Transformer for use in a static inverter

A transformer comprising:

• A. a core of substantially linear magnetic material for main flux pursuing first and second closed magnetic paths arranged adjacently in a FIG. "8" configuration,
• a small aperture in said core disposed substantially at the boundary between flux paths for minimum interception of main flux, said closed paths separating at said aperture,
• said aperture being bounded by three contiguous regions collectively forming a small virtual toroid, the first region also providing a portion of the path for main flux in said first closed path, the second region also providing a portion of the path for main flux in the second closed magnetic path, and the third region providing a path between said first and second regions substantially free of main flux in the absence of saturation effects,
• B. a substantially helical power winding coupled to said core for generating and responding to main flux in said first and second closed flux paths,
• C. feedback winding means for deriving a control output having a sense which reverses upon saturation of a predetermined toroidal region, said means comprising:
• (1) a primary feedback winding wound through said aperture to generate flux about said virtual toroid;
• and
• (2) a secondary feedback winding wound through said aperture and embracing said third toroidal region for deriving a control output in response to flux therein.