In this article, an improved ripple-free input current boost-based high step-up (HSU) dc/dc converter compared to the coupled inductor (CI) ones is proposed, where the large CI is replaced by an inductor and a built-in transformer. By doing so, the energy is transferred to the output by two smaller magnetic components. Hence, a more compact and more efficient coupled magnetic component with greater flexibility in increasing its turns ratio is succeeded, allowing us to achieve higher dc voltage gains (higher than 20). Additionally, an active clamp is employed to recycle the leakage energy of the transformer, eliminating at the same time the switching losses. Therefore, by increasing the switching frequency it is feasible to build a highly efficient, reduced-size HSU converter that can be integrated along with a low maximum power point voltage photovoltaic module for dc microgrid applications. Finally, a 250-W-rated prototype has been implemented to verify the functionality of the presented converter in continuous conduction mode operation with an input voltage range of 16-20 V and an output voltage of 400 V.
This article focuses on the development of an embedded control scheme coupled to an advanced power electronic amplifier for a Travelling Wave Ultrasonic Motor (TWUM). The operation of TWUMs relies on the formation of a mechanically induced travelling wave on the motors stator. Utilizing a customized full-bridge resonant inverter and a micro-controller that monitors the error between the desired rotors angle and the actual one, a command control is derived relying on fuzzy logic principles. This command affects the ultrasonic electrical resonant frequency, the relative amplitude and the phase-difference between the provided voltages by the amplifier. The concurrent control of these critical parameters affects the performance of the TWUM and experimental studies illustrate the efficiency of the proposed scheme.
This article proposes a galvanically isolated high step-up dc–dc converter for dc microgrid applications. By the use of an inductor, a transformer, a voltage multiplier, and an active clamp, the proposed converter is able to provide very high dc voltage gains along with reduced voltage stress across the semiconductors, zero-voltage and zero-current switching for the switches and the diodes, respectively, low ripple input current, and reduced component count. The analysis of the converter in continuous conduction mode (CCM) and a comparison with other previously published isolated topologies are also presented. Finally, a prototype has been built for a power of 250 W to verify the functionality of the proposed converter in CCM operation, with an input voltage range of 20–28 V and an output voltage of 400 V.
In this paper, an improved non-isolated high step-up (HSU) converter which consists of an inductor, a built-in transformer and a voltage multiplier is presented. The energy stored in the leakage inductance is recycled with the use of an active clamp circuit. The voltage stress on both power switches is also reduced, therefore, power switches with low resistance R DS,on can be used to reduce the conduction losses. To verify the performance of the presented converter, a 250W laboratory prototype is implemented. The results validate the proper operation and the practicability of the proposed improved high step-up converter.
In this article, the impact of the coupling coefficient K on the static continuous conduction mode (CCM) dc voltage gain of the basic passive clamp coupled inductor boost converter is investigated. First, an analytical method for the extraction of the accurate static CCM dc voltage gain and all the necessary formulas for the comprehensively description of the operating behavior of the converter is presented. Next, a comparison between the previous methods from which the proposed approximate static CCM dc voltage gain formulas are derived and the proposed one takes place. Subsequently, from the analysis and the plots, it appears that the coupling coefficient creates a dependence on the operation by the output current of the converter, which is more intense as the coupling coefficient decreases. Furthermore, it is concluded that the decrease in the dc voltage gain depends not only on the coupling coefficient K, but also on the turns ratio of the coupled magnetic component. Finally, experimental results based on a 250-W laboratory prototype with four different magnetic components are presented for the evaluation of the theoretical analysis.
In this paper, the impact of the coupling coefficient K on the operation of the passive clamp coupled inductor Boost converter is investigated and an accurate dc voltage gain V N for Continues Conduction Mode (CCM) is deduced. It appears the dc voltage gain of the coupled inductor Boost converter is negatively affected, not only by the coupling coefficient, but also from the output current I o of the converter. The steady state analysis and the appropriate procedure for the dc voltage gain derivation are described. In order to examine the operation of the converter and the impact of the coupling coefficient K as well as the output current I o in CCM on the dc voltage gain V N of the converter, various curves are presented. Furthermore, experimental results based on a 250W laboratory prototype with two magnetic elements of different coupling coefficient are also presented for the evaluation of the theoretical analysis.
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