Search

This article proposes a controller for dc–dc converters to achieve fast load-transient responses. The controller is developed for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) of operation. The main idea is developed for buck converters, but it is shown that the proposed controller can be applied to other topologies, such as the noninverting buck–boost converter. The controller derivation, analysis, and experimental verifications are provided in both CCM and DCM, and its performance is compared with other methods. The main advantage of the proposed controller is that it minimizes the recovery times associated with load-transient responses in dc–dc converters while maintaining component sizes and other system parameters within the acceptable range. The proposed controller can be used to minimize load transients in electronic portable devices and electric vehicle charging. [ABSTRACT FROM AUTHOR]

Power outage, also known as blackout, is inevitable despite all operator efforts. Accordingly, an exhaustive restoration plan should be prepared beforehand. Considering all the static and dynamic constraints of power systems during system restoration leads to a comprehensive restoration plan which, in turn, results in the alleviation of its negative impacts. One of the challenges in developing the restoration plan is switching transients in energizing no-load or lightly loaded transformers and its effect on other power system equipment, arresters in particular. In this article, a restoration plan in the Iran power system is studied, focusing on switching transients. First, the flux–current curve is plotted applying three different methods, utilizing the real standard test data of a transformer; then, the thermal effect of switching transients on an arrester existing in Iran electric grid is studied. Results yielded that the arrester may be damaged in the absence of preventive actions; therefore, a proper countermeasure which takes into consideration the frequency and voltage constraints, as well as the asynchronous operation of circuit breaker contacts, is proposed. The simulation shows that the proposed countermeasure guarantees arrester safety. [ABSTRACT FROM AUTHOR]

A fast and robust fixed switching frequency peak current controller for DC–AC converters is presented. The proposed method tends to mimic the switching behavior of pulse width modulation (PWM) techniques, so it features all the advantages of peak current controllers (such as simplicity, fast transient, and optimum dynamic response), with the superiority of fixed switching frequency and harmonic free output. The proposed method is a generalized approach that can be applied to different PWM schemes. The method is specifically elaborated for single-phase distributed generation applications, using various inverter topologies and mimicking different PWM schemes. Moreover, adaptive bands are proposed to provide active damping for the controller, to extend use of the proposed method for inverters with LCL output filters. Feasibility and performance of the controller is shown by means of simulations and experiments. [ABSTRACT FROM AUTHOR]