Fast average current mode control of dual-active-bridge DC-DC converter using cycle-by-cycle sensing and self-calibrated digital feedforward

摘要

The Dual-Active-Bridge (DAB) dc-dc converter is commonly used in isolated and bi-directional applications. The use of high-speed Analog to Digital Converters (ADCs) in high-bandwidth current mode controllers is costly for on-chip implementation. Furthermore, inductor current sensing is susceptible to interference from switching noise and can cause false over-current protection triggers. The DAB converter also has a slow response time using conventional linear PI compensators. Two solutions are demonstrated to tackle these challenges: 1) a cycle-by-cycle analog integrator with synchronous reset for input current averaging to mitigate noise susceptibility and eliminate the need for oversampling ADCs, and a 2) feedforward based controller with self-calibration to drastically decrease the settling time of the DAB converter for large step transients. The proposed system is implemented on a 500W, 95.9% efficient DAB converter prototype. The results show a 600× improvement in response time compared with the traditional PI based average current mode control.