Comparative Study of Output-based and Error-based ADRC Schemes in Application to Buck Converter-fed DC Motor System

The majority of currently used active disturbance rejection control (ADRC) techniques is expressed in 2DOF output-based form. For relatively high-order systems, this imposes limitations on the conventional ADRC, like the necessity of having certain higher-order terms available for controller synthesis and the lack of direct compatibility with standard industrial control software, which favors simplicity and intuitiveness of feedback error-based designs. That is why, in this work, a comparative study is conducted between the conventional 2DOF output-based ADRC and the recently proposed 1DOF error-based formulation of ADRC. Through a set of hardware experiments on a converter-fed motor testbed, the error-based ADRC is shown to retain the robustness of the 2DOF design, while having a simplified controller, being free from assumptions on availability of particular signals, and with the entire observer-based control structure being represented in a practically appealing, compact form. The obtained results also show that a major design simplification can be achieved with error-based ADRC without sacrificing the performance of the original output-based form.