An Optimal Switching Sequence Model Predictive Control Scheme for the 3L-NPC with Output LC Filter

Herrera, Felipe; Mora, Andrés; Cárdenas, Roberto; Díaz, Matías; Rodríguez, José; Rivera, Marco

Abstract

In some applications of microgrids and distributed generation, it is necessary to feed islanded or stand-alone loads with high-quality voltage to provide low total harmonic distortion (THD). To fulfil these demands, an 𝐿𝐶 filter is usuallyconnected to the output terminals of power electronics converters. A cascaded voltage and current control loop with pulse-width modulation schemes are used to regulate the voltages and currents in these systems. However, these strategies have some drawbacks, particularly when multiple-input–multiple-output plants (MIMO) are controlled using single-input–single-output (SISO) design methods. This methodology usually produces a sluggish transient response and cross–coupling between different control loops and state variables. In this paper, a model predictive control (MPC) strategy based on the concept of optimal switching sequences (OSS) is designed to control voltage and current in an 𝐿𝐶 filter connected to a three-level neutral-point clamped converter. The strategy solves an optimisation problem to achieve control of the 𝐿𝐶 filter variables, i.e., currents and output voltages. Hardware-in-the-loop (HIL) results are obtained to validate the feasibility of the proposed strategy, using a PLECS–RT HIL platform and a dSPACE Microlab Box controller. In addition to the good dynamic performance of the proposed OSS–MPC, it is demonstrated using HIL results that the control algorithm is capable of obtaining low total harmonic distortion (THD) in the output voltage for different operating conditions.

Citation

Herrera, F., Mora, A., Cárdenas, R., Díaz, M., Rodríguez, J., & Rivera, M. (2024). An Optimal Switching Sequence Model Predictive Control Scheme for the 3L-NPC with Output LC Filter. Processes, 12(2), Article 348. https://doi.org/10.3390/pr12020348

• Journal Article Type: Article
• Acceptance Date: Jan 31, 2024
• Online Publication Date: Feb 6, 2024
• Publication Date: Feb 6, 2024
• Deposit Date: Nov 18, 2024
• Publicly Available Date: Nov 19, 2024
• Electronic ISSN: 2227-9717
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 2
• Article Number: 348
• DOI: https://doi.org/10.3390/pr12020348
• Keywords: model predictive control (MPC); optimal switching sequence (OSS); multilevel inverters; optimal control
• Public URL: https://nottingham-repository.worktribe.com/output/35716737
• Publisher URL: https://www.mdpi.com/2227-9717/12/2/348