

This paper presents a simple and novel generalized pulse width modulation (GPWM) algorithm for voltage source inverter fed induction motor drives. The classical space vector approach requires angle and sector information for the calculation of switching times, which increases the complexity of the PWM algorithm. Hence, to reduce the complexity, the proposed GPWM algorithm generates the modulating signals by using the instantaneous phase voltages only. In the proposed algorithm, a unique zero sequence signal is added to the instantaneous phase voltages in order to generate the modulating waveforms. By varying a constant in the zero sequence signal from 0 to 1, various PWM algorithms such as space vector PWM (SVPWM) and discontinuous PWM (DPWM) algorithms are generated. Moreover, a simple overmodulation algorithm is also presented in this paper. Thus, the proposed GPWM algorithm generates all possible PWM algorithms in the entire modulation region. To validate the proposed algorithm, several simulation and experimental results are presented and compared. The results show the best agreement with the published work.

Switching time and energy in bistable injection-locked semiconductor multi-quantum-well Fabry-Perot lasers

In this paper, we investigate the influence of the linewidth enhancement factor and active region volume on the switching characteristics of bistable injection-locked multi-quantum-well Fabry-Perot lasers. In this analysis we start from the full scale model of the multimode rate equation system describing dynamics of injection-locked lasers. On the basis of this model, we derive a simple analytical procedure for calculation of switching time and energy with respect to the injection power, and for different values of frequency detuning between the master and the slave laser. We find that the higher values of linewidth and active region volume can improve switching characteristics of injection-locked Fabry-Perot lasers, providing either shorter switching times ($\ensuremath{\sim}$10 ps) or lower switching energies ($\ensuremath{\sim}$1 fJ).

Vector-based reference location estimating for space vector modulation technique

Space vector modulation (SVM) has become a popular pulse width modulation technique (PWM) for multilevel inverters. In SVM technique, the determination of the angular position of the reference voltage vector is very important to generate the required output voltage by the inverter. The switching time and switching sequence of SVM are calculated by vector location. The calculation of vector location and switching time become difficult and more complex when the numbers of output voltage levels increase for a given number of inverter levels. In this paper, a new SVM method is developed to determine the actual vector location. The proposed method can increase RMS value of the inverter output voltage; can reduce the algorithm complexity and computation time when compared to conventional SVM methods. In addition, the calculation of switching times for two-level inverter is generalized for N-level inverters. PSCAD/EMTDC simulation program is used to create the test system and to perform the case studies. Extensive simulation results are given to validate the performance of the proposed algorithm.

Calculation of switching times in the genetic toggle switch and other bistable systems

Genetic circuits with feedback such as the toggle switch often exhibit bistability, namely, two stable states with rare spontaneous transitions between them. These systems can be characterized by the average time between such transitions (referred to as the switching time). However, commonly used deterministic models, based on rate equations, do not account for these fluctuation-induced transitions. Stochastic methods, such as the direct integration of the master equation, do account for the transitions. However, they cannot be used to evaluate the switching time. In order to obtain the switching time, one needs to use Monte Carlo simulations. These methods require the accumulation of statistical data, which limits their accuracy. They may become infeasible when the switching time is long. Here we present an accurate and efficient method for the calculation of the switching time. The method consists of coupled recursion equations for the transition times between microscopic states of the system. Using a suitable definition of the two macroscopic bistable states (in terms of the microscopic states) and the probabilities obtained from the master equation, the method provides the switching time between the two states of the system. The method is demonstrated for the genetic toggle switch. It can be used to evaluate the switching times in a broad range of bistable and multistable systems. We also show that it is suitable for the evaluation of the oscillation periods in oscillatory systems such as the repressilator.

Modeling of Average Current Mode Control in PWM DC/DC Converters

In this paper, an improved averaging technique for average current mode controlled (ACMC) pulse width modulated (PWM) DC/DC converter is proposed. The modeling procedure provides a ripple estimation and improves switching time calculation for ACMC PWM DC DC converters. As an application of the theory, an ACMC boost converter witjh two proportional-integral (PI) controllers for both current loop and voltage loop is presented. Results confirm that the new averaged models are more accurate than conventional averaged models.

Finite element formulation for non-smooth oscillations of an elastic beam with a friction device

Calculated are forced oscillations of a clamped elastic beam with a friction device at its free end. Considering partial states, namely sticking and sliding, and applying FEM leads to a discrete non-smooth dynamic problem. Stationary oscillations are of interest, depending on the number of finite elements and on different types of friction laws. Due to the linearity of partial states of motion, the numerical integration is reduced to the calculation of switching times which separate the sequence of partial states. Appropriate chosen internal damping diminishes the numerical effort considerably.

Prediction of Propagation Delay in RTL Circuits by Charge Control Approach

ABSTRACTThis paper describes a charge control approach to the analysis of the transient response of an RTL inverter. The procedure adopted in predicting the propagation delay of RTL inverters consists of a preliminary worst case d.c. design of the circuit, followed by the evaluation of the individual components of the propagation delay time, viz. the storage, fall, delay and rise times. In the calculation of switching times, the driving waveform which is actually an exponential time function is approximated by a ramp time function.The present investigation has yielded formulae which enable the prediction of propagation delay time as a function of the fan-in and fan-out and the value of the transfer resistance. This analysis enables the circuit designer to choose such values of the circuit resistances which will yield minimum propagation delay under the worst transient conditions without violating the d.c. stability criteria. Experimental verification of the predicted times has also been carried out.