Controlling a VFD with Ardunio

We’re trying to control a Variable Frequency Drive (Mitsubishi d720s) with Arduino.

The VFD as a 24V control signal circuit, where activating pins triggers functions on the VFD. We’re attempting to use a MOSFET based circuit, such that we can map the 5V digital-write pins on the Arduino to the various input signals (STF, STR, RH, RM, RL) on the VFD.

Our circuit work with a separate 24V circuit (activating a lamp f.ex.), but when connect to the VFD it seems to be unable to fully activate the MOSFETs.

Also, we can’t really make out what should be the common ground for the Arduino and the MOSFETS, we tried placing it in the SD sink of the VFD, but with out success.

20170506_ludo, circuit.pdf (477 KB)

irf3708pbf_eng_tds.pdf (278 KB)

Hi,
Welcome to the Forum.

If all the control signals digital.

If so why not use opto-couplers to transfer control signals, that way you will have isolation and simple control.

The circuit you have at the moment relies on gnd of the Arduino being connect to the gnd of the VSD 24V supply.

Tom... :slight_smile:

The datasheet shows a jumper that switches from sourcing to sinking inputs using the SD terminal for common, you would connect the (for example) SDF input to the MOSFET drain and source to SD along with Arduino GND.
Why are you using big power transistors to switch a few milliAmps?
See page 2.3 of datasheet:
http://www.mitsubishielectric.com/dl/fa/document/manual/inv/ib0600477eng/ib0600477engb.pdf