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Brushed ESCs

Started by sanjayrai55, July 11, 2013, 07:55:57 AM

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sundaram

No you are getting me wrong. I was referring about one of methods to prevent a connected ESC from spinning motor is to disconnect one of the three wires. There will be no latkas or jatka. Motor will behave dead. But you can hear tones of programing  ;)

VC

Why do you intelligent big wigs have to rely upon the old idiot to show you the way? Now stop talking and get down to work:

Growing old is mandatory, growing up is optional!

sundaram

Not without modifications  VC.  I watched whole video thinking its some method without modifications. There is a part -II and part -III also.   :giggle:

girishsarwal

VC sir,
QuoteWhy do you intelligent big wigs have to rely upon the old idiot to show you the way?
Because we love grampa.

Quotebig wigs
don't know about Sandy sir, but I totally have a receding hairline, so the wig is necessary...lol

QuoteNow stop talking and get down to work:
I could barely hear any audio in the clip, but from the looks of it he is trying to make a ESC programming connector so he can reprogram it for brushed. The 6 diode suggested by sandy sir, is a generic solution which will not require one to mod existing ESC but will sit between the ESC and the motor

Sandy sir, got what you mean.
gs

RCNeil21

Girish sir cant we reflash the esc to run on brushed?
Anyway, a brushed motor needs DC power whilst brusless need ac to commute. With direct DC brushless motors have no way of commuting. While brushed motors have a mechanical commute. So direct current is used this is what i understood. So either we remove the FET's from the esc to stop switching or convert the ac back to DC with a bridge rectifier like sundaram sir said. Or if we could reflash it to run brushed.
Build planes like feathers rather than tanks, both handle bullets equally well.

girishsarwal

Sandy sir's idea seems doable without any modding/opening ESC...I believe it's a much easier option and independent of other variables in the equation such as ESC freq, ESC has a microchip-firmware or not, can be reprogrammed or not, etc etc.
gs

sundaram

#31
Seriously none of you guys tried till now any of the methods?????.  >:D


Ok guys let me give you heads up. Unlike a brushless motor if you connect a brushed motor between two terminals of brushless ESC it will run but only at a very very slow interminant manner say 20% its full speed. This is  because ESC is designed to give drive pulse to motor timed by the back emf of the pole.  But if you re write the firmware with correct timings then you will be able to drive a brushed motor. Mind you the Brushless ESC is still not designed to run a brushed motor.

Even if you use bridge method with 6 diodes even then it run a shade better. But not at all to full capacity. However it will stop after some seconds for lack of back EMF.

Go on try it I have tried it.  :)

Yes if you able to supply commutator contacts directly with brushless ESC. It will run to full capacity.

AnjanBabu

Quote from: sundaram on July 11, 2013, 07:39:39 PM
Seriously none of you guys tried till now any of the methods?????.  >:D


Ok guys let me give you heads up. Unlike a brushless motor if you connect a brushed motor between two terminals of brushless ESC it will run but only at a very very slow interminant manner say 20% its full speed. This is  because ESC is designed to give drive pulse to motor timed by the back emf of the pole.  But if you re write the firmware with correct timings then you will be able to drive a brushed motor. Mind you the Brushless ESC is still not designed to run a brushed motor.

Even if you use bridge method with 6 diodes even then it run a shade better. But not at all to full capacity. To get full capacity you will have to rewrite firmware with correct timings.

Go on try it I have tried it.  :)

Yes if you able to supply commutator contacts directly with brushless ESC. It will run to full capacity.
Right.
I tried the 6 diode bridge now and the brushed motor doesn't really run that well. I don't know if its the diodes I used that were inappropriate, used 1N4007s. Also, the motor started stalling as I went above half throttle on the stick, not sure why.
Mechatronics engineer . Hopeless realist

anjanbabu.wordpress.com

sanjayrai55

When do you sleep Anjan? This post was at 4:30 am!

sundaram

Brushless ESC don't have sensors for keeping the timing for the drive pulse generated by ESC and they are largely dependant on the feedback of the back EMF generated by the Motor. So if you connect the brushless to two wires of brushless ESC it will still run slowly but if you are going to connect it using a single diode then it will not run at all. when you are using a bridge rectifier it will run for some time and then stop due to lack of back EMF.

AnjanBabu

Quote from: sanjayrai55 on July 12, 2013, 06:28:59 AM
When do you sleep Anjan? This post was at 4:30 am!
When your daytime wasn't productive enough, you make it up in the nighttime   :giggle:
Mechatronics engineer . Hopeless realist

anjanbabu.wordpress.com

AnjanBabu

Quote from: sundaram on July 12, 2013, 08:43:04 AM
Brushless ESC don't have sensors for keeping the timing for the drive pulse generated by ESC and they are largely dependant on the feedback of the back EMF generated by the Motor. So if you connect the brushless to two wires of brushless ESC it will still run slowly but if you are going to connect it using a single diode then it will not run at all. when you are using a bridge rectifier it will run for some time and then stop due to lack of back EMF.

