Modified Third Harmonic Injection Modulation for Voltage Balancing in Multilevel Inverters

Inhalt:
To provide balanced energy extraction from different DC sources in a multilevel inverter, a new modulation method based on harmonic injection is proposed in this paper. The proposed method is inspired by the well-known 3rd harmonic injection method and can be implemented in any multilevel topology. Since the proposed method uses the sources sequentially and does not need to make any of the sources bypassed, it particularly suits binary multilevel inverters. The proposed method is studied with sinusoidal and triangular injected waveforms to compare their effectiveness for different output voltages. The functionality of the proposed method is approved by simulation results and the improvements in the case of balanced energy extraction is compared with the conventional method.