Generalised transformerless ultra step‐up DC–DC converter with reduced voltage stress on semiconductors

Abstract

A non-isolated DC-DC converter with high-voltage gain and low-voltage stress across the semiconductors is proposed in this study. The proposed converter consists of n stages of diode-capacitor-inductor (D-C-L) units at the input side and m units of voltage multiplier cells (VMCs) at the output side. Increasing of D-C-L units and VMCs, lead to high-voltage gain at low duty cycle. Lower values of duty cycle will result in increasing of converter controllability and increasing of operation region. Also by increasing of VMCs, the voltage stress across the main switch and other semiconductors is reduced severely. Decreasing of voltage stress across the main switch leads to use a switch with lower R DS-ON that reduces on state losses of the proposed converter. Besides, by decreasing of voltage stress across the diode rectifiers, diodes with less forward voltage drop can be adopted. The circuit performance will be compared with other solutions that were previously proposed for voltage step-up in the terms of voltage gain, main switch voltage stress and number of components. Finally, a 357 V-65.5 W laboratory prototype with 92% conversion efficiency is built in order to prove the satisfying operation of the proposed converter and carried mathematical analysis.

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.…”

“…The normalized voltage stress across the diodes in the proposed converter is lower than the converter D o 1, o 2, x 11, x 21 in and D o . in For M CCM < 14, the diodes D 11 and D 22 have higher normalized voltage stress compared with the proposed converter. Besides, with increasing M CCM , the normalized voltage stress across the diodes in proposed converter approaches to 0.25.…”

“…The comparison between the normalized diodes voltage stress in the proposed converter and other structures is demonstrated in Figure C. The normalized voltage stress across the diodes in the proposed converter is lower than the converter D o 1, o 2, x 11, x 21 in and D o . in For M CCM < 14, the diodes D 11 and D 22 have higher normalized voltage stress compared with the proposed converter.…”

“…Also, in addition to the existence of pulsed input current, there is a resonant circuit between leakage inductance of the coupled inductor and the parasitic capacitor of the output diode, which causes the nominal voltage of the used switch to be high. Moreover, increasing the turn ratio of coupled inductor for enhancing the voltage gain causes the input current ripple to be increased . Another group of high voltage gain DC‐DC converters is interleaved converters.…”

High Step-up DC-DC Converter by Switched Inductor and Voltage Multiplier Cell for Automotive Applications

“…Two-phase interleaved boost converter with voltage multiplier in [6], n stages of diode-capacitorinductor (D-C-L) unit in [7], combining voltage lift, voltage multiplier, clamp mode and coupled inductor stages in [8], switched capacitor combined with a classical boost converter in [9], connecting n stages of diodecapacitor-inductor (D-C-L) units on the input side and m number of units of voltage multiplier cells in [10], multistage switched-capacitor-voltage-multiplier/divider in [11], interleaved soft switched converter with voltage multiplier in [12], combining coupled inductor and a voltage multiplier module in [13] are used to achieve high gain in the converter. The main disadvantage of combining coupled inductor and a voltage multiplier module is that the duty cycle of each switch shall be not less than 50% under the interleaved control with 180° phase shift.…”