Alright, I'm waiting for a solution now, if there is one.
Mechatronics engineer . Hopeless realist

anjanbabu.wordpress.com

Tanmay.mathur

what about removing the back plastic cover and connicting 3 pads of the commutator to the 3 wires of the esc and set the esc timing to auto detect and save. that shall[or might] work as an outrunner brushless motor
there is one problem we can only use it as a pusher prop configuration .
until unless the bell is stopped to slip out by e ring lock or bearing lock .
thats what i  think . could it work ??
Regards,
Tanmay mathur

girishsarwal

Here's a video for the eager beavers



This is a half wave rectifier scheme. My observations:

- Response time is not great, much like a nitro engine running rich
- One will lose 0.7v due to the p.d of the diodes.
- Use fast switching dioides.
- Use diodes that can handle current and temperature. They will get really hot with higher currents, and poof if go beyond thermal/electric tolerance.
- Could use MOSFETs but it would lead to unnecessary complexities
- Proportional control is not too good .  The range or proportional control aint great either. 10% and 40% sound similar but yea i was using crappy 1.5v motor so can't complain. May get better results with a full wave
- No reverse without added circuitry, use an H-bridge but yes then getting hold of a brushed is easier
gs

Balakrishna Reddy

Why people are knocking your head this much. There is simple method of doing this with arduino. Just calculate incoming pulse width using pulseIn and accordingly drive a mosfet using a GPIO pin on MCU. If not interested in arduino The pulse width can be measured using interrupts or pin change interrupts and then according program PWM to a MOSFET. If you want to add more features then try to merge them with it.Its lot more easy.

girishsarwal

Agreed Bala, in fact even an Arudino is an overkill, a PWM to PAM converter is all that is required (can be wired with a 555 and a few opamps). Here is a PDF http://www.elektro.undip.ac.id/sukiswo/?download=PT2_4_%20PWM%20Demod.pdf&usg=AFQjCNFzdSLgQFMepFrGfrfgqFASziTCpw&bvm=bv.117868183,d.c2E that talks about PWM to PAM conversion. Feed the output to a MOSFET and we have a basic brushed ESC. Use an Hbridge and we have reversal

There has been a discussion on this topic that warranted a video to demonstrate the concept that was being theorized amongst us tinkerers; The idea was to use a brushless ESC without modding or creating something new...   ;D
gs

Tanmay.mathur

i think every brushed motor have 3 poles/terminals/pads on the rotating stator , couldnt we connect it to bldc esc . And we will have a outrunner bldc motor ?
Regards,
Tanmay mathur

Balakrishna Reddy

Quote from: Tanmay.mathur on March 29, 2016, 05:04:42 PM
i think every brushed motor have 3 poles/terminals/pads on the rotating stator , couldnt we connect it to bldc esc . And we will have a outrunner bldc motor ?
Yes we can connect it like that but you have to small modifications to it.
remove all connections connecting three poles is series such that you will have 6 terminals with you i.e cut the connections of wires internally on commutator.
Now this 6 wires are same as bldc 6 terminals join one end of three wires as neutral and remaining three to ESC will do the job.

Balakrishna Reddy

Quote from: girishsarwal on March 29, 2016, 10:59:04 AM
Agreed Bala, in fact even an Arudino is an overkill, a PWM to PAM converter is all that is required (can be wired with a 555 and a few opamps). Here is a PDF http://www.elektro.undip.ac.id/sukiswo/?download=PT2_4_%20PWM%20Demod.pdf&usg=AFQjCNFzdSLgQFMepFrGfrfgqFASziTCpw&bvm=bv.117868183,d.c2E that talks about PWM to PAM conversion. Feed the output to a MOSFET and we have a basic brushed ESC. Use an Hbridge and we have reversal
There has been a discussion on this topic that warranted a video to demonstrate the concept that was being theorized amongst us tinkerers; The idea was to use a brushless ESC without modding or creating something new...   ;D
I am not very much sure about this circuit because the PWM of receiver is only 10-20% duty cycle so when connected like that your motor won't rotate with full speed it will rotate at very less speeds so a micro controller just with one PWM pin and an additional timer will be very much efficient in using board space as well as we can add extra features such as throttle setting and configuring for min/max throttles etc.

Tanmay.mathur

could reversin possible in above setup without H bridge ?
Regards,
Tanmay mathur

Balakrishna Reddy

For motor reversal the potential across it must be reversed. In order to do that we need a H-bridge only. The brushless esc can be made into brushed ESC by writing a small software to it because there is already bridges in it.

Tanmay.mathur

okay sir got you.
Whats needed to do if i have a atmega8s from a brushless esc and a l293 h bridge.
Schematics and circuit info
Regards,
Tanmay mathur

Balakrishna Reddy

You dont need to have both ESC and l293 for brushed motor, one bldc ESC is enough if you have its circuit diagram to drive brushed motor. Else if you have an atmega8,l293 and if you know to program it then half of work is easy. First read pwm of receiver which will be at 10-20% duty cycle and convert to 0-100% duty cycle in your program.
First let the micro controller start
Now start two timers. One to calculate pulse width and other to drive motor.
using interrupts capture rising edge and falling edge of PWM signal and take the time of pulse width.
Now modify this time value to required output to atmega PWM pin which is connected to l293
if you want to have motor reversal connect 2 atmega PWM pins to 2 pins of l293
if you want one side rotation connect one i/p to ground and other to atmega PWM pin.

kartp3112

You could use an attiny85 or any microcontroller to convert the pwm to values between 0-255 and then run a high amperage motor driver with the outputs i have made one with an arduino pro mini and a dual 40 amp l293d motor driver.
When the whole world runs to a cliff he who runs in the opposite direction appears to have lost his mind

Balakrishna Reddy

I suggest using some attiny instead you can save a lot of board space and so does the power and weight of your total ESC.