High step‐up dc/dc converter using switch‐capacitor techniques and lower losses for renewable energy applications

Abstract

In this study, a non-isolated high step-up direct current (dc)/dc converter with a diode-capacitor is presented. To obtain high-voltage gain, the voltage multiplier units (diode-capacitor) can be extended to n stages which are used between the phases in up section and down section of the proposed converter. By increasing the number of voltage multiplier units, the nominal value of the components decreases. Therefore, the maximum voltage value of diodes and power switches compared with the output voltage is decreased and finally, the normalised voltage of these devices will decrease, significantly. In addition, the power level of the proposed converter can be increased for different values of duty cycles and voltage multiplier units and also leads to high efficiency. To illustrate the advantages of the proposed converter, comparison results with other topologies are provided. The principle of operation at n = 1, 2 stages, both theoretical analysis and experimental results of two prototypes in 100 and 250 W with operating at 40 kHz are provided. 2 Proposed converter and principle of operation The power circuit of the proposed structure is shown in Fig. 1. The proposed converter is a non-isolated four-phase high step-up dc/dc converter which consists of the input dc voltage source, four power IET Power Electron.

High step‐up DC‐DC converter with reduced voltage stress on devices

“…For better understanding, the results of the comparison are plotted for n = 2 and m = 1 of converters of Table . As shown in Figure A, for all values of the duty cycle, the converters in previous studies have higher voltage gain compared with the proposed converter. For D > 0.2, the converter has higher voltage gain in comparison with the proposed converter.…”

“…In Figure B, comparison of normalized switch voltage stress of the proposed converter and other topologies is shown. As can be seen, the converter has the lowest normalized switches voltage stress compared with the others. The normalized switch voltage stress of the other converters in literature is higher than the proposed converter.…”

“…3. The value of the critical conduction parameter K e,c can be evaluated from Equation 30, and it is given by…”

Interleaved High Step-Up Converter With Coupled Inductor and Voltage Multiplier for Renewable Energy System

“…According to mode II and mode VI, the expression of the output voltage can be obtained as in the following equations: (10) Therefore, the voltage gain is attained as follow (11) Fig. 5 shows the relationship between voltage gain, the coupling coefficient, and duty cycle.…”

“…In fact, an extremely duty cycle will lead to the reverse recovery of output diode, electro magnetic interference(EMI),large current ripple and low efficiency. Switched-capacitor technology is applied in some converters to achieve high conversion ratio [10]- [13]. However, the switched-capacitor circuit often requires lots of active switches, and the active switches will also suffer instantaneous large current, increasing conduction loss.…”