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Topic: Need to help with circuit adapts to 5-48V drive DC motor design (Read 907 times) previous topic - next topic

Paul__B

It's not the voltage rating of the MOSFET, it is the fact that that particular one requires more than 10 V to turn on, and when you apply 5 V to the base of the 2N3904, it pulls the gate down to 5 V.  10 + 5 is 15 V, so the FET will not turn on with a lower supply voltage.

6v6gt

If you also want the motor to be reversible, search for H-Bridge motor control circuits.

HellasT

How will you correct the circuit?
I will try to lay out a diagram for you. I just dont have the time to do so right low. Ill probably do it tomorrow.

TomGeorge

Hi,
Is there a reason you are using HIGH SIDE switching?
If not.
LOW SIDE switching uses less components and is less complicated.

Can you tell us your electronics, programming, arduino, hardware experience?

Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

HellasT

This is what i can think of. I dont know if it will work for you.

Note that the IRL540 can handle up to 100V drain to source and up to 20A maximum
If the motor requires less than 20A then you should be ok whthout relay but with a heatsink.

If your supply voltage is not steady then you will probably not be able to use the relay version.

P.S.
in suggestion 2 i mention "if motor needs more than 18A"...
The correct is "if motor needs NO more than 18A". 

TomGeorge

Hi,
@HellasT images;
Sugg 1.

Sugg 2.


Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

HellasT

Thank you. I dont know how to do  that :)

Please note :

In suggestion 2 i mention "if motor needs more than 18A"...
The correct is "if motor needs NO more than 18A". 

MarkT

Need to design a circuit that uses Arduino to control a 5-48V DC motor. Is the circuit shown feasible?
If you lost R1, R2, R6, Q1, D2 and limited the supply to 12V and up, and put the motor on the FET's drain
it might work, but at 48V R3 would have to be rated at 2W or more.  You also need a free-wheel diode across
the motor.

The normal approach is a logic-level nFET, not a pFET, as the circuit is even simpler, only 3 components
needed, gate resistor, FET, freewheel diode.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

kmimax

Thank you. I dont know how to do  that :)

Please note :

In suggestion 2 i mention "if motor needs more than 18A"...
The correct is "if motor needs NO more than 18A". 
If you lost R1, R2, R6, Q1, D2 and limited the supply to 12V and up, and put the motor on the FET's drain
it might work, but at 48V R3 would have to be rated at 2W or more.  You also need a free-wheel diode across
the motor.

The normal approach is a logic-level nFET, not a pFET, as the circuit is even simpler, only 3 components
needed, gate resistor, FET, freewheel diode.
Thank you. I dont know how to do  that :)

Please note :

In suggestion 2 i mention "if motor needs more than 18A"...
The correct is "if motor needs NO more than 18A". 
Thanks HellasT, MARKT

I really appreciate your help with this and the circuit diagram provided,
This circuit diagram is similar to Nick's circuit diagram. In fact, I tested it with a 48V/8A power supply and a 48V6A DC motor. Under the condition of 48V power supply, it can basically operate normally, but once the voltage rises to 48V, the MOSFET (IRF540N) is immediately broken and damaged. Is it because the capacitive coupling spike causes the gate voltage to exceed the safe range? Need to add a Zener diode to the gate-source terminal?

raschemmel

I don't think you specified whether or not the mosfet is heatsinked and if so what kind.
Please post a photo of the mosfet as it was when it was damaged (with or without heatsink at the time it
was damaged)

Are you monitoring the mosfet temperature with a DS18B20 temp sensor ?
If not, you should stop work on the circuit until you have a working DS18B20 sensor mounted directly to the mosfet with thermal epoxy.

If you have a cooking thermometer that could provide useful information temporarily until the DS18B20
is installed.

Do you have a small cooling fan you can use ?
Do you  have a flyback diode across the mosfet ?
Are you measuring drain current with a DMM ?

You need to measure the mosfet temp and drain current until your system is stable.
You're wasting your time until then.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

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