This example shows the operation of two-level and three-level voltage source controllers.
The upper circuit represents a two-level voltage source converter represented by a six pulse IGBT bridge with inverse-parallel diodes. The voltage at the AC terminals of each phase is switched between the positive and negative potential values of the DC terminals.
The lower circuit represents a three-level voltage source converter with neutral-point clamp. This topology can synthesize three voltage levels from positive DC value, zero (neutral), and negative DC value at the AC terminal of each phase. In this neutral-point clamped configuration, the clamping diode valves are replaced by IGBT valves, to allow more control on the generated AC waveforms.