Calculation Of Switching Angles Research Articles

An Improved Type of Synchronized Space Vector PWM Based on Switching Angles for High‐Power AC Drive Application

Synchronized space vector pulse width modulation (SSVPWM) is widely employed in high‐power AC drive systems. The existing methods are carrier‐based, in which the carrier ratio, position of samples, and switching sequences used to generate every sample for a given SSVPWM are settled, which causes two problems: (i) the control delay changes, and a voltage phase modulation error appears suddenly during transition between different SSVPWMs with different carrier ratios, which causes motor current spikes; (ii) due to the particular switching sequences, some kinds of SSVPWM cannot get into six‐step operation by overmodulation. This paper proposes an improved type of SSVPWM based on switching angles, in which the carrier ratio of a given SSVPWM can change flexibly, and the problems mentioned above can be solved. Theories including switching angle calculation, overmodulation strategy, carrier ratio setting principle, and transition rules between different SSVPWM modes are given in this paper. Meanwhile, the switching angles change linearly with modulation index which makes it easy to implement, and the modulation error in the overmodulation region is effectively limited so that the proposed scheme is suitable in the whole modulation index range. A case study of a 5.5‐kW experimental platform is presented to validate the proposed method. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Quasi-modified-Newton method-based selective harmonic elimination in cascaded H bridge inverters

Multilevel converters have gained significant popularity in medium-voltage and high-power applications due to their numerous advantages over traditional two-level converters. These advantages include reduced harmonic distortion, improved efficiency, and lower stress on power semiconductors. Selective harmonic elimination (SHE) is a modulation method that can be employed with multilevel converters to achieve high-quality output voltage waveforms. In this work, an extension of Broyden’s method, known as the Quasi-Modified Newton Method, is implemented for selective harmonic elimination and accurate calculation of switching angles for a wide range of modulation indices. The proposed method is applied to cascaded H bridge inverters operating at levels 5, 7, and 9. The method offers simplicity, reduced computational burden, and faster convergence, making it easily implementable, reducing total harmonic distortion (THD), and reducing RMSE and MAD errors. The paper includes simulation and experimental results that validate the accuracy and effectiveness of the proposed approach.

Red deer algorithm-based selective harmonic elimination technique for multilevel inverters

This paper proposed a red deer algorithm (RDA)-based selective harmonic elimination (SHE) method for multilevel inverters (MLIs). To eliminate the desired harmonic orders, the optimum switching angles of the MLI have been calculated using the proposed RDA. The calculated switching angles have been applied to the 3-phase cascaded H-bridged 11-level inverter. In addition, the performance of the proposed RDA method was compared with the results of methods such as the Newton-Raphson (NR) method, LSHADE/EpSin technique (LSHADE), whale optimization algorithm (WOA), and particle swarm optimization (PSO) used for the SHE problem in the literature. The results obtained prove that the proposed RDA optimization solves the SHE problems more effectively than other methods. It has also been observed that RDA produces good solutions in different modulation indexes.

Online adaptive SHE algorithm for multilevel converters and implementation with embedded control system

Selective harmonic elimination pulse-width modulation (SHE-PWM) method has been widely used in various industrial multilevel converters befitting from low switching frequencies and precise elimination of low-order harmonics. Most of existing studies focus on accelerating calculation of switching angles or optimizing predictive neural networks. However, these offline methods cannot dynamically deal with the errors introduced by nonuniform dc sources of multilevel converters or biased placements of switching angles. This paper proposes an online adaptive SHE (OA-SHE) algorithm to compensate these errors. Errors caused by nonideal dc (NID) sources and leading-lagging placements (LLPs) are analyzed in detail. The error of output waveform is comprehensive result of NID sources and LLPs. By introducing feedback, the output waveform accuracy of multilevel converters can be increased greatly. Realization of the particle swarm optimization (PSO) with an embedded control system is presented to acquire good real-time performance. With the OA-SHE method, the value of particles has been higher than the initial value. High order harmonics, including 1st, 5th, 7th, 11th, and 13th components, are suppressed by the low-pass filter. Comparing to existing studies, this online algorithm does not need detailed model parameters and can be directly applied to practical applications achieving multi-objective optimization. Finally, both simulations and experiments are carried out to verify the effectiveness of this algorithm.

