Comparison of Inductive Generators (IG) built on Common Magnetic Core and Separate Cores

High-voltage power supplies (HVPS) for dc and long-pulse operation for a range of tens to several hundred kV are often built as cascade generators (CG). CGs can be roughly divided into two categories, those with capacitive and inductive energy coupling between the cascades. We will call here CGs with inductive coupling “Inductive Cascade Generators” (IG). Between several IG available topologies, two have been a matter of contention for decades: a) built on a common core; b) built in modules employing identical separate cores. The main argument against scheme b) is redundant insulation required to insulate the secondaries from the yokes, and the strong argument for it is the possibility of interleaving the modules for achieving low stored energy, fast dynamics, etc. This paper compares the two topologies based on core losses and cooling in practical configurations using U-cores. Both analytical and numerical thermal analyses are done. The first assumes constant volumetric losses, whereas the second uses core losses determined both by flux density and temperature in coupled magnetic field-thermal analyses. The losses for thermals are determined with Steinmetz approximations. While there is no universal preference for one or the other IG scheme, the derived dependencies can facilitate the choice between them accounting for the operational scenarios. For instance, there is a clear-cut preference for separate cores if high average power and fast dynamics are required at a very high output voltage.