Disturbance Rejection Control Method of Double-Switch Buck-Boost Converter Using Combined Control Strategy

Since it has strong ability to realize a conversion to adapt to a wide variation of input voltage, the double-switch buck-boost (DSBB) converter is usually employed as a front-end converter in two-stage power converter systems, where conversion efficiency is always highly valued. Because there is only one switch in the Pulse Width Modulation (PWM) state in the buck or boost work mode, the combined control scheme was investigated for its advantages in inductor average current and conversion efficiency. However, in this method, the operation mode should be determined by additional logic according to the change of input voltage. Moreover, different control systems should be designed for different operation modes to guarantee dynamic control performance and smooth transition between different work modes. To address these issues, the linear active disturbance rejection control (LADRC) method is introduced to develop an inner current control loop in this paper. In this method, the model deviations in different work modes are considered as a generalized disturbance, and a unified current control plant can be derived for current controller design. Furthermore, the duty cycle limitations in practice are considered, an additional mode for transitional operation is produced, and the corresponding control scheme is also developed. Simulation and experimental test results are provided to validate the correctness and effectiveness of the proposed control scheme.