CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2017/064797, filed on Jun. 16, 2017, and claims benefit to British Patent Application No. GB 1610901.9, filed on Jun. 22, 2016. The International Application was published in English on Dec. 28, 2017 as WO 2017/220443 under PCT Article 21(2).

FIELD

The present invention relates to a direct current circuit breaker providing a number of operational and safety related functionalities, such as overcurrent protection.

BACKGROUND

International patent publication WO2015/028634 discloses an alternating current circuit breaker with a first galvanic separation switch and a bypass switch in a live line, and a second galvanic separation switch in a neutral line. A semiconductor switch element is connected parallel to the bypass switch. The semiconductor switch element comprises a combination of a rectifier bridge and an isolated gate bipolar transistor. A processing unit is connected to a current measurement unit arranged in the live line, and is arranged to control the bypass switch, first and second galvanic separation switches and the conducting state of the isolated gate bipolar transistor in case of detection of a short circuit condition.

European patent publication EP-A-2 320 535 discloses a current limiting circuit breaker including a short circuit functionality, which recloses after a set period of time after a first short circuit detection. If the short circuit fault is then again detected, a control unit is used to open the electrical circuit using a disconnector. A method for limiting current circulating in an electric circuit between an incoming line of an upstream circuit breaker and an outgoing line equipped with a downstream circuit breaker and/or divisional contactor is also disclosed.

International patent publication WO2011/057675 discloses a device to break an electrical current flowing through a power transmission or distribution line, specifically for high voltage DC applications. A parallel connection of a main breaker and a non-linear resistor is disclosed, the main breaker comprising at least one power semiconductor switch of a first current direction. Furthermore, a high speed switch in series with an auxiliary breaker is connected in parallel to the main breaker. First the auxiliary breaker is opened, thereby commutating the current to the main breaker, afterwards the high speed switch is safely opened. Then the main breaker is opened thereby commutating the current to the non-linear resistor.

SUMMARY

In an embodiment, the present invention provides a direct current circuit breaker, comprising: a positive supply line between a positive input terminal and a positive output terminal; a negative supply line between a negative input terminal and a negative output terminal connecting a direct current load to a supply; a series connection of a first galvanic separation switch and a bypass switch in the positive supply line, and a second galvanic separation switch in the negative supply line; a semiconductor switch element connected parallel to the bypass switch; and a series connected inductor in the positive supply line, wherein the first and second galvanic separation switch, the bypass switch, and the semiconductor switch element are controlled using a processing unit.

