Improved Fractional-Order Model-Free Adaptive Control of Z-Source Inverters

Aiming at the tracking control of the Z-source inverter (ZSI), this paper takes into account the dependence of existing control methods on system dynamic models and the low tracking accuracy of conventional model-based control. To address these issues, an improved fractional-order model-free adaptive control (IFOMFAC) strategy is proposed. First, the dynamic process of the ZSI is analyzed to identify the control inputs and objectives of the control system. Then, a PID-IFOMFAC algorithm is designed, based on the fractional-order dynamic linearization data model of the system, to achieve voltage stabilization control with the ZSI. The method combines fractional-order dynamic linearization with a PID-type structure, enhancing the inverter’s response speed and tracking accuracy under input voltage disturbances and load variations. Using a data-driven method, IFOMFAC reduces the reliance of traditional control strategies on precise system models. It only uses the input–output data from the ZSI during operation for control input. This approach achieves effective dynamic control and ensures good adaptability. Numerical simulations show that the proposed method achieves better performance than conventional FOMFAC and PI control in terms of capacitor voltage dynamic response, shoot-through duty cycle regulation, and system stability, especially under abrupt input voltage changes, demonstrating stronger dynamic adaptation and lower overshoot.