IPD and APOD Modulation Schemes for Multilevel Diode Clamped

Neutral point clamped inverter with the in-phase disposition (IPD) and alternative phase opposite disposition (APOD) PWM scheme.

The 3-level neutral point clamped inverter is simulated with level-shifted pulse width modulation (PWM) in-phase disposition (IPD) and alternative phase opposite disposition (APOD) and their harmonics compared. A simulation comparison of 3-level and 4-level NPC inverter proves the 4-level inverter has better harmonics. However, the 4-level inverter in reality has many drawbacks. Therefore, the 3-level topology is the preferred topology in application.