Sharif Digital Repository

In the regulated switching power supplies, the output voltage is usually sampled across a resistive voltage divider. In high voltage applications, the resistance of the voltage divider is very high in order to reduce its power loss. Therefore, these resistors are very good receivers of environment noise. This paper introduces a new control method for a high power, high voltage Flyback converter insensitive to the noise caused by ringing due to the leakage reactance of a high voltage Flyback converter. In this method, output voltage is sampled in an intentionally extended cycle to be sure that all the oscillations are damped. Therefore there is no need to additional damping circuits and... 

FPGAs are interesting choices for control of power electronics converters and electrical drives. In this paper, implementation of the control method of a reduced switch- count five-leg converter is carried out. Two PWM methods are studied. For verification of the implemented controller in a practical manner, without risking the damaging of the real system, "FPGA in the loop" experiments are performed. It is shown that using the proposed methodology, FPGA implementation and verification is fast and effective. The provided results show the high performance of the implemented controller on the FPGA, therefore the feasibility and suitability of the FPGA for this application is approved  

Robust performance controller design for duty-cycle controlled series resonant converter is proposed in this paper. The uncertainties of the converter are analyzed with load variation and power circuit components tolerances are taken into consideration. Additionally, a nominal performance H ∞ controller is designed. Closed-loop system is simulated and simulation results of robust controller are compared with H∞ nominal performance controller  

In this study, a new isolated high-gain switched-boost DC/DC converter employing two symmetrical switched-boost networks along with a modified control algorithm based on the combination of the pulse-width modulation (PWM) and phase-shift modulation is proposed. Utilising symmetrical switched-boost networks increase the voltage gain of the proposed converter, significantly. Moreover, applying the proposed switching algorithm on the proposed isolated switched-boost DC/DC converter leads to the following advantages: (i) high-voltage gain, (ii) zero voltage switching (ZVS) turn-on of two switches, (iii) ZVS turnoff of two switches and (iv) appearing three controllable parameters (the... 

In this paper, a new control strategy is proposed to improve the performance of a wind generator system composed of a three-phase PMSG and a Back-to-Back three-phase to single-phase converter. With the use of the large inductance of the synchronous generator, the control method minimizes the generator torque ripple when the system supplies a single-phase load. The problem arises from the fact that the instantaneous power of a single-phase load is pulsating at the double of the system frequency. This paper tries to minimize the effect of this pulsating power on the PMSG torque without using a large capacitor on the DC link. Simulation results show the effectiveness of the proposed method. ©... 

The state-space averaging applied to switched networks generally results in nonlinear systems. It is common to perform a small signal linearization about an operating point to obtain a linear system. When the variations in signals are large, e.g., in PFC rectifiers, the small signal approximation produces results that are susceptible to instability problems. In this paper a class of piecewise linear models merged by fuzzy system are introduced for PWM converters. The necessary and sufficient and conditions for stability of fuzzy models using fuzzy state-feedback controllers are given. The results obtained are illustrated with a buck-boost converter. The simulation and experimental results... 

This paper proposes a new variable frequency zero voltage switching (ZVS) control method for boost converter operating in boundary conduction mode (BCM). The intended method keeps the converter in BCM despide of the load and input voltage variations. This is done by changing switching frequency in a certain specified range. The proposed method can guarantee circuit performance in BCM via zero-crossing detection of the inductor current and changing the switching frequency. In addition, with a slight modification in control structure, it is possible to achieve a fully ZVS in all cases. This converter control is carried out in analog form without using microprocessors which, compared with the... 

This paper presents a decentralized control strategy for the autonomous (islanded) operation of parallel connection of two distributed generation (DG) units. The DG units are electronically interfaced to the host grid at the same point of common coupling (PCC), where the local load is also supplied. In the grid-connected mode, the voltage-sourced converter (VSC) of each DG unit controls the exchange of real and reactive power components with the host grid, based on the conventional dq-current control strategy. In the islanded mode, one of the DG units provides voltage and frequency control for the island, and the other DG unit continues to operate with the pre-islanding dq-current control...