RC Motors

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Woodj

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Arrma RC's
When a rc motor brakes or goes Into reverse mode, does it charge the battery similar to a f1 e car
 
Apply power to a motor it spins. Spin a motor and it will make power.

If you go to most modern front load washers, you can unplug them from the wall- but if you reach inside and spin it quickly, it will power up the control board until the drum slows down. (a few seconds)

But hitting the reverse on an RC is still putting power to the motor. It is DC, not AC.

AC doesn't care about polarity, flip the wires and it still runs the same direction- alternating current. Reverse DC (direct current) and you reverse direction.
 
No regenerative braking on RC cars that I know of. It could be done , but that would require a lot more electronics and software for very little gain.
 
Actually, there is a small amount of regenerative braking going on in modern bldc escs but its more of esc design necessity in requiring the stored energy to be released to the battery than stored in the esc, than an intended purpose.... and the results probably create more of a problem in the form of small but high current voltage spikes and needing cap packs to smooth it rather than any real runtime advantage worth using as a marketing selling point.



Quote from Castle creations head engineer Patrick del Castillo..


"Regenerative braking does occur in all Castle ESCs. And yes, the actual braking action is achieved by just shorting the windings together through the FETs.

What happens is this -- the ESC shorts the windings of the motor, and forces the motor to start acting like a generator. Remember that a turning motor generates a specific voltage -- back EMF. This voltage is actually the voltage induced in the windings by the moving magnets.

Because the motor windings are shorted, the voltage drops to a very low level (usually less than .1V) and current rises very high, very quickly (often hundreds of amps.) As energy is generated (by the drag created by the voltage difference) current rises, and energy is circulated through the windings and the FETs - -- And a large magnetic field (with a LOT of energy) is stored in the winding.

After a short time, the FETs turn off -- and this is when the regeneration occurs. The current that was flowing through the windings suddenly has nowhere to go. Inductors (like a motor winding) abhor a change in current, so the stored energy (in the motor winding magnetic field) forces the voltage to rise until the winding current can continue to flow. The current flows from the battery negative, up through the body diodes of the low side FETs, through the motor winding, back through the body diodes of the high side FETs, and into the capacitors (and battery...)

This is similar to how a boost converter works:

http://en.wikipedia.org/wiki/Boost_converter

(stolen from the Wiki:) The key principle that drives the boost converter is the tendency of an inductor to resist changes in current. When being charged it acts as a load and absorbs energy (somewhat like a resistor), when being discharged, it acts as an energy source (somewhat like a battery). The voltage it produces during the discharge phase is related to the rate of change of current, and not to the original charging voltage, thus allowing different input and output voltages.

But instead of a supply, there is a magnet passing the coil that creates the current source.


Hope that clears it up for you all!"



Patrick del Castillo
President, Principle Engineer
Castle Creations
 
In the old slot-cars, we'd put a diode across the motor to short out the reverse EMF the motor produced when the controller was released. It was crude attempt at Dynamic Braking, but if you didn't do it right, it was like hitting a brick wall when you let off the controller.
 
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