Repetitive Control Strategies in Power Electronics Systems

Repetitive control is a specialised digital control paradigm designed to track or reject periodic signals by embedding an internal model of the disturbance into the control loop. In power electronics applications, where switching converters and inverters interact with grids and nonlinear loads, periodic disturbances manifest as harmonics that degrade power quality and system stability. By employing a delay line equal to the fundamental period and injecting corrective action at each cycle, repetitive controllers achieve high attenuation of harmonics with limited bandwidth, enhancing steady-state accuracy and dynamic response. Recent advances have extended the classic scheme through multi-rate sampling, fractional-order compensation and adaptive algorithms to address issues of inherent delay, robustness under weak-grid conditions and variable operating frequency. These developments have been applied to three-phase boost rectifiers, hybrid active filters, grid-connected photovoltaic and wind converters, electric drives and microgrids. The global significance lies in the capacity of repetitive control to improve power quality across renewable energy integration, industrial drive systems and distributed generation, while maintaining compact hardware implementation and low computational burden.

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Repetitive Control Strategies in Power Electronics Systems publication trend

The graph below shows the total number of articles in repetitive control strategies in power electronics systems across all publications each year (not limited to Nature Index journals).

Technical terms

Repetitive Controller: A digital control strategy that embeds a periodic internal model into the feedback loop to achieve zero steady-state error for signals and disturbances repeating every fundamental period.

Internal Model Principle: A theoretical concept stating that exact disturbance rejection or reference tracking is achieved only if the controller contains a model of the exogenous signal.

Harmonic Distortion: The presence of frequency components at integer multiples of a fundamental frequency, often caused by switching converters and non-linear loads, which degrade power quality.

Delay Line: A memory element in repetitive control that stores one period of the error signal, enabling corrections to be applied at the same phase in subsequent cycles.

Fractional-Order Controller: A controller employing non-integer order differentiation or integration, allowing more flexible phase compensation and robustness tuning than integer-order designs.

References

1. Performance Improvement of Three-Phase Boost Power Factor Correction Rectifier Through Combined Parameters Optimization of Proportional-Integral and Repetitive Controller. IEEE Access (2021).
2. A Repetitive Control Scheme Aimed at Compensating the 6k + 1 Harmonics for a Three-Phase Hybrid Active Filter. Energies (2016).
3. State of the Art of Repetitive Control in Power Electronics and Drive Applications. IEEE Open Journal of Industry Applications (2021).
4. Analysis and Design of PI Plus Repetitive Control for Grid-Side Converters of Direct-Drive Wind Power Systems Considering the Effect of Hardware Sampling Circuits. IEEE Access (2020).
5. A Fractional Phase Compensation Scheme of PRMRC for LCL Inverter Connected to Weak Grid. IEEE Access (2021).
6. Constant Delay-Line Repetitive Control Analysis for Variable Frequency Operation. IEEE Open Journal of Power Electronics (2022).