ABSTRACT:
1. High-frequency ac
(HFAC) microgrids
2. Quasi-resonant
switched-capacitor (QRSC)
3. Multilevel inverter
(MLI)
4. Self-voltage
balancing
Fig.1.Circuir of the proposed QRSC MLI when outputting 2n+1 levels
Fig. 2. Simulation waveforms of the output voltages and currents under different load-types. (a) Vin = 100 V, fo = 500 Hz, ZL = 24 . (b) Vin = 100 V, fo = 500 Hz, ZL = 7.4+j11.3 (|ZL| = 13.5
Fig. 3. (a) Simulation waveforms of the voltages on capacitors C1~C4. (b) Simulation frequency spectrum of the staircase output.
Fig. 4. Simulation waveforms of the capacitors’ charging currents. (a) With quasi-resonant inductor. (b) Without quasi-resonant inductor.
CONCLUSION:
To make up for the deficiency that existing SC MLIs are inappropriate for the preferred series-connected input occasions like mode 2 in Fig. 1, a novel SC MLI is proposed in this paper with different structure and operational mechanism from the traditional ones, and to suppress the current spikes caused by the capacitors’ instant charging from the input source, a quasi-resonant inductor is embedded into the capacitors’ charging loop, reducing the EMI and longing the capacitors’ lifetimes. Meanwhile, the proposed QRSC MLI combines the advantages of the traditional SC MLI, such as self-voltage balancing under FFM and smaller voltage ripples for capacitors when used as HF power conversion, thus, especially adapted for HFAC microgrids.
The
circuit configuration and the power loss analysis of the proposed QRSC MLI have
been presented in this paper, as well as the comparisons with typical SC
topologies. Lastly, a nine-level prototype is designed and implemented in both
simulation and experiment. The results have validated the superior performances
of the proposed topology.
REFERENCES:
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