  We propose an arbitrary driven spin as the working fluid of a quantum Otto
cycle in the presence of internal friction. The role of total allocated time to
the adiabatic branches of the cycle, generated by different control field
profiles, on the extractable work and the thermal efficiency are analyzed in
detail. The internal friction is characterized by the excess entropy production
and quantitatively determined by studying the closeness of an actual unitary
process to an infinitely long one via quantum relative entropy. It is found
that the non-ideal, finite-time adiabatic transformations negatively effect the
work output and the thermal efficiency of the quantum heat engine. The
non-monotone dependence of the work output, thermal efficiency, entropy
production and the internal friction on the total adiabatic time are
elucidated. It is also found that almost frictionless adiabatic transformations
with small entropy production can be obtained in a short adiabatic time.
