Input-parallel–output-series control strategy for three-level medium-voltage DC grid-type converter

Abstract

A control topology input-parallel–output-series converter system is investigated, which is suitable for high-voltage and high-output power applications. In this control method input current sharing (ICS) and output current sharing (OVS) taken into account. As observed, ICS is automatically attained as OVS sharing is controlled. In this design, two modules are connected in series, Module 1 provided variable voltage but in Module 2 by using three-level neutral-point-clamped converter and designing a comprehensive control feedback system, which regulates the DC voltages at the constant magnitude and constant frequency, helps to provide constant output voltages in the event of uncertain disturbance and load variation, A feedback double closed-loop control topology (inner current loop control and outer voltage loop control) with the combination of sliding mode control and a proportional–integral control method. A simulation model is built, by using MATLAB/Simulink, and the simulation results show excellent performance and feasibility of this system. This will be beneficial for research and improvement for the grid-connected converter.

Keywords

• power convertors
• closed loop systems
• variable structure systems
• PI control
• electric current control
• power grids
• control system synthesis
• DC-DC power convertors
• feedback
• voltage control
• variable voltage
• three-level neutral-point-clamped converter
• comprehensive control feedback system
• DC voltages
• constant magnitude
• constant frequency
• constant output voltages
• closed-loop control topology
• inner current loop control
• outer voltage loop control
• proportional–integral control method
• grid-connected converter
• input-parallel–output-series control strategy
• three-level medium-voltage DC grid-type converter
• control topology input-parallel–output-series converter system
• high-output power applications
• ICS
• input current sharing
• output current sharing
• sliding mode control