basic regeneration in DC motor

[p]

control regeneration which takes place when a motor drives a
item, up and down a hill

http://www.roboteq.com/files/apnotes/AN70614-Understanding%20Regeneration.pdf

[Jagi]

Very interesting article. If I remember correctly, this technique has long been used by the railways.For instance when the electric train is going uphill, power is taken from the grid to run the motor. Conversely, when the train is going downhill, the motor works as a generator and puts the power back into the grid (effectively regeneration is taking place).