current transformer problems
please can you help here?
.....i need to make current transformer to act as current sense in this ~150W boost converter (12 to 42V)
however, as i have done it so far.....
.....when the MOSFET is ON..
..if twelve amps flows in the primary of the current transformer....
..then 300mA will flow in the secondary (40:1 turns ratio)
..this 300mA will put 1 volt across the 3R3 resistor
..and there will be 0.7V across the diode....
..therefore there will be 1.7V across the secondary
..therefore , there must in turn be 1.7 * 40 = 68V across the primary
.....but if there is 68V across the primary then there will be minus 56 volts (=68-12) across the boost inductor (?)
How can there be 68 Volts across the current transformer primary?