Looking for help with sourcing speed controller with variable braking

Electric Motors and Controllers
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allezgrand   1 µW

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Looking for help with sourcing speed controller with variable braking

Post by allezgrand » Feb 12 2018 3:05pm

Hi all,

I’m looking for guidance in selecting an electronic speed controller for a BLDC motor. This isn’t for an electric vehicle, but this seems like the best group to ask since you all tend to have the most experience with and knowledge of BLDC motors.

I’m looking for an ESC with forward, reverse, and variable braking which I can control using a microcontroller (virtually any hardwired input signal (PWM, PPM, 0-5V, etc.)).

For braking, I’m looking for one of two options, or ideally, both:

A) If you imagine a heavy car going downhill, I’d like to apply the brakes so that it moves at 5 mph, 10 mph, or 20 mph, depending on the signal the ESC receives.

B) I’d like to be able to resist a fixed amount which I can vary. If you imagine a car going into a turn, you want to be able to brake a different amount depending on the track conditions and the point in the turn. For example, I want to be able to vary the resist from 10 Nm to 100 Nm. I’m guessing this would be common in the electric car world, but I don’t know.

For forward or reverse, I’d like to be able to set the RPM based on the PWM signal such that as the load varies, the motor speed does not. Is this commonly the way they are setup, or does the PWM signal from a receiver typically control power from 0-100% instead of RPM?

The motor I’m controlling will be using a 24V power supply with a maximum load of 10A. It is 4 pole and equipped with a hall effect sensor. The range will be 120 to 480 RPM. Any help or direction you can offer is greatly appreciated!

MotorboaterBen   1 mW

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Re: Looking for help with sourcing speed controller with variable braking

Post by MotorboaterBen » Mar 08 2018 9:06pm

emsiso emdrive150 is programmable and can do most if not all of that.
-separate throttle and brake inputs
-control via CAN, 0-5V analog, or PWM
-controllable in speed or torque mode (so you can set a constant rpm and vary power to match varying loads)

https://www.emdrive-mobility.com/copy-of-emdrive-500

A little overkill but I am not aware of any smaller controller with these capabilities

casainho   100 MW

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Re: Looking for help with sourcing speed controller with variable braking

Post by casainho » Mar 19 2018 11:58pm

Our Flexible OpenSource firmware will o that and the controller can be commanded by UART, from an external Arduino or Bluetooth module...
Developer of the Flexible OpenSource firmware for EBike motor controllers and LCD3:
- Unlock and get more power with the TSDZ2 Flexible OpenSource firmware: https://github.com/OpenSource-EBike-fir ... _wiki/wiki
- Kunteng/BMSBattery VLR FOC motor controller: https://github.com/stancecoke/BMSBatter ... mware/wiki

allezgrand   1 µW

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Re: Looking for help with sourcing speed controller with variable braking

Post by allezgrand » Mar 20 2018 11:32am

Thanks to both of you.

Casainho, how much power can one of those systems dissipate if I'm not using a battery for regen? That seems to be the biggest limitation with every system I've looked at.

casainho   100 MW

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Re: Looking for help with sourcing speed controller with variable braking

Post by casainho » Mar 20 2018 11:39am

Just uses the battery for energy storing, no nother option.
Developer of the Flexible OpenSource firmware for EBike motor controllers and LCD3:
- Unlock and get more power with the TSDZ2 Flexible OpenSource firmware: https://github.com/OpenSource-EBike-fir ... _wiki/wiki
- Kunteng/BMSBattery VLR FOC motor controller: https://github.com/stancecoke/BMSBatter ... mware/wiki

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amberwolf   100 GW

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Re: Looking for help with sourcing speed controller with variable braking

Post by amberwolf » Mar 20 2018 12:39pm

If you don't mind building the controller yourself, at least partially, there's a lot of threads about the Lebowski controllers that would probably do what you want, too.

allezgrand wrote:
Mar 20 2018 11:32am
how much power can one of those systems dissipate if I'm not using a battery for regen? That seems to be the biggest limitation with every system I've looked at.
Regen pretty much always goes to the battery (or other power source) in a typical EV system. That's just how regen is designed to work in all the controllers I've seen.

There are at least a few controllers with "EABS" (though not all use the term, and not all that do actually do it this way), where they actively power the wheel against it's present rotation direction, but this will *use up* power, at about the same rate it would have regained it from regen. So if you would've gotten 5% power back if you used regen, you'll waste an *extra* 5% with this form of braking. That means you actually lost 10% power over using regen for the same thing. However, it can brake down to nearly zero speed (sometimes all the way to zero), and it could be more powerful if the controller can dish out the current to do it, and it should work about the same regardless of battery level, as long as it's not nearly empty (where regen is the other way--works better the emptier the battery is, and sometimes is disabled near full to prevent overcharge).

To do anything else, you'd probably have to build it yourself. There's a lot of discussion about power-sheddng/wasting systems like Plug Braking, but generally you aren't going to have any control over how much braking force you get, unless you make it complicated and probably heavy and large like using a brushed controller powered off teh motor and running a giant resistor off the output with the throttle of that being your ebrake, or a giant variable resistor (like a 20-30lb lighting pot dimmer), etc.

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