Abstract
In this paper, a new switched capacitor-based multilevel inverter structure is suggested. The proposed topology can generate seven-level output voltage waveform using ten power electronic switches and two floating capacitors. This structure has the ability to boost the input DC voltage, up to 1.5 times. Although this topology can generate an output waveform with large number of levels, it does not increase the voltage stress on the power electronic switches. There is no need for capacitor voltage balancing in this structure since the capacitors are balanced through charging and discharging modes of operation. In addition, the suggested switched capacitor inverter reduces the number of input dc power supplies and uses a single dc source such as a photovoltaic (PV) panel. Since the proposed inverter is an neutral point clamp based multilevel inverter topology, the leakage current is minimized and as a result the overall efficiency of the proposed system is increased. The operation modes and steady-state analysis of the proposed structure are explained in detail. In order to validate the feasibility of the proposed topology, some experimental results are presented in the grid connected mode of operation.
Highlights
Multilevel inverters have been a popular division of inverters for power conversion systems since it has been introduced in early 80s [1]
The multilevel inverters can be classified to three categories of, cascaded H-bridge inverters (CHB), flying capacitors (FC) and neutral point clamped inverters (NPC)
As in the previous mode, the capacitors are in parallel with the input source and are being charged to half of the input dc voltage (VC1 = VC2 = VPV 2) Considering Fig. 3 (b), it can be seen that, the switches S1, S3, S5 and S6 are in ON-state and the amplitude of generated output voltage level of the inverter is equal to 0.5 VPV
Summary
Multilevel inverters have been a popular division of inverters for power conversion systems since it has been introduced in early 80s [1]. Multilevel inverters are more efficacious than the conventional two-level inverters in generating high voltages output using lower rating elements These inverters by the way, have some drawbacks such as, the need for a greater number of power electronic switches and supply sources and complex control methods. To overcome the mentioned disadvantage of multilevel inverters to have high voltage stress on the power electronic switches, in this paper a new multilevel inverter based on switched-capacitor topology is presented. This topology generates a seven-level output voltage waveform with voltage boosting capability having lower voltage stress across the power switches. To validate the accurate performance of the proposed switched capacitor inverter, some experimental results are obtained when it is tied to grid and these results will be presented in Section VI of this paper, last but not the least is the conclusion drawn in final section
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