Rising time minimization of DC voltage after output short-circuit of a boost type rectifier

This paper describes a novel short-circuit protection method with a boost type rectifier using a multilevel ac/dc power converter. Since the output dc capacitors of the proposed scheme have ability to keep a floating state, the dc capacitors do not discharge even in the case of a short-circuit of a dc load. The output dc power of the proposed converter can be disconnected from the load within several hundred microseconds at the instant of short-circuit fault. Once the fault has been cleared the dc power is reapplied to the load. The rising time of the dc load voltage is as small as several hundred microseconds, and there is no overshoot of the dc voltage because the dc output capacitors hold undischarged state. Therefore, the proposed converter can be used for a power supply requiring not only a rapid disconnection the load from the power supply dc output in the case of a short circuit but also a rapid connection the load to the output after the clear of the short circuit condition. The proposed converter has the characteristics of a simplified structure, reduced cost, weight, and volume compared with a conventional power supply with a frequent output short circuit. Experimental results are presented to verify the usefulness of the proposed converter.