I want to make a low-cost solution regarding the control of a three-phase AC asynchronous motor. I want to be able to control it using an Arduino board(set the frequency from it).

Motor specification:

  • Power: 0.3KW
  • rotations: 1400
  • Nominal current 1A at 220Vac/0.6A at 400V

I am relatively new into power-electronics, so it would be highly appreciated if you could tell me what circuits would I need?

So far I understood that I need an inverter circuit for the 3 phases of the motor. Do I need special controllers for every IGBT or can I control all of them from the Arduino?

Also, is this schematic remotely ok? If not, where could I find a complete schematic? enter image description here

  • 2
    \$\begingroup\$ You can purchase a complete AC drive in that power range for about $125 US. I wouldn't bother trying to roll your own. \$\endgroup\$
    – R Drast
    Nov 11, 2016 at 14:30
  • \$\begingroup\$ One factor to learn about all motors is the surge current is due to DCR of coil and lack of back EMF when starting so Imax = 5~8x (I_rated) in large motors and 8~10x in small. and for low loss you want motor power surge to be 50x more than loss in IGBT switches. For efficiency this is why they use VFD inverters with V/F constant for speed control while I=torque used for rotational mass or delivered to load when changing speeds. DIY is not cost effective but a learn by mistake on many assumptions of the process. \$\endgroup\$ Nov 11, 2016 at 14:42

1 Answer 1


That schematic is correct, but a huge simplification only intended for understanding the core function of a voltage source topology variable frequency drive.

It lacks a lot of stuff: gate drivers for the IGBTs, snubbers for the IGBTs, power supplies for the gate drivers, control logic (in the form of an ASIC, a digital signal processor and/or a FPGA), power supply for the control logic, galvanic isolation of the external control inputs, user interface, current sensing circuitry, voltage sensing circuitry, possible cooling system (fan), input filtering, output filtering and more.

Then there is the software to control it all, which isn't trivial to do properly. A crude implementation might only take a week or so for an experienced embedded programmer to do, but a proper control system like direct torque control would take much more development effort.

It's certainly possible to make a homemade VFD (especially if you sacrifice reliability, safety and feature set), but it's not going to be economical in either money or time. I'd buy a commercial one.

  • \$\begingroup\$ Thank you for your answer.Could you please tell me where could i find more information about all the circuitry i need?I plan to research on this topic.Also i want a simplistic inverter,nothing too complicated.I want make a low-cost inverter..i worked previously with an Altivar-71 which is 1500$.My teacher said it would be a great research topic. \$\endgroup\$ Nov 12, 2016 at 3:18
  • \$\begingroup\$ @jms, please help me with this problem electronics.stackexchange.com/questions/350657/… \$\endgroup\$ Jan 18, 2018 at 14:17
  • \$\begingroup\$ If you spent that much for a .3kW VFD, you were taken to the cleaners... You can buy one that small for under $100. \$\endgroup\$
    – JRaef
    Jun 9, 2018 at 0:18

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