# Hub motor controller

#### pjreijiri

Joined Aug 19, 2015
101
Hello everyone I am building a robot and I am using hub motors to drive it.
I attached a picture of the control circuit. I was wondering if you can take a look at it and let me know if it works and if it is possible to have the motor run in reverse or should I create another circuit that has the poles flipped and connected to the motor.

Regards,
Patrick

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#### Sensacell

Joined Jun 19, 2012
2,835
Your driver is only capable of driving the motor in one direction.

You need an H-Bridge to make it reversible.

#### pjreijiri

Joined Aug 19, 2015
101
would it be able to handle 48V?

#### pjreijiri

Joined Aug 19, 2015
101
PS: it has to handle 8A

#### mcgyvr

Joined Oct 15, 2009
5,394
Sure one can make an hbridge that supports 48V and 8A..

#### pjreijiri

Joined Aug 19, 2015
101
Hello guys, I have been looking for H-bridges and either they are very expensive modules or can support up to 5A.
So I decided to make a simplified version.
What do you think of this circuit. I used IRFP4468 MOSFETs with a 220ohm resistor bank connected to the PIC microcontroller.
I used 4 MOSFETs for each motor and I "turn on" 2 at a time to drive it forward or reverse. Also for the second motor I flipped the motor connector.

What do you think?

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Joined Jul 18, 2013
23,141

#### pjreijiri

Joined Aug 19, 2015
101
why do i need a whole circuit since the IRFP4468 can be run with a voltage of 2-4V? I am using a pic16 so the 3.3 volts should work
Am I wrong?

#### Alec_t

Joined Sep 17, 2013
12,089
the IRFP4468 can be run with a voltage of 2-4V
Most unlikely. Vgs(th) for that FET is specified as min 2V, max 4V. That means in the worst case scenario you may need Vgs=4V to make the FET just begin to turn on and pass a measly 250uA .

#### pjreijiri

Joined Aug 19, 2015
101
I need to be controlling the motors with a PWM so I can control the speed.
I tried using the MIC4451 to run the MOSFETs. Both MIC are connected to the PWM of the microcontroller and they will be on the whole time. However I will use npn junctions that are connected to the microntroller and they in turn will control which way the motor is turning.
Would that work?
Would connecting a transistor to the VDD of the MIC instead of the MOSFETs be a better idea?

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#### Alec_t

Joined Sep 17, 2013
12,089
I will use npn junctions that are connected to the microntroller and they in turn will control which way the motor is turning.
Would that work?
Not with the motor connections shown. What are the diodes for? The lower ones seem the wrong way round.

#### pjreijiri

Joined Aug 19, 2015
101
Alec_t you are right, my mistake.
I fixed it, took two diodes out and uploaded the new schematics.

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#### Alec_t

Joined Sep 17, 2013
12,089
Can't see the detail in that pic .

#### pjreijiri

Joined Aug 19, 2015
101

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#### Alec_t

Joined Sep 17, 2013
12,089
Your circuit can't switch the upper FETs on. If you want to drive the motor with 48V then it needs ~58V on the upper FET gates to turn them on. That calls for a high-side FET driver IC such as the IR2110 which Max pointed out in post #7. The MIC4451 used in your circuit is a low-side driver only.

#### pjreijiri

Joined Aug 19, 2015
101
Your circuit can't switch the upper FETs on. If you want to drive the motor with 48V then it needs ~58V on the upper FET gates to turn them on. That calls for a high-side FET driver IC such as the IR2110 which Max pointed out in post #7. The MIC4451 used in your circuit is a low-side driver only.
But would I be able to drive the IR2110 with a PWM from the PIC16? Because I want to set the speed of the motor

#### Alec_t

Joined Sep 17, 2013
12,089
that it too expensive,
What is? An IR2210 is £1.57 from Mouser, £1.84 from Digikey.