New multilevel carrier-based pulse width modulation techniques applied to a diode-clamped converter for use as a universal power conditioner

This work presents the development of a control scheme for a multilevel diode-clamped converter connected in a series-parallel fashion to the electrical system such that it can compensate for deviations in utility voltage and act as a harmonic and/or reactive current source for a load. Novel carrier-based multilevel pulse width modulation techniques are developed to maximize and/or balance the switch utilization of the two back-to-back diode-clamped inverters that constitute the universal power conditioner. Methods for maximizing switch usage during low amplitude modulation index operating conditions are also identified.; The effects of different compensation objectives of a universal power conditioner on the ratings and level usage in the multilevel converter are also discussed. A procedure for sizing the multilevel inverter based on its specified functions is outlined. A real-time control scheme is developed for a complete universal multilevel power conditioner system.; Experimental verification of the real-time control scheme is implemented with a six-level hardware prototype for different power conditioning objectives: voltage regulation, voltage balancing, current harmonic compensation, and reactive power compensation.