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Three Electrolytic Capacitor Elimination Schemes in Quasi-Z-Source Converter: Theory and Experimental Verification
  • Weillong Hong
Weillong Hong
Guangdong University of Technology School of Automation
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Electrolytic capacitors (ECs) are important components in power converters. However, their lifespan is much shorter than other components, and their sizes increase greatly with larger capacitance. As a result, ECs limit power converters’ lifespans and contribute to larger sizes. This study proposes three schemes of eliminating ECs in the quasi-Z-source DC-DC converter (QZSC). In scheme A, a non-electrolytic capacitor quasi-Z-source DC-DC converter (NEC-A-QZSC) is realized to minimize the converter size and with low-cost design, but has high voltage ripples. The schemes B and C are then proposed to add a low-pass filter to different voltage ports on QZSC to reduce output voltage ripples with the same boost capability, hence achieving a better performance and stability. For proof of concept, theoretical analysis with small-signal models, simulation studies and prototype experiments of the proposed NEC-QZSC converter are presented. Simulation and experimental results well agree with the theoretical analysis. The NEC-QZSCs proposed in the schemes B and C achieve small converter sizes while improving the voltage conversion performance, realizing better nonlinear response, and having high economic advantages.