Multilevel modular resonant switched-capacitor converter can achieve either zero-current switching (ZCS) or zero-voltage switching (ZVS) by utilizing different converter control strategies. This paper presents a comprehensive way to compare the root mean square (RMS) value of current flowing through switching devices in both ZCS operation and ZVS operation. The study shows that with appropriate converter parameter design, the ZVS operation allows the RMS value of switch current at most 10% lower than that in ZCS operation. Therefore, the converter operating at ZVS mode has the potential to achieve higher efficiency comparing to the converter that operates at ZCS mode due to less semiconductor conduction loss. Furthermore, the ZVS operation can reduce the power loss due to MOSFET output capacitance. A 6x converter with 54V input voltage, 9V output voltage and 600W power rating is used as an example to show the detailed design procedure. Simulation results are provided to verify the theoretical analysis. Also, a 600W lab prototype that has 6 to 1 voltage conversion ratio has been built to verify the theoretical analysis.
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Resonant Multilevel Modular Boost Inverters for Single-Phase Transformerless Photovoltaic Systems
This paper presents two novel single-phase resonant multilevel modular boost inverters based on resonant switched capacitor cells and a partial power processed voltage regulator. Compared with other multilevel boost inverters applied in PV systems, one remarkable advantage of the proposed topologies is that the bulky AC filtering inductor is replaced by a smaller-size one in the partial power processed buck converter. Constant duty cycle PWM method is attractive for the multilevel inverter controller design. GaN Enhancement Mode Power Transistors help both the modular resonant switched capacitor cells and the full-bridge unfolder be realized in a small size with high power density. The clamp capacitors in the resonant switched capacitor cells effectively alleviate the switch voltage spikes. These two inverter topologies are analyzed and simulated in PLECS. Simulation results verify the validity of boost inverter function. Stress analysis shows that the inverter has relatively small total normalized switch conduction power stress and total normalized switch stress ratio. Relative total semiconductor chip area comparison results reflect that the proposed topology achieves more efficient semiconductor utilization compared with typical non-resonant multilevel modular switched capacitor boost inverters. Test results indicate that the proposed topology can be used for single-phase non-isolated PV boost inverter applications with small ground leakage current, high voltage conversion ratio, small volume and potential high efficiency.
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- Award ID(s):
- 1810428
- NSF-PAR ID:
- 10109856
- Date Published:
- Journal Name:
- 2018 IEEE Energy Conversion Congress and Exposition (ECCE)
- Page Range / eLocation ID:
- 2555 to 2562
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ECCE.2018.8558049
