Autotuing a PID Controller for DC- DC Buck Converter by Improved Relay Feedback Test

Autotuing a PID Controller for DC- DC Buck Converter by Improved Relay Feedback Test

This paper proposes a method for the design and auto-tuning of a proportional integral derivative (PID) controller for a DC-DC buck converter. The main advantage of the proposed method is eliminating the need for an operator for retuning the controller when the model of the converter changes. The proposed method is based on the relay feedback test and consists two phases. First the DC-DC converter is identified by a single run of the relay feedback test. Through this test the transfer function of the converter is identified automatically by deriving its unknown parameters. Then, the provided model is used for auto-tuning of the PID parameters. The proposed PID controller is a two degree of freedom structures with the ability of providing good set-point and disturbance rejection responses simultaneously. The advantage of the proposed auto-tuning scheme is that it prevents performance degradation of the controller when the model of the converter changes due to the normal ageing or replacements of the elements for maintenance purposes. It helps to remodel the converter automatically and provides new PID parameters by tuning a single design parameter. Simulation studies on the DC-DC buck converter demonstrate the merits of the method.