CogniPower Technology Applied to Computers and File Servers
Conventional Switched Mode Power Converters (SMPCs) are based on Pulse Width Modulation
(PWM). They are notoriously difficult to control under changing operational conditions because
the output filter causes phase shift which destabilizes the control loop. To address these
deficiencies, CogniPower's technology uses prediction to remove the problematic filter pole
from the control loop. Basing switching decisions on the anticipated future, instead of on the
past, removes the crucial delay and allows CogniPower converters to be both instantly
responsive and intrinsically stable.
Sometimes, under changing conditions, the inductor will contain much more energy than the
load requires. Conventional SMPCs exhibit overshoot in these circumstances. Because of
CogniPower's agile response, we can return excess energy to the power source instead of
oversupplying the load. The resulting bidirectionality can also be useful for improving regulation
and efficiency when driving reactive loads. Bidirectionality allows the recovery of energy held in
both filter capacitance and distributed load capacitance whenever the output voltage of a power
converter is reduced. In some circumstances, this feature can save surprising amounts of energy.
As industry power supply voltages drop, a larger percentage of the total power required goes to
leakage, present at all times, instead of clocking. Reducing the clock rate is no longer a sufficient
means to reduce power. The power supply voltage needs to be temporarily reduced or removed
to save the most energy. Using conventional power converters, the inactive period must be long
in order to achieve net power savings. Since it is unusual to have advance knowledge of a long
period of inactivity, computers and computer circuitry are often left ON all the time, even though
they are only actually performing useful tasks for a small percentage of the time. With
CogniPower converters, the time required to stabilize after turn-on is a few microseconds, not
hundreds of microseconds, so there is no large latency cost for the saved energy. Energy
recovery through bidirectionality allows further power savings, even if the periods when the
output is reduced are very brief. Volatile memory and circuitry needing an extended initialization
period can be powered down to a minimum voltage for state retention when not in use.
Server farms often operate at under 15% utilization rates. With CogniPower technology, a large
portion of that unproductive energy can be recovered without a noticeable performance penalty.
When applied to the annual $10 billion data center global power bill, the operational savings can