Enhanced Observer with Series-Correction for Active Disturbance Rejection Control in DAB Converters

The power supply for pulsed power loads demands exceptional dynamic performance, requiring fast and precise regulation of the output voltage. Active disturbance rejection control (ADRC) with a linear extended state observer (LESO) stands out among control strategies due to its model independence and simplified parameter design. A crucial element of ADRC is the LESO, which effectively tracks total disturbances with limited system information. However, the LESO’s tracking speed is constrained by the crossover frequency, and it exhibits significant steady-state errors when disturbances take the form of ramp, acceleration, or sinusoidal function. To enhance the speed and accuracy of disturbance tracking, a series-correction-based LESO incorporating an incomplete differential proportional-integral-derivative (PID) controller is proposed for an ADRC-controlled dual active bridge (DAB) converter. The proposed optimized LESO offers a faster dynamic response and smaller steady-state errors compared to traditional LESO. Additionally, the article addresses system stability and parameter optimization for the improved converter. The effectiveness of the optimized LESO design is validated using a 500W DAB experimental prototype, demonstrating excellent dynamic response and low susceptibility to parameter variations.