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The purpose of this paper is to propose a method of optimal control of current commutation of switched reluctance motor drive.

The problem of optimal current commutation control is solved by off‐line selection of switching‐on and switching‐off angles. Selection of optimal values of angles is provided on computer model of the drive with help of particle swarm optimisation method. The optimal angle values are detected as functions of phase current and rotor speed. These calculated optimal values are stored in microcomputer control system memory in form of two‐input look‐up tables. The results are validated on laboratory set up.

Three different criteria of optimal control, which are taken into account: the maximum electromagnetic torque for given reference current, the maximum ratio of electromagnetic torque to root mean square value of phase current and the minimum electromagnetic torque ripples, gave a good results validated by simulation and experimental investigations.

A simple control method is proposed to optimise switched reluctance motors drive behaviour. Such an approach can be recommended for practical implementations.

The off‐line optimisation of switching angles, which is realised on computer model, is sufficient to obtain a good control effect.

Optimal switching angles are investigated for minimizing accumulated numerical errors when the dual‐Euler method is used in the simulation of angular rotation.

First, round‐off errors are theoretically modeled with a simplified mathematical representation of rotation. Round‐off errors take critical roles in the vicinity of indefinite points because they cause major numerical inaccuracy in very large numerical values represented with limited binary numbers. Optimal switching angles of (±π/4, ±3π/4) are derived and numerically examined. With a more practical and severe rotational model, the switching angles are numerically tested.

In conclusion, switching pitch angles of (±π/4, ±3π/4) yield near minimum numerical errors in angular parameters of pitch, yaw, and roll if truncation errors are not dominant by using high‐order integration algorithms and small step sizes. It is also noticed that accumulated numerical errors increase dramatically if pitch and roll angles are switched beyond the optimal angles with a little margin.

Optimal switching angles in the dual‐Euler method are identified based on the truncation error analysis. The mechanism of accumulated numerical errors in the dual‐Euler method, which depends on switching angles, is also revealed.

The purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output voltage THD.

In cascaded multi‐level inverters, it is usually assumed that the DC sources have the same constant voltage and output harmonics minimization is accomplished by applying proper switching angles. Employing different DC voltages with proper ratios can result in further reduction of the harmonics. After formulation of the system, i.e. describing the inverter's output voltage components in terms of the switching angles and unequal DC source voltages, a rule is applied to obtain the step heights of the staircase output waveform (DC source voltages), so that the output waveform becomes as close to the required fundamental sine wave as possible. Substituting the obtained DC source voltages into the harmonics elimination equations results in a set of equations, which are functions of switching angles only. Solving these equations leads to proper switching angles, which, regardless of the fundamental component's value, provide the specified harmonic conditions. The output voltage is then controlled by DC sources voltage regulation.

Computer simulations show that employing the proposed concept results in substantial improvement in the harmonic minimization, as well as, extending the operating range of the inverter, compared to the conventional methods with equal DC source voltage multi‐level inverters.

The proposed concept according to which the ratio of the DC source voltages are determined, is original.

This paper aims to examine the design and control of a symmetric multilevel inverter (MLI) using grey wolf optimization and differential evolution algorithms.

The optimal modulation index along with the switching angles are calculated for an 11 level inverter. Harmonics are used to estimate the quality of output voltage and measuring the improvement of the power quality.

The simulation is carried out in MATLAB/Simulink for 11 levels of symmetric MLI and compared with the conventional inverter design. A solar photovoltaic array-based experimental setup is considered to provide the input for symmetric MLI. Field Programmable Gate Array (FPGA) based controller is used to provide the switching pulses for the inverter switches.

Attempted to develop a system with different optimization techniques.

The purpose of this paper is to present a simple and effective method to search the optimal turn-on and turn-off angles on-line for the control of the switched reluctance motor (SRM). The optimal turn-on and turn-off angles are defined as the ones that can meet torque production requirements with minimum copper loss.

The optimal turn-on and turn-off angles are first defined based on the analysis of the SRM losses and torque production principles. Then the algorithm for optimal angles searching is developed, and the searching parameters are determined through analytical computation. The optimal angles are approached on-line with iterative process. Simulation and experiments are finally performed to verify the proposed method.

The presented method can meet torque production requirements while copper loss is minimized. The optimal turn-on and turn-off angles are generally approached within five phase cycles for most of the SRM operation modes. Furthermore, the SRM drive system using the presented method exhibits good dynamics during starting and sudden load operations.

The presented method is simple, and implementation of it is easy. It is an eligible candidate for industrial applications where energy conversion efficiency is crucial.

The optimal turn-off angle definition that considers both torque production and copper loss minimization is proposed. The turn-on and turn-off angles are searched independently on-line with little SRM geometrical information. The searching steps are derived through analytical computation and qualitative analysis so that both the searching speed and algorithm convergence are balanced.

In this paper, a new application of the Selected Harmonic Elimination Pulse Width Modulation (SHEPWM) technique used in the cascade multilevel inverter topology which is formed by series connections of one‐phase bridge type inverters (H‐bridge) is introduced. The advantage of the SHEPWM technique is its ability to operate in low switching frequency that makes it suitable for high power applications.

