MATLAB Power Electronics: Inverter Repetitive Controller Design and Implementation

In power electronics systems, inverters serve as critical devices that convert DC power to AC power, widely used in renewable energy generation, motor drives, and other applications. Due to nonlinear loads and switching device characteristics, inverter outputs often exhibit periodic harmonic distortions. Repetitive Controller offers an effective solution to address such periodic disturbances. The fundamental principle of repetitive control relies on the internal model principle, utilizing error signals from previous cycles to correct current control outputs, thereby achieving progressive elimination of periodic disturbances. In MATLAB implementation, this can be accomplished through the following steps: Model Establishment: First, establish the mathematical model of the inverter, including main circuit topology (such as H-bridge, three-phase inverter) and PWM modulation strategies. In code implementation, use Simulink's Power Systems library to build circuit components and implement switching logic through Stateflow or MATLAB Function blocks. Repetitive Control Design: The core involves constructing the repetitive control internal model (such as the delay element in z-domain 1/(1-z^{-N}), where N represents the number of sampling points per fundamental cycle). Combine this with compensators (like low-pass filters) to enhance stability. Algorithm implementation typically requires designing the compensator transfer function using tf() or zpk() functions, and implementing the delay chain through discrete-time blocks with careful sample-time configuration. Simulation Verification: Build a closed-loop system in Simulink to compare the harmonic suppression performance (such as 3rd and 5th harmonics) between traditional PI control and repetitive control. Observe THD (Total Harmonic Distortion) improvement through FFT analysis using the Powergui tool or Signal Processing Toolbox functions. The simulation should include performance metrics calculation through custom MATLAB scripts analyzing output voltage spectra. Extension Considerations: The limitation of repetitive control lies in its relatively slow dynamic response. It often requires combination with other control strategies (such as proportional resonant control or model predictive control) to balance steady-state accuracy and transient performance. Code implementation for hybrid controllers involves designing multi-loop structures with proper weighting factors and transition logic between control modes.