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The reliability of meshed DC grids mainly relies on their ability in DC fault protection and line power flow managing. Multiple DC circuit breakers (DCCB) and current flow controller (CFC) need to be installed, which significantly increases the system cost. A novel current flow controller integrated with hybrid dc circuit breaker (CFC-IHCB) is proposed to significantly reduce the loss and cost of the whole system. Only one unidirectional IGBT string based main breaker branch is needed for n lines, and the CFC function is integrated into the load communication switches (LCSs). The basic working principle of proposed topology is presented and analyzed. The functionality is verified and a comparison of the proposed solution and other DCCB/CFC solutions is given based on a multi-terminal HVDC system case study. [ABSTRACT FROM AUTHOR]

Hybrid dc circuit breakers (HCBs) are recognized as suitable devices for protecting high-voltage direct-current (HVDC) systems, along with other dc circuit breakers (DCCB). However, compared to mechanical circuit breakers, HCBs exhibit higher conduction losses. Such losses are inevitable under no-fault conditions as current may flow through some of the semiconductor switches. An integrated circuit breaker (ICB) minimizing these losses is presented in this paper, and this is achieved by replacing semiconductor switches by mechanical components in the current path. For completeness, the topology design, operating sequence and a mathematical analysis for component sizing of the device are provided. In addition, an estimation of the conduction losses is quantified. It is estimated that the power losses of an ICB are 2 to 30% of an HCB only. The ICB has been implemented in PSCAD/EMTDC to demonstrate its effectiveness for isolating dc faults, with simulations conducted on a three-terminal HVDC grid. [ABSTRACT FROM AUTHOR]

Autonomous-driving features necessitate a fault-tolerant (FT) power-management unit in 48-V automotive applications. This article presents a monolithic single-phase closed-loop masterless FT four-to-one hybrid Dickson converter IC for high-conversion-ratio 48-V automotive multi-phase applications. The chip includes: 1) a mixed-signal droop-based valley-current ON-time quasi-fixed-frequency control, which enables masterless multi-phase operation capability; 2) single-point short-circuit fault and open-circuit fault detection and blocking of any power switches or flying capacitors; 3) an optimized high-voltage (HV) power stage with fully integrated flying-capacitor-sourced gate drivers without any external bootstrap capacitors; 4) a glitch-free cross-coupled bootstrapped HV level shifter; and 5) a dual-leg bidirectional closed-loop current-sensing circuit optimized for the hybrid Dickson topology. The design was fabricated in a 0.13- $\mu \text{m}$ 90-V automotive silicon-on-insulator (SOI) bipolar-CMOS–DMOS (BCD) process. The measured results confirm the operation over 20–60-V input, 3.3-V nominal output, 3-A maximum load, and 320-kHz effective switching frequency within the automotive-grade −40 °C–+125 °C ambient temperature. The design achieves above 90% measured efficiency at maximum conversion ratio and load at room temperature. A three-phase system is used to evaluate and confirm the fault-blocking capability and continuous power delivery upon detection of a fault. [ABSTRACT FROM AUTHOR]

Hybrid circuit breaker (HCB) has shown good performance for interrupting dc fault current. However, a massive number of IGBTs in series is needed. These will lead to high costs and significant difficulty in balancing IGBT dynamic voltage. This paper proposes a bidirectional hybrid circuit breaker based on a cascaded half-bridge submodule structure to reduce the overall costs and implementation difficulty of HCB. The number of IGBTs is reduced by 50%, and the operating speed is fast enough. A model of a four-terminal modular multilevel converter (MMC) system with a proposed hybrid circuit breaker in different stages is developed to describe the fault blocking process more clearly. The performance of the proposed HCB is validated and compared with other HCB structure through both theoretical derivation and time-domain simulation. [ABSTRACT FROM AUTHOR]