A new digital resonant current controller for AC power converters based on the advanced Z-transform

Area of Science:

• Electrical Engineering
• Control Systems
• Power Electronics

Background:

• Pulse Width Modulation (PWM) in power converters introduces fractional time delays due to sampling and command updating.
• Accurate modeling of these delays is crucial for effective controller design.

Purpose of the Study:

• To develop a new digital resonant current controller for AC power converters (single-phase and three-phase).
• To precisely model and compensate for fractional time delays inherent in PWM-based voltage source inverters (VSIs).

Main Methods:

• Application of the advanced Z-transform to model AC controllers in VSIs with fractional time delays.
• Development of a modified resonant AC current controller using pole-placement parameter tuning for VSIs with RL load.
• Inclusion of fractional time delays in controller parameter derivation for minimal order resonant controller design.

Main Results:

• The proposed controller enables strict placement of all closed-loop control system poles.
• Simulations and experimental tests demonstrate improved dynamic performance and robustness.
• The novel solution outperforms conventional resonant current controllers.

Conclusions:

• The advanced Z-transform provides an effective tool for modeling fractional time delays in PWM-based power converters.
• The developed digital resonant current controller offers significant improvements in performance and robustness.
• This work contributes a precise and efficient control strategy for AC power converters.