Electronic – Is it possible to store flyback voltage in capacitors


I recently put together a circuit that I use to control an electrical motor. I use an Arduino's PWM through darlington-pair transistors to control the speed of the motor. During construction of this circuit I was advised to use a flyback-diode to block flyback voltage spikes created during the collapse of the motor's magnetic field to prevent a spike from damaging parts of the circuit.

Would it be possible to somehow harness this spike of voltage and store it in a capacitor? I am a hobbyist and know enough to put together some basic DC circuits, so I'm not super well versed in the capabilities of different components.

I figured if this was possible, I would somehow have that short burst of energy the capacitor(s?) store then applied to the motor when a sudden increase in RPMs is needed.

Any thoughts, ideas or reference material on how to store flyback voltage in a capacitor? Or am I just coming up with silly ideas I don't understand? 😉

Best Answer

Yes, it is possible to store that energy in a capacitor; after all, that's exactly what flyback-mode switching power converters do! So your idea isn't silly at that level.

However, using that energy to "boost" the motor drive is a little misguided, because the amount of energy you get from the flyback effect (which is due to "leakage" inductance in the motor) is orders of magnitude smaller than the amount of energy required to accelerate the rotor to any signficant degree. In other words, the effort required to implement this would not be rewarded with any practical benefit.

You may be thinking about regenerative braking systems. But such systems are not storing "flyback" energy — they're actually using the motor as a generator and storing the energy created by physically slowing down the motor (and the attached machine or vehicle, etc.).