DC-Link Voltage-Balancing Strategy Based on Optimal Switching Sequence Model Predictive Control for Single-Phase H-NPC Converters

Abstract

In this paper, a model predictive control (MPC) strategy based on the optimal switching sequence (OSS) concept for a single-phase grid-connected H-bridge neutral-point-clamped (HNPC) power converter is presented. The proposed OSS-MPC algorithm considers both the grid current tracking error and the dc-link capacitor voltage balance. Special emphasis is placed on the power converter control region in order to design suitable switching sequence candidates for this multi-objective control problem. Additionally, based on an analysis of the weighting factor effect over closed-loop performance, it is possible to demonstrate that this controller parameter is relatively easy to adjust. In fact, the weighting factor only affects the peak current during transients, with no effect over the steady-state performance. As a result, the proposed OSS-MPC provides a fast closed-loop dynamic to the H-NPC converter, which operates with a fixed switching frequency at all times. This predictive control strategy is experimentally validated in a 3.5 kVA laboratory setup. I. INTRODUCTIONP OWER converters are key components for the penetration of technologies such as renewable energy, energy storage, etc [1], [2]. Among these applications, low-power renewable energy generation, like rooftop photovoltaic (PV), and highpower railway traction systems use single-phase power converters as grid and catenary interface [3]-[5]. One interesting topology for these applications is the single-phase H-bridge neutral-point-clamped (H-NPC) converter. Compared to the

Model Predictive Control of Power Electronic Systems: Methods, Results, and Challenges

“…More specifically, these methods-and in contrast to the aforementioned direct MPC strategies-introduce the concept of variable switching time instants by changing the state of the switches at any time instant within the sampling interval. This is done by computing both the optimal switch positions and the associated duty cycles [49]- [60]. In doing so, higher granularity of switching is introduced enabling the reduction of the harmonic distortion in the variables of concern.…”

A High-Gain Observer-Based Adaptive Super-Twisting Algorithm for DC-Link Voltage Control of NPC Converters

“…For this system, h 1 and h 2 are set as some positive constants to meet the requirements. In addition, due to the existence of σ (x, t) in (11), the effect of σ (x, t) on e should be considered. To alleviate this influence, the gains of the HGO can be designed as…”

“…Lemma 1. [21] Assume that x 2 andẋ 2 are bounded, then for system (11), there is a scalar ζ > 0 existed such that the following condition is satisfied…”

“…To mitigate these issues, numerous seminal solutions have been proposed in various literature. These approaches are commonly based on a variety of advanced nonlinear controllers, including sliding mode control (SMC) [5][6][7][8], model predictive control [9][10][11], neural networks control [12], ect., bearing in mind the distinct features of nonlinear algorithms [13]. In this work, the focus is the SMC method owing to its superior ability to deal with nonlinear problems [14,15].…”

Efficient FPSoC Prototyping of FCS-MPC for Three-Phase Voltage Source Inverters

“…Among all the types of control schemes proposed for these converters, Finite Control Set Model Predictive Control (FCS-MPC) has been developed in previous research [5][6][7][8], leading to an improved dynamic response and the capability to achieve simultaneous control targets. This result has led to growing attention for this type of control in the field of power electronics [9][10][11].…”