[image]http://www.envero.net/images/Fullbridge.jpg[/image]


Given above is a sample H/Full bridge, . I want to detect the phase difference between the current through the load and the voltage developed acroos it . Once this is done the output would be sent to a control circuit which would be programmed to increase or decrease the switching freq of the switches depending on the phase difference between the current and voltage.

Now I have no experience in digital electronics (i am more of a power electronics guy) and the whole phase detection business is driving me crazy .

What i have done is added diode clippers(schottky) that would clip the output voltage to somewhere around 0.4V (coz any phase detection device cannot handle the voltage across the load)


NOW IS THE MILLION $$$$ QUESTION

HOW DO I DETECT CURRENT AS WELL AS THE VOLTAGE JUST USING A SINGLE DEVICE (FOR EG A COMPARATOR????).....

GUYS PLZ HELP ME OUT OVER HERE ....REALLY NEED THIS !!!!!



CHEERS!!!

Attached Images

Fullbridge.jpg (31.6 KB, 11 views)

 

Current: Voltage drop across a very small resistor inline with a load lead (will be + or - depending on motor direction)
Voltage: Voltage between poles of motor (will also be + or - depending on motor direction)

Use current limiting resistors for the appropriate voltages to drive two photocouplers, from the output of the photocouplers you have the inputs for your logic.

The resistance for measuring current can simply be that of the wire between source and motor terminal, if you can measure it accurately enough, provided the wire is at least 6", and huge temperature swings don't occur.