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.
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