Hi all!

I am new here, so please guide me. I am currently working on a project which involves working with H-bridges for motor control. It is required that I am able to wire up the circuit and make it work. The only problem is that I am a Mechanical Engineering student, so I have no knowledge of how this circuit is supposed to work. Since it was passed on to me by the previous year students who are no longer working on this project, I have no way to confirm what is happening in the circuit.

The circuit is attempting to create 3 phases (A, B and C) to run a BLDC motor using 3 identical H-bridges, and while I understand the concept of what is supposed to happen, I am confused as to why it doesn't work in real life when plugged in. Could someone please advise if the circuit is correct, what is happening inside it and whether it will work as intended when plugged in to a breadboard, since I have tried wiring everything up exactly as specified and it didn't work (I know that the N-channel MOSFETs and the other components are not fried because they show continuity)?

Thank you!

 

You don't. You can expend the time and effort to learn what you need to learn, you can try to simulate the circuit as an aid to understanding, you can ask for assistance from a mentor, or you can try to breadboard the thing to see if you can get something working. There are lots of different ways you can go, choose one and get on with it. what else can you do?

 

I suggest you try to find an upper classman, electronic engineering student to help you.

 

The circuit is attempting to create 3 phases (A, B and C) to run a BLDC motor using 3 identical H-bridges,

Although both types of motors are virtually identical , Strictly speaking you are describing two types of motor as one, IOW it is ran either as 3 ph AC or BLDC,
The former is a full 3ph signal, usually sine wave, the BLDC has only two windings energized at any one time, and essentially resembles a DC motor commutated motor, turned inside-out.
The drawing indicates the AC 3ph version.
What happens when you "plug it in" oscillates?, hums,? what symptom from the motor?

 

Welcome to AAC!

I know that the N-channel MOSFETs and the other components are not fried because they show continuity

They only show "continuity" when they're on. When they're off, the S/D will show a very high resistance in one direction and a diode in the other.

 

I noticed on your schematics the hand written notes about capacitor polarities being wrong, and one of the chip symbols being mirrored. Those indicate that what you have is not a final schematic, has at least some errors and may be incomplete. Also there is a microcontroller involved, which implies there is a software component as well (someone needs to program that chip). I would start by grabbing someone from the electrical department and ask them to help you make sure what's on paper is correct, and that what you've implemented on the breadboard reflects the corrected version on paper, and that the program has been flashed to the chip.

Also, motor controllers are very common and available off the shelf. If there's not a specific reason to use this design, it might be less painful to just buy one.

 

There are stages on what you might consider being complete rarely do you get perfection on a first shot breadboard, but it is possible.
When it works partially then you will identify or isolate that sub-section that works or even better you might determine if is within specs.
I like to start at the power source and build toward a working section on copper soldering right angle dupont connectors
as straight connectors tend to stack away from the ground plane. It gets fun when all the sub-circuits are mounted on a revised pcb instead of being all plugged together. Sometimes you have to cut into the revision adding connectors but that stage of development can have different issues. If you cannot isolate what is good then how will you isolate what is bad. After much time I have found that a more careful look at the spec sheet says " I told you so !"

What if you don't need to build the way I described. OK, Here is a video about a project that was standard enough and hopefully you have accumulated enough experience like this person did and work through all the frustration without knowing all the tricks in the art of pcb design processes. I think she was able to implement each component either in or out of the circuit because she understood how to set up and test from the data sheet.

 

Hi all!

I am new here, so please guide me. I am currently working on a project which involves working with H-bridges for motor control. It is required that I am able to wire up the circuit and make it work. The only problem is that I am a Mechanical Engineering student, so I have no knowledge of how this circuit is supposed to work. Since it was passed on to me by the previous year students who are no longer working on this project, I have no way to confirm what is happening in the circuit.

The circuit is attempting to create 3 phases (A, B and C) to run a BLDC motor using 3 identical H-bridges, and while I understand the concept of what is supposed to happen, I am confused as to why it doesn't work in real life when plugged in. Could someone please advise if the circuit is correct, what is happening inside it and whether it will work as intended when plugged in to a breadboard, since I have tried wiring everything up exactly as specified and it didn't work (I know that the N-channel MOSFETs and the other components are not fried because they show continuity)?

Thank you!

Get this book from Amazon- it will help you:

Title: Understanding Basic Electronics, 1st Ed.
Publisher: The American Radio Relay League
ISBN: 0-87259-398-3