24v DC Motor Controller HELP!!

Hello,

I am hoping to make a project EV and am planning on making my own motor controller from an Arduino Uno R3. I am using a 350W 24V 17A Brushed DC Motor that I want going forward and not backward so no need to worry about reverse. And x2 12V Lithium batteries that I will have wired in series to supply the motor with the 24V.

I was advised to use something like a P30NF10 MOSFET within the circuit to provide the necessary power to the motor without burning out the board. In preference I would like to use a breadboard to work on but doubt it can hold the power.

I created a basic schematic (attached) for what I think I need to do but not too sure if it will work or if there is a better solution out there for this. I’m also curious as to whether the resistor will support this circuit and if not, what would I need instead?

I hope to have a LCD Screen displaying the motor power % or RPM in the future and/or potentiometer to control the power output to the motor however I am happy with a simple Depressed Button.

Thank you in advance and any help and advise would be much appreciated.

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html

The OPs circuit;

Tom.. :slight_smile:

In preference I would like to use a breadboard to work on but doubt it can hold the power.

Quite correct, that motor would melt a breadboard.

As to the schematic you need a 10K pull down resistor from the gate to ground on the FET, and I would put a 150R resistor in series with the gate.

However the FET is totally unsuitable, it requires a 10V gate signal to turn it on and the rated current of 35A in a TO220 package is too close to what you want to drive. FET headline currents can rarely be achieved in practice due to thermal considerations.

I would also wire the push button properly, that is with the buttons between input and ground and an external pull up resistor of 1K. With that sort of load using the internal pull up resistor would not have enough immunity against interference.

Hi,
I would check on that MOSFET, I don't think it is a logic level MOSFET, that is it will not turn fully ON with only 5V of gate to source voltage.
I would be putting a fuse in the high current power line to act as protection.

Prototype boards will not take that sort of current and you will need some decent size wiring for the 24V power circuit.

Place a 10K resistor between gate and source to prevent the MOSFET turning ON due to stray current and during the bootup of the UNO.

Tom... :slight_smile:
EDIT: Beat me to it, I'm off to bed, goodnight Grumpy_Mike. :sleeping:

I’ve made a few alterations to the circuit and looked into a few more MOSFETs and this one has ±16V MAX, would this be suitable for the intended use?

I’ve included a 30AMP fuse as a safety measure, should I go for something larger or is this okay?

The grounding will be made on the chassis of the EV and also have adjusted the push button to be made directly from the source and inline resistor to reduce interference as requested.

I apologise if I missed anything out or interpreted what was said wrong as I’m still relatively new to this.

Thank you again for any assistance and support.

3924f4a4fef6115ff8ae5f132acf0c2cb5e9355a.png

Mikey3011:
I’ve made a few alterations to the circuit and looked into a few more MOSFETs and this one has ±16V MAX, would this be suitable for the intended use?

Of course not, as you’re switching 24V.

Do a search on Digikey, you for sure can find something suitable for your requirements (logic level, V(DS), current). There are some really beefy MOSFETs out there that can still be switched with 5V gate levels.

Otherwise you need a driver circuit, e.g. use an optocoupler to pull the gate up to 24V (if that’s allowed - check spec sheet).

Try something like an IRLB8721, 30V 60A, Rds 13mOhms at Vgs 4.5V. You may still need a heatsink but that's more like the sort of MOSFET specification you want. There are plenty of others.

Steve

Grumpy_Mike:
I would also wire the push button properly, that is with the buttons between input and ground and an external pull up resistor of 1K. With that sort of load using the internal pull up resistor would not have enough immunity against interference.

You seem to be ignoring this advice, why?

Also that data sheet says "VGS @ 10V" and you only have 5V unless you add a transistor to drive it.

Thank you wvmarle and Steve for the recommendations, I shall look into it, particularly the MOSFET advised!

Forgive me Grumpy_Mike, it was not intentional. I was unsure as to what you mean by an " external " pull up resistor and as to how/where this would be wired in. Are you suggesting in run in parallel with the button?

Again I apologise if I seem to miss anything obvious as i'm currently learning about the Arduino world and electrical components.

Thank you for all your patience, I greatly appreciate it!

Plenty of info around on how to connect a switch and pull-up resistor. If the explanation here :o isn't clear enough then you should do youself some good and check it out.

I will have a look into it bluejets. Thank you!

You mentioned that you also wanted to display power % displayed on an LCD. An easy way to make that work is to get a board like the Attopilot current and voltage sensor from Sparkfun. With current and voltage you can derive watts which is your consumption. Then you can display either the number of watts being consumed or correlate this number to a % output and display that.

A pull up resistor goes from the input pin to the 5V rail. Then the input pin is wired to one side of the button and the ground to the other.

Thank you f4b and Grumpy_mike. I think I have now got an appropriate schematic so thank you.

In regards to the diode to use. What would be suitable/cost effective a silicon or schottkey diode.

I was thinking about a 3A 1000V Unidirectional Silicon Diode or 6A alternative? I've tried to learn about diodes and their spec requirements however still struggling with it.

Cheers.

Hi, I'm looking to build a similar circuit and also have youthful experience in building circuits. Would it be possible to connect via email? I have some questions about your approach.

Hi,
Can you post your final circuit diagram please.
It will help anyone wanting to use this thread for there own queries.

Thanks.. Tom... :slight_smile:

Mikey3011:
I was thinking about a 3A 1000V Unidirectional Silicon Diode or 6A alternative?

What is a "Unidirectional Silicon Diode" the words Unidirectional are exactly what diodes are not.
EDIT :- Sorry brain fart.

That voltage is way over the top. The reverse rating only needs to be able to cope with the supply voltage so 50V would be fine. When the motor is generating hundreds of volts back EMF the diode is conducting and so the reverse voltage rating is not an issue.

The current rating of 3A sounds light, you should have a current rating of the same order of magnitude as the normal running current.

Hi,
Unidirectional == one direction.
Bidirectional == two directions.

Diode == Unidirectional.
TVS , Diac == Bidirectional ?

Sounds like the OP is quoting directly off the parts list.

Tom... :slight_smile: