DC microgrid has attracted more and more attention due to its unique characteristics, but the development of DC microgrid is also facing some challenges, such as interruption and isolation of short circuit fault currents. Therefore, DC circuit breaker plays an important role in ensuring the normal work of DC microgrid. In this paper, a novel bidirectional DC solid-state circuit breaker is proposed to realize the bidirectional flow of energy, which ensures the higher operating efficiency of the DC microgrid. Compared with other solid-state circuit breakers, the proposed novel topology has simpler structure, common ground and fewer components. Firstly, this paper makes a detailed analysis of the different working stages of the circuit when the fault occurs in combination with simulation results of the circuit topology. Then, the standard of selecting the components through the calculation and analysis of the circuit is given in this paper. Finally, the performance of the novel bidirectional solid-state circuit breaker is verified by experiments.

The multilevel boost converter (MBC) has been widely adopted in the DC microgrid systems due to its high voltage gain and simple structure. In recent years, the power electronic loads, which usually behave as constant power loads (CPLs), are penetrating in microgrids. The incremental negative impedance of CPLs degrades the stability of microgrid systems. To ensure effective power flow and guarantee system stability, eliminating the undesired effects of CPLs is a necessity. In this paper, a novel assorted nonlinear stabilizer, which is integrated with an extended nonlinear disturbance observer (NDO) and an adaptive backstepping controller, is proposed for stabilizing the MBC fed microgrid system with CPLs. First, the reduced-order MBC model is transformed into the Brunovsky's canonical form using the exact feedback linearization technique. Second, thanks to the NDO, fast system dynamic responses are achieved. Using the estimations of NDO, an adaptive backstepping controller is developed to strictly guarantee the microgrid bus voltage stability in the sense of large-signal. Simulation and experiment results are presented to verify the effectiveness and feasibility of the proposed stabilizer.

In dc microgrid, energy storage system (ESS) plays a crucial role to provide short-or-long term and high-quality electric energy. The different control strategies for bidirectional dc-dc converter (BDC) of ESS in grid-tied and islanded modes pose challenges to the coordination control of the dc microgrid. This paper proposes an autonomous control scheme for the BDC in dc microgrid. The proposed control scheme is based on $V^{2-P}$ droop control and unifies bus voltage regulation and power regulation in a single control structure. Thus, global smooth transition between various operation modes can be achieved without any control strategy changes, which avoids various mode switch detection mechanisms and improves system stability. Furthermore, the proposed control scheme is fully decentralized which reduces the reliance on communication, and enhances the reliability of the microgrid. On the other hand, $V^{2-P}$ droop approach eliminates the negative effect of widespread constant power loads (CPLs) in dc microgrid. The stability of the proposed control method is illustrated, and the design guideline of some critical control gains is addressed. Finally, the effectiveness of the proposed control scheme is validated by the real-time hardware-in- loop (HIL) platform.

The silicon carbide (SiC) MOSFET is characterized by high operating voltage, temperature, switching frequency and efficiency which enables a converter to achieve high power density. However, at high switching frequency, the crosstalk phenomenon occurs when the gate voltage spike introduced by high dv/dt and voltage ringing forces false turn-on of SiC MOSFET which causes a crow-bar current thereby increasing switching losses. In order to increase the immunity against the crosstalk phenomenon in a half-bridge configuration, this paper presents a gate driver for SiC MOSFET capable of generating the negative turn-off voltage without using a negative power supply. In addition, the effect of parasitic inductances on the switching response is analyzed and an RC snubber is designed using high-frequency based circuit reduction technique to dampen the switching ringing. The performance of the proposed gate driver and the designed RC snubber is validated using simulation and experiment at the 1 MHz switching frequency. The results show that the proposed gate driver with RC snubber eliminates crosstalk by maintaining any spurious gate spike below the gate threshold voltage.

The battery (ESb)-supercapacitor (ESsc) hybrid energy storage system (HESS) is the most promising solution for DC microgrids (MGs) to realize the power balance, where system instability caused by the high penetration of constant power loads (CPLs) is also a critical concern. To achieve the decentralized automatic power sharing and DC bus voltage regulation of the HESS in DC MGs towards large-signal stability, a novel autonomous finite-time backstepping control (FTBC) algorithm is proposed in this article. First, taking the characteristics of the DC bus configuration caused by CPLs into consideration, the $v_{0}^{2}-P_{0}$ droop algorithm has been proposed for the HESS to realize the dynamic power sharing among energy storages (ESs) and to maintain the DC bus voltage. With the help of the proposed scheme, the ESb supplies the low-frequency part of the load fluctuations while the ESsc compensates for the high-frequency ones. Second, with the help of extended finite-time observers (EFTOs), various disturbances, such as power coupling between ES-interfaced converters and parameter uncertainties are automatically eliminated by the EFTOs in a finite time, so that the proposed controller can achieve autonomous and decentralized control with no output current sensors and communication links. Then, the FTBC can precisely offset the estimations and stabilize the DC bus voltage in the large-signal sense. Simulation and experimental results verify the effectiveness and superiority of the proposed controller.

The power electronic loads usually behave as constant power loads (CPLs) in DC microgrids (MGs), which degrades the system stability due to their high-order non-linearity and negative impedance characteristics. Furthermore, the stability concern will be more complicated for the distributed generators (DGs) in DC MGs considering both economic efficiency and plug-and-play performance. In this paper, an autonomous finite-time backstepping controller (FTBC) for decentralized economic power dispatch and precise DC bus voltage regulation of a DC MG is proposed. The high-order nonlinear disturbance observer (HONDO) technique is adopted to estimate the power exchanges between the DGs and loads. So that the decentralized economic power dispatch and rapid voltage regulation can be achieved without any extra output current sensors. In addition, the use of HONDO improves the system's dynamic performance by estimating the disturbances and system uncertainties, and the FTBC guarantees the bus voltage tightly tracking within a finite-time convergence. A rigorous stability analysis is performed to prove the large-signal stability of the regulated system, and some simulations and experiments are carried out.