Bidirectional Hybrid DC Circuit Breaker with Zero Voltage and Current Switching for Radar Power System

This paper proposes a novel zero-voltage switching (ZVS) and zero-current switching (ZCS) based hybrid DC circuit breaker for a radar power system. Long-range radars demand huge power, in the order of hundreds of kW. Radar's phased array antenna houses a large number of electronic devices and works primarily on a DC power supply. Typically, military systems are required to have the highest operational reliability, as a result, electrical system protection plays a crucial role. A high power 310 V DC electrical power grid in radar carries hundreds of amperes of current under nominal operating conditions, results in significant fault current due to very low impedance, and demands a very fast fault interruption device. This paper proposes and demonstrates the complete operation of a hybrid DC circuit breaker topology for radar applications. The proposed DC circuit breaker employs a mechanical switch that carries the entire current during the nominal operating conditions, and a Power Electronic Module (PEM) connected in parallel helps in diverting the fault current from the main path. Fault current transfers to the PEM branch in a fraction of a second (5μs), which ensures faster load-side isolation. During the fault interruption process, mechanical switch contact opening experiences both ZVS and ZCS features, resulting in arcless operation, and also helps in faster contact separation. The ZVS and ZCS feature greatly improve the reliability of the mechanical switch. The proposed concept does not involve any capacitors and corresponding pre-charging circuits for the ZVS/ZCS features. The proposed DC circuit breaker is analyzed theoretically, and also by simulations in LTspice. Additionally, an experimental prototype with a DC system rating of 310 V - 10 A is developed to experimentally validate the performance of the proposed breaker topology. The paper also presents a detailed design and comparative analysis, along with a discussion on the limitations of the proposed DC circuit breaker, and the scope for improvements.