Electronic speed controllers for brushed DC motors

[p.gholap93]

Recently I used BLDC motors and came to know about ESCs used for that. Now I also came to know that there are ESCs for brushed DC motors also. An ESC can provide much higher continuous current which hardly any driver provides and is much smaller in size. Its control input is compatible with controllers and requires few connections as opposed to designing a PCB for motor drivers. So,why do we go for special motor driver ICs and not ESCs for brushed DC motors?

 

[misterT]

So,why do we go for special motor driver ICs and not ESCs for brushed DC motors?

ESC stands for "Electronic Speed Controller" and all of them have special driver IC inside. Some applications need better control than the small and cheap commercial ESC provide and then the only option is to design and build your own controller (or buy a servo controller).. and sometimes people design and build motor controllers just because they think it is fun and educating.

The key point here is to understand the difference between simple speed controller and a servo drive.

 

[shimniok]

Funny, I was just thinking about switching over to using a brushed ESC to drive the 'fan' on my firefighting robot. I'm going to be using a motor and prop combo that lends itself well to a small ESC versus me dinking around with a FET or BJT driver.

Like any situation you fit the available options to the problem to be solved. Sometimes the current demands are too high for an affordable ESC (thinking of one very large robot I saw at a local Maker Faire with dozens of TO220-sized driver) or are so low that an ESC is pointless overkill, like the Mabuchi 180 drive motors on Pokey, my firefighting robot. They draw something like 2A stalled.

Using off the shelf parts where all the hard work has been done for you is certainly a good strategy when you're interested in working on higher level problems and not getting caught up and delayed in the details.

Asking your question another way, why would we use an ESC if a simple motor driver IC would do the trick?

 

[Sceadwian]

Because Motor Driver IC's require the use of additional circuit components, such as caps resistor possibly inductors, which you have to mount on a PCB and connect. A fully furnished ESC Is power in. signal in, motor out, plug and play. The time you spend learning out to properly utilize the IC and understand how it works and optimize it is time you could be spending simply using a finished product. The cost is obviously higher in finances, but the cost in time and learning is something else. IF all you want to DO is make robots you don't need to know electronics at ALL. You just need to know how to put the right off the shelf components together, granted their's some way better things you can do with experience in electronics it's up to you to weight the pros and cons and the amount of time and energy you have to invest and make sure you invest it properly, or you'll get no practical returns.

 

[p.gholap93]

Because Motor Driver IC's require the use of additional circuit components, such as caps resistor possibly inductors, which you have to mount on a PCB and connect. A fully furnished ESC Is power in. signal in, motor out, plug and play. The time you spend learning out to properly utilize the IC and understand how it works and optimize it is time you could be spending simply using a finished product. The cost is obviously higher in finances, but the cost in time and learning is something else. IF all you want to DO is make robots you don't need to know electronics at ALL. You just need to know how to put the right off the shelf components together, granted their's some way better things you can do with experience in electronics it's up to you to weight the pros and cons and the amount of time and energy you have to invest and make sure you invest it properly, or you'll get no practical returns.

One more problem while using motor driver has been its low current rating. Very few drivers are available in market with o/p current of the order of 20A.
Some doubts regarding ESCs-
1) Can I control speed of brushed DC motor using ESCs?
2)Can I rotate motor forward or reverse through software instructions like the way I do with motor drivers(simply reverse a and b)?

 

[Sceadwian]

Your best bet is going to be with hobby ESC's, the answer to all your questions is yes. You will be able to find a brushed motor ESC that has forward reverse, and likely a braking feature as well (once you have the full bridge for forward/reverse the breaking feature is free) They're easy to drive with a simple PWM.

 

[p.gholap93]

Your best bet is going to be with hobby ESC's, the answer to all your questions is yes. You will be able to find a brushed motor ESC that has forward reverse, and likely a braking feature as well (once you have the full bridge for forward/reverse the breaking feature is free) They're easy to drive with a simple PWM.

I think that with ESCs I can control speed only and for reversing the motor I will have to swap the two terminals.(i.e. can't be achieved through software instruction) Is there any datasheet available for these ESCs because I googled a lot but can't get good information.(Like the characteristics of the PWM signal)

 

[Mr RB]

The use brushless hobby ESCs for boat and car motors, which may be reversible as boats and cars normally use reverse at times.

 

[p.gholap93]

The use brushless hobby ESCs for boat and car motors, which may be reversible as boats and cars normally use reverse at times.

I want ESCs for brushed motors!

 

[Sceadwian]

p.gholap93. I'm sorry but you've failed Google 101... Learn to modify your keywords and use the proper ones to get results.
https://www.hobbypartz.com/es20abrmoesc.html
If that's within your voltage range, that's just one example, not much information on that site, but you should be able to find plenty of other units out there that support forward/reverse/brake.

Hobby servo signals (which the ESCS use) are neutral at 1.5ms far left at 1ms and far right at 2ms wide pulses. The pulses are repeated 20 times per second.