3 Phase motor control application.

Dear all

I am looking for a simple circuit for controlling 3 phase motor. I Have an application. I would like to create a small demo project before going into bigger implementation

I have a borewell. 3 phase motors are used to pump water from the borewell. I am going to connect a water flow sensor to check volume or whether water is flowing or not. if there is no water flowing in the sensor motor will be running idle state. I wanted to cut off the motor supply when the water flow is zero. else it should keep running.

Can someone suggest to me the necessary component and schematic to execute the project?

I am planning to use node MCU/ Water flow sensor/ DC motor/Relay board to make the demo version.

My question how can replicate this application.

Let me know if any better application and sensor can be used.



What is the rating of the motor, in voltage, Hp etc?
I'm afraid there's no "simple circuit" doing what You want. Buy a ready three face driver that Your microcontroller might control.

In your design, consider the water flow sensor DOES NOT care which direction the water is flowing.


reading your post, the motor exists and is not to be controlled ?

3-phase motors are typically used to describe 230 or 480 AC voltage motors.
if that is the case, then you only need to buy a variable speed drive rated for the motor horsepower.

DC 3-phase motors are call BLDC and the answer is simple again, get the proper driver for the motor.

Control of the motor is the easy part. all you need to do is to output the signal that the driver needs.

the rest is simple as well. connect the flow sensor

the motor start-stop will be to the motor driver, not to the power.

if your mock-up is for a DC pump, like a pond pump, then you can use the relay or even a MOSFET.

A watchdog style of arrangement using a pressure switch and a start by-pass push button ( or similar if auto start) setup anywhere in the discharge line would be a simple and effective alternative.
Probably the most common approach as well in the real world.

i am trying to replicate similar workinghttps://www.youtube.com/watch?v=3qB12Ck96tU

but i would like to add flow sensor appliction here to measure flow rate

That sounds like two different projects - or at least two independent parts of the same project.

The video (I skipped through it) seems to show you how to do the on/off control of the motor. Start with that (if you do not have the skills to deal with 3 phase mains power safely and to your local regulations, ask help from an electrician, as mistakes here can do serious damage). Get that control to work first.

Next, find a flow sensor that's suited to the size of your pipe and the typical flow rate your pump produces. Most such sensors have a pulse based output, count pulses per time and you can calculate the flow rate. Get that working.

Now all that's left is integrate the two. Pump switches on; some time later you check for flow (it needs a little time to start up I suppose), and if there's no flow switch off the pump and send back a message so the user knows what's going on.