Optimization Analysis and Design of DC Solid State Circuit Breaker Buffer Circuit Based on RCD and MOV

In order to protect the solid state circuit breaker from transient shocks, an efficient and economical design of the buffer is of paramount importance. Conventional resistance capacitor diode(RCD) buffers are widely used because of their excellent voltage clamping capability and short fault clearance time. At the same time, metal oxide varistors(MOV )can also be used as a suitable solution because of its non-linear U-I characteristics. In order to optimize the design of the buffer, four indicators, including, peak SSCB voltage, peak bus current, fault clearing time and cost, are selected to analyze the performance of the RCD buffer and MOV. Finally, based on the full consideration of the advantages and disadvantages of the two, a new buffer topology based on RCD and MOV is proposed. The voltage peak of new topology is 264 V, which decreases by 10.4% and 30.8% compared with RCD and MOV respectively, when the dc bus voltage is 200 V. A hybrid buffer topology can make use of the advantages of different buffer topologies. This paper provides reliable references for this kind of design thoughts. In addition, four indicators proposed in this paper have the reference value for the evaluation of functions of buffer circuits. © 2019, High Voltage Engineering Editorial Department of CEPRI. All right reserved.