Experimental Analysis of a 10kW Wide Input Voltage Range Modular Three-Phase Unity Power Factor PWM ∆-Rectifier

The three-phase three-level ∆-Rectifier is formed by a delta-connection of single-phase three-level PWM rectifier modules and does provide the full rated output power also in case of a mains phase loss. Furthermore, the system shows a low harmonic content of the mains phase currents if the modulation is with respect to the formation of a maximum zero-sequence component of the module input current ripples which circulates inside the delta connection and does not take influence on the phase current formation. This concept has been proposed based on theoretical considerations and digital simulations and is verified in this paper experimentally at the example of a 10kW laboratory prototype of the ∆-Rectifier. The influence of non-idealities of the practical realization on the current ripple formation is analyzed and a high input current quality of the system is demonstrated. Finally, a star-connection of the three-level PWM rectifier modules, i.e. the Y-Rectifier is proposed and discussed briefly. As compared to the ∆-Rectifier, the Y-Rectifier is expected to allow a further increase of the power density and the efficiency and therefore will be treated in the course of the continuation of the research.