Analysis of magnetic proportional drive circuits for bipolar junction transistors

A comparison is presented of some advantages and disadvantages of three popular magnetic proportional drive circuits for bipolar junction transistors (BJT) used in spacecraft switched mode power supplies (SMPS). A generic classification of these drives is introduced. A novel adaptation of one of these drives, the multiple mode proportional drive (MMPD), is developed to provide a total proportional drive for BJT's using resonant turn-off snubbers. Circuit operational description and design rational is presented for this new MMPD.