IGBTs' Energy Reduction for Advanced Hybrid Circuit Breakers Used in DC Traction Networks by Controlling the Current Commutation Rate

High operating speed makes the Hybrid DC Circuit Breaker (HDCB) a good choice for DC traction network protection. HDCBs contain a mechanical switch (MS), so structures to zero its current are necessary. However, the current zeroing structures of the MS faced challenges from the high energy of IGBT stack switches (ISS) and arc-prone operation of MS in the current commutation drive circuit (CCDC), high voltage/current levels of control switches in series-type HDCBs (ST-HDCBs), and significant pre-fault losses in the load commutation switch (LCS). This paper offers a current commutator switch with a magnetic coupling for parallel HDCB, whose single-turn coil is after the MS on the network side, and the other coil is coupled to the control voltage source through two IGBTs to overcome the drawbacks. Tuning the control switches' duty cycle adapts the commutation rate to the MS medium, allowing the MS to interrupt the current at the first zero current, decreasing ISS energy. In addition, the current, voltage, and temperature stresses of the ISS branch have been significantly reduced compared to other current injection methods. The order of the control unit and MS operation causes an arc-less MS opening. Also, for the HDCBs employing the slow actuators, the hysteresis band limits the current of the MS after the commutation, so the MS can operate arc-free. Moreover, the single-turn network coil lowers pre-fault loss. The lowered injected current to achieve ZC in MS reduces the current and voltage of the control switches. Maxwell, Simplorer, and MATLAB co-simulations match experimental results, verifying the suggested structure's performance for traction system specification.