First, the switching angles are calculated using constrained optimization technique. By using these switching angles, the fundamental harmonic can be controlled and the selected harmonics can be eliminated. Then, using these calculated switching angles, a set of equation is formed which calculate the switching angles with respect to the modulation index. The switching angles at any modulation index can be easily obtained by solving the equation set. In this study, this equation set has been solved online using dSPACE DS1103 controller board. Using this technique, three‐phase voltages have been obtained from a five‐level cascade inverter. These voltages are applied to an induction motor.

The simulation results are verified by the experimental results. The results show that selected harmonics can be eliminated and an ac voltage with variable amplitude and frequency can be obtained using the proposed technique.

This paper presents a new application of the (SHEPWM) technique for multilevel inverters.

This paper proposes an improved algorithm to compute selective harmonics elimination pulse width modulation (SHEPWM) angles, based on the Newton‐Raphson (NR) iteration for cascaded multilevel inverter (CMI).

Newton Raphson (NR) is a very popular numerical method for transcendental equations that lack analytical solutions. It has been successfully used to compute the angles for selective harmonics elimination pulse width modulation (SHEPWM) schemes. Despite its effectiveness, NR has not been used for SHEPWM with cascaded multilevel inverter (CMI) structure with equal and non‐equal DC voltage sources. It is known that for CMI, inappropriate selection of initial angles causes long‐iteration time and possibly non‐convergence takes place. The computational difficulty is compounded by the fact that the SHEPWM switching angles need to be correctly sequenced, i.e. each angle must be assigned to the correct output voltage level of the CMI. In this work, an attempt is made to reduce the iteration time and to resolve the non‐convergence problem. The main idea is to relax the switching angle constraint by placing the switching angle sequencing outside the main loop of NR iteration. This allows for the program to run more freely and able to generate more possible solutions for the switching angles. Then these angles are selected to fulfill the requirements of multilevel sequencing. The performance of the proposed technique will be compared with the standard NR for CMI with equal and non‐equal DC sources. The latter case is quite common for CMI with renewable energy applications because the sources normally have different voltage levels.

Using MATLAB simulation, it will be shown that using this scheme, accurate SHEPWM angles can be achieved for a wide range of fundamental components. Furthermore, significant reduction in iteration time to compute the SHEPWM switching angles is achieved.

This paper proposes an improved algorithm to compute SHEPWM angles based on NR iteration.

The purpose of this paper is to propose an on‐line algorithm to calculate the switching angles of the harmonics elimination pulse‐width modulation (HEPWM) scheme that can be suitably implemented using a simple microprocessor/microcontroller. It is to be used for three‐phase voltage source inverter (VSI).

Approximate equations for the HEPWM angles are obtained by performing quadratic curve fittings of the trajectories of the exact HEPWM angles. This paper aims to obtain approximate equation that can be programmed on‐line using microprocessor/microcontroller.

The main feature of the algorithm is simplicity, whereby only addition and multiplications functions are required. It shall be shown that the proposed scheme allows for an efficient real‐time computation with acceptable error margins. The workability of the algorithm is validated with hardware results.

Since the algorithm allows for on‐line changes of the number of harmonics to be eliminated and an independent control of the fundamental component of the VSI, it is very suitable for motor drive applications.

Owing to the transcendental nature of the HEPWM equations, the exact solution for the switching angles requires vast computing power. The quadratic curve fitting method proposed in this paper simplifies the angle calculations to only multiplication and addition functions. It can be easily implemented using a simple microprocessor/microcontroller.

This study aims to present the experimental results for neural network (NN) based harmonic elimination technique for single-phase inverters.

Switching angles applied to power switches are determined using the NN technique based on the harmonics to be suppressed. Thus, besides controlling the output voltage, NN controller provides elimination of predetermined harmonics from output signal of single-phase inverter. Simulation and experimental results for the elimination of 15 and 20 low-order harmonics are presented. The switching angle values calculated by a NN , fuzzy logic and Newton–Raphson are compared for elimination of first 10 harmonics.

This paper provides the harmonic spectra showing that first 15 and 20 harmonics are suppressed from output signal. The NN is proved to give closest results to angle values calculated by Newton–Raphson’s numerical solution method.

The value of this paper is to verify the simulation results with the experimental result for the elimination of 15 and 20 low-order harmonics. Both the simulation and the experimental results demonstrate the success of the NN based selected harmonic elimination.

The purpose of this study is to present a new methodology of selective harmonics elimination (SHE) technique suitable for single-phase photovoltaic (PV) tied pulse width modulated (PWM) inverter.

In the proposed SHE, switching angles for inverter control are determined offline through numerical techniques and stored in a microcontroller memory as a function of modulation index (md). The methodology uses the solution that leads to a lower change of switching angles from the previous modulation index (md) for storing in the processor memory for multiple solutions. This leads to a smaller number of sections when a piecewise mixed model is considered for storing the entire switching angle curve for the online inverter control. The proposed idea is simulated and experimentally validated on a laboratory prototype of PV (500 W) grid-tied PWM inverter. The control environment is then realized in NI c-RIO 9082.

This proposed technique is suitable for limiting voltage total harmonics distortion (THD) in single-phase PV tied grid connected voltage source inverter (VSI). Moreover, it is found that filter (L-C) size requirement is less.

The proposed SHE with piecewise mixed model technique effectively reduces voltage THD with less filter size (L-C) in a single-phase PV-tied system.