Design and Development of Fixed-Frequency Double-Integral SM-Controlled Solar-Integrated Bidirectional Quasi Z-Source DC-DC Converter in Standalone Battery Connected System

Abstract

DC microgrids have been quite popular in recent times. The operational challenges like control and energy management of the renewable-driven standalone DC microgrids have been an interest of research. This paper presents a bidirectional quasi Z-source DC-DC converter (BQZSDC). This converter topology has been developed based on a conventional buck-boost type bidirectional converter, and it interfaces the storage system and the common DC bus. The challenge, however, lies in effectively managing the uncertain renewable energy sources and the storage system and catering for the loads simultaneously. An effective control strategy is needed for that energy management and to achieve various microgrid objectives. This paper deals with one such effective control strategy implemented for BQZSDC. That is, the fixed-frequency double-integral sliding mode control (FF-DISMC) controls the converter to regulate the DC bus voltage and battery current. A detailed analysis of the controller is conducted, and its performance is evaluated for both charging (buck) and discharging (boost) modes. Simulations have been performed in MATLAB, showing that the controller performs satisfactorily in achieving the objectives of voltage regulation and battery current regulation. Finally, the performance of the proposed controller is validated with the hardware setup.

Stability Analysis and Controller Synthesis

“…While single-loop voltage management has traditionally been the preferred option for low pulse ratio inverters, it is challenging to fulfill the performance requirements of high-power inverters. For a traditional three-phase inverter, the standard in three-phase applications and the building block of almost all later advanced three-phase inverters such as HERIC, and Z-source [5][6][7][8]. A controller that controls a three-phase inverter is integral to the inverter [9].…”

Bidirectional quasi‐Z‐source DC‐DC converter with Lyapunov function‐based controller in stand‐alone photovoltaic‐connected system

“…18,19 Double integral SMC has a quicker response for a wide range of operating conditions with a significant reduction in SSE. 20,21 The MPC provides a solution for trajectory optimization; however, because MPC calculates its control input from the system dynamic model, differences between the actual system and dynamic model can degrade the performance of MPC. Moreover, because of the enormous amount of computations, MPC is unsuitable for converters with high switching frequencies.…”

“…However, the inadequate switching control action would result in a steady‐state error in the output voltage—integral SMC, which can minimize SSE 18,19 . Double integral SMC has a quicker response for a wide range of operating conditions with a significant reduction in SSE 20,21 . The MPC provides a solution for trajectory optimization; however, because MPC calculates its control input from the system dynamic model, differences between the actual system and dynamic model can degrade the performance of MPC.…”