Friday, July 20, 2012

AC Motor Driver opto-isolation interface

I had to deal with some inverters that are generating too much interference to allow direct connection with AMC644USB board. No signals, no common ground is allowed with these devices.

So I sat down and developed this solution to separate the analog/digital signals with some cheap optocouplers. Even the analog signal is driven through the optocoupler but needs to be amplified on the other  isolated end too as the optocouplers only output 4v max in linear range. With another amplifier and an DC-DC converter I get again the 10v analog signal for the speed of the inverter.

I build a prototype in printer circuit board (perfboard), but I plan to redesign it into a real PCB board if there is enough interest. In the photo I was short two optocouplers...