| Abstract |
This paper proposes a novel DC grid component that supplements conventional DC circuit breakers with a pre- and discharging functionality, thereby replacing conventional electromechanical solutions including lossy, bulky, and fault-prone pre- and discharging resistors. To reduce operational costs and energy consumption, this article proposes a bidirectional DC-DC converter for pre- and discharging purposes, which is based on an extended flyback topology with a dual-switch configuration on bothprimary and secondary side. This reduces the high voltage stress on the power semiconductors andprovides both a constant current behavior over a wide voltage range and an inherent overload protection for all capacitors on the load side. The operating principle, characteristic waveforms, and the converter design are presented. The proposed concept was verified on the basis of a realized prototype setup. With this, we are able to charge and discharge a 500 µF DC-link capacitor within less than 500 ms to and from a voltage of 700 V. Furthermore, the pre- and discharging unit fulfills increased functional safety requirements as the converter is self-sufficient after start-up and does not require an auxiliary power supply. Due to a very low quiescent current in the stand-by mode of merely 8.5 µA, it is particularly suited for battery-powered applications. |
