Why is the inductor necessary?
The motor driver was designed to drive an inductive load (motors have a lot of inductance).
The input to the UBEC is a large capacitor. If you were to connect the input directly to the
motor driver output then it effectively shorts the UBEC input capacitor to the battery voltage
when the motor driver turns on.
Since the capacitor is initially discharged, a very large current flows in quickly and causes
the motor driver to trip the current limit and turn off to protect itself. Installing the inductor
between the motor driver and the UBEC adds the inductance back into the circuit and limits
the rate of current rise so that the input capacitor can be charged without tripping the
current limit.
How do inductors work?
An inductor obeys the following formula: V = L * di/dt
V Voltage across the inductor (volts)
L Value of inductance (Henrys)
di Change in current (amps)
dt Change in time (seconds)
If a positive voltage is applied across an inductor then the current flowing through it
increases over time. There is also energy stored in the inductor. If a negative voltage is
applied across the same inductor then the current flowing through the inductor decreases
over time and the energy stored in the inductor is transferred to the other circuitry. Inductors
are used in power supplies to control current and store energy.
Acknowledgments
Thanks to Instructables user ASCAS for the inspiration:
https://www.instructables.com/member/ASCAS/instructables/
So What’s Next?
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