High quality DC current is smooth and constant with very low ripple or noise. The "quality" of the DC current is important.

Ripples of power supply reduces TEC performance in operation.

In a case of sinusoidal ripples the effect is the following concerning maximal TEC cooling capability DTmax:

where

DTmax - maximal specified delta T of a TEC at "smooth" DC current Im;

DT'max - maximal DT at rippled DC current with average Im;

Im - average current;

N - ripple amplitude in % to average current Im.

For rectangular ripples the ratio includes also dependence on ripple duty cycle:

where

Q- duty cycle ( Q=t_ON / t);

t - period of cycling;

t_ON - ON time.

Sinusoidal ripples

Rectangular  ripples