Paralleled Power Supplies, A Comparison of Methods of Paralleling Power Supplies with the Method Used in the AEGIS Low-Voltage Power System.

摘要

This report was prepared as part of the reliability studies of the AEGIS low-voltage power supply and compares methods of paralleling power supplies to determine the method most suitable for the AEGIS system. The two fundamental methods of paralleling power supplies are the automatic crossover method and master/slave method. The automatic crossover method as two subdivisions: (1) automatic crossover method (used by AEGIS system); and (2) the spoiler resistor method. The master/slave method has three subdivisions: (1) master pass element drive; (2) master voltage reference; and (3) current sense. The degree of current sharing that may be expected from these methods varies and depends on the method and how it was used. The automatic crossover method is characterized by unequal current sharing and closely regulated power supplies; however, if regulation can be sacrificed, a degree of current sharing may be achieved. The master/slave method theoretically offers equal current sharing but, because of inescapable component differences, only the current sense method offers a reliable method for achieving this. A comparison of the methods of paralleling power supplies show advantages and disadvantages for each; The master/slave method may have a slightly higher individual power supply reliability because of its equal load-sharing characteristics; however, this reliability advantage does not consider the additional control circuitry that would reduce reliability.