TheBackShed.com

Forum Index : EV's : brushless motor doubling as generator

Author

Message

Ninja Chris

Newbie

Joined: 26/04/2011
Location: New Zealand
Posts: 2

Posted: 06:24pm 30 Dec 2015

Copy link to clipboard

Print this post

Hello all, not a frequent visitor here but I thought this might be the appropriate place to ask this question: Does anyone know of an off-the-shelf solution for controlling a brushless motor that can also handle generation when that motor is driven?

My question relates to Bryan Roberts' gyromill concept and the practicalities of turning a quadrocopter into one by replacing the fixed propellors with variable pitch ones like this. The motor/generation control system seems to be the major technical challenge to overcome here.

Thanks,
NC

Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5012

Posted: 04:04pm 31 Dec 2015

Copy link to clipboard

Print this post

Tough one. Dont know of anything off the shelf.

You could connect a 3 phase bridge rectifier across the motor terminals, and it should not affect the motor controller when the "device" is running as a motor, provided the bridge rectifier output is open circuit. When you want to run the device as a alternator, you can connect a load to the rectifier output, and that will work, but the motor controller may has a hissy fit, depending on how smart/dumb it is.

If the motor controller can be disabled, so its drive signals to the power mosfets are all off, then it should be OK.

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

Ninja Chris

Newbie

Joined: 26/04/2011
Location: New Zealand
Posts: 2

Posted: 10:44pm 31 Dec 2015

Copy link to clipboard

Print this post

Hi Glenn, thanks for the reply. I've been thinking about this some more and had a bit of a revelation: I think the functionality I desire is identical to the regenerative braking that is built-in to e-bike brushless motor controllers. This seems to be well described here.

Edit: Also found cheap, simple, regenerative brushed motor drivers: https://www.dimensionengineering.com/datasheets/SyRen10-25.pdf

Further edit: There's a useful discussion of regenerative braking in e-bike controllers here. The short version is that some do offer this function but that it is not particularly efficient or well handled. The function I desire, where power is fed back into the battery from a brushless motor operating as a generator in an optimised manner, is termed "variable regenerative braking" and is not yet available on off-the-shelf units. It does seem to be close, though. Edited by Ninja Chris 2016-01-02

Print this page

To reply to this topic, you need to log in.