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This paper describes a new digital current sharing method for parallel interleaved dc-dc converters. The difference between sensed inductor current values can cause unequal current distribution in the parallel dc-dc converters even though they are controlled by the same average current mode controller with a common current reference. To overcome this problem, a simple digital current sharing algorithm using input voltage ripple difference is proposed. The digital current sharing algorithm calculates the required current reference adjustment value using only the input ripple voltage difference information. No additional input current sensing circuit is required. The proposed algorithm achieves equal current distribution between phases of the parallel converters with high parameter insensitivity. For the experimental verification, a 500 W two phase interleaved synchronous buck dc-dc converter which charges a 24 V Li-ion battery is implemented.
Date of Publication: Aug. 2012