Phase Margin Oriented Design and Analysis of UDE-Based Controllers under Actuator Constraints

A loop compensator design for power electronic converters is typically phase margin oriented due to widely varying operation point and actuator delay. The former challenge has been successfully treated recently by uncertainty and disturbance estimator (UDE) based controllers owing to their two-degrees-of-freedom nature, allowing nearly independent tuning of tracking and disturbance rejection performance. On the other hand, actuator-imposed constraints have not been discussed in UDE-related literature by far. It is well known that in order to fully utilize the available control bandwidth, actuator dynamics must be taken into consideration. Consequently, this paper reveals guidelines for UDE-based controllers design considering typical actuator dynamics under phase margin constraint, set a priori. The proposed method is then applied to power control of a multimode bidirectional noninverting buck-boost converter, connecting two dc microgrids. Simulations and experimental results are given to support the revealed findings.