Hybrid Control Law for a Three-Level NPC Rectifier

Abstract

In this article, a hybrid control law is proposed for the three-phase three-level Neutral Point Clamped (NPC) converter working as a rectifier in order to regulate the output DC voltage. The control problem deals with the unbalance capacitor voltages as well as the phase currents. The proposed algorithm is based on the Hybrid Dynamical System theory, which takes into account the hybrid nature of the NPC converter, i.e., the continuous and discrete dynamics, ensuring uniform global asymptotic stability of the operating point. Finally, the effectiveness of the proposed control algorithm is validated in simulation. Index Terms-Three-phase three-level neutral point clamped converter, rectifier, hybrid dynamical system, nonlinear time-varying system.

A Comprehensive Review of Power Converters for E-Mobility

“…Other characteristics of this converter include its very low THD in input line current, small passive filtering requirements, and explicit creation of a bipolar DC-bus, which has been investigated by [43] to implement a charging station, allowing DC-DC converters to connect to half of the DC-bus voltage [34]. The requirement for capacitor voltage balancing algorithms [44,45] is one of the most difficult challenges associated with the use of this converter. If the voltage drops across the capacitors are left unbalanced, it may result in poor output voltage quality, affecting control performance or even causing semiconductor devices to fail [46].…”

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“…In the third category, one can include finite control-set model predictive control (FCS-MPC) [11,12] where knowledge about the system is used to select the more appropriate discrete state according to a model-based prediction. In the same line, there are other techniques that optimize a certain performance index, as in [13] where genetic algorithms are used to eliminate specific harmonics from the output voltage; or in [14] where hybrid dynamical systems theory is used to obtain a new control law for three-level converters with stability guarantee.…”