In the input stage, the primary voltage is divided equally between
the input stage modules. Each module’s voltage is rectified
using a unity-power factor rectifier. Each isolation stage
module generates a high-frequency square wave from the incoming
dc, transforms and isolates it, and re-rectifies the transformer
output. The bipolar dc outputs can then be connected in
parallel to supply the output stage. The series to parallel connection
provides the bulk of the voltage reduction.