With the emergence of power electronic technology and advancements in highly efficient electric power converters, DC-DC converters play a significant role in DC networks and DC distribution systems. Not being fully understood, nevertheless, the stability, protection and safety of DC systems present an open challenge for the research community. In this study, a high quality low voltage DC distribution system has been proposed, which provides a constant power in the event of voltage disturbance (sag), fluctuations, and fault. A three wire line system is adopted: +375 V line, neutral and -375 V line. Furthermore, the required DC power is transformed from DC or AC voltages by using load side converters, and these power converters do not need any transformers to adopt the proper DC voltage. In this research work double-closed-loop control strategy, the outer voltage control loop and inner current loop (decoupled without the exact value of boost inductance) are proposed. If short circuit or any fault occurs on the load side, the proposed strategy prevents the effect of remaining load. Also, the grid reconnection and disconnection is very smooth. Furthermore, a voltage balancer is proposed near to low voltage side. To confirm the effectiveness of the suggested control topology, simulations are performed in Matlab/Simulink and PSCAD software. The results obtained from simulation show that the suggested control system topology can provide excellent power in various conditions.

With direct current (DC) power generation from renewable sources, as well as the current relocation of loads from alternating current (AC) to DC, medium-voltage DC (MVDC) should fill gaps in the areas of distribution and transmission, thereby improving energy efficiency. The MVDC system is a platform that interconnects electric power generation renewables (solar, wind) with loads such as data centers, industrial facilities and electric vehicle (EV) charging stations (also using MVDC technology). DC–DC power converters are part of the rising technology for interconnecting future DC grids, providing good controllability, reliability and bi-directional power flow. The contribution of this work is a novel and efficient multi-port DC–DC converter topology having interconnections between two converters, three-level neutral point clamping (NPC) on the high-voltage (HV) side and two converters on the low-voltage (LV) side, providing two nominal low voltages of 400 V (constant) and 500 V (variable), respectively. The design of this new and effective control strategy on the LV side has taken into condition load disturbances, fluctuations and voltage dips. A double-closed-loop control topology is suggested, where an outside voltage control loop (in which the capacitance energies are analyzed as variable, and the inside current loop is decoupled without the precise value of boost inductance) is used. The simulation results show the effectiveness of the proposed control system. In the second part of this study, wide-bandgap SiC and Si devices are compared by using comprehensive mathematical modeling and LT-spice software. Improving power loss efficiency and overall cost comparisons are also discussed.

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.