This paper proposes a novel isolated high step-up converter for sustainable energy applications. Through an adjustable voltage-multiplier module, the proposed converter achieves a high step-up gain without utilizing either a large duty ratio or a high turns ratio.
The voltage-multiplier modules are composed of coupled inductors and switched capacitors. Due to the passive lossless clamped performance, leakage energy is recycled, which alleviates a large voltage spike across the main switches and improves efficiency.
Thus, power switches with low levels of voltage stress can be adopted for reducing conduction losses. In addition, the isolated topology of the proposed converter satisfies electrical-isolation and safety regulations.
The proposed converter also possesses continuous and smooth input current, which decreases the conduction losses, lengthens life time of the input source, and constrains conducted electromagnetic-interference problems.
Finally, a prototype circuit with 40 V input voltage, 380 V output, and 500 W maximum output power is operated to verify its performance. The maximum efficiency is 94.71 % at 200 W, and the full-load efficiency is 90.67 % at 500 W.
- High Step-Up
- Voltage-Multiplier Module
- Isolated Converter
Fig. 1. Block diagram of a typically sustainable energy system.
Fig. 2. Proposed isolated high step-up converter for sustainable e
(a) Measured waveforms of vDS1, vDS2, iLin and iLk
(b) Measured waveforms of vDc, vDr and iDr
(C)Measured waveforms of vDf1, vDf2, iDf1 and iDf2
(d) Measured waveforms of vDo, iDo and Vo
Fig.3 The experimental waveforms measured at a full load of 500 W.
This paper has presented the theoretical analysis of steady-state and experimental results for the proposed converter, which successfully demonstrates its performance. A prototype isolated converter has been successfully implemented with a high step-up ratio and high efficiency for sustainable energy applications.
The presented circuit topology inherently makes the input current continuous and smooth, which decreases the conduction losses, lengthens the life time of the input source, and constrains conducted EMI problems. In addition, the lossless passive clamp function recycles the leakage energy and constrains/lowers the voltage spikes across the power switches.
Meanwhile, the voltage stress on the power switch is restricted and is much lower than the output voltage Vo, which is 380 V. Furthermore, the full-load efficiency is 90.67% at Po =500 W, and the maximum efficiency is 94.71% at Po = 200 W. Thus, the proposed converter is suitable for renewable-energy applications that need high step-up conversion and have electrical-isolation requirements.
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