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DC microgrids have received remarkable interest in both the academia and the industry for over a decade, yet the protection of dc microgrids remains as a major challenge. This challenge is rooted in the nonexistence of natural zero-crossing point in dc microgrids which rapidly increase the fault current. In this article, a novel bidirectional dc solid-state circuit breaker (dc SSCB) to reinforce the bidirectional flow of energy which significantly boosts the overall efficiency of the power supply of dc microgrids is presented. The proposed topology can perform the operating duty of reclosing and rebreaking, and the commutation capacitor is charged and recharged naturally without any complex control of the main or auxiliary thyristors, which is considered atypical of existing topologies. A clear and detailed analysis of the operation of the proposed topology is presented. Finally, the experimental results are presented to confirm the effectiveness of the proposed novel bidirectional dc SSCB.

DC grid has attracted a major interest due to the advent of renewable energy such as photovoltaic energy and wind power. For the safety and protection of the DC grid, the DC circuit breaker as fundamental component to the DC gird has received a lot of concern. A new thyristor DC solid-state circuit breaker (DC SSCB) is proposed in this paper. Its main advantage is to have the capability of naturally charging the commutation capacitor for stable and reliable interruption function. That is, the proposed DC SSCB have no need of additional switching operation for the purpose of charging the commutation capacitor. Moreover, the proposed DC SSCB can carry out the operating duty which performs the reclosing and rebreaking operation. The prototype of proposed SSCB is fabricated with the design specification of a rating of 5 [kW] and 380 [V], and its operating features are verified by the experimental results.

Recently, with the development of renewable energy such as solar power and wind power, the DC grid has become a major concern. Accordingly, DC breaker which is essential in the DC gird has been actively studied. This paper proposes the new thyristor DC Solid-State circuit breaker (DC SSCB) which can naturally charge the commutation capacitor for the fault current breaking operation. The proposed thyristor DC Solid-State circuit breaker does not require switching operation to charge the commutation capacitor. In addition, it is possible to quickly perform the operating duty of the reclosing and rebreaking operation. The proposed DC SSCB is designed with 380 [V], 5 [kW] and the operating characteristics are verified through simulation.

Induction heating can convert electrical energy to thermal energy with high conversion efficiency and quick heating. Currently, a current source rectifier/inverter-fed parallel resonant circuit is widely used as an induction heating power supply for forging applications. However, the conventional induction heating power supplies composed of phase-controlled rectifier and SCR inverter have low efficiency and low power factor at input side, and require additional starting circuitry. Thus, many topologies have been studied for high power factor and low current THD characteristics. This paper proposes the new high power factor induction heating power supply using 3-phase, 3-switch PWM rectifier with power factor control and low cost and simple control. Also, this paper proposes a design method for the proposed power supply and verifies the validity of the proposed power supply through simulation.