Low and High Frequency Control Strategy for Asymmetrically Switched Cascaded Multilevel Inverter

This paper proposes low and high frequency control techniques for asymmetrically switched cascaded multilevel inverters (MLI). Initially, Low frequency-based switching angle calculation methods are proposed for the suggested topology. Then high frequency-based Multi-carrier pulse width modulation (MCPWM) techniques are used to control the switching states of multilevel inverters for asymmetrical sources. The proposed multilevel inverter is a reduced switch topology with a modular version realized. From the modular version of the topology, three asymmetrically switched (7, 13 & 21) levels are simulated by MATLAB/Simulink environment and comparisons among themselves are also considered according to method of switching techniques and power quality, i.e. total harmonic distortion (THD). The designed inverters are recommended for photovoltaic power generation as they are suitable to integrate separate DC power sources. The inverters are designed and simulated with a proper simulation environment and experimentally verified through hardware in loop (HIL) using OPAL-RT (OP-5600) testbed.

Red deer algorithm based selective harmonic elimination for renewable energy application with unequal DC sources

This study aims to find the optimal switching angles in a cascaded H-bridge multilevel inverter (CHB-MLI) fed by photovoltaic (PV) panels, keeping the output voltage constant regardless of the panel voltage change and eliminating low-order harmonics. For this purpose, Red Deer Algorithm (RDA), a newly developed algorithm, has been applied to solve selective harmonic elimination (SHE) equations. Calculated switching angles are simulated by applying three-phase 7-level CHB-MLI in Matlab/Simulink environment. RDA optimization has been compared in performance to evolutionary algorithms such as particle swarm optimization (PSO), genetic algorithm (GA) and pigeon inspired optimization (PIO). The results show that in the case of unequal DC voltage, RDA can suppress selected harmonics accurately and quickly while controlling the fundamental voltage with a 0.02% error. The proposed RDA optimization can be used for multilevel inverters fed by any number of variable input voltages to eliminate selected harmonics and reduce total harmonic distortion (THD) without complex analytical calculations.

Harmonic analysis in modified cascaded multilevel inverter with nature-inspired switching-angle optimization algorithm

Selective harmonic elimination pulse width modulation (SHEPWM) is a fundamental frequency switching angles calculation technique that eliminates the undesired low order harmonics while maintaining the desired fundamental component. A natured-inspired optimization algorithm, grasshopper optimization algorithm (GOA), is applied in SHEPWM to obtain the optimized switching angles. Compared to Newton Raphson (NR), GOA is able to provide wider range of solutions. Optimize switching angles obtained from MATLAB analysis are applied to a 5-phase 7-level modified cascaded multilevel inverter (MCMLI). This paper presents the performance of GOA applied to the MCMLI. The 3rd and 7th harmonics are chosen to be eliminated while the desired fundamental component is maintained.

Comparative analysis of switching angle calculation methods for multilevel inverters

A multilevel inverter produces an output to approximate a desired sine wave. The closeness of the output waveform to the sine wave depends on the logic applied for switching angle calculation, resulting in different switching angle calculation methods. In this paper, various switching angle calculation methods are compared based on of the parameters quantifying the quality of the output waveform. The main focus of this work is on the study of convergence of the output waveform to a smooth waveform as number of levels increases theoretically. The convergence is analytically proved and validated numerically by computing up to 201 levels. Also, a parameter quantifying the deviation of the output waveform from the sine wave is defined, and its closed form expression is derived. This parameter is strongly correlated to and computationally less expensive than the total harmonic distortion. Hence, the deviation is proposed as a better measure of the quality of the output wave form. The convergence and the deviation of the output waveform are also used as the basis of the comparison of different switching angle calculation methods. These two give a better insight into the switching angle calculation methods. The analysis presented in this paper provides a good understanding of various switching angle computation methods and helps in choosing an appropriate method for a given application.

Analysis and Simulation of a Single Phase Nine Level Inverter with Reduction in Power Switching Devices

This paper present analysis and modelling of single phase nine level inverter, a Wide range of Modulation index (M) varied between 0.05-1.05 is achieved by two switching strategies (Optimized harmonic stepped waveform (OHSW), (Optimal minimization of total harmonic distortion (OTHD)) the first strategy focusses on harmonic elimination and the other on reducing output voltage total harmonic distortion (THD). Calculation of switching angles for both equal and unequal dc sources is done by Genetic Algorithm (GA). simulation in Matlab, PSpice and PSIM is presented in this work.

