ANALYSIS OF PWM TECHNIQUES APPLIED TO HALF BRIDGE ANPC INVERTER CONNECTED TO GRID

electrical engineering

This paper presents a PV based Inverter for higher efficiency and safety driven grid connected system. Several Inverter topologies have been proposed and many of them are available commercially today. Among them, the Neutral Point Clamped (NPC) and derived topologies offers high efficiency, low leakage current and low EMI. However one main disadvantage of the NPC inverter is given by an unequal distribution of the losses in the semiconductor devices, which leads to an unequal distribution of temperature that can affect life time. By using the Active NPC topology, where the clamping diodes are replaced by bidirectional switches, the power losses distribution problem is alleviated. The modulation strategy is a key issue for losses distribution in this topology. In this paper two known strategies such as multi-carrier PWM are discussed and a new PWM strategy, namely the Adjustable Losses Distribution is proposed for better losses distribution in the Active NPC topology. A three phase grid connected system is also proposed as an extension work to this. Simulations analysis using MATLAB/SIMULINK software results help in evaluating the modulation strategies.

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