Forward Converter


Working principle

A forward converter transforms a DC voltage at the input to a DC voltage at the output. The operating principle is similar to the buck converter, but an additional transformer is used to achieve galvanic isolation of the input and output. To show the working principle of the circuit the magnetizing inductance (Lm) and a primary side demagnetizing winding are neglected for simplicity.

For a flyback converter in continuous conduction mode the output voltage across resistor R is given by:

Vout = N2/N· · Vin

where D is the duty cycle, and N1 and N2 are the turns numbers of the primary and secondary windings.


  • Change the winding ratio from 1:1 to 0.5:1 and observe how the output voltage increases by a factor of 2.