Abstract: In one implementation, an environmental controller operates a cooling system in an electronic device. The environmental controller includes a closed loop control system for operating a cooling fan at a target speed. The environmental controller may select the target speed based on one or more temperature sensors. The environmental controller may select the target speed based on the speeds of additional fans or the fans may be controlled in unison. The closed loop control system includes a proportional weight. When a measured cooling fan speed deviates from the target speed by more than a threshold error value, the proportional weight is constant. As the measured cooling fan speed approaches the target speed, and the threshold error value is crossed, the proportional weight is variable. The variance may be a function of time such as a periodic stair step function.

Abstract: In one implementation, an environmental controller operates a cooling system in an electronic device. The environmental controller includes a closed loop control system for operating a cooling fan at a target speed. The environmental controller may select the target speed based on one or more temperature sensors. The environmental controller may select the target speed based on the speeds of additional fans or the fans may be controlled in unison. The closed loop control system includes a proportional weight. When a measured cooling fan speed deviates from the target speed by more than a threshold error value, the proportional weight is constant. As the measured cooling fan speed approaches the target speed, and the threshold error value is crossed, the proportional weight is variable. The variance may be a function of time such as a periodic stair step function.