Sharif Digital Repository

This paper proposes a straightforward control method for voltage control of a three-phase transformer-based inverter in uninterruptible power supplies or distributed generation systems. The approach offers a dual-loop design consisting inner current control loop and outer voltage loop. Sliding mode current controller provides desired bandwidth for voltage controller which consists of a state feedback term for stabilization and resonant term for harmonic damping. The proposed scheme provides fast dynamic response and low total harmonic distortion even for high power inverters with the limitations of switching frequency and LC filter components. Experimental studies for 2KVA linear and... 

This article contributes a torque control based on hysteresis for Brushless Doubly Fed Induction Machine (BDFM) through machine analysis and extracting the d-q parameters that influence on the machine behavior. In this research, a Direct Torque Control (DTC) based on stator flux-oriented vectors and machine's relation and equations with voltage and current of both stators have been introduced. The control for the BDFM is implemented by a voltage source inverter connected to the second stator as a torque controller that uses the classical field-oriented control method widely used in voltage sector selection. Finally BDFM as a closed loop model with DTC is simulated and evaluated  

This article contributes a torque control based on hysteresis for Brushless Doubly Fed Induction Machine (BDFM) through machine analysis and extracting the d-q parameters that influence on the machine behavior. In this research, a Direct Torque Control (DTC) based on stator flux-oriented vectors and machine's relation and equations with voltage and current of both stators have been introduced. The control for the BDFM is implemented by a voltage source inverter connected to the second stator as a torque controller that uses the classical field-oriented control method widely used in voltage sector selection. Finally BDFM as closed loop model with DTC is simulated and evaluated  

In this paper, the whale optimization algorithm is proposed for harmonics elimination in a cascaded multilevel inverter. In selective harmonic elimination pulse width modulation, the selected low-order harmonics are eliminated by solving nonlinear equations, while the fundamental of output waveform is adjusted to a desired value. In this paper, whale optimization algorithm is applied to a 7-level cascaded H-bridge inverter to solve the equations. Also, it was validated by experimental results, since this algorithm has an ability to search in entire solution space, the probability of catching a global best solution is very high. This method has higher accuracy and probability of convergence... 

In this paper, the whale optimization algorithm is proposed for harmonics elimination in a cascaded multilevel inverter. In selective harmonic elimination pulse width modulation, the selected low-order harmonics are eliminated by solving nonlinear equations, while the fundamental of output waveform is adjusted to a desired value. In this paper, whale optimization algorithm is applied to a 7-level cascaded H-bridge inverter to solve the equations. Also, it was validated by experimental results, since this algorithm has an ability to search in entire solution space, the probability of catching a global best solution is very high. This method has higher accuracy and probability of convergence... 

This paper investigates several current control methods for load balancing and power factor correction based on distribution Static Compensator (STATCOM). Two different configurations are considered for STATCOM; a three leg inverter, and three single phase inverters. It is assumed that the STATCOM is associated with a load that is remote from the supply. After a brief introduction, control structure based on PWM method and simulation results using PSCAD are presented. Next, the same system is simulated using hystersis control method. Both methods employ the instantaneous symmetrical components theory for load balancing and power factor correction. At the end, a comparison between two methods... 

Leakage current is originated from common-mode voltage (CMV) time variations in a grid-connected photovoltaic (PV) system and results in several deficiencies. In this paper, a new method is proposed for CMV reduction in a three-phase voltage source inverter (VSI) system. The proposed method is based on space vector modulation and it utilizes only odd and zero vectors. By using the proposed method, the number of fluctuations of the CMV waveform per switching cycle is reduced; therefore, the amount of high-frequency harmonics of CMV is decreased. In addition, because of applying both active and zero vectors by the proposed method, the total harmonic distortion becomes less than most of other... 

Voltage unbalance and short circuits in distribution networks adversely affect the performance of grid-tied voltage source inverters (VSIs). Consequently, the dc-link voltage ripple may significantly increase leading to operation of VSI in an unsatisfactory manner. Conventionally in order to maintain the negative sequence current under unbalanced conditions, low-pass/trap filter in the current control loop are required which significantly reduce the controller bandwidth. In order to minimize the dc-link voltage ripple without impairing the controller bandwidth, this paper investigates the design and performance of Proportional-Integral-Resonant (PIR) controller in improving the performance... 

This paper describes a novel Direct Torque Control (DTC) method for adjustable speed Doubly-Fed Induction Machine (DFIM) drives which is supplied by a two-level Space Vector Modulation (SVM) voltage source inverter (DTC-SVM) in the rotor circuit. The inverter reference voltage vector is obtained by using input-output feedback linearization control and a DFIM model in the stator a-b axes reference frame with stator currents and rotor fluxes as state variables. Moreover, to make this nonlinear controller stable and robust to most varying electrical parameter uncertainties, a two layer recurrent Artificial Neural Network (ANN) is used to estimate a certain function which shows the machine... 

This paper presents a powerful application of genetic algorithm (GA) for the minimization of the total harmonic current distortion (THCD) in high-power induction motors fed by voltage source inverters, based on an approximate harmonic model. That is, having defined a desired fundamental output voltage, optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for the two cases of three and five switching instants in the first quarter period of pulse width modulation (PWM) waveform are presented. Presence of harmonics in the stator excitation leads to a pulsing-torque component. Considering the fact that...