Improved Inner-Loop Current Control Strategy Based on Deadbeat Current Prediction

In practical digital control systems for Modular Multilevel Matrix Converters (M3C), the inherent delays caused by signal sampling and algorithm execution lead to pulse output lags in conventional deadbeat control, subsequently resulting in current tracking deviations and grid-side current distortions. To address this issue, an improved deadbeat inner-loop control strategy based on current state prediction is proposed in this paper. First, the mathematical model of the M3C in the abc coordinate system is established, and a dual αβ0 coordinate transformation is introduced to decouple the system, achieving independent control of the input-side, output-side, and internal electrical quantities. Subsequently, to eliminate the control error caused by the one-step delay, an interpolation prediction method is employed to equivalently evaluate the voltage variation within an ultra-short control period. By predicting the current reference state at the k + 2 instant, the deadbeat control equation is modified to achieve delay compensation. Simulation and experimental results demonstrate that the proposed strategy effectively overcomes the delay limitations inherent in conventional digital control, significantly enhancing the dynamic current tracking accuracy and waveform quality of the M3C system.