Abstract
Conventional dc-dc boost converter has limited boost capacity, and its power device suffers high voltage stress. A novel hybrid Z-source dc-dc converter featured with high step-up capability and low device voltage stress is proposed in this article. Compared with the basic structure, the proposed topology can achieve higher voltage gain under the same duty ratio, and reduce the voltage stresses on the switch and diode under the same output condition. Moreover, the duty ratio is not limited. The detailed analysis and a comparison considering the proposed and other structures are also presented, which confirms its unique advantages. To verify the proposed converter performance, a prototype circuit with 40V-60V input voltage, 400V output voltage and 200W output power is built in the laboratory. Experiment results confirm the analysis and the boost capacity of the proposed converter.
Highlights
Nowadays, with the depletion of fossil fuels, renewable energy power systems such as fuel cells have been developing rapidly [1]–[3]
A novel hybrid Z-source converter is proposed, which is capable of achieving high voltage conversion ratio and low voltage stresses on devices
We assume that DTS is the time interval of state 1, and the time interval corresponding to state 2 is DS2TS(in conduction mode (CCM), DS2 = 1−D), the time interval corresponding to state 3 is obtained by (1−D−DS2)TS
Summary
With the depletion of fossil fuels, renewable energy power systems such as fuel cells have been developing rapidly [1]–[3]. J. Zhao et al.: Transformerless High Step-Up DC-DC Converter With Low Voltage Stress for Fuel Cells the couple-inductor based quasi-Z-source converters are proposed in [19] and [20], named T-source and trans-Z-source, the proposed structure can improve the boost factor by adjusting the transformer turns ratio. In [24], the inductor in the Z-source network is replaced by the switched-inductor to improve the voltage gain, the conception of hybrid Z-source dcdc converter is first proposed in [25], whose boost factor can increase to 1/(1-4D) by replacing the inductor in the Z-source network with the quasi-Z-source networks Both of the above-mentioned converters can be used to invert and the advantages of single-stage power conversion and improved modulation factor can be retained. A novel hybrid Z-source converter is proposed, which is capable of achieving high voltage conversion ratio and low voltage stresses on devices.
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