Robust Control Design for High-Power Density PV Converters in Weak Grids

Nima Amouzegar Ashtiani, S. Mohsen Azizi, S. Ali Khajehoddin

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


This paper proposes a robust current controller (CC) and dc-link voltage controller based on μ-synthesis and H∞ method, respectively, for a single-phase photovoltaic (PV) converter with an LCL-filter under weak grid operation. The μ-synthesis CC guarantees system robustness against weak grid uncertainties such as grid impedance variations and voltage harmonics. Moreover, the controller compensates the system delays arising from the calculation, pulsewidth modulation, and zero order hold, as well as delay uncertainties. The CC only uses the grid current feedback which eliminates the requirement for additional loops or state measurements utilized in partial or full state-feedback systems. In addition, the H∞ dc-link voltage controller minimizes the bus voltage fluctuations caused by variations of PV system power generation. Also, the controller ensures system robustness against such power variations, which conventional controllers fail to perform. Moreover, power decoupling is achieved by the control system without any auxiliary circuit. In addition, the stability and robust performance of the phase-locked loop in a weak grid with major impedance changes is verified. Simulation and experimental results prove the superior performance of the proposed controllers in both cases of a nominal system and a system with deviated parameters.

Original languageEnglish (US)
Article number8463498
Pages (from-to)2361-2373
Number of pages13
JournalIEEE Transactions on Control Systems Technology
Issue number6
StatePublished - Nov 2019

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


  • Current control
  • dc-link control
  • high-power density converters
  • photovoltaic (PV) application
  • robust control
  • weak grid


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