A generalized model-based controller for the n-level CHB multilevel converter used as a shunt active filter

Abstract

This paper presents the modeling and control design of a single-phase cascaded H-bridge multilevel converter used as a shunt active filter in the general case of n-levels. Based on a general model, a controller is proposed to compensate harmonic distortion and reactive power caused by nonlinear loads. For this, the controller must guarantee tracking of the line current towards an appropriately defined reference. In the proposed approach, the current reference has been selected to be proportional to the line voltage. The proposed controller also includes voltage loops to guarantee regulation and balance of the involved capacitor voltages. Simulation results are presented to assess the performance of the proposed controller.

Model‐based strategy for open‐circuit faults diagnosis inn‐level CHB multilevel converters

“…The electric parameters in the SAPF are L as the input inductor, C the capacitance in the DC bus, and R the associated discharge resistance (assumed both equal in all H-bridges). For more details on the mathematical modelling, the reader may refer to [2]. The nominal controller proposed in [2] is considered in this work for the SAPF application, which is briefly described next.…”

“…For more details on the mathematical modelling, the reader may refer to [2]. The nominal controller proposed in [2] is considered in this work for the SAPF application, which is briefly described next. The overall feedback structure consists of three feedback paths:…”

“…1 illustrates the studied single‐phase CHB‐ n L multilevel converter. The application of this converter as an SAPF is considered in this research work [2]. By applying Kirchhoff's law to the equivalent circuit in Fig.…”

“…The electric parameters in the SAPF are L as the input inductor, C the capacitance in the DC bus, and R the associated discharge resistance (assumed both equal in all H‐bridges). For more details on the mathematical modelling, the reader may refer to [2].…”

“…Cascaded H-bridge (CHB) multilevel converters have been used in alternative energy systems and industrial applications by its modular structure and capacity to synthesise voltage waveforms with low distortion [1]. In this sense, active power filters (APFs) are one of the most relevant applications of CHB multilevel converters to achieve an efficient harmonic suppression device [2]. However, multilevel converters are susceptible to faults in their constitutive components, since they contain a large number of power devices that work under high switching frequencies and thermal stresses for a long time [3][4][5].…”