DSP-based implementation of a self-tuning fuzzy controller for three-level boost converter

The three-level boost converter (TLBC) has the advantages of lower inductor current ripple and lower switch withstanding voltage compared to the classical boost converter. However, disadvantages are the requirement of capacitor voltage sensing and separate control of the mid-point voltage by the controller. Therefore, this paper proposes a self-tuning fuzzy (STF) controller for the three-level boost converter. For each operating point, a proportional integral (PI) controller is designed. The nonlinear feature of the transfer function relating the output voltage to the duty cycle is handled by using a Takagi-Sugeno fuzzy approximator (TSFA). Based on the duty cycle, the STF-PI controller can derive a control signal for any operating point. Thus, a dc bus voltage control is achieved. An additional classical PI controller is used to control the mid-point voltage. The hardware circuit of the three-level boost converter is implemented to illustrate the efficiency of the proposed approach. The hardware is divided into two parts: the dSPACE DS1104-based control circuit and the power circuit prototype developed within our laboratory. This implementation is important, particularly for the objective of methodological transfer to the industrial environment. The results verify that the proposed control strategy can yield good performance via two scenarios: (i) step variations in the reference voltage and (ii) the reference voltage tracking.