Brushless controller - motor lock for mobility aid

MVS

1 mW
Joined
Jan 11, 2014
Messages
11
Is there on the market a brushless motor controller for 60V 750W (nominal motor power) that can be programmed or wire set up to fight to lock the motor on Hall throttle release?

Can the motor lock wires on cheap brushless motor controllers be of any use for this situation?

General controller regen braking doesn't work well at low motor speeds.
 
I have seen several inexpensive brushless controller that have an "anti-theif" feature that uses battery power to resist any rotation of the motor. It effectively locks the wheel, but could drain the battery if used for a long time.

The problem I see is the motor needs to be stopped before engaging this feature or you may have a pretty violent stop and/or break something.

I have seen some other, more expensive FOC controllers (like the PhaseRunner I believe) that have an active regen that will still slow the motor at very low speeds by using battery power when needed, similar to the anti-theif feature. This would probably be ideal but more difficult to get set up.
 
The expected violent stop with the cheap trapezoidal "anti-theft" solution would be a serious issue.

The more expensive FOC controller would be the preferred solution.

I have experience setting up FOC solutions with Sevcon, Sabvoton and LBMC motor controllers.

Never used Phaserunner though. I already browsed the user manual. Looks very generic. It has variable analog input regen. I can't find configuration parameters to use torque to maintain the rotor stopped with idle throttle or brake line (like a servo, it only uses power if the motor has to produce torque to maintain the standstill condition).

The controller that best emulates what I am trying to do is the Sevcon Gen4 but the price and setup for a new cheap motor is a mess. I don't want to go down this road. The lack of professional support for small projects is appalling.
 
You might check in Justin_LE's unicycle threads; since they are self-balancing they may do what you are after, though it may require adaptation for your purposes.

Keep in mind that the current needed to hold something in position on a slope may heat the motor (and controller) significantly, depending on the weight, rolling resistance, and slope itself.

This is part of why the typical powerchair/etc uses a solenoid-controlled mechanical brake on the wheels instead (regardless of whether they have brushed or brushless motors).

The extra power usage is another reason for that. It takes less power to control the solenoid than to hold the motor directly by current thru it.


Another reason is safety: The ones I've opened up use the fail-safe method of requiring power to disengage the solenoid brake, so if power fails it locks the wheels and it can't accidentally just roll down a slope. If motor power is required to brake, with no fail-safe mechanical brake, then the rider will be unable to stop it from rolling forward or backward down the slope.
 
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