Fig 1.
Existing H-bridge derived CGT boost Inverters: (a) structure presented in [10], (b) structure presented in [11,12], (c) structure presented.
Fig 2.
The proposed three-level common ground type inverter topology.
Fig 3.
Modes of operation of the proposed type topology: (a) mode 1, (b) mode 2, (c) mode 3, (d) mode 4 and (e) mode 5.
Table 1.
Switching sequence of the proposed boost inverter.
Fig 4.
Typical two-level output voltage waveform and gate pulses.
Fig 5.
PLECS power loss calculation: (a) total cycle average losses calculation method and (b) power loss breakdown for the different components.
Table 2.
Component comparison between the proposed topology and different existing topologies*.
Fig 6.
Extended structure of two DC sources with common ground.
Fig 7.
Simulation results: (a) inverter output voltage (vinv), (b) grid voltage (vg) and current (ig), (c) capacitor voltage (vC1), (d) capacitor voltage (vC2), (e) inductor voltage (vL), and (f) inductor current (iL).
Fig 8.
Hardware setup of the proposed topology.
Fig 9.
Experimental result: (a) vo and io at (R=50 Ω, L=50 mH), (b) vo and io at (R=50 Ω, L=50 mH) to (50 Ω+100 mH), and (c) vC1, vL, vC2, and iL for (R=50 Ω, L=50 mH).
Fig 10.
Experimental results in case of changing the input voltage from 75 V to 100 V: (a) vo and io, (b) vC1, vL, vC2, and iL and (c) output voltage and current at a modulation index of 0.5.
Fig 11.
Control scheme for grid-tied PV system with the proposed inverter.
Fig 12.
LCL filter design: (a) circuit diagram and (b) bode plot.
Table 3.
LCL Filter design value.
Fig 13.
Experimental result of vo, vg, and ig after LCL filter placement with load variation.
Fig 14.
Experimental results of closed-loop (a) at unity PF, (b) at 0.71 lagging PF, (c) at 0.71 leading PF, and (d) during change of reference current (ig, ref) from 1.5 A to 3 A.
Table 4.
Cost comparison of the proposed topology with the existing topologies for vo=200 v.
Fig 15.
Efficiency variation for various power levels.
Fig 16.
FFT analysis (a) Voltage THD (VTHD), (b) Current THD (ITHD).