Fuzzy Logic Based Three-Phase Z-Source AC/DC Converter for Improving the Output Voltage Transient Characteristics

This paper describes the improvement of the dynamic characteristics of the output voltage of the three-phase Z-source AC/DC converter (ZSC) using a fuzzy logic controller. The fuzzy controller uses a single input fuzzy theory, and the analysis structure of a simple fuzzy controller is derived through a triangular membership function. The fuzzy controller is designed by setting the membership function of the fuzzy rule. The operation mode of the ZSC with the output voltage fuzzy controller is analyzed, and the relationship between modulation index and buck-boost voltage gain are derived. Experiments were conducted to verify the validity of the proposed method for improving the transient characteristics of the output voltage. The experiment uses a DSP (TMS320F28335) controller to calculate the reference of the modulation index and generate PWM pulses. The performance of the previous PI controller and fuzzy controller for improving the transient characteristics of the output voltage control of the ZSC is compared. As a result, it can be observed that the ZSC is capable of the buck-boost of the output voltage, and the fuzzy controller has better performance than the previous PI controller through transient state analysis.