Isolated high step‐up switched‐boost DC/DC converter with modified control method

Abstract

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 phaseshift 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 shoot-through duty cycle, the phase shift and the transformer turns ratio) in all of the equations including the voltage gain equation, which enhances the flexibility of the converter. In this study, the steady-state analysis, design procedure of the elements, and voltage and current stress of the semiconductors are given. Then, the proposed converter and the proposed switching algorithm are compared with similar converters and modulation techniques in order to highlight their features and drawbacks. Finally, experimental results are obtained to substantiate the theoretical analysis accuracy.

Multi‐input high step‐up inverter with soft‐switching capability, applicable in photovoltaic systems

“…However, their output voltage gains are low, and switch stresses are high in higher power ranges. Except flyback converters, the proposed DC-DC converter, [23,25,27,32] have the least semiconductors in comparison with other competitors, considering [24,28,29,35,36] with the highest semiconductors count. Note that, high numbers of semiconductors are placed in the secondary side of [35] to suppress their high voltage stress in high power applications.…”

Comparative evaluation of a family of isolated Ćuk DC/DC converter with step‐up techniques

“…Table 1 shows the characteristics of the PV Canadian Solar CS5A‐200M. As can be seen, the range of PV voltage is from 33.77 to 37.4 V. For the mentioned applications; it usually requires a bus voltage [9, 10]. This implies that the power processing from PV to , requires the isolated converter to have a range of voltage gain M = 11.84–10.69.…”

“…Standard PWM isolated converters, such as flyback, forward, push–pull and current‐fed isolated boost, can achieve high voltage gain by increasing the turns ratio ( N ) of the transformer or increasing the duty cycle ( D ). Increasing these factors, there is an increase in the dispersion inductance, circuit wire inductance, voltage spike in the switch and diodes, high levels of current stress on the components, among others [9, 7, 15–17]. Consequently, the efficiency of these converters deteriorates.…”

Isolated boost converter based high step‐up topologies for PV microinverter applications

“…The transformer in use can be a high‐frequency (HF) transformer on the DC/DC side or a low‐frequency (LF) transformer on the DC–AC side. In addition to stepping up the voltage, it plays an important role in safety by providing galvanic isolation, thus eliminating leakage current, avoiding dc current injection into the grid and creating the risk of electric shock of the service personnel [13–15].…”

“…Therefore, in order to reduce voltage spikes, dissipative clampers, an addition to a soft switching circuit, can be used. So, to achieve good performance, the circuit techniques feature must be for voltage gain and also to clamp the spikes [13, 14, 16]. This increases converter complexity.…”