An Active Disturbance Rejection Control Approach to Fan Control in Servers

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As more and more massive data storage drives are used in super high density, the power used to cool the servers has become an increasingly large component of the total power consumption. Therefore, improving server cooling efficiency has become an essential requirement in data centers. However, because the thermal dynamics of the server system has characteristics such as nonlinearity, significant inter-loop coupling, and continuously fast changing/unknown workload disturbances, these pose huge challenges to control engineers and data center architect engineers. To address the above concerns, this paper presents an active disturbance rejection control (ADRC) based temperature control solution to realize the thermal regulation in a one-unit (1U) server to simultaneously improve fan power consumption efficiency and regulate the server components' temperature to avoid downgraded performance caused by overheating. In this study, an experimental testbed is built and modeled to capture the thermal dynamics of a typical 1U blade server where the thermal characteristics and existing solutions are both systematically evaluated. Performance of the design concept is proved both in simulation and hardware testbed. Experimental results show that, with the proposed control solution, temperature overshoot is greatly eliminated, temperatures are more tightly controlled and the server components' throttling rate are greatly decreased. Furthermore, the proposed method is shown to be able to save up to 22% energy when the temperature set-point is increased.