Parallel Operation of Quasi-Resonant, Zero-Current Switching DC-DC Converters

摘要

Current sharing becomes an important consideration when power architects parallel multiple power supplies or converters to increase output power or provide fault tolerance. Most current-sharing schemes employed with power converters involve either artificially increasing the output impedance of the converter module or actually sensing each output current, forcing all of the currents to be equal by feedback control. In a synchronous current-sharing scheme, however, there is no need for having a current-sensing or current-measuring device on each module; nor is there a need to compromise load regulation by artificially increasing the output impedance. Synchronous current sharing is possible only in converter topologies where the energy transferred per switching cycle is fixed. An example of such a topology would be Vicor's zero-current switching, quasi-resonant, high-density DC-DC converters. In such a synchronous array, each module has the capability to assume control; that is, it constitutes a democratic array. The module that is in command transmits a pulse on a communications bus to which all. other modules in the array synchronize.