Application of PDM control to a multilevel AC/AC converter with self power factor correction

The application of pulse density modulation (PDM) control to a rectifier-series resonant inverter set makes it possible to implement an AC/AC converter with good performances (size and efficiency). The converter´s power factor decreases, however, when the load power decreases. We propose a PDM control strategy adapted to a multilevel AC/AC converter using several inverters to obtain mutual compensation of the harmonic distortion. The set presents a power factor close to 1 for power levels ranging between 100/G² % and 100% of the full power, where G is the number of inverters in the system.