Fault-Tolerant DC Power Distribution Unit Based on Nonexclusive Redundant Modules

Reliability of the power distribution unit (PDU) is very important in electrical systems. Since any failure in this unit leads to system failure. A commonly used method for increasing the reliability of a dc PDU is using the redundant modules. If a fault occurs in a voltage regulator of PDU, it is replaced by its redundant module. In conventional redundancy, each dc voltage regulator has its exclusive redundant modules. Therefore, if both a regulator and its redundant modules fail, the system is stopped. It is an important drawback since the exclusive redundant modules of other voltage regulators may not be used, but, the PDU cannot use them instead of faulty regulators. In this paper, the application of the nonexclusive redundant regulators is presented for solving this problem. In the proposed method, dc power distribution unit consists of a number of redundant modules, which can be adjusted to a desired voltage and can be used instead of faulty regulators. An analysis based on Markov model is presented to compare reliability of the proposed structure with the conventional structure presuming a variable failure probability. Theoretical study indicates more reliable operation of the proposed PDU structure than the conventional structure. Experimental results are presented to show practical considerations of the proposed structure and its proper performance.