Fan speed control

An apparatus comprising:

• an interface configured to receive speed data and transmit a control signal;
• a memory configured to store a threshold value and a target value;
• and
• a processor configured to calculate an input comprising a difference value between the speed data and the threshold value and generate the control signal based on the input difference value and the target value,
• wherein when the input difference value is greater than the threshold value, the control signal includes a constant proportion applied to the input difference value and when the input difference value is less than the threshold value, the control signal includes a varying proportion applied to the input difference value, the varying proportion incrementing according to a periodic oscillating function from a lower bound greater than the constant proportion towards an upper bound and then returning towards the lower bound, based on a predetermined time period or a predetermined number of cycles of the control signal.

One or more non-transitory tangible media having logic encoded thereon, the logic executable by a processor and operable to:

• calculate an input comprising an error value as a difference between fan speed data and a target speed;
• compare the input error value to an error threshold;
• and
• control fan speed by applying a constant proportion to the input error value where the input error value is greater than the error threshold and by applying a dynamic proportion to the input error value where the input error value is less than the error threshold, and where the dynamic proportion increments according to a periodic stair-step function from a lower bound on the dynamic proportion towards an upper bound on the dynamic proportion, and returns towards the lower bound that comprises a value greater than the constant proportion.