In this paper, a novel multilevel dc–ac inverter is proposed. The proposed multilevel inverter generates seven-level ac output voltage with the appropriate gate signals’ design. Also, the low-pass filter is used to reduce the total harmonic distortion of the sinusoidal output voltage. The switching losses and the voltage stress of power devices can be reduced in the proposed multilevel inverter. The operating principles of the proposed inverter and the voltage balancing method of input capacitors are discussed. Finally, a laboratory prototype multilevel inverter with 400-V input voltage and output 220 Vrms/2 kW is implemented. The multilevel inverter is controlled with sinusoidal pulse-width modulation (SPWM) by TMS320LF2407 digital signal processor (DSP). Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.
1. DC–AC inverter
2. Digital signal processor (DSP)
3. Maximum power point tracking (MPPT)
Fig. 1. Block diagram of renewable system.
EXPECTED SIMULATION RESULTS:
Fig. 2. Waveforms of vgs1, vab, vo, and io at 500 W.
Fig. 3. Output voltage harmonic spectrum of vab calculated by FFT.
Fig. 4. Output voltage harmonic spectrum of vo calculated by FFT
Fig. 5. Waveforms of vC2, vo, and io at 1000 W.
Fig. 6. Waveforms of vC2, vo, and io at 2000 W.
Fig. 7. Waveforms of vo and io at 400 VA.
A novel seven-level inverter was designed and implemented with DSP in this paper. The main idea of the proposed configuration is to reduce the number of power device. The reduction of power device is proved by comparing with traditional structures. Finally, a laboratory prototype of seven-level inverter with 400-V input voltage and output 220 Vrms/2kW is implemented. Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.
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