Search results for "modulation index"
showing 9 items of 9 documents
Electrostatic synchronous generator model of an Inverter-Based Distributed Generators
2015
In this paper, the idea of modelling the Inverter-Based Distributed Generators by using the concept of Electrostatic synchronous machines is discussed. A mathematical model of the inverter has been established which depends on the dc bus voltage, modulation index and frequency of the system. Two mathematical models have been developed: a small signal model and a steady-state model. These mathematical models will be helpful in studying the stability of a microgrid; especially when studying the transient stability performance of on-grid operation of converter-based distributed generator with multi-machine microgrid. Simulation results using Matlab/Simulink are carried out.
Decoupled control scheme of grid-connected split-source inverters
2017
Grid-connected power conversion systems for renewable energy sources must fulfill several requirements, e.g., the high efficiency, the reduced cost and complexity, and, quite often, the boost capabilities that is usually achieved using a front-end dc–dc boost converter before the inversion stage, leading to a two-stage architecture. Meanwhile, single-stage power conversion systems, which perform the boosting operation within the inversion one, offer some potential advantages, in terms of reducing the complexity and the volume of the whole system. Among several proposed options, the split-source inverter (SSI) has been recently proposed by Abdelhakim et al. as an alternative option with some…
Temporal-spatial characteristics of phase-amplitude coupling in electrocorticogram for human temporal lobe epilepsy.
2017
Objective Neural activity of the epileptic human brain contains low- and high-frequency oscillations in different frequency bands, some of which have been used as reliable biomarkers of the epileptogenic brain areas. However, the relationship between the low- and high-frequency oscillations in different cortical areas during the period from pre-seizure to post-seizure has not been completely clarified. Methods We recorded electrocorticogram data from the temporal lobe and hippocampus of seven patients with temporal lobe epilepsy. The modulation index based on the Kullback-Leibler distance and the phase-amplitude coupling co-modulogram were adopted to quantify the coupling strength between t…
Practical Implementation of a Synchronous PWM Strategy for Low Switching Frequency FOC of im Drives with ATSAM3X8E Microcontroller
2021
This paper presents a practical implementation of synchronous PWM modulation algorithm for an induction motor field oriented control powered by a DC/AC inverter and implemented on a low-cost microcontroller, the ATSAM3X8E. In particular, a simple algorithm, capable to calculate automatically an optimized set of frequency modulation indexes will be presented. Hysteresis bands are also introduced in the algorithm in order to avoid multiple changeovers during modulation index transitions. Experimental tests and their results will be shown and discussed, highlighting the benefits of the present algorithm, such as reduction of current harmonic content, reduction of current ripple and, consequent…
Graphical THD minimization procedure for single phase five-level converters
2017
This paper proposes two graphycal procedure to mitigate h harmonics and to minimize the total harmonic distortion (THD), respectively. The paper considers a five-level inverter and fundamental frequency modulation: it computes the two switching angles able to reduce low order harmonics and able to minimize the THD. Simulation results are obtained and, in order to validate the proposed procedure, an experimental prototype is built and experimental results are carried out. The comparison between simulation and experimental results confirms the accuracy of the proposed graphycal procedure. It is shown that the switching angles to mitigate the third-fifth and the third-fifth-seventh harmonics e…
Harmonic reduction in CHB 13-level inverters by PAM fundamental-frequency strategy
2019
In this paper cascaded H-bridges (CHB) 13-level inverters are considered and a particular pulse amplitude modulation (PAM) strategy is introduced to mitigate or eliminate many harmonic components on the output voltage, in order to obtain low Total Harmonic Distortion (THD) factor. This procedure defines different dc voltage sources and sets of six switching angles, depending on an integer parameter $q$ belonging to the close interval $I=[11, 15]$ . The obtained THD doesn't depend on modulation index $m$ . The control of $m$ is made by changing the dc voltage sources that depend linearly on m, while the switching angles remain constant. An investigation about the role of the $q$ parameter on…
Experimental Comparative Analysis of Efficiency and THD for a Three-phase Five-level Cascaded H-Bridge Inverter Controlled by Several MC-PWM Schemes
2021
Cascaded H-Bridges Multilevel Inverters are an innovative and promising solution in different application fields. This topology allows obtaining an improvement in the performance (e.g. reduced harmonic content, the low voltage stress on power components, and high efficiency) in respect to the traditional two-level inverters. In this context, the Multicarrier-PWM strategies play an important role thanks to their features. This paper presents an experimental investigation on the performance of a three-phase five-level Cascaded H-Bridge inverter by using different PWM modulation strategies. In particular, the paper is focused on the experimental validation of the main features of Multicarrier …
Mixed Harmonic Elimination Control for a Single-Phase 9 Level Grid-Connected Inverter
2018
The power quality requirements are increasingly stringent, due to the continuous growth of devices connected to the grid that introduce harmonics. These devices include DC to AC energy conversion systems, i.e. grid connected inverters. The design, control and operation of these systems must take into account the rules of interconnection to the electricity grid. To improve the quality of the output waveform of the grid-connected inverter, Multilevel Converters (MC) with selective harmonic elimination modulation technique can be used. This paper presents a single-phase nine level grid-connected inverter with DC/DC input stages. The obtained switching angles for THD minimization are independen…
A study on spectral optimisation in partial response CPM signals
1995
An optimisation technique for the minimisation of the effective bandwidth in partial response CPM signals is described. The minimum Euclidean distance is used as optimisation constraint because the bit error probability is a function of this parameter for high values of signal to noise ratio. The procedure has been implemented for a correlation length corresponding to two signalling intervals. The optimisation problem leads to a system of two nonlinear differential equations for the pulse shape, together with some boundary conditions. Numerical solution of the differential equations has been performed; initial conditions have been adjusted, to satisfy the boundary conditions using an iterat…