PWM controlled DC motor using 2n3055: Is it okay? How can be improved? + Proteus file

PWM controlled DC motor using 2n3055: Is it okay? How can be inproved? + Proteus file

Hello, I am building a PWM controlled power stage for a motor.

I have created a circuit in proteus and it works, kinda cool, but, I have the feeling it has to be inproved and some questions about Integrating the signal and how the transistor 2n3055 works. I would like somebody elses opinions and corrections.

The target is to regulate the voltage of a load via PWM duty and 2n3305 transistor.


Resources:
Proteus files :


Project schematic:




A fast brief.

How to test it: Once downloaded and opened proteus file, Send characters 0 to 5 through the virtual terminal to easyly set the PWM duty, this was done like this for testing purpouses. As shown in this video:

We work on TTL so:
Vpwm = 5v

As output a DC motor with full variable values, current will vary depending on the resistance applyed on the rotor, and voltage by the PWM.
Motor Voltage Range=0v-12v
Motor Current Range= 0A-10A

Explanation

1. PWM signal.
No problems with this. An arduino creates a signal via analogWrite, ino file included in sources.

2. Integration.
In order to convert incoming signal from PWM into a integrated signal, I built up this Rc filter, I can see is not the best one because R2 is too high and its take to long to become stable.
I would like to inprove this in order to flaten the signal. Is the way Im using correct?

3. Amplification.
A Non-Inverting Operational Amplifier will amplify the voltage of the integrated signal X2 volts aprox, in order to create 0-12 volts from a 0-5 volts range.
Should I use a BC547 or TIP31 or any BJT transistor? or OPAMP is better, I think the second one is more appropiate but I may be wrong.

4. Power driver
I have to use a 2n3055 transistor because i have it, and because due to hardware settings it has to be npn.
He is able to work in the power range I need as we can see in the table above.
I reached the resistor values by empirically trying with proteus, thats why i have serious doubts about if its right.
I dont know how make it safe and be sure. It seems it works, but I dont know if this is the best way.

2n3055 table


Questions

I would like to read your opinions and critics before I start building it, and I would be very thankful with al advises and proposals.

Re: PWM controlled DC motor using 2n3055: Is it okay? How can be inproved? + Proteus

Wiring the motor in the transistor collector is a better solution. The reason is that to provide enough bias current (could be quite high for a 2N3055) you have to lift the base voltage above the emitter voltage and the emitter already has the motor voltage on it. If you ground the emitter, the base current is always referenced to ground. Consider adding a diode across the motor, wired so it is normally NOT conducting to trap any reverse voltage spikes it might produce.

To be honest, if you are driving a DC motor like that, you can probably feed it the PWM directly and leave out the filter and amplifier. A MOSFET rather than 2N3055 would work with far fewer losses. I control 2A motor loads from a small TO-92 MOSFET using PWM and it doesn't even get warm.

Brian.