Uniform voltage distribution control for paralleled-input, series-output connected converters

This paper 1,2 extends the application of current-mode, shared-bus converters to power system architectures configured as Parallel-Input, Series-Output (PISO). By employing a PISO interconnect method, current-mode commercial-off-the-shelf (COTS) dc-dc converters can deliver higher output voltages, provide flexible options for power system expansion, and preserve system efficiencies equal to that obtained from standalone converters. However, without proper control, non-uniformly distributed voltages occur due to converter component mismatch. System reliability suffers as a-result of thermal overstress to the converters that contribute a greater portion of the output power. Conversely, robust system stability and uniform output voltage distribution among series-connected converters is realized through output voltage distribution control. Through both computer simulation and experimental prototype, the uniform voltage distribution power converter architecture is validated and successfully applied during power converter bum-in testing whereby converter load energy is recycled to the power system input, resulting in 49% to 80% conservation of energy.