Modified W-type configuration for a single-phase reduced parts count 81-level inverter

Abstract

The technology of modern power systems is revolutionizing as renewable energy sources are being integrated with electric power grids. In the form of inverters, power electronic converters are becoming an integral part of power systems due to their massive demand for grid integration of photovoltaic (PV) systems. Existing multilevel inverter topologies either require an output filter to get a sinusoidal voltage or generate a higher number of output voltage levels at the expense of many hardware resources. This paper presents a new single-phase 81-level inverter configuration with the name given as ‘Modified W-Type Multilevel Inverter’. The proposed inverter configuration uses only eighteen power switches and four DC voltage sources to generate an 81-level output voltage approaching a sinusoidal waveform without an output filter. The general design equations are developed to calculate the number of switches, the number of voltage levels, and the number of DC sources for the proposed configuration. Loss and efficiency analysis is carried out that verifies a good practical efficiency of the proposed inverter configuration during the dynamic operation. A comparative analysis with the existing MLI topologies is also carried out that validates the effectiveness and novelty in reducing parts count and higher number of voltage levels. The proposed topology offers 1.04% total harmonic distortion of the output voltage which is within the benchmarks specified for grid integration without any filter requirements. The proposed inverter configuration is simulated in MATLAB/Simulink, and the results are validated by the design and development of a hardware prototype.

A Modified Multi-Level Inverter System for Grid-Tied DES Applications

“…The waveform results show that any combination of active and reactive power flow to the grid has approximately no impact on the waveshape of the MWMLI voltage. Since the THD of the MWMLI, as reported in [23], is 1.04%, there is no need for an output filter for the interconnection with the electric grid. The efficiency graph reveals that the MWMLI topology has an efficiency above 90% at unity power factor, whereas its efficiency for 0.85 lagging power factor loads is slightly less than 90%.…”

“…The maximum blocking voltage (MBV), also denoted as the total standing voltage in [23], is the sum of the reverse blocking voltage of individual switching devices in the MWMLI topology. The MBV is an important parameter in the selection of suitable switches for a given power and voltage rating of an inverter.…”

“…The efficiency of the grid-connected MWMLI system for unity power factor loads is above 90%, whereas the efficiency for lagging power factor loads is The proposed grid-connected system is analyzed for efficiency computation at different loading conditions. Based on the loss and efficiency analysis equations presented in [23], the losses of the MWMLI are computed to determine the efficiency of the gridconnected operation. The efficiency of the grid-connected MWMLI system for unity power factor loads is above 90%, whereas the efficiency for lagging power factor loads is The proposed grid-connected system is analyzed for efficiency computation at different loading conditions.…”

“…The efficiency of the grid-connected MWMLI system for unity power factor loads is above 90%, whereas the efficiency for lagging power factor loads is The proposed grid-connected system is analyzed for efficiency computation at different loading conditions. Based on the loss and efficiency analysis equations presented in [23], the losses of the MWMLI are computed to determine the efficiency of the grid-connected operation. The efficiency of the grid-connected MWMLI system for unity power factor loads is above 90%, whereas the efficiency for lagging power factor loads is slightly less than 90%.…”

“…This paper proposes a single-phase grid-connected 81-level inverter with the modified W-type multilevel inverter (MWMLI) topology previously presented in [23] for grid integration. The MWMLI configuration uses four input DC power sources, eighteen unidirectional switches, and eight isolated gate drivers to obtain an 81-level output voltage using an H-bridge.…”