In this paper a XILINX FPGA based multilevel PWM single-phase inverter was constructed by adding a bi-directional switchs to the conventional bridge topology. The inverter can produce three and five different output voltage levels across the load. XILINX FPGA is a programmable logic device developed by XILINX which is considered as an efficient hardware for rapid prototyping. It is used as a PWM generator to apply the appropriate signals to inverter switches. In addition to XILINX FPGA, Matlab/Simulink software was used for simulation and verification of the proposed circuit before implementation, Simulation and experimental results show that both are in close agreement.
Fig.1 The proposed circuit of the multilevel PWM single phase inverter
EXPECTED SIMULATION AND EXPERIMENTAL RESULTS:
Fig.2.Multilevel PWM single phase simulation results using XILINX FPGA at Ma = 0.8.
Fig.3 Multilevel PWM single phase simulation results using XILINX FPGA at Ma = 0.4.
Fig.4 Multilevel single-phase PWM at Ma=0.8 Simulated, (b) Experimental
Fig.5 Multilevel single-phase PWM at Ma=0.4 (a) Simulated, (b) Experimental
Fig.6.Unfiltered output voltage five levels at Ma=0.8
Fig.7 Unfiltered output voltage five levels at Ma=0.4
Fig.8. Ac voltage waveform before and after the filter in the proposed multilevel PWM inverter at modulationindexes (a) 0.8 and (b) 0.4.
Fig.9.Ac voltage and current output waveforms for resistive load.
Fig.10 Ac voltage and current output waveforms for (resistive- inductive) load.
Fig.11 Ac voltage output harmonic spectral after filter
The switching patterns adopted are applied at the six inverter switches to generate five or three output voltage levels at different modulation indexes. XILINX FPGA enables to make easy, fast and flexible design and implementation. The experimental and simulated results are show satisfactory results in term of total harmonic distortion and output voltage and current waveform shapes.
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