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I made a 1 phase to 3 phase inverter using arduino and IR2104 to control the speed of an induction motor and it is working perfectly.

To complete the protection scheme, I need to monitor voltage of each phase to protect motor if one phase is lost due to malfunction of IGBT or something else.

In addition, I need to monitor current for overcurrent protection.

In case of voltage I know that it is possible to use optocoupler to convert high level voltage to logic level 5 VDC. Is there any better and simpler practical method to monitor voltage and current of each phase for such application?!

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    \$\begingroup\$ It depends. Post a schematic for what you've got. \$\endgroup\$ – Transistor Jan 6 '19 at 17:36
  • \$\begingroup\$ Monitor ground current imbalance from current sensor to neutral, rectified and averaged for each cycle and compensate balance error next PWM cycle for V on A,B,C if necessary and if sustained more than x Cycles , check voltage , disable all , and check again. Then report either low Vdc, low AC voltage or imbalance error or excess current or excess current imbalance error or driver fault whichever is root cause. Is this delta or WYE? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 6 '19 at 17:42
  • \$\begingroup\$ @Transistor, schematic was added for one phase. \$\endgroup\$ – Mas F Jan 6 '19 at 20:00
  • \$\begingroup\$ @Tony, the connection is delta, can you please explain more about your described method, or provide me web resources to read more? \$\endgroup\$ – Mas F Jan 6 '19 at 20:03
  • \$\begingroup\$ I only speak from experience, not web sources but I am sure you can find some. I'll try to sketch something \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 6 '19 at 20:04
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schematic

simulate this circuit – Schematic created using CircuitLab

Just for your consideration. Not a direct answer. Too many details.

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Since you are already using an Arduino, your best bet would be to use a Current Transformer that will sense the current being delivered to your motors. This is a safe, and non-invasive way to monitor the Vac that you are consuming. It usually looks kind of like this.

enter image description here

It's not the cheapest way, but those things don't really cost that much in the first place.

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