Reverse Current Braking (Plugging)
Hard braking performed by applying reverse-polarity voltage to the motor terminals while it is still turning. The applied voltage and the back-EMF add up, so the current can rise even above the stall current. It stops very quickly but puts severe stress on the driver, the motor and the mechanics.
If you apply reverse voltage to a motor producing 20 V of back-EMF on a 24 V supply, the net voltage across the winding becomes 44 V. With a 0.4 ohm winding resistance that means an instantaneous 110 A. This value is far above the peak current window of most drivers.
That is why a waiting period is placed between direction change commands. The correct sequence is:
- The command is removed and the speed is ramped down.
- A short wait is applied so the motor can stop.
- The reverse direction command is given.
Direction interlock logic serves the same purpose: not accepting two direction commands at the same time prevents both shoot-through in the leg and this type of current surge. In systems using relay-based direction change the wait is even more critical; the contacts arc under load and their life shortens quickly.
Reverse current braking is not recommended in practice except with specially designed, current-limited drivers.
The context in which this term is used: DC Motor Driver Selection Guide