PWM-control of multi-level voltage-source inverters

Many different PWM-strategies for multi-level inverters exist. Usually the modulator is chosen to match the hardware topology, although this does not always optimizes the harmonic content. The least-harmonics PWM-strategy can be used for all hardware topologies. It behaves like a three-dimensional A/D-converter. A carrier signal improves the output quality of the low-resolution A/D-converter and generates the well-known PWM-signals. Using this description, the state-space averaging procedure becomes very straight-forward and fundamental inverter behavior can be easily modeled and analyzed