Control technique for series input-parallel output converter topologies

A series input-parallel output dc-dc converter topology inherently provides output current sharing among the phases, provided the input voltages are forced to share. With conventional output voltage feedback controls, input voltage sharing is unstable. Recent literature work proposes complicated feedback loops to provide stable voltage sharing, at the expense of dynamic performance. In the current work, a simple controller based on the sensorless current mode approach (SCM) stabilizes voltage sharing without compromising system performance. The SCM controllers reject source disturbances, and allow the output voltage to be tightly regulated by additional feedback control. With SCM control in place, a "super-matched" current sharing control emerges. Sharing occurs through transients, evolving naturally according to the power circuit parameters. The control approach has considerable promise for high-performance voltage regulator modules, and for other applications requiring high conversion ratios. Experimental results confirm the control operation. A sample four-phase converter has demonstrated good disturbance rejection, static sharing, and dynamic sharing.