Design and Development of N-Level Symmetrical Multilevel Inverter Topology with Reduced Switches

In this paper, 11-level multilevel inverter with reduced power switch configuration is developed and investigated. This proposed configuration can be extended for [Formula: see text] levels with the required number of power switches. Comparative analysis between the proposed multilevel inverter topology and well-known existing multilevel inverter topologies is carried out. Fundamental switching angle calculation for the power switches of the proposed topology has been optimized using black widow optimization algorithm technique and also the proposed topology has been tested with the classical multicarrier alternative phase opposition disposition PWM technique. To test the effectiveness of the proposed topology, different tests have been conducted such as testing with different modulation indexes, DC input voltages, load settings and voltage ride-through capabilities. This paper presents various simulation and experimental results under various operating conditions to prove the performance of the proposed multilevel inverter topology.

Application of Grasshopper Optimization Algorithm for Selective Harmonics Elimination in Low-Frequency Voltage Source Inverter

In this paper, an application of the recently developed Grasshopper Optimization Algorithm (GOA) for calculation of switching angles for Selective Harmonic Elimination (SHE) PWM in low-frequency voltage source inverter is proposed. The algorithm is based on insect behavior in the food foraging swarm of grasshoppers. The characteristic feature of GOA is the movement of agents is based on the position of all agents in the swarm. This method represents a higher probability of convergence than Particle Swarm Optimization (PSO) Modifications of GOA have been examined regarding their effect on the algorithm’s convergence. The proposed modifications were based on the following techniques: Grey Wolf Optimizer (GWO), Natural Selection (NS), Adaptive Grasshopper Optimization Algorithm (AGOA), and Opposite Based Learning (OBL). The performance of GOA and its modifications were compared with well-known PSO. Areas, where GOA is superior to PSO in terms of probability of convergence, have been shown. The efficiency of the GOA algorithm applied for solving the SHE problem was confirmed by measurements in the laboratory.

Analysis of a switching angle calculation by ANN for nine level inverter apply into experimental case study with elimination of lower and higher order harmonics

This paper confers an investigation of a Selective Harmonic Elimination (SHE) technique has gained wide acceptance for many AC drive applications, due to a higher DC bus voltage utilization (higher output voltage compared with the Sinusoidal Pulse Width Modulation (SPWM), lower harmonic distortions and easy digital realization.” In recent years, the SHE technique was extensively adopted in multilevel inverters since it offers greater numbers of switching for obtaining further improvements of AC drive performances. “Nevertheless, the use of SHE-associated multilevel inverters will optimize the switching angles based on Artificial Neural Networks (ANN) compared with Particle Swarm Optimization (PSO) to reduce the Total Harmonic Distortion (THD) of the modified CHB-MLI output voltage within permissible limits. The main objectives of this paper are the design and testing of the CHB-MLI modified topology laboratory for a nine-level single-phase prototype.” Also demonstrated were the experimental effects of using Digital Signal Processing (DSP) TMS320F2812 into a prototype. The controls were applied to the modified multilevel inverter, based on ANN and PSO. The proposed controller was then coded onto a board of DSP TMS320F2812. Compared with the PSO method, the inverter gives fewer THD using ANN scheme.

Analysis of a switching angle calculation by ANN for nine level inverter apply into experimental case study with elimination of lower and higher order harmonics

Analysis of a switching angle calculation by ANN for nine level inverter apply into experimental case study with elimination of lower and higher order harmonics

Performance comparison between optimization algorithms for asymmetrical cascaded multilevel inverter control

This paper discusses the hardware and control system design of the asymmetric cascade multilevel inverter. The asymmetric cascaded multilevel inverter structure is adopted to minimize bridges, gate drive circuits and DC power source number. Therefore, the proposed structure is able to generate higher voltage at higher speed with low switching losses and high efficiency. Selective Harmonic Elimination (SHE) based on Newton-Raphson (N-R) algorithm is developed to calculate a switching angle for a range of modulation index to control asymmetric cascade multilevel inverter. Simulation results prove that Newton-Raphson technique is more effective than genetic algorithm (G-A) and equal calculated switching angles method (ECSA). A comparison between the algorithm performance for 9-level asymmetric cascade H-bridge inverter control was evaluated and experimentally tested on FPGA-based prototypes

Modeling and control of 41-level inverter using best switching angles calculation method

<div data-canvas-width="257.02725257004636">In this paper, analysis and modeling of a single-phase H-bridge forty-one level inverter are con sidered. The control of proposed inverter by equal-phase and half-height methods is implemented. MATLAB/Simulink environments are used to simulate the model an d show obtained results of waveforms with FFT analysis. Eventually, the total harmonic distortion obtained for each level with the two methods is presented, comparatively, for a comparison.</div>

Modeling and control of 41-level inverter using best switching angles calculation method

Modeling and control of 41-level inverter using best switching angles calculation method

Multiwinding Transformer Fed CHB Inverter With On-Line Switching Angle Calculation Based SHE Technique for Vector Controlled Induction Motor Drive

A multiwinding transformer for ac–dc converter with multilevel inverter fed induction motor drive (IMD) is presented in this article. An 18 pulse ac–dc conversion is used on input side of the IMD, to meet the power quality requirement as per the IEEE-519 standard. At IM side, a ternary configured nine-level cascaded H-bridge (CHB)-inverter is used to enhance the response of the IMD. A simple online calculation of switching angles and its implementation of selective harmonic elimination strategy, are proposed to control a nine-level CHB-inverter. In this article, a nine-level CHB-inverter is operated at fundamental frequency switching for reducing the losses and suppressing the lower order harmonics (fifth, seventh, and eleventh) to a negligible value and to enhance the torque profile of the IMD. The performances of IMD are evaluated in MATLAB-Simulink environment and then simulated results are verified by test results taken from developed prototype in the laboratory to show its effectiveness for medium power applications.

Improved Step Load Response of a Dual-Active-Bridge DC–DC Converter

This paper proposes a fast load transient control for a bidirectional dual-active-bridge (DAB) DC/DC converter. It is capable of maintaining voltage–time balance during a step load change process so that no overshoot current and DC offset current exist. The transient control has been applied for all possible transition cases and the calculation of intermediate switching angles referring to the fixed reference points is independent from the converter parameters and the instantaneous current. The results have been validated by extended experimental tests.

Application of swarm optimisation‐based modified algorithm for selective harmonic elimination in reduced switch count multilevel inverter

Multilevel inverters (MLIs) are nowadays extensively used in integration with renewable energy sources and in drives applications. The converter cost and voltage quality improvement are the utmost importance in such application of MLI. A six-switch seven-level reduced switch symmetrical MLI (6S-7L MLI) is proposed here. Compared to the conventional and similar existing MLI topologies, the proposed MLI uses less active switches and has less driver circuit requirement. A particle swarm optimisation (PSO)-based modified selected harmonic elimination technique is derived and analysed for computing optimal switching angles of proposed 6S-7L MLI to eliminate third- and fifth-order harmonics. Moreover, the performance of the proposed algorithm is compared with the two most commonly used PSO variants. The analysis shows the modified version of PSO is most suitable for optimising the output voltage of proposed MLI through targeted harmonic elimination. The proposed topology is investigated through simulation by applying the calculated switching angles using modified PSO algorithm. Finally, a single-phase experimental prototype is designed to verify the validity of the proposed structure.

Middle-Level SHE Pulse-Amplitude Modulation for Cascaded Multilevel Inverters

This letter presents a novel middle-level selective harmonic elimination-pulse-amplitude modulation (SHE-PAM) method to calculate switching angles and to synthesize reference voltage for variable dc voltage sources connected to multilevel inverter. Instead of conventional multivariable nonlinear transcendental SHE-pulse-width modulation (SHE-PWM) equations or polynomial equations derived from them, the proposed method works on univariate linear equations. Due to reduced computational complexities, it can be implemented in real-time for the inverter having a large number of levels. Without amplifying the magnitude of higher order harmonics, proposed method eliminates a significant number of harmonics as compared to SHE-PWM and conventional SHE-PAM methods. The total harmonic distortion (THD) of the output voltage is a function of only number of voltage levels and remains constant for a whole range of modulation index. The theoretical analysis and working characteristics of suggested method are validated by simulation and experimental studies.