Variable Structure Control in Natural Frame for Three-Phase Grid-Connected Inverters With LCL Filter

Abstract

Abstract-This paper presents a variable structure control in natural frame for a three-phase gird-connected voltage source inverter with LCL filter. The proposed control method is based on modifying the converter model in natural reference frame, preserving the low frequency state space variables dynamics. Using this model in a Kalman filter, the system state-space variables are estimated allowing to design three independent current sliding-mode controllers. The main closed-loop features of the proposed method are: 1) robustness against grid inductance variations because the proposed model is independent of the grid inductance, 2) the power losses are reduced since physical damping resistors are avoided, 3) the control bandwidth can be increased due to the combination of a variable hysteresis comparator with the Kalman filter, and 4) the grid-side current is directly controlled providing high robustness against harmonics in the grid. To complete the control scheme, a theoretical stability analysis is developed. Finally, selected experimental results validate the proposed control strategy and permit illustrating all its appealing features.

Analytical Design and Performance Validation of Finite Set MPC Regulated Power Converters

“…9 the impact of deviations of ±30% on the rated values of filter inductance were analyzed. Similar tests for variation of the converter output filter parameters have been performed in [45] for sliding mode control algorithm with Kalman filter, in [41] for a combination of robust control, state estimator, and linear matrix inequality (LMI) optimizations, and in [46] for a linear single current loop control with hybrid damper. As it can be seen from obtained results the overestimation and underestimation of the filter values didn't significantly effect the steady state performance of the converter which proves that the resistance to parameter variations is comparable to [41], [45], [46].…”

“…Similar tests for variation of the converter output filter parameters have been performed in [45] for sliding mode control algorithm with Kalman filter, in [41] for a combination of robust control, state estimator, and linear matrix inequality (LMI) optimizations, and in [46] for a linear single current loop control with hybrid damper. As it can be seen from obtained results the overestimation and underestimation of the filter values didn't significantly effect the steady state performance of the converter which proves that the resistance to parameter variations is comparable to [41], [45], [46]. For a more detailed experimental study on parameter variation effects for FCS-MPC operated converters for UPS the reader is refereed to [7] where it is demonstrated that stability is not lost even under heavy mismatch between the model parameters used by the algorithm and those in the experimental set-up.…”

“…Table III shows the summary of tested probabilities for transient load with parameter uncertainty introduced into the model as false estimation of L f . Both overestimation and underestimation of the filter inductance were taken into account as in [41], [45], [46]. The uncertainty of estimation process was set to = 0.05.…”

Research on Attitude Control Method of Agile Satellite Based on Variable Structure Control Algorithm

“…A hybrid steering logic was presented in the work of [3], analysis and simulations are presented to demonstrate the performance of the hybrid steering logic in the work of [4]. A variable structure control in natural frame for a three-phase girdconnected voltage-source inverter with LCL filter was presented in [5].The proposed control method is based on modifying the converter model in natural reference frame, preserving the low-frequency state-space variables dynamics. Some problems about the attitude maneuver control are discussed in this paper.…”

Full-Speed Range Encoderless Control for Salient-Pole PMSM with a Novel Full-Order SMO

“…To facilitate digital control applications, the sliding mode observer is studied in the discrete-time field. Pole placement technique [18,19] is used to design the switching surface; desired dynamic characteristics can be achieved through eigenvalue placement. To force the state trajectories reach and subsequently remain on the eventual sliding surface with a good movement quality, free hierarchical law is adopted as switching scheme, and discretized reaching law [20] is used to design the quasi-sliding mode and reaching process.…”