High current harmonic control strategy for A T-NPC interleaved AC Active Electronic Power Loads

The project of controllers for an AC Active Electronic Power Load capable of emulating non-linear currents brings some challenges, like the necessity of high performance controllers and damping of the resonant coupling filter with the Equipment Under Test. On the other hand, high dynamic controllers require high switching frequencies in a Pulse Width Modulation, but power semiconductors with high currents and high frequency capabilities are difficult to obtain. In this paper, it is proposed a control strategy for the T-Type Neutral Point Clamped Interleaved Converter in a single-phase active electronic load application. State observer and state feedback in addition with classic controller are used for high current harmonics tracking. The control oriented modeling and the control system design are presented. Simulation and experimental results obtained from a 10 kW single-phase three-level converter prototype illustrate and demonstrate the feasibility of the proposed control